Author Topic: Tighten front suspension  (Read 1239 times)

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Offline Steve_Lindford

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Tighten front suspension
« on: Sunday,October 09, 2016, 12:50:20 AM »
Did I read somewhere that when I tighten up all my refurbished front suspension I am supposed to have someone in the driver seat to get the weight balance right??

If this is so important - surely that logically means I should consider the passenger side - is it usually empty or do I carry overweight passengers on a regular basis. When I sat in the car the other day the suspension didnt appear to move at all! - Im around 10 stone.

ALSO - the previous owner - and another ex Europa owner have both told me 'whatever you do - make sure you have something heavy like a bag of cement in the front of the car to help the general balance' - (and probably reduce understeer) I know what Colin Chapman would say.

Steve

Offline EuropaTC

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Re: Tighten front suspension
« Reply #1 on: Sunday,October 09, 2016, 12:58:44 AM »
Technically, yes you should have weight in the car. The idea is that when you finally tighten up the bolts the rubber in the wishbone bushes is at neutral position so movement up or down as the suspension moves will be at a minimum. As an extreme example, if you tightened the bolts when the suspension was on full droop then the rubber would be under a torsional load at normal ride height and over-stressed as the suspension compressed.

That's with OEM rubber bushes. If you use poly bushes, it doesn't count because the stainless tubes aren't bonded to the poly. 

Personally I haven't loaded up the car. What I do is assemble everything loosely, drive the car in and out of the workshop which settles it down and then grovel underneath to tighten everything up. Not technically correct but I'm ok with it. YMMV.....   ;)

Brian

Offline Steve_Lindford

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Re: Tighten front suspension
« Reply #2 on: Sunday,October 09, 2016, 02:17:08 AM »
I think what you have said is logical - Brian - I am using original type bushes.

It is the passenger situation which ruins the 'weight in car' theory for me. It would mean if it was set up for a passenger and you have none - you would have to hunt around for heavy objects to get the car balance right! Also the amount of rotation on those bushes must be amazingly small...

Offline BDA

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Re: Tighten front suspension
« Reply #3 on: Sunday,October 09, 2016, 07:40:34 AM »
An alternate method to Brian's is to jack up the car to it's normal ride height and with the wheel off, prop up the suspension to it's normal height with the wheel on (the radius of the tire). Then tighten everything. Less groveling!  :)

Offline EuropaTC

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Re: Tighten front suspension
« Reply #4 on: Sunday,October 09, 2016, 08:09:45 AM »
It is the passenger situation which ruins the 'weight in car' theory for me. It would mean if it was set up for a passenger and you have none - you would have to hunt around for heavy objects to get the car balance right! Also the amount of rotation on those bushes must be amazingly small...

I suppose it all depends on your viewpoint and for a track car it's probably more important but on normal roads I'm less convinced. The method I've outlined is what I've done for years on both an Elan & the Europa. The Europa went onto poly bushes last year, more out of my curiosity rather than  needing new bushes. The ones I took out were original 1990s ones that Spyder supplied with their tubular wishbones back then. 20-odd years service tells me it's not a critical procedure !

BDA - I think a small amount of grovelling is character building for a would-be Europa driver...     gets you ready for all those roadside maintenance jobs in the rain....    ;)

Offline Runningwild

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Re: Tighten front suspension
« Reply #5 on: Sunday,October 09, 2016, 08:40:30 AM »
I've replaced all the bushings with Poly.  With the body off the chassis Am I correct in thinking that now I can torque the front end completely?  Or should I add weight over the front wheels?

Offline jbcollier

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Re: Tighten front suspension
« Reply #6 on: Sunday,October 09, 2016, 08:48:18 AM »
You do not have to add weight to the car when tightening up the front suspension.  You do need to have the suspension at its "normal" position.  Put wooden blocks (not cement), ramps under the wheels so you can get under it.  Once on the ramps, wiggle the steering back and forth to settle the car before tightening up the a-arm nuts.

What you are trying to avoid is tightening the a-arms while the suspension is hanging free.  The a-arm bushings use bonded rubber as a "pivot".  The rubber twists when the suspension moves.  If you tighten things up with the suspension hanging then the rubber only twists the one way and it twists a long way that way!  It's too much and will tear the rubber in short order.  If you tighten the a-arms while the wheels are on the ground/ramps, then normally there is little to no "twist" on the rubber bush and it only deflects a reasonable amount in both directions.
« Last Edit: Sunday,October 09, 2016, 12:00:00 PM by jbcollier »

Offline jbcollier

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Re: Tighten front suspension
« Reply #7 on: Sunday,October 09, 2016, 08:49:20 AM »
Polyurethane bushings do not twist and can be tightened with the suspicion hanging.