DogT
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- Joined
- Jan 20, 2009
- Messages
- 7,394
Maybe this will help others in installing/repairing the isolastics. This is for non-Hemmings or other type adjusters, but it will be pretty much the same for them except for the shims. First thing is to get the parts. I got mine from OldBrits and I think they are the softer rubber ones for the early 750 bikes.
2 - 061226 Isolastic bush, front
1 - 061277 Isolastic spacer tube front
2 - 061278 Isolastic buffer, front
3 - 061227 Isolastic bush, rear
2 - 061279 Isolastic spacertube, rear
2 - 061280 Isolastic buffer, rear
8 - 063927 Circlip, isolastic spacers
4 - 064748 Isolastic thrust washer
Remove all the old rubber crap and get rid of it. Clean everything up. I soaked my old boots in Meguiar's NXT vinyl-rubber-plastic sauce for several years and it really helped them, but a few days would work.
Old, bottom and new, top front isolastics, rear ones just have more parts.
Cleaned the inside of the front isolastic motor mount tube and the rear isolastic cradle tube. Slathered lots of silicone grease on the rubbers, pushed them in by hand, once they start in the tube you can push them around easily. I even greased up the inside of the tubes with this silicone grease I had left over from my electronics days. It feels just like the RTV silicone, but it doesn't have the stuff in it to make it set up, it remains grease. This tube must be as old as my bike. Center the bushings in the front mount or the cradle as best as you can, they will move around during assembly.
Clean up the mounting tube cap and stud collar (4 pieces, 2 front, 2 rear). Left is front washer side, right is rear nut and tube side. Notice the rear one has a longer stud collar and is smaller around, but the PTFE washers fit on both. I lightly sanded the faces where the PTFE washer mounted against both the cap and collar because I had some rust there..
Install the parts in their proper sequence, left to right collar, PTFE washer, tube cap, shims, same order in reverse on the other side. Of course if you have an adjustable collar, you won't need the shims.
Make sure the shims are in the tube caps correctly, and the PTFE washers have a bend in them, I installed the convex side against the collar so it didn't tend to fall out and get misaligned, the collar has a lip the washers fit on. You will have to guess at the shims to start with or measure without and add what you need to make .010 clearance. Notice on the front mount in the picture, I have a spacer from the rear isolastic to take up the space and I think I used an old 1/2" nut from somewhere that was not a nylock so I didn't mess up my new one. Tighten the assembly, 25fp I think, and push a feeler gauge in between the PTFE washer and the collar or the cap. It appears that this is a pretty subjective measurement, I can get .013 in some places and .008 in others, so I assume it averages out to somewhere around .010.
As you can see this is much easier with the parts off the bike and no boot. The front is easy enough to get off and there should be no reason to do it on the bike, but the rear one may be quite hard to do without some major dis-assembly. After all this, it looks like you can put the boots on and then install everything in the bike and be done with it.
As you see, the collars tighten up against the tubes mounted on the 1/2" bolt and it leaves some space between the tube collar and the PTFE washer which is the clearance you are looking for. Doesn't matter what you mount outside the collars after this, the clearance will remain the same.
I hope this helps someone. I was always confused about it, but it is quite simple. If anyone has improvements or corrections, fine.
Dave
69S
2 - 061226 Isolastic bush, front
1 - 061277 Isolastic spacer tube front
2 - 061278 Isolastic buffer, front
3 - 061227 Isolastic bush, rear
2 - 061279 Isolastic spacertube, rear
2 - 061280 Isolastic buffer, rear
8 - 063927 Circlip, isolastic spacers
4 - 064748 Isolastic thrust washer
Remove all the old rubber crap and get rid of it. Clean everything up. I soaked my old boots in Meguiar's NXT vinyl-rubber-plastic sauce for several years and it really helped them, but a few days would work.
Old, bottom and new, top front isolastics, rear ones just have more parts.
Cleaned the inside of the front isolastic motor mount tube and the rear isolastic cradle tube. Slathered lots of silicone grease on the rubbers, pushed them in by hand, once they start in the tube you can push them around easily. I even greased up the inside of the tubes with this silicone grease I had left over from my electronics days. It feels just like the RTV silicone, but it doesn't have the stuff in it to make it set up, it remains grease. This tube must be as old as my bike. Center the bushings in the front mount or the cradle as best as you can, they will move around during assembly.
Clean up the mounting tube cap and stud collar (4 pieces, 2 front, 2 rear). Left is front washer side, right is rear nut and tube side. Notice the rear one has a longer stud collar and is smaller around, but the PTFE washers fit on both. I lightly sanded the faces where the PTFE washer mounted against both the cap and collar because I had some rust there..
Install the parts in their proper sequence, left to right collar, PTFE washer, tube cap, shims, same order in reverse on the other side. Of course if you have an adjustable collar, you won't need the shims.
Make sure the shims are in the tube caps correctly, and the PTFE washers have a bend in them, I installed the convex side against the collar so it didn't tend to fall out and get misaligned, the collar has a lip the washers fit on. You will have to guess at the shims to start with or measure without and add what you need to make .010 clearance. Notice on the front mount in the picture, I have a spacer from the rear isolastic to take up the space and I think I used an old 1/2" nut from somewhere that was not a nylock so I didn't mess up my new one. Tighten the assembly, 25fp I think, and push a feeler gauge in between the PTFE washer and the collar or the cap. It appears that this is a pretty subjective measurement, I can get .013 in some places and .008 in others, so I assume it averages out to somewhere around .010.
As you can see this is much easier with the parts off the bike and no boot. The front is easy enough to get off and there should be no reason to do it on the bike, but the rear one may be quite hard to do without some major dis-assembly. After all this, it looks like you can put the boots on and then install everything in the bike and be done with it.
As you see, the collars tighten up against the tubes mounted on the 1/2" bolt and it leaves some space between the tube collar and the PTFE washer which is the clearance you are looking for. Doesn't matter what you mount outside the collars after this, the clearance will remain the same.
I hope this helps someone. I was always confused about it, but it is quite simple. If anyone has improvements or corrections, fine.
Dave
69S