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Can anyone tell me what torque the front upper wishbone stud nuts should be tightened to?

Spent the day fitting new wishbone bushes, new shockers and rebuilding my front brakes. Don't want to screw up the job at the final stage by over tightening the stud!

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So that's just about 70 nm then. Same as for the rear lower link/hub stud? (did that one last week...!)

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Hi Neil,

Which shocks/ bushes did you end up going for?

Ta, Dave

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Hi Neil,

Which shocks/ bushes did you end up going for?

Ta, Dave

 

I went for the standard top wishbone bushes from SJ. I subsequently read that Polybushes aren't a good idea for top wishbones so that turned out to be the right decision.

 

The lower arm bushes are also standard from SJ but in the lower (fixed) wishbone I used SJ Polybushes because I had a couple left over from another job on the rear.

 

All pushed in using a large engineers vice.

 

The shocks are standard Lotus, direct from my local dealer for just about £37 each. Cheaper than I could find at any of the specialists!

 

I also changed the ARB bushes in the lower arm using a special tool borrowed from PilotSteve and some 10mm studding/washers to wind them in.  See this thread http://www.thelotusforums.com/forums/topic/68222-arb-bush-insertion-tool/

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So you did all the rears with the SJ polys? Interested to know how you find them in service when you get her ready.

Got my eye on Steve's tool ( oooeerr missus :)) for my dead ARB bushes too. Again, SJ polys or otherwise?

Which dealer did you go to, at that price it's not worth the hassle of rebushing my current ones...yours are probably different from mine(82), but might be worth a look..

Good luck with the alignment btw.

D

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So you did all the rears with the SJ polys? Interested to know how you find them in service when you get her ready.

Got my eye on Steve's tool ( oooeerr missus :)) for my dead ARB bushes too. Again, SJ polys or otherwise?

Which dealer did you go to, at that price it's not worth the hassle of rebushing my current ones...yours are probably different from mine(82), but might be worth a look..

Good luck with the alignment btw.

D

 

The only thing I've done at the rear is to replace one of the lower links, which was bent by the PO. I'd planned to Polybush the opposing link to match but after my experience with the lower link stud removal I decided to leave well alone... Hence I had a couple of Polys left over that turned out to be the ones I needed for the front  :D 

 

I got the shocks and standard Lotus ARB bushes from Snows Lotus in Hedge End, Southampton. The parts guy down there Cliff ([email protected]) is pretty helpful.

 

The ARB bushes were about £25 each, so a few pence cheaper than SJ and I could collect them to avoid any postage.

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Hello Neil,

 

I see from your above post that "I went for the standard top wishbone bushes from SJ. I subsequently read that Polybushes aren't a good idea for top wishbones so that turned out to be the right decision."

 

As I am in the process of re-bushing my Excel suspension where did you get that information please - don't want to make the same mistake

 

Though I do note that Superflex make a Front Upper Wishbone Kit as well as a Rear Transverse Link Kit which if not good I'm surprised at.

 

I also note that Superflex do not make lower link to chassis bushes either, but tha\t's perhaps another matter

 

 

 

Brian

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Hello Neil,

 

I see from your above post that "I went for the standard top wishbone bushes from SJ. I subsequently read that Polybushes aren't a good idea for top wishbones so that turned out to be the right decision."

 

As I am in the process of re-bushing my Excel suspension where did you get that information please - don't want to make the same mistake

 

Though I do note that Superflex make a Front Upper Wishbone Kit as well as a Rear Transverse Link Kit which if not good I'm surprised at.

 

I also note that Superflex do not make lower link to chassis bushes either, but tha\t's perhaps another matter

 

 

 

Brian

 

I read it here on the forum somewhere. IIRC it was something to do with the ability of the polybushes to rotate around the central collar and the fact that they are so small the poly doesn't really make any difference anyway.

 

I'm sure i read that some people who have used them have found they have 'wound' out of the wishbone somehow over time. Not sure how that happens...

 

I'm no expert on this and i'd already plumped for the standard rubber ones anyway. They were easy to wind in with a large vice so no need for a press unless you already have access to one.

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Note that the early Turbo chassis (pre-SE) used an anti-dive suspension geometry which also contributed to pitch control. It also incorporated a built-in pivot axis misalignment for the front arms which resulted in the bushings being put into a bind condition as the suspension moved off the normal ride height position. By doing that, and carefully balancing bushing durometer, Lotus was using bushing compliance to fine-tune overall wheel-rate in as the suspension moved.
From the SE onward, the chassis used pro-dive (opposite of anti-dive) and no bushing compliance geometry. (Therefore, directly comparing the effects of spring rates between early and later models isn't really possible).

 

In a system designed to require compliance, something has to give. In a contest between steel and urethane, I'd bet on the steel bits surviving, and the urethane bits taking the brunt of the abuse. I doubt that the polybush vendors who recommend hard bushings for the Esprit are aware of the Lotus design's offset axis, and it's reliance upon compliance

Edited by MrDangerUS

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So MrDangerUS, does that mean, that on the SE onwards, you can use poly bushings?

 

Kind regards,

Jacques.

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Here's the rest of that quote 

http://www.thelotusforums.com/forums/topic/64078-spring-and-damper-recommendations-for-86-turbo/?p=506289

 

Here is a good explanation from Tim Engel:

 

Note that the early Turbo chassis (pre-SE) used an anti-dive suspension geometry which also contributed to pitch control. It also incorporated a built-in pivot axis misalignment for the front arms which resulted in the bushings being put into a bind condition as the suspension moved off the normal ride height position. By doing that, and carefully balancing bushing durometer, they were using bushing compliance to fine-tune overall wheel-rate in as the suspension moved.
From the SE onward, the chassis used pro-dive (opposite of anti-dive) and no bushing compliance geometry. So, directly comparing the effects of spring rates between early and later models isn't really possible.

For the X180R, Lotus actually welded the old anti-dive/ bushing compliance "T" cross-member to the SE chassis because they wanted to better control pitch in the race car. Lotus introduced its own polybush set. Theirs was unique compared to most aftermarket bushings in that Lotus kept the durometer down in a range similar to the original rubber bushings. Generically speaking of all applications, most aftermarket polybushings are considerably harder than stock.  Their selling-point is to firm-up the suspension for better performance.

However, in a system designed to require compliance, something has to give. In a contest between steel and urethane, I'd bet on the steel bits surviving, and the urethane bits taking the brunt of the abuse. I doubt that the polybush vendors who recommend hard bushings for the Esprit are aware of the Lotus design's offset axis, and it's reliance upon compliance.
*~*~*
The Esprit (Europa, Elite-Eclat) trailing arm rear suspension has a similar but different requirement for compliance. The hub carrier doesn't just go straight up and down. It's hard-bolted to the end of the trailing arm, which swings in an arc in side view.  If the trailing arm swings down 10 degrees, then the hub carrier rotates 10 degrees as it goes down. As a result, the studs for the shock and lateral link also rotate 10 degrees, while the bushing eyes in the shock and lateral links do not. That creates a bind. Both the Lotus OEM rubber bushing and Lotus' own polybush kit use a softer durometer that provides sufficient compliance to absorb the hub's rotation from full droop to full bounce. It's a requirement, not an option.
If you put hard polybushings in the rear suspension, you'll create a similar bind between steel and urethane. A hard urethane will lose, while a softer, more compliant urethane will survive. Rubber is particularly good at compliance.

Have you ever replaced the Esprit's rear shocks?  With the suspension at full droop, there's a significant miss-alignment between the stud in the hub carrier and the bottom eye of the shock.  To ease assembly, use a floor jack to raise the hub carrier to normal ride height position with the stud horizontal.  Then it's necessary to compress the spring in order to shorten the shock to meet the stud.  Then they align and slide together easily. It's variation on the same issue... at full droop the stud is no longer horizontal.

Polyurethane is an acceptable bushing material for rubber, especially if the OEM rubber parts are unobtainium. The point to all this is to maintain a similar durometer for the Esprit's 'required' compliance.

Polyurethane is available in grades all the way from rock hard to squishy GummyBear/ fake bait soft. To some, "urethane" automatically means "harder" for suspension bushings. No! It doesn't have to, and harder is a poor choice for the Esprit's suspension.  As I mentioned previously, the rubber in the stock Esprit bushings is about 60 Shore A durometer.  Ball park +/-

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Good writeup. Thanks Travis. I shall be steering well clear of generic polybushes. 

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I think if you're going to fit anything it should be the genuine Lotac poly bushes, Vanya. They're bloody expensive for what they are, made me wince a bit when I checked, but at least you know they're for for purpose, with the correct hardness.

I don't know what model of Esprit is being referred to in the passage, but I didn't experience the kind of misalignment described on the rear dampers, nor did I have to compress the springs at all. Maybe the S4s dampers are a different length? There's very little compression from unloaded to loaded on the rear of my car, but much more movement on the front suspension.

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Yeah I haven't had the courage to buy the new LOTAC stuff - it's just incredibly costly. I'm going to go with original bushes all round and LOTAC where originals are unobtanium. 

 

Re: misalignment - this is most easily seen if you undo the lower link to chassis in the rear - you won't be able to re-attach it unless the spring is compressed because it's at an angle. I think that's what he meant, except at the hub. 

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Yeah, I get what he meant, it just didn't happen that way for me, though.

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