Author Topic: GTR Crank rebuild  (Read 2908 times)

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Offline nysz1b

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GTR Crank rebuild
« on: June 21, 2016, 02:41:49 PM »
I acquired a couple of years ago a '67 GTR with very low miles on the clock (3300). I was able to get it running without too much effort, but it's smoking on the rh. side. I was told that the labyrinth seal needs to be replaced. The bike had been sitting for about 30 years, but idled smoothly once running. This project has been on the back-burner, but am now ready to move forward. Since the bike had been sitting for around 30 years, I would assume that the other crank seals need to be replaced, as well? I was also told that someone on this site (Reed) was able to replace the labyrinth seal without spiltting the cases? Any advice appreciated.

Thanks to Mike Anderson for re-comending a shop for crank rebuilding.

Offline slawsonb

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Re: GTR Crank rebuild
« Reply #1 on: June 21, 2016, 04:06:41 PM »
Steve does have a trick that he uses to replace the labyrinth seal O-ring without disassembling the crank which he did on a crank of mine. (I have no idea what he does..??) But I don't think the aluminum seal is coming out without taking the crank down. I hope he's willing to share the magic. ;D
...bert
« Last Edit: June 21, 2016, 04:41:26 PM by slawsonb »

Offline BS Mechanic

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Re: GTR Crank rebuild
« Reply #2 on: June 21, 2016, 05:14:42 PM »
I just heated mine up in hot water, coated it with oil, and stretched it slowly.  Went on without any trouble.  The old one came off almost as easily, in one piece.  If you go slowly, it will stretch out, then slowly shrink back to size.

Offline OldSwartout

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Re: GTR Crank rebuild
« Reply #3 on: June 21, 2016, 08:42:40 PM »
A labyrinth seal won't cause it to smoke on the right hand side, a bad right hand crankshaft seal does that (draws oil out of the transmission). That is a simple (relatively speaking) fix - remove the r.h. carburetor, clutch side housings, clutch and rotary valve cover, replace the seal in the center of the rotary valve cover, put it back together. A bad center seal will cause hard starting, maybe poor idle if it's pretty bad.
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline nysz1b

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Re: GTR Crank rebuild
« Reply #4 on: June 22, 2016, 12:25:56 PM »
Thanks for the feedback, esp. OldSwartout regarding the rotary cover seal.


Offline OldSwartout

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Re: GTR Crank rebuild
« Reply #5 on: June 24, 2016, 11:38:09 AM »
Just to avoid any confusion, I mean the 09090-128 32mm oil seal is the problem.   As suggested above, there is also a probability the o-ring around the aluminum labyrinth seal in the center of the crankshaft may be hardened, but it's trapped and probably is usable until the cases are split, at which time it should be replaced. The 09090-121 o-ring around the O.D. of the rotary valve cover is probably hard and won't seal well once removed, so you might order two of those when you order the 09090-128 oil seal (a spare  one for the left side rotary valve cover if you take it apart sometime).
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline OldSwartout

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Re: GTR Crank rebuild
« Reply #6 on: June 24, 2016, 11:56:52 AM »
BTW, your e-mail listed on this site bounces, I couldn't reply to your e-mail.
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline davis

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Re: GTR Crank rebuild
« Reply #7 on: July 09, 2016, 11:09:35 AM »
BS Mechanic is right. I tried the same procedure and it worked. If there are doubts, heat the existing 09066-120 o-ring with a hair dryer, lube it and carefully take it off using the path of least stretch. If the old rubber doesn't snap, new rubber won't going the opposite direction. F.Y.I., the o-ring is 3.0 mm with a 59.0mm  nominal I.D. I ordered 58.0 mm seals to make sure there is no slack in the groove when installed.

 


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