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Suspension question

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rgsSpider
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Suspension question

Postby rgsSpider » 28 Oct 2012 16:49

I have replaced the rear shocks/springs. I went with original setup as I wasn't interested in getting fancy with it for now. So now my rear feels nice and comfy, but the front feels more like there are steel rods in place rather than any sort of suspension. My mechanic mentioned once about how stiff the front was and that someone must have put in stiffer components...no kidding! My question is, is this due to stiffer springs? Stiffer struts? Both? I really just want it to be like original, no interest in a stiffer suspension for now.

Randy

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FI Spyder
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Postby FI Spyder » 28 Oct 2012 17:00

I think the front is (feels) stiffer naturally and quite possibly the reason the tire pressure specs are 24lb. front 28lb. rear. I run mine 30 to 32 anyways. My suspension is new standard springs/inserts front and old springs/existing Koni's rear.


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bottomtop
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Postby bottomtop » 29 Oct 2012 00:04

I'm no expert on suspension, but as I understand it different types of suspension tweaks will give different impressions or results in terms of stiffness or rigidity. If what you mean is stiffness over bumps or imperfections in the road, then both springs and struts can be responsible for that. Harder bushings on some of the suspension components can also create that effect, but I think probably springs and struts would have more of a noticable effect in day to day driving. Many of the struts that are very hard are in fact adjustable, so the effect may be able to be reduced. But if the struts have been tuned to match a particular spring rate, I wouldn't feel confident to re-adjust them just for comfort purposes for fear of creating unpredicatable consequences.

Mr Hasbeen and Mr Beans who post here regularly have sometimes disclosed an intricate knowledge of the black art that is suspension tuning.....

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Postby Hasbeen » 29 Oct 2012 07:08

Randy no one can tell you how to set up your car for your usage, in your district, but for what it is worth, here's mine.

I live out of town, with most driving on reasonable standard country roads, not smooth, but not full of pot holes either.

My 7 is a 100% road car. The engine is a little warmed over UK spec, so a probably about 115 BHP.

It is on after market 13" X 6" wheels, with 185 front & 205 rear tyres.

I have stock springs front & back, reset & retempered by a good spring works to stock length front, & 11/16" shorter at the back.

I have medium polly bushes through out the front, with an anti dive kit. The rear has the same polly bushes on the diff, but hard rubber bushes at the body end of the radius rods & trailing arms.

The shocks are as new, stock front & back.

The main improvement is 30% heavier anti roll bars, front & back. These make virtually no difference to spring rate, so do not destroy the ride, but dramatically reduce body roll, & make a great improvement in "turn in" behaviour. The car is nicely set up for our roads, & is a joy on gravel.

My 8 is a 4.6L, with over 320 BHP, & is expected to perform occasionally on the sprint track, but it's main job is road car.

It is on 15"X7" wheels with 185s front & 215s rear. The fender/guards have rolled lips to handle these.

It has 200Lb springs, lowered 1.5" front, & stock springs lowered also 1.5" at the rear.

it has heavy polly bushes everywhere, with the front sub frame lowered 28mm, [bit over an inch], an anti dive kit, & competition heavy adjustable shocks all round.

It also has the 30% heavier anti boll bars front & rear.

Add a ZF high stall auto, & a stronger diff, with a good LSD, & you have a car that is pretty quick on good roads, but a bit compromised on average country stuff.

It is biased to rear traction, & you can understeer it off the road, if you don't drive it properly. It is also a pain around speed bumps.

The only way I know that would answer your question would be to remove a strut, take the spring off & test it. Time consuming, but not hard, & worth doing if you think your car has modifications unsuitable for you.

Hasbeen

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Postby Beans » 30 Oct 2012 20:28

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hasbeen</i>

The only way I know that would answer your question would be to remove a strut, take the spring off & test it ... <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Can't fault this advise, it also gives you the opportunity to check the front shock absorbers.
Could be that they are either set to firm or need replacing due to blocked valves.

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rgsSpider
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Postby rgsSpider » 31 Oct 2012 01:28

So again it sounds like I've got my work cut out for me! Thanks everyone for the advice.

Randy

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Postby busheytrader » 03 Nov 2012 20:13

Just a thought.............maybe the front of the car is sitting just off the bumpstops? There's many a 7 that's lost its front ride height because the original springs sag over the years..

Back in the late 80's, the std front shocks on my 7 were worn out after just 33,000 miles. I bought a pair of Spax and Triumphtune's shortened poly bumpstops and uprated springs to upgrade the front.

IIRC, Triumphtune’s literature stated that the std rear suspension on a 7 had around 8" of travel but the front had much less at around 1 1/2 - 2". Once the front springs start to sag, there’s even less travel before hitting the bumpstops. The shorter poly bumpstops allowed almost twice the travel and because they were conical were much more progressive if the suspension grounded. They are still fitted to the car which rarely bottoms out even now on the bumpiest roads.

Adam


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rgsSpider
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Postby rgsSpider » 03 Nov 2012 21:34

Thanks Adam, I'll have to check on that. The front springs/struts were replaced by PO but that doesn't mean it was done correctly!

Randy

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