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Replacing ISO rubbers

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Hi all,

Apologies if this has been covered before - I've had a root around prior to this post.

I'm nearing the end of my '74 ex Police Interpol restoration and a few test rides have highlighted some excessive vibration. It's OK at around 50mph but a twist of the throttle and I get a lot of vibration via the pegs and on the overrun, again lots of vibration in the pegs.

Both ISO's had been built when I bought the bike (with verniers) - so I've not been in there as yet.

Can I replace the rear ISO rubbers with the engine in situation and what do I have to do to move the engine forward to gain access to the rear ISO?

Just to note the front ISO is an RGM ali job.

Thanks - Paul.

 

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I can't  comment on the RGM iso set up but replaced both of mine with Verneer type from Norvil. They are very simple to adjust and must have come with instructions. Get in touch with RGM and check. In my opinion if they are new then it will be a matter of adjustment. There isn't very much to them to be honest, from memory my instructions were hand tight it up then back off half a turn job done and it works on mine.

It will be a big job to replace them, the rear being the difficult one, good luck.

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Mike Taglieri in the USA had a method for doing the rear iso’s with engine in frame, i did mine that way and it worked a treat.

I am on the road at the moment, can post in a few days time when I get back If no-one else does in the meantime, and if I don’t forget...

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From Michael Taglieri

Subject: Easier Way to Rebuild the Rear Isolastic

The standard workshop manuals for the Commando generally tell you that the rear Isolastic mount can be rebuilt only by removing the engine, or even the entire power train. Today, helping Chuck Contrino rebuild the rear Isolastic on his '72 Interstate. I was finally able to test a procedure I've been contemplating for a long time that lets you rebuild the rear Isolastic without significantly dismantling the rest of the bike. It worked very well, and this is how you do it: 1. Remove the tank.

2. Remove the primary (optional -- see below).

3. Remove the horn (optional -- see below)

4. Remove the air filter(s) and the exhaust pipes.

5. Put the bike on the centerstand and fasten the centerstand with safety wire, electrical ties, bungee cords, etc., so it cannot possibly collapse. Do not fasten it to any part of the frame, but only to the engine plates or some other part of the bike that hangs on the Isolastic mounts.

6. Slightly loosen the nuts on the large central bolt that runs through the rear Isolastic, and also loosen the nuts on the headsteady.

7. Put a small hydraulic jack, etc., under the middle of the left frame tube (with padding to protect the frame) and slowly raise the side of the frame until the left foot of the centerstand just leaves the floor. At this point, the weight of the frame does not rest on the central bolt of the rear Isolastic, and you can remove it easily. Using a suitable drift (a 1/2" socket extension works well), tap the big bolt loose, catching the various metal parts of the Isolastic that fall free when it's out. (By the way, using a hydraulic jack this way is also useful for getting the bolt back IN when you're done, and you can look through the hole with a flashlight andove the frame until the parts are exactly aligned).

8. Lower the hydraulic jack. Now the frame is hanging on the powertrain by the front and top Isolastics, and the top Isolastics show it by twisting slightly under the weight. Lift the rear wheel (with a 2x4", brick, etc.) until the top Isolastics are no longer twisted. Now, remove the side plates of the top Isolastics. (You do not have to remove the engine steady from the top of the engine). 9. The powertrain is now resting on the floor, held up the centerstand, but it's attached to the rest of the bike only by the front Isolastic. Now, put more stuff under the rear wheel to raise the frame until the centerstand almost comes off the floor.

10. At this point, the frame tubes are out of the way and the rear Isolastic is completely exposed on both sides for rebuilding.

THE "OPTIONAL" STEPS: If you didn't remove the primary, the Isolastic is completely exposed  only on the right side, and you will need some kind of hook to pull the rubber parts out. If you didn't remove the horn, the frame tubes will be partly out of the way but not entirely. I recommend taking off both of these items if you're removing the original Isolastic rubber parts, because if they're truly stuck in there, it's a %$#@ of a job to get them out. On the other hand, considering how awful a job it is to remove the horn, you may want to try this first with the horn in place and remove it only as a last resort. (By the way, if you pound on the central rubber with an ordinary drift to get it out, the rubber absorbs the shock of the hammer blows before they get transmitted to the edges. The best way is to pound on the edges of the rubber by using a very large socket on an extension as your drift).

REMOVING THE HORN: As anyone knows who has tried it, this is one of the ultimate bastard jobs on the bike. You can do it with the rear wheel in place by unbolting just the front part of the rear fender (two bolts near the top, two nuts on studs near the bottom), and flexing the fender enough to "pop" it off the studs and move it down. These studs turn out to be the bolts that hold the horn mount, which you remove (teaching children in the area several new words in the process). Finally, you can squeeze the horn out of the space between the frame and the fender -moving the rear axle as far back as you can will help.

 

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