Suspension rumbles from new setup

[pj_sibley]

Recently fitted freshly refurbished (BG Motorsport) original front Sachs dampers onto my Trophy, along with new PMS solid top mounts and new Cooksport springs. The car had already been fitted with new wishbones, lower ball joints, inner/outer tie rods and a full compliment of poly bushes.

Just after fitting the Sachs etc, the car sailed through its MoT with the tester confirming that there was zero play in ANY of the suspension components.

Which brings me to my issue...since fitting the Sachs, I've been experiencing a rumbling sound from the front of the car, particularly over smaller road imperfections. If reversing and turning off the drive for example, the rumble happens with one wheel and then the other, so it's not 'sided'. In ALL other respects, the car drives and handles superbly, and I wouldn't describe the ride quality as 'crashy'. I just can't seem to place it and neither can my mechanic(!).

Starting to wonder whether it's just an artefact of having such a super-stiff setup on the car and perhaps I should just live with it?!

Any thoughts or advice much appreciated.

 

[pj_sibley]

Still struggling with this. I've managed to replicate the noise on the stationary car by manually rocking the engine (holding onto the inlet manifold) from side to side quite hard. All of the engine mounts are new and/or uprated poly items, so the whole car moves!

The noise is coming from high up on the passenger side and seems to be come from the scuttle area as opposed to the top mount or strut, its very strange. There's nothing obviously hitting anything else.

I think some dismantling is required, just to check it isn't any of the recently fitted components. I'd be pretty pi**ed if a pair of freshly refurbished Sachs dampers were past their best after 50 miles of use!!

 

[pj_sibley]

So, for those that are interested, this issue has now been properly diagnosed and resolved!

It turns out that the combination of freshly refurbished Trophy Sachs dampers and Pure Motorsport solid top mounts was just too STIFF, resulting in the noise associated with normal (very slight) axial driveshaft movement being transmitted up the strut into the turret/chassis.

The fix? We refitted standard top mounts onto the Sachs dampers and the noise has completely disappeared on both sides. The car drives superbly and the ride is more than acceptable [emoji106]

It does make me think - how many Trophy cars run the PMS solid top mounts and are there any other damper/top mount combinations that give rise to this issue?

PS. a pair of <50 mile old PMS solid top mounts will be appearing in the classifieds soon!


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[flebay]

So, for those that are interested, this issue has now been properly diagnosed and resolved!

It turns out that the combination of freshly refurbished Trophy Sachs dampers and Pure Motorsport solid top mounts was just too STIFF, resulting in the noise associated with normal (very slight) axial driveshaft movement being transmitted up the strut into the turret/chassis.

The fix? We refitted standard top mounts onto the Sachs dampers and the noise has completely disappeared on both sides. The car drives superbly and the ride is more than acceptable [emoji106]

It does make me think - how many Trophy cars run the PMS solid top mounts and are there any other damper/top mount combinations that give rise to this issue?

PS. a pair of <50 mile old PMS solid top mounts will be appearing in the classifieds soon!


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There rubber for a reason.

 

[pj_sibley]

This is true.

Thought it would be interesting to try them anyway but IMO they're more suited to a track biased car.

They obviously use the thin turret top, whereas the standard rubber items sit lower down in the turret body.


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[bloke]

any form of solid mount will transmit noise/vibration etc.

 

[pj_sibley]

It drove me mad LOL! I can see the benefits for track use though.


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