isolastic life

MikeG · Aug 2, 2022

Just wondering, how long should isolastic rubbers last? I replaced mine when I got the bike 10 years ago with adjustables from either Old Britts or Clubman racing, can't remember which. I now seem to have a harshness through the foot pegs and a bit of side to side play in the swing arm, maybe a 1/2 inch or so max. I'll change them again over the winter but are any recommended over another brand?

KiwiShane · Aug 2, 2022

MikeG said:
Just wondering, how long should isolastic rubbers last? I replaced mine when I got the bike 10 years ago with adjustables from either Old Britts or Clubman racing, can't remember which. I now seem to have a harshness through the foot pegs and a bit of side to side play in the swing arm, maybe a 1/2 inch or so max. I'll change them again over the winter but are any recommended over another brand?

Nip the adjusters both up a touch and check your swing arm bushes

Torontonian · Aug 2, 2022

KiwiShane said:
Nip the adjusters both up a touch and check your swing arm bushes

1/2 inch play is huge , so likely your swingarm is wallowed out in the cradle . Put the bike on it's center stand , grab the rear tire and move it sideways back n' forth to observe for slop.

concours · Aug 3, 2022

Have you done your Kegels?

MikeG · Aug 3, 2022

concours said:
Have you done your Keigels?

Looked at them over the winter when I reworked the rear rim, all looked OK and tight. Since I installed the rear set pegs it's always seemed a bit buzzier. Last week I turned the rear iso adjuster out a bit to try and lessen that. Perhaps I went the wrong way?

elefantrider · Aug 3, 2022

The rears last until they go oblong shape in the cradle.

BERT · Aug 3, 2022

During the off season layup of the bike, is there a prefered way to neutralize the weight on the iso's to keep them concentric?

Thomasa · Aug 3, 2022

Keigles? I don't know this term.

The rear isolastics are not fun to change, particularly if the rubber boots have gone hard and you have to cut them off. Shimming them is tedious and time consuming. IMHO the MKIII or other adjustable ones are well worth the price if the isolastic rubbers are gone and you're about to replace them. If you have to take this part of the bike apart, do the upgrades all at once, i.e. swing-arm bushes, cradle support mods, lube upgrade, etc. Your time is worth more than you may think. None of us is getting younger.

Of course, if all it seems to need is a shim job, be prepared to replace the PTFE washers (many have crumbled in my hand as I removed them) and have a selection of shims readily to hand. In this case there is no need to do the swing-arm mounts or bushes if they are not loose. But now I'm commenting on the obvious and contradicting myself.

L.A.B. · Aug 3, 2022

MikeG said:
Just wondering, how long should isolastic rubbers last? I replaced mine when I got the bike 10 years ago with adjustables from either Old Britts or Clubman racing, can't remember which. I now seem to have a harshness through the foot pegs and a bit of side to side play in the swing arm, maybe a 1/2 inch or so max. I'll change them again over the winter but are any recommended over another brand?

Lateral movement of the Isos. is restricted by the abutments (or abutment and vernier adjuster). The rubbers are only free to move/shake in the fore-and-aft and vertical planes so if there's excessive side-to-side play (1/2 inch is excessive in my opinion) at the rear wheel then the Isolastic rubbers shouldn't be the cause.

Thomasa said:
Keigles? I don't know this term.

Keglers (Kegler clamps).

Kegler Swing Arm Clamps

I have a question about installing these clamps. I have read previous threads but have not come across my query yet. My question is, can these be installed with the bolt heads and lock nuts at the '12 o'clock' position, the same position the locating screw is located?. I think they would be free...

www.accessnorton.com

Heinz Kegler Clamps

does anyone know where I can by a set of these?

www.accessnorton.com

Jdub · Aug 3, 2022

Am I the only reader who caught the Keigles reference? That is pretty funny...Concurs you are SO bad!

998cc · Aug 3, 2022

Jdub said:
Am I the only reader who caught the Keigles reference? That is pretty funny...Concurs you are SO bad!

Nope...I did as well! LOL!

KiwiShane · Aug 3, 2022

Thomasa said:
Keigles? I don't know this term.

The rear isolastics are not fun to change, particularly if the rubber boots have gone hard and you have to cut them off. Shimming them is tedious and time consuming. IMHO the MKIII or other adjustable ones are well worth the price if the isolastic rubbers are gone and you're about to replace them. If you have to take this part of the bike apart, do the upgrades all at once, i.e. swing-arm bushes, cradle support mods, lube upgrade, etc. Your time is worth more than you may think. None of us is getting younger.

Of course, if all it seems to need is a shim job, be prepared to replace the PTFE washers (many have crumbled in my hand as I removed them) and have a selection of shims readily to hand. In this case there is no need to do the swing-arm mounts or bushes if they are not loose. But now I'm commenting on the obvious and contradicting myself.

The isolastics were upgraded to "adjustables" as mentioned in first post...sounds more like a swingarm bushing issue ...

MikeG · Aug 3, 2022

Jdub said:
Am I the only reader who caught the Keigles reference? That is pretty funny...Concurs you are SO bad!

I caught it, I just don't think any amount of exercise can bring back a hole that worn out....

elefantrider · Aug 4, 2022

BERT said:
During the off season layup of the bike, is there a prefered way to neutralize the weight on the iso's to keep them concentric?

Not the center stand.

I use the "MX" chocks by Baxley. Having the bike on 2 wheels distributes the load better.
I have also used an motorcycle jack which keeps the bike upright, holding the bike up by both the frame and craddle, but keeping the some of the weight on the wheels.

The rear buffers AN sells are not cheap and a PITA to replace.

YouTube

olympus · Aug 5, 2022

BERT said:
During the off season layup of the bike, is there a prefered way to neutralize the weight on the iso's to keep them concentric?

Very good question this... as in riding the weight is pushing down on the rubbers but when on the main stand (cradle mounted stand) its pushing up

elefantrider · Aug 5, 2022

It pushes it up but this force is concentrated on the rear isos on '71 up bikes. This is why the rears go ovalized. A common Commando problem. This is also the reason why I do not like the MK3 "Vernier" upgrade kits for earlier bikes.

Derek Wilson · Aug 5, 2022

I definitely would agree with trying to take up the slack in your isolastics before replacing them completely. The isolastics in both of my Commandos are around 20 years old, and both are nowhere near end of life. Harshness can occur when they are too loose and when they are too tight. When checking their adjustment, I use the relative movement between the primary cover and the left-side Z-plate as a guide. Move the rear wheel back and forth as described above and adjust the rear isolastic until there is a minute amount of movement. Check the front the same way.

I set threaded adjusters by feel. Tighten until vibration is felt, then slack them off a hole at a time until it is smooth.

For shimable isolastics, I use a dial indicator, anchored to the battery tray and measure the amount of movement of the primary. Subtract 0.005" from the movement, and this is the rough amount of shims that should be added.

FWIW

isolastic life

MikeG

Mikeg

KiwiShane

Torontonian

concours

MikeG

Mikeg

elefantrider

BERT

Thomasa

L.A.B.

Moderator

Kegler Swing Arm Clamps

Heinz Kegler Clamps

Jdub

998cc

KiwiShane

MikeG

Mikeg

elefantrider

olympus

elefantrider

Derek Wilson

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