Syncro front shock top mount damage how to fix

[MarkWard]

The upper and lower control arms do not move up and down parallel to the chassis. They move in an arc. Camber also changes lock to lock measured as caster. The shock is obliged to follow only its design is linear movement. The upper rubber and lower shock bushing to a point absorb this. A lifted or lowered suspension is beyond what the engineers had designed in. That could aggravate it. Well, that’s my guess.

[Sodo]

Yes with all that monkey motion a rubber lower shock mount would exert some side-force upon the top mount.

Fox Shocks have a “Heim” joint at the bottom (a spherical ball joint).
So I doubt the Fox Shock puts much side force on the upper mount.
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[Scubavw]

This is the top of the Bump stop.
That small washer came out of the top in the small grove. I believe that the bump stops are a very bad reproduction. I do not see any signs of the large washer. The bump stops are 4 years old that I bought from a well known vendor. I am really easy on the van.
This is the sleeve that goes over the end, luckily no damage on the shock rod. The sleeve slides down into the bump stop.

[vanatic]

This happened to me too. The vendor gave me a refund without issue. I believe they have since updated the design. I put the original ones back in as they were still ok.
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1990 Weinsberg Triple Knob Bostig Syncro

[Sodo]

Here’s my right side shock tower hole.
I suspect that its a clearance hole that’s never intended
to contact the (.59” diam) shock shaft bushing.

But you can see its worn out-of-round in two places.
That pipe is .750” diameter.

Here’s the shock tower bushing (.59”diam) which shows recent contact.
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[vanatic]

For you that have had this happen...Was is making any noise?
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1990 Weinsberg Triple Knob Bostig Syncro

[Sodo]

I haven't heard anything,
but you can bet I'll be listening more now
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[Sodo]

During "normal driving" not bottoming, the force compressing that the shock-top bushing is only the shock absorber.
A little gas pressure and a LOT of compression damping.

[big swifty]

[Sodo]

I only have the original shock-tower rubbers, which appear to be in good condition.
I've never even seen a GW bushing in-person.

original measures .59 OD x .41 ID x 1.04 Length

And sorry I have NOT tested shortening my steel-bushings (to squeeze the rubber donut more).
I suppose I would try 0.10 reduction ( .94 length. )

I would like to try this.
Or "read of someone else trying it".

I think ya gotta drive a rough road before, listen, and video the sound etc.
Shorten bushings (or exchange shorter bushings out in the boonies)
Then drive the same rough road after exchange.

I "should at least" make these 0.94" bushings and carry them in the van....
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[Sodo]

I made some shorter bushings.
Two lengths. 0riginal was 1.04". O made 0.91" and 0.81"
Carried in the van for the next time I hear that shock-tower rattle.

With luck, I can stop,
replace the bushings with shorter
test-drive the same road that caused the rattle.

.....and report back.
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb