Bridgestone Motorcycle Parts Discussion Board

Bridgestone Tech Talk => 350 Talk => Topic started by: nysz1b on June 12, 2018, 04:10:28 PM

Title: GTR Rubber engine mounts
Post by: nysz1b on June 12, 2018, 04:10:28 PM
Is it a wise thing to replace the rubber engine mounts ( part #'s 3358-9000 & 3367-9000) as a matter of course when restoring a '67 GTR? Mine look to be in good condition, but I'm sure the rubber is rock hard after all these years. Thanks in advance!
Title: Re: GTR Rubber engine mounts
Post by: OldSwartout on June 12, 2018, 05:38:00 PM
Actually, I'd check it. Put a bolt through the middle, clamp it in a vise and see if there is much flexibility when twisting it.  It is surprising how some rubber parts survive well for 50 years and others don't. It probably depends on storage conditions, amount of sun, etc., but you just never know.  You also have to consider how much riding time you are planning on.  Richard has repros if you need them.
Title: Re: GTR Rubber engine mounts
Post by: moonpup on June 12, 2018, 05:50:34 PM
Actually, I'd check it. Put a bolt through the middle, clamp it in a vise and see if there is much flexibility when twisting it.  It is surprising how some rubber parts survive well for 50 years and others don't. It probably depends on storage conditions, amount of sun, etc., but you just never know.  You also have to consider how much riding time you are planning on.  Richard has repros if you need them.

 iagree
Title: Re: GTR Rubber engine mounts
Post by: hardy on June 12, 2018, 06:07:59 PM
A little of topic but worth mentioning, while checking your rubber mounts, check your rear engine/frame mount for cracks. It is a known weak point due to vibration. :-\

I had to remove my motor to weld up and repair. ^-^

Hardy
Title: Re: GTR Rubber engine mounts
Post by: moonpup on June 12, 2018, 07:14:55 PM
A little of topic but worth mentioning, while checking your rubber mounts, check your rear engine/frame mount for cracks. It is a known weak point due to vibration. :-\

I had to remove my motor to weld up and repair. ^-^

Hardy

 iagree 
Title: Re: GTR Rubber engine mounts
Post by: nysz1b on June 12, 2018, 08:58:30 PM
Thanks moon pup and Hardy!
Title: Re: GTR Rubber engine mounts
Post by: moonpup on June 12, 2018, 10:13:45 PM
Haha, don't thank me..... thank Karl & Hardy, I just agreed with everyone!  ;D
Title: Re: GTR Rubber engine mounts
Post by: hardy on June 13, 2018, 06:07:16 PM
Haha, don't thank me..... thank Karl & Hardy, I just agreed with everyone!  ;D

 iagree
Title: Re: GTR Rubber engine mounts
Post by: hardy on June 13, 2018, 06:08:56 PM
Don’t forget to align the motor after replacing the bushes, having it out of alignment will put excessive load into one or two bushes and cause premature failure.
Title: Re: GTR Rubber engine mounts
Post by: coxy on June 14, 2018, 02:13:39 AM
one other thing while your doing it is to see if the stay on the frame for the rear brake spring is not bent
Title: Re: GTR Rubber engine mounts
Post by: BRT-GTR on June 14, 2018, 06:44:57 AM
         A few pointers I've learned along the way :-
       Bottom bushes have to come out upwards, there is a small lip stopping them being pushed downwards.

       Wider inner flange on bush goes against the alloy engine case.

       When installing engine, put bottom bolts in first otherwise it is a struggle to line them up.
     BS used special small diameter washers on the mounting bolts to avoid bridging the rubbers.  2 on the rear bolt, 2 on the bottom bolts and 4 on the front bolt where there is a extra washer between the engine case and the rubber mount. These are items 45 & 46 on the frame parts diagram.

    Replacement large bushes can be made by cutting in half a Yamaha swingarm bush, 102-22123-00.
    Anyone found an alternative to the smaller front bush ?   

     In my opinion, these bushes are too small for the job they have to do, the front and rear suffering from the engine twist generated by the chain pull. I intend to try fitting longer bushes on one of my bikes and see if it makes a difference.
                                Brian.

     

Title: Re: GTR Rubber engine mounts
Post by: OldSwartout on June 14, 2018, 08:17:27 AM
I bought a set of repro replacement bushings from Richard to fix mine that were falling apart.  I had replaced them years ago when NOS parts were still available. When I got ready to replace the front ones, they were the large size like the bottom ones. Looking at the brackets and the not-up-to-factory-standards welds, apparently I had "fixed" that issue all those years ago, but didn't remember it.  ::)  Since I had the small bushings already, I used a set of original brackets off a roller that was in the barn. Maybe that was the wrong decision????
Title: Re: GTR Rubber engine mounts
Post by: Bridgestoneboy on June 14, 2018, 11:05:06 AM
If looking for a somewhat cheaper alternative, you can actually purchase window weld from your local auto parts store to make your own engine mounts. Just put a piece of tape on one side and the bushing in the center. The window weld comes in a tube so you can just use it like caulk and fill in the space around the bushing. If you really want you can use a razor blade or something flat to smooth out the sides and so far the have worked very well on my bike. I do believe they are just a tad stiffer than NOS but it does work.
Title: Re: GTR Rubber engine mounts
Post by: BRT-GTR on June 14, 2018, 03:44:41 PM
              Once again, full credit for your innovative and enterprising solution to restoring these bushes.
      3m windo weld doesn't appear to be readily available in the UK but I'm sure there will be an alternative window adhesive and may give it a try.                                               Brian