Bridgestone Motorcycle Parts Discussion Board

Bridgestone Tech Talk => 175 & 200 Talk => Topic started by: bsracer on December 07, 2016, 11:29:51 AM

Title: 175/200 Crankshaft Project
Post by: bsracer on December 07, 2016, 11:29:51 AM
I said I'd start a thread on the 175/200 crankshaft rebuild upgrade for my SR175 racer. The cranks are a bit of a weak point when you push them beyond their standard designs. The first crank I broke was in 2004 at Sandia NM which is basically outside of Albuquerque. I think I've broken 3 or 4 over the years. That first one was a standard SR175 crank. I had a spare so after I determined it was broken I switched it out at the track. Unfortunately after I got it together for the next days races, I got a little over enthusiastic trying to make up for lost time and crashed it. Needless to say that crank got ruined because I cleaned it as best as I could without taking the motor apart using all the carb and brake cleaner. Miracle it ran but running dirt thru the motor doesn't due wonders for anything. Even the Nikasil plating on the cylinders looked beat.

I don't recall when the second crank broke but by this time I had spoken to Karl Swartout (Old Swartout) and he had confirmed his broken cranks. He had some center pins made that were stepped on both sides. I sent him a couple of cranks (the broken SR175 and another I think NOS crank that I broke) and he had the broken portion turned out and bored to accept the new pin. The Bridgestone 175/200 center crank webs have a hole in one side and the center pin is part of the other half. I put the SR175 crank back together and put the other back into my racer. I eventually broke the pin in this one. I was going to use the SR175 with the new pin but the crank wasn't pressed together properly and it was too tight (or too wide?). I had purchased another NOS crank from a friend. I think I used this one as a last resort a few seasons ago only to ruin it the first season I ran aluminum rotary valve covers. The covers weren't coated and the disc rubbed enough material off to destroy all the bearings (still ran though!).

The pics are of the SR175 crank broken in the pits. The second is after I crashed the next day. The third is the pin that broke that Old Swartout had made. I'll update this a little later with where I'm at now and what I plan as a fix.

paul
Title: Re: 175/200 Crankshaft Project
Post by: slawsonb on December 07, 2016, 01:57:04 PM
Yeah, that's a bummer mouthful of dirt! No wonder it gave up the ghost.
...bert
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 08, 2016, 12:36:16 AM
Hey Bert,

It ran good enough too finish a couple of races! I was trying to compare it to a pretty fast CT1 Yamaha and lost where I was on the track. Got lucky when I hit some soft dirt off the track! My wife was timing me and saw a plume of dust in the distance. She got nervous when I didn't come around where she was timing.

paul
Title: Re: 175/200 Crankshaft Project
Post by: dcr on December 08, 2016, 09:04:46 AM
Paul,

What are your options for addressing this weak spot on the 175 cranks? I know very little about modifications for racing applications but am very curious on what could be done to modify a stock crank.

Is this a result of running at a higher rpm than the factory intended or is it the constant up and down torque demands of racing around a track?

Dan
Title: Re: 175/200 Crankshaft Project
Post by: slawsonb on December 08, 2016, 10:38:58 AM
Hey Paul. So I guess it didn't "inhale".  ;D
Always good to send up a distress signal (cloud of dust) when the guy with the bucket finds the fan!
Enjoying this thread (maybe too much), so I'll let you get back to the tech part. Thanks for posting.
...bert
Title: Re: 175/200 Crankshaft Project
Post by: OldSwartout on December 08, 2016, 10:56:05 AM
Is this a result of running at a higher rpm than the factory intended or is it the constant up and down torque demands of racing around a track?

Dan

The failures are always rotating bending, not torsional, starting at the radius of the step in the center shaft.  I suspect the crankshafts go into a sine wave resonance mode when they get above 10,000 RPM, flexing the center shaft (they seldom break if you keep them below 10,000 RPM).  Of course, the higher torque/horsepower Paul is getting just adds to the stress.

I think Paul is working to add two center bearings to better support and stiffen the center, which should push any resonance to a higher RPM, plus he's been working on using a straight center shaft with no step, which would eliminate the stress riser where the break starts.  He'll have more details as he works them out.
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 08, 2016, 10:59:37 AM
 
Hey Paul. So I guess it didn't "inhale".  ;D
Always good to send up a distress signal (cloud of dust) when the guy with the bucket finds the fan!
Enjoying this thread (maybe too much), so I'll let you get back to the tech part. Thanks for posting.
...bert


Oh it did! Postmortem shot.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 08, 2016, 11:42:41 AM
Paul,

What are your options for addressing this weak spot on the 175 cranks? I know very little about modifications for racing applications but am very curious on what could be done to modify a stock crank.

Is this a result of running at a higher rpm than the factory intended or is it the constant up and down torque demands of racing around a track?

Dan

Hi Dan,

I have a couple of options. Not quite sure if they will work but at least have to give them a try. The first is to remove the center pin that connects the two center webs and where the center bearing and seal ride. The original setup has that shaft step from 20mm to 16mm where they press together. I plan on removing the shaft and boring both center holes to 20mm. I've found some hardened dowels that are 20 x80mm. This will replace the original shaft. I'll detail more in posts to come.


First pic is of crank showing where they typically break. Second is of the crank I already had this done to but using the pin Old Swartout had made. That pin ultimately broke in the same fashion.

Karl is the engineer. I can't say exactly what happens. The bikes were not designed to rev much past 9-9500 rpm in my opinion. For a street bike that's pretty good. I can only attribute the breakage to anytime the bike is not in a normal type of tune. It seems that every time either the ignition or carburation causes the bike to run poorly I've broken a crank when pushed. I assume the "lugging" of one cylinder over the other causes stress at the weak point or in this case the step.  Just like snapping your fingers. That quick and simple. Funny thing is the bike will remain running on one cylinder. I think I did break one crank when I was just messing with the bike on the stand. I didn't really think it rev'd to 14K. I was testing different hand held tachs against the Scitsu tach I run. I held it open a couple times too many and snap! This is the only time the bike seemed "in tune".

The 175/200's have a terrible transmission for racing as far as ratio goes. Vince might not have the problems as he has a transmission that's more "geared" for racing.

My current setup has peaky pipes. Doesn't do much under 8K. Pulls like a freight train from 10-12k and will rev to almost 13.5-14K. not too ideal for crank life.

paul

Title: Re: 175/200 Crankshaft Project
Post by: slawsonb on December 08, 2016, 12:06:11 PM
Any step in the center pin will cause a stress riser/concentration and will lead to this kind of a failure when pushed beyond design limits. The idea of using a straight 20mm pin will eliminate that stress focus, but as you know that will just expose the next weak link. Hopefully it will occur above the desired RPM range.
...bert
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 08, 2016, 12:19:56 PM
I spent last Saturday going thru some of the various cranks that I have already pressed apart for some reason or another. In attempting to remedy the fact that I don't have any suitable cranks that are ready to go, there are many operations involved. The stock connecting rods are tough as nails but have a "heavy" big end bearing. Not to mention the pin size is 19mm, which is only common with some Suzuki's and I think a rare Kawasaki. My first crank to build should be considered the "simplest". I plan to use a straight 20mm center pin. I plan on using the stock main bearings. I won't have to modify any cases and can use the ones I already run. since the rods are scarce, I plan on using Yamaha KT100/RD125 rods. Almost the exact dimensions as the Bridgetsone rods except they have a 20mm big end pin. So the holes for the connecting rods will be opened to 20mm along with the center holes for a straight pin. The Bridgestone rods do not use shims or washers on the big end. The Yamaha rods do. Some of the cranks that either broke or had some damage from the rod edge no longer have a nice smooth surface for the rod. Vince removes 1mm from each crank cheek because the rod he uses is 2mm wider than the Bridgestone rod. But it has a 19mm pin so that much easier to fit. I want to try using the washers so I will remove 1mm for each web to account for the washer and bore the holes to 20mm. I have found some "light" big end bearings that take loose rollers. The cages are silver coated and I think there are 14 rollers as opposed to 11 on the stock bearing. The rollers are also wider than the stock ones. This should hopefully "fix" the galling that happens from the portion of the cage that drags on the inner face of the rod after much abuse.

More to come. Pics of various crank pieces that I marked so I can relate to the machinist what operations will be performed. Bottom pic is of a couple Bridgestone rods.

paul
Title: Re: 175/200 Crankshaft Project
Post by: dcr on December 09, 2016, 11:25:17 AM
Karl - awesome explanation and I think I understand but I have to admit, I think a lot of that went over my head. Not your fault.

Paul, please keep the updates coming. This fascinates me to no end. Although I am not a racer and most of this is territory I will never venture into, I really am interested in your progress and solutions.

Dan
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 09, 2016, 12:03:15 PM
Top pic is some samples of the Yamaha KT100 rods. These are available in a light, medium and heavy. From my understanding the rods can stretch under extreme conditions. Some karts are capable of rev'n to almost 20K. I have a set of the light rods that I will use first along with the bearings and washers (actually for a Honda CR85). If you compare a stock Bridgestone rod to one of the heavy rods, they are an almost exact match. Makes me think TKR which I believe made the original BS rods and is now TKRJ make the Yamaha rods.

The second pic is of two center webs. I had the rusty one rough bored (big Drill bit!) to get an idea of how close the pins will end up. The hole is just shy of 20mm. I didn't open the connecting rod hole at the time though. Not much difference between 19 and 20mm.

The third pic is of the pins I plan to try. They are industrial metric dowel pins. I was just going to use them to mock up the crank prior to having some special pins made. When I showed them to my machinist, he suggested to give them a try. He said he can shorten them and put centers in the ends for truing after they're pressed together. We'll see. Nice thing is they are cheap compared to having special pins made.

I was trying to find thinner washers/shims for the big end. Some Vespa scooters use a 20mm pin and have washers that are 0.5mm think. stock ones are plain copper but there are some for racing applications that are silver coated. Can't seem to find them separately. The less I have to take off the inner cheeks would be nice but I will probably just use the 1.0mm washers for now.

I have to sit down and write up all the operations that I need the machinist to do to each crank. I have the taper on the outside crank webs (the part you see thru the port opening) cut so as to have a smoother flow with no abrupt shoulder. When you open the port in the case, there is then a shoulder at the bottom edge. Most tuning books would have you build up the bottom wall of the cases with an epoxy but I would not want it to ever come loose! I've had a couple of cranks cut this way and I need a few more cut.

I stamped every crank with a set of numbers so I can write down what operations need to be done to each crank ie cut outer web P1 taper, bore P1 outer connecting rod hole to 20mm, bore P1 inner center holes to 20mm, remove 1mm material from P1 inner connecting rod face etc. I plan just starting with two and see how it goes.

I will probably have a fixture made to press the center halves together so they are 180 deg apart. I have seen some examples (lots for singles not many for twins) online but can't remember where I saw them. Punch press die sets are easy to find and modify. These are used for making all kinds of parts. They have big thick top and bottom plates and have ground guide pins to keep them aligned. I have a friend who has a Suzuki X-6 and the inner webs are slightly larger than the Bridgestones. My idea was to bore the top and bottoms of the press plates to accept a round die, say 5-6in in diameter. I would have the die machined to fit the Bridgestone inner web. Another die could be made to fit the Suzuki web. This way the dies could be interchanged to the same press plate. Still have a few things to figure out on that but just have to sit down and do that too.

paul
Title: Re: 175/200 Crankshaft Project
Post by: vinny g on December 09, 2016, 02:36:36 PM
Good work,Paul,you're certainly getting there with these cranks.I've just rebuilt the current crankshaft and this one runs Yamaha rods.I use the Samarin silver plated cages..with Samarin pins and silver plated thrust washers with the crank cheeks machined to take them as you describe.The rods are stock generic Yamaha 125/200.
We went the other way with crankpins...we run the 20mm pin with the ends (Fitting into crank cheeks) ground down to 19mm.I think the KT100 bearing is a nice option..along with the thrust washers.

This crank failed at Anglesea in June though to be fair i was destruction testing it...get this:It had done six seasons of racing without fault.This ran a 20mm straight pin between cranks and was also running a ball bearing center main..as opposed to the standard roller.Does the ball allow a little more whip that helps with the snapping issue? Not sure.One thing that is for sure..i can't see you snapping a straight pin..the shoulder is,in my view,the killer.

Ever thought,while it's apart,of indexing the pin and crank wheels at 180 degrees with keyways? Quite a simple task for a decent machinist and guarantees future alignment.Maybe a woodruff keyway cut at the 3 o'clock and 9 o'clock positions in the wheels with the crankpins at tdc ..or even both at the 6 o'clock position?

   Karl? Your thoughts.

    Vince
Title: Re: 175/200 Crankshaft Project
Post by: OldSwartout on December 09, 2016, 04:58:06 PM
I think both you and Paul have good solutions.  The straight center pin certainly will help and I think Paul's trial of a stock off-the-shelf pin will probably be sufficient.  Commercial dowels are pretty tough material, and the original BS crank is relatively soft material, which contributes to the failures.  It sounds as if you've proven a straight pin is the answer.

I think it's great that you guys have found rods and bearings that can be used, especially the silver plated bearings.  In my opinion, that's a weak link in the connecting rod area as the wear of the rod bore from the cage OD causes more roller load transferred to the cage bars, which will eventually cause the cage to break up.  I saw some of that in my previous life as a transmission engineer dealing with planetary gearsets.  Silver plating is a significant improvement, although the cage design details are important too.
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 12, 2016, 11:52:24 AM
Hey Vince,

I have thought about using stepped pins for the connecting rod pins (well at the insistence of the guy who usually builds my cranks). He thinks it would be easier to press together if the pins were stepped so they won't "push thru". I'm not convinced but will try a couple cranks with 20mm holes. I've thought  about indexing the center pins like a Kawasaki triple with key ways also.

I think I may have exceeded the max on photos. I can't seem to post anymore. I'll try and figure it out.

paul
Title: Re: 175/200 Crankshaft Project
Post by: OldSwartout on December 13, 2016, 08:38:31 AM
Hey Vince,

I have thought about using stepped pins for the connecting rod pins (well at the insistence of the guy who usually builds my cranks). He thinks it would be easier to press together if the pins were stepped so they won't "push thru". I'm not convinced but will try a couple cranks with 20mm holes. I've thought  about indexing the center pins like a Kawasaki triple with key ways also.

I think I may have exceeded the max on photos. I can't seem to post anymore. I'll try and figure it out.

paul
The correct space between crankshaft flywheels on each side is 7.10 mm (.279 in.). I was lucky enough  to find a couple of parallel plates that exact thickness that I use to space the the crankshaft when pressing them together, but it wouldn't be any problem to grind off a couple 8 mm nuts to the correct thickness to use as stops between the flywheels. 

I've only ever had one connecting rod pin push thru, now I just put a very thin washer or shim under the end against the support plate and that solves it. Actually, the inner end needs to be nearly flush or the outer end will protrude.

Putting a keyway in the center pin will cause a stress concentration, just what you are trying to avoid.
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 19, 2016, 11:34:15 AM
This is a tool that I was making to check shift forks for straightness. It gave me part of the idea for making dies that could be interchanged in a jig to press to centers together on different cranks. I dropped two cranks off last week at the machinists. Hopefully he can make sense of all the operations that need to be done.
-Center holes opened to 20mm (19.96/7mm) on both inner webs (remove broken center pin).
-All connecting rod holes opened to 20mm (19.96/7mm)
-Remove 1mm (approx) from each web for thrust washer
-Bring angle cut on the outer webs deeper to connecting rod hole for smoother flow from intake port
-Shorten new center pin to -2mm of orig length of standard crank center pin. Allows for thrust washers
-Add centers to new pin to allow for checking true

Next will be onto the press tool and maybe the new ignition.

I ordered more of the big end bearings. One other option for rods is to have some stock rods resized for the same big end bearing. I spoke with a different machinist and he said he could probably do it. I have a pile of rods that got galled on the big end. It would be nice to recycle some.

paul

Title: Re: 175/200 Crankshaft Project
Post by: bsracer on December 31, 2016, 10:52:06 PM
I picked up the first cranks parts from the machinist today. They look pretty good. He was able to shorten the new center pins and add locating centers. He opened the connecting rod holes to 20mm. He removed the broken center pin and bored both center webs to 20mm. He removed the material for the shims and cut the outside taper. The only thing I forgot to specify was to put a chamfer on some of the holes he opened up. Some machinists need it all spelled out and some either question or know what to do. This is the first thing I've had this machinist do. He's a retired aero space guy and probably doesn't just do it unless it's spelled out. Shouldn't be too much of a problem. I'll get some pics when it clears up (yes, it does rain in So Cal now and then). I'll start working on the assembly jig soon!

paul

Happy New Year!
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 02, 2017, 11:58:46 AM
The first two sets of cranks for rebuild. I need to get started on the assembly jig.

paul

p.s. Vince, the machinist said the pins are hard!
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 02, 2017, 12:08:15 PM
The first pic is of the new pin and washer that I plan on using. The washer is for a Honda CR80 or 85. The pin fits a Suzuki T20 or TC250. The second pic is of the fixture the machinist made to hold the webs. He made it so any of the webs can be held to bore the holes for the connecting rod or new center hole. The material can also be removed for the washer or shim. Pretty slick.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 02, 2017, 09:42:25 PM
I had the day off and had some time to clean up the crank pieces. Lucky for me Rob North has his shop about 10 min from my house. Great thing is I'm friends with him. (If you don't know who he is you can probably google him. He built the frames for the BSA/Triumph racers back in the 70's for the factory that won Daytona and a bunch of other races. He also did a lot of work on Don/Rick Vesco's various stream liners over the years including the Turbinator which still holds the record at 458mph of something like that).  I cleaned up all the sharp edges with some handy de-burring tools. I polished the outside edges where the fuel comes in thru the inlet. We talked about the press tool for the cranks. A bit of back and forth about my idea of using a punch press die set for the jig. I showed him some of the pieces and he wasn't seeing it. Great thing about Rob is he can usually picture something in his head. When I explained that I wanted two identical pieces similar to what I was showing him, he could see it. After we talked a bit more I said that I was still looking for a die set that would be big enough to hold the dies I want made. He then says to check under a shelf (bottom shelf) where he keeps a bunch of different press tools. There on the bottom was an old punch press die set from Rhor Industries used to make some kind of airplane part. Probably been sitting there 15-20 years or more. I removed the dies and cleaned it up a little bit. I'll take it to my work tomorrow and clean it up some more. Funny thing is scrap guys come to his shop all the time and haul his scrap metal away. He said if he would have remembered it was there when the came in last week he would have had them haul it away. 2017 is looking up already! I'll get some pics in the next few days.

paul
Title: Re: 175/200 Crankshaft Project
Post by: OldSwartout on January 03, 2017, 08:48:09 AM
Parts are looking good!
Title: Re: 175/200 Crankshaft Project
Post by: slawsonb on January 03, 2017, 10:27:51 AM
Sounds like serendipity is alive and well in SOCAL.
...bert
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 06, 2017, 12:38:35 AM
Not quite yet. The die set cleaned up pretty well. The height might not be enough though. I had pressed the outer webs off a crank so I can use it to set up the press jig. This is what I should end up with when pressing the parts together. Picked up some 5x2 steel rounds for the upper and lower dies today. I'll meet with Rob this weekend and see. I still might be able to get longer guide pins.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 07, 2017, 02:39:28 PM
I dropped of a couple sets of BS stock 175/200 rods at a local auto machine shop to have the big end re-sized to a bigger bearing. These rods had gotten galled from the bearing cage. They will go from 25mm ID to 26mm ID. Should be enough to clean them up and save them from the scrap pile. Pics below are of the punch press die set that I'm hoping to use along with the 5x2 rounds that will hold the crank webs.

paul
Title: Re: 175/200 Crankshaft Project
Post by: OldSwartout on January 07, 2017, 07:10:11 PM
Now that's an impressive find.  You could use that for all sorts of things.  What does it weigh?
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 07, 2017, 08:52:49 PM
The press tool weighs around 65lbs and the rounds about 25lbs. looks like it was already used for a million different things. Even has some pieces welded on the base. Unbelievable how smooth it moves up and down on the posts though.

paul
Title: Re: 175/200 Crankshaft Project
Post by: BRT-GTR on January 08, 2017, 08:29:04 AM
             Seeing that press tool brings back memories. Spent two years as an apprentice toolmaker as my very first proper job. Had to wash 'em off with paraffin, take 'em apart and have all the punches and dies resharpened.   Every 3 months they would ship in the tool that punched the holes in 'Dexion' angle strip. Like the one in the photos but 20ft long.!! I set the record by turning it round in 3 days. Guy before me used to take a week and a half. I was quietly told to 'take my time', we learn, happy days.  :D
      Good job, Paul, we're all interested in following your progress.                                     Brian.
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on January 21, 2017, 12:00:11 PM
I had to retrieve the BS rods from the machine shop. They are too small for them to fit their boring bar and they tried honing them for a half an hour without much progress. Too hard for the stones to open them from 25mm to 26mm. I will have another machinist bore them out on the mill to within 0.003" (of 26mm) then have the first machine shop finish hone them. Just a minor delay.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on February 19, 2017, 08:52:39 PM
I had the rods bored out to within a few thou of the final size. I took them back to the engine machine shop and had them honed to size. I now have BS rods that take a more modern big end pin and bearing with more rollers. I also had the machine work started on the crank tool. The machinist roughed out the pieces so far. I pressed in the new pins for the center and connecting rods and dropped them off for some final fitment with the machinist today. When I get everything back next week I'll snap some pics and hopefully start assembling a crank or two!

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on March 10, 2017, 03:05:48 AM
I got the crank tool back today. Still needs a couple of tweaks but I hope to put a crank or two together next weekend.


paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on March 10, 2017, 03:11:25 AM
More pics
Title: Re: 175/200 Crankshaft Project
Post by: dcr on March 10, 2017, 11:08:48 AM
At what point will you be in the 175/200 crank assembly business??

Looks really good and simple as far as an assembly solution.

Dan
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on March 15, 2017, 10:01:57 AM
At what point will you be in the 175/200 crank assembly business??

Looks really good and simple as far as an assembly solution.

Dan

I'm not really sure. This setup is for the webs that are modified for 20mm connecting rod pins and new 20mm center pin. I think it can be used with stock crank webs. I still have to make a small lever/arm to hold the web in the upper half. I also have to have some stops made so the cranks will be pressed to the proper width. I was going to use some old connecting rod pins since I have plenty of them. This only presses the center halves together very close to 180 deg apart. They will still be checked for true then the outer webs still have to be put on one at a time and trued respectively. One problem with rebuilding the stock cranks is lack of some of the parts. The center seals and the collar they ride on are not available. The connecting rods are getting pretty thin on NOS. There are always options down the road like using the Yamaha connecting rods like I'm going to use and having the 20mm pins ground to 19mm on the ends so the crank webs do not have to be modified. There is probably an alternative seal out there to use.

I'm just trying to get some cranks to hold up under race conditions. I've got $1300 in just the set up of the tool and machine work on the webs. Still have to factor in the cost of new connecting rods, pins and bearings. I also had some stock rods machined (around $325) to fit the 20mm big end bearing. these might also work for a stock rebuild as I mentioned above. The pins would be ground to 19mm on the ends and the whole thing would remain pretty stock. Before I could ever provide a rebuild I'd have to test them out (hopefully on the race track) to ensure they are going to hold up for street use.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on March 23, 2017, 11:39:37 AM
I got the crank tool set up. I made some stops out of old 175 connecting rod pins. I have plenty of them. These ensure that the center webs are the correct distance apart. The pins are really hard. There is an automotive machine shop down the street from where I work. I asked if they could machine them to be all the exact length. They said sure. I cut down the pins to close to length (or so I thought) with a cut off wheel and die grinder. When I dropped them off the guy I talked to had left. I left the measurement and my number and the guy there said "do you know how long this is going to take?" I left and a while later I got a call and didn't recognize the number. After I figured out it was the machine shop I called back and the guy said if I came in sat morning, Greg (the other guy) would be in and he would probably show me the setup on their machine and let me do it myself.

Saturday morning I met Greg at the machine shop and he showed me how to setup the pins in a Sioux pin grinder. One grinder was more powerful but the pins were too short for the holder. The other machine looked to be about 50 years old but not as powerful. You have to make small cuts in fine increments. After a while and lots of sparks, I thought I was making enough progress to measure the first pin. I could barely tell I had it on the grinding machine. After about a half an hour I decided to take the pins back down to my shop and speed things up on the old bench grinder. I ground them to around a few thou of what I thought I needed. I went back and finished them up. My first measurement must have been off as I had to grind them a little more than that. After the first one was good, I finished the other two.

I pressed the first centers together later that day after making a simple arm to hold the upper web in the tool. Everything went just as expected. Pressed together very nice. The only problem is I thought the new connecting rod pins were within a few thou of the BS pins. The BS pins are 48mm and the Suzuki pins are 48.8mm. They seem to be too close to rubbing on the inside of the cases so I need to grind them down first before I can assemble the rest of the crank.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on April 02, 2017, 11:48:17 AM
I pressed the center webs apart and pressed out the Suzuki pins last weekend. Went back to the machine shop down the street and borrowed their pin grinder again (well gave the guy $40 to use it both times). Shortened the pins down to 48mm and then took them to Rob North's to dress the edges. He let me use one of his lathes to put a nice chamfer on them. He has a big 40T press that is easy to raise the table to accommodate the fact the press tool is tall. I pressed two center sections together and now I'm waiting to check the alignment before the center pins will be tig welded to ensure they won't move. After that it's off to another friend's place to assemble the outer webs.

I'm racing on April 22nd so it's getting a bit down to the wire. I took the bike down to the bare frame since I didn't have all the bits to put the motor together. Found a few problems and already replaced the front fork seals. Need to add some extensions to the fork stops and give it a quick and dirty paint job (the frame). Hopefully I can get the cranks together today/tonight and start putting the motor together.

paul

p.s  Dan, you were asking how soon I would be in the crank rebuilding business? Still a ways off. I have to rely on too many people to get the whole thing done. I'm looking at a set of bench centers the will accommodate vee blocks to true the cranks and check alignment but the one I'm looking at is $500. Then I would need the measuring instruments. I'm tapped a bit thin since the races are right around the corner. Doesn't help that I just got the bill for some CNC work for new rotary valve covers.   
Title: Re: 175/200 Crankshaft Project
Post by: dcr on April 06, 2017, 11:36:07 AM
Impressive stuff here. I was sort of fascinated by the "press the crank together with no structural alignment mechanism" process that BS used. This makes it look a lot simpler than I imagined, but still looks complex. I imagine you are heavily invested in this setup.

Dan
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on April 06, 2017, 12:28:00 PM
It is getting up there. The crank tool works pretty good. The first crank pressed together pretty true. The second not so much. Not due to the tool but the machining might be off on the webs or pin. The first crank was true then we welded it and was off a little. My friend was able to true it up so we'll see. I'll put that one in a motor for the upcoming races in two weeks. The second one I think had a ridge on the center pin. It moved material when pressed into the web. I couldn't get it true no matter what.

I think I have to tweak the way the web holes are done. A jig boring machine would be the best for the job. Unfortunately I can't find a shop around that has one (well one that's not in the Aerospace specific). I did find a used Moore jig bore machine online in Tuscon for $650. Bummer is it's min Tuscon and it weighs 3800lbs! Nowhere for that in the garage. The bench center I was looking at did come down in price. I'll keep my eye on that.

paul
Title: Re: 175/200 Crankshaft Project
Post by: skiri251 on April 07, 2017, 11:39:08 AM
> I'm racing on April 22nd

I assume this is ARHMA @ Willow Springs.
I may be there. There will be "Rider Clinic" event at the cart track and I may ride my BS200.

Title: Re: 175/200 Crankshaft Project
Post by: bsracer on April 08, 2017, 11:18:44 AM
> I'm racing on April 22nd

I assume this is ARHMA @ Willow Springs.
I may be there. There will be "Rider Clinic" event at the cart track and I may ride my BS200.

Yes. Then off to Sears Point he following week. I'll be in either a garage on the front row or the one by itself when you first enter the track. #108 yellow and red paint. Still got a little ways to go. Gotta put the motor and the rest together!

paul

p.s. See you there

Title: Re: 175/200 Crankshaft Project
Post by: skiri251 on April 08, 2017, 01:06:32 PM

Yes. Then off to Sears Point he following week. I'll be in either a garage on the front row or the one by itself when you first enter the track. #108 yellow and red paint. Still got a little ways to go. Gotta put the motor and the rest together!

paul

p.s. See you there

Great!
Hope I can make it.
Title: Re: 175/200 Crankshaft Project
Post by: bert Lilley on April 19, 2017, 06:02:32 PM
Hi guys , just reading your posts regarding the 175/200 center pin breakage and have a question
What material are you upgrading to when you replace the stock cente pin ?

I do undestand and support what karl indicates regarding the hormonics above 10,000rpm. Yes a 4 bearing crank would elevate a lot of the issues, i also think a professional balancing done would truly help as well.
A good friend of mine purchased a factory TD3 crank from Japan he took his pistons/rings  new crank etc  iand had tested for balance and it was realy out of balance. He was not impressed.

Bert Lilley
Title: Re: 175/200 Crankshaft Project
Post by: OldSwartout on April 19, 2017, 08:49:26 PM
i also think a professional balancing done would truly help as well.
Bert Lilley

I got a quote about 10 years ago from a reputable balancing business here in Indy, it was going to be about $200 for a balance job on my 175 crank.  It had to be assembled without rods, they substituted balance weights for  the recommended percentage weight of rod, bearings, piston & rings and balanced the crank, then the crank ends had to be disassembled and the rods and lower rod bearings installed. Unfortunately, I never got around to doing it. It probably would have been a smart thing to do.
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on April 20, 2017, 11:43:08 AM
I'm using an industrial dowel pin from Grainger that is 80 x 20mm. I originally bought them just to use for mock up and the machinist i use said they were pretty hard so why not give it a try. He shortened them and added centers. The original BS bearings fit well. The only problem I think I have so far is the way the holes were bored in the webs, not as accurate as it should be. One crank went together ok. The pin fit was a bit soft on the press gauge in my opinion. I'll see how it goes this weekend. Fired the bike up last night with that crank. The second crank had material move when the pin was installed and would not true to anything respectable.

I agree that balancing would be nice. Maybe in the future. We'll see how this one behaves this weekend. Ideally the new pin holes should be done with a Jig Bore machine. Still can't find a place that has one that isn't some big Gov contractor.

paul

p.s. I think I will try just a new center pin to 20mm on the next one and have connecting rod pins stepped to minimize variable on the alignment of so many holes. 
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on April 30, 2017, 03:27:01 AM
Well the first crank made it thru 6 races so far. Ended up stripping the teeth off the idle gear and missed two races because I didn't pack a spare.

paul
Title: Re: 175/200 Crankshaft Project
Post by: old smokey on May 01, 2017, 12:13:06 AM
That sounds like pretty good results, now you just have to pack more spare parts.... ::)
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on May 01, 2017, 01:32:16 AM
I already pack too many. I just have to bring the right parts I need.


paul
Title: Re: 175/200 Crankshaft Project
Post by: craig641 on May 23, 2017, 12:31:09 PM
So, are you ready to sell one yet?  I broke another one in a race yesterday.  It was my last crank.  I need to find one to have hope of getting something out of this season.

Craig
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on June 06, 2017, 01:26:35 AM
Hey Craig,

did you come up with any donor cranks? I'm meeting with another machinist this week about the cranks.


paul
Title: Re: 175/200 Crankshaft Project
Post by: craig641 on June 12, 2017, 09:59:30 PM
Paul,

I had parts for five cranks.  I talked with my local guy and he's going to get my flywheels bored for the main crank pins but then I need to talk to you again.  If you've got the jig to press these together we should try to get them all done at once.

Let's also compare machining costs and pin costs.  My guy seemed very reasonable.

I had a race this past weekend in New Hampshire.  My stock crank survived.  The pistons didn't. 

Craig
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on June 14, 2017, 12:30:20 AM
Hey Craig,

the connecting rod pins I used are Suzuki T20 TC250 Part# 12211-11000 or 12211-08201. 20mm x 48.8mm. I shortened these to 48mm.

The shims I used where Honda Part# 132002-GC4-600. These are 1mm thick (roughly) big end shim washers that fit CR80 or CR85.

If you got stock KT100 big end bearings they should be fine. The KT100 big end pin is probably too short.

The pin I got for the new center is from Grainger. 20mm x 80mm long metric hardened dowel pin.

The newest machinist that I went to yesterday morning charges $75 an hour. He thinks 2 hours to bore holes in the centers for the new 20mm pins (4-5 crankshafts so 8-10 holes) and remove existing pin. The pins from Grainger are hard and so is the crank (I think cranks are case hardened to around 60-62 Rockwell). I had the pins  shortened to around 72-73mm. I'd have to measure one to get the exact length. I also had centers added.

The fixture I made is only for aligning the center webs to 180 deg. Then they're checked for true. The outer webs still have to be done the old school way and trued as well. I pressed the centers together and had someone else true the outer webs.

paul
Title: Re: 175/200 Crankshaft Project
Post by: bsracer on June 18, 2017, 02:08:30 PM
Hey Craig,

the part numbers for the base shims I had made out of aluminum at Cometic are

B1055SP1025A  .025"
B1055SP1032A  .032"
B1055SP1040A  .040"

These are for a 175 cylinder and they need to be trimmed to fit. I'm sure they can be used on a 200 cylinder as well. They were around $6-7 each.


Title: Re: 175/200 Crankshaft Project
Post by: bsracer on August 27, 2017, 01:58:39 PM
I picked up the bench center that I was looking at to use as a truing stand. I was set on around $250 and the guy finally came down to $260. Long drive to get it (2hrs each way) but I think it will work well. I still want to get some machinist V-blocks. Then I can check using both the ends and on the bearing surfaces.

paul