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Front suspension investigations


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Having stripped down the front nearside on the Vitesse after hearing knocking,i found the following:

Wishbone bushes knackered,bottom Avo shock bush mullered and the spring top plates have a large oval hole in them.

Top plates may be older but the rest has only done a few thousand miles.There is a conversion for spherical bearings instead of polybushes for the Avo`s,but they say it makes the ride worse and more vibration through the suspension.

Rebuild one side tomorrow.

Steve

 

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I had the same problem many years ago after fitting Spax shocks at the front. I replaced the Stanpart top spring pan  shock bushes with the Spax version of the same thing. I think the poor quality rubber collapsed very quickly causing the shock to tramp about in the top spring pan and wrecking it. They hadn't done many miles either, so I wasn't very impressed. I replaced them with Koni's and have had no problems since.

Gav.

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Sorry to say the newer style AVOs with the narrow bush sleeve are a very poor design and the bushes fail very quickly. Couple of historical threads from Sideways - you might have hoped the design would have been improved in 12 years! Their previous design was fine.

http://sideways-technologies.co.uk/forums/index.php?/topic/6987-those-darn-avo-bushes/&tab=comments#comment-92082

http://sideways-technologies.co.uk/forums/index.php?/topic/1214-avo-damper-bush-failures-polybush-general-failure/&tab=comments#comment-1530
 

Spherical bearings should be clatter free as they are always loaded in the same direction. I considered doing that after about the 4th set of bushes but by then the dampers themselves were shot to bits so I binned them and fitted Konis. So much better..... though the AVO adjustable spring seats are useful.

Whats happening with the spring too plated? Not come across that before?

Nick

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I have seen the top plates wear, and on a spax the top fixing "bolt" worn halfway through. I have always assumed the bushes have failed allowing the shock to move about in the top plate, or the other possibility the shock was not tightened up enough (unlikely).

Another fan of Koni here... 24 years old now.Though only about 50K as several years they were in storage while I built my spit,  No issues to report.

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i had some Gaz wear the top plate to a silly shape,  makes an squeak you cannot trace easily .

guess it all down to forces and  alignments of the top shaft and the rather poorly located rubber bushes , never tried poly but the rubbers are not that positive 

with quite small locations 

pete

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Interesting thread on Sideways there,with contributions from GT :)

I was reading on the Merlin website,they say Avo`s with polybushes are not suitable for use if the shock isn`t upright or near upright.

They also do the bearing conversion for about £10 a side,no spacers though.

I have fitted new bushes which are a tad narrower than original,now the tube protrudes 1mm each side.Will keep an eye on it.

I think the top plates may have been ovalled when i had Spax on it,i remember on the 2012 RBRR the top nut came off and the shock  jumped out of the plate.

Steve

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On 23/08/2020 at 11:19, Steve P said:

I was reading on the Merlin website,they say Avo`s with polybushes are not suitable for use if the shock isn`t upright or near upright.

I think this is spot on. It’s not the angle itself that matters, but that shocks mounted at an angle usually change angle a fair bit as the suspension moves through its travel, and so rotate on their bushes. The AVO design has such a small contact area that this rotation years the bushes apart very quickly. It’s a clear design fault and it is disappointing that it has persisted for about 15 years now. Moral of the story?  Avoid AVO.....

Nick

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I've got a set of new GAZ Adjustables to fit on the Vitesse with some dark blue new poly top bush's which are quite hard. I will probably do in the next month anything to watch out for in fitting and setting them up, noting Pete's comment re subsequent wear in the top plate.

Were running adjustable Koni's on the Mk2 Spit been on 15+ years and still good, brought cheap on local eBay as NOS and I took them to the local Koni Service Centre who confirmed they were new, BUT that model/year/age had a fibre washer in them that didn't last so suggested a service to replace it, I was never sure if I wasn't taken, but the cost fitted cost me just under $230 so I was happy.

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2 hours ago, Peter Truman said:

I've got a set of new GAZ Adjustables to fit on the Vitesse

Peter,

I've fitted GAZ adjustables with blue poly bushes and they seem fine. Don't go any higher than a handful of clicks or your vision blurs! My fronts are on 3 clicks which seems fine but the rears on 1 but that's too soft for me.

Iain

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