Lotus Elan

Rear damper problems

PostPost by: paddy » Mon Apr 27, 2009 10:18 am

I've been tracking down some rear suspension noise and have a few problems / questions relating to the rear dampers. I'll know more when I get it fully apart but perhaps someone recognises these problems.

First, there is free movement of 2-3mm at the top end, with the entire strut assembly moving relative to the chassis mount. I assume this is a lotacone problem, or perhaps the nut at the top of the damper rod not being tight enough.

Second, there is free movement of 2-3mm of the damper insert in the strut itself. I don't know yet if it is just loose or incorrectly sized.

Third, the dampers seem to take a few strokes up and down before they do anything. If the car is left standing for a while (say an hour) and then you bounce up and down on the back, it will happily go up and down 4 or 5 times before the dampers kick in and start actually damping anything. Is this normal? I haven't experienced this with any other dampers before.

The dampers are ostensibly quite new, fitted by PO, and there is no evidence of any leaks. They are top-adjustable - I don't know the make yet but they might be the protech ones.

Assuming I can easily fix the problem at the top end, it looks like I have one or two problems to address:

- the fit in the strut - perhaps a spacer needed to stop any movement?
- the dampers might just be knackered and require replacement.

Has anyone had any problems with the protech ones? I've look back through the archives but didn't see anything specific about fit problems. Any recommendations for replacements?

I have standard (full width) springs and don't have a need to go to narrow ones. I'm not racing either.

I think this at least might explain why the rear end is so nervous. There is around 5 mm of travel that isn't damped and perhaps they're just not working properly at all.

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PostPost by: Elanintheforest » Mon Apr 27, 2009 11:24 am

Paddy, I think you?ll be amazed at how your Elan will handle when the rear suspension is set up properly?nervous it certainly ain?t! It sounds like the wrong sort of shocks, and they?re knackered, and the lotocones may well have passed their sell by date?.but you knew all that!

I would replace the shocks with Koni adjustable inserts, set on the softest setting, and available from the normal guys. Check that the rear springs are std as well, and while you?re in the area, check out the A frame bushes, diff mounts and diff tie rod bushes. Any one of these (cheap to replace) components being defective makes a big difference to the car. If the car is for road use, don?t be tempted to use polybushes. They transform the car alright, into something harsh, hard and horrible!

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PostPost by: paddy » Mon Apr 27, 2009 11:48 am

Thanks. All other bushes, diff mounts etc, all replaced quite recently (first attempt to eliminate the noise).

I'm annoyed I didn't find the damper problems when I had it apart last time. I definitely recommend fitting spring compressors when the car is at normal ride height, then lifting it and seeing what comes loose - it shows problems that are much harder to detect when at full droop and when the spring is forcing everything tight. I'm surprised it's not standard practice for an MOT - my daily driver just got a brand new certificate but on inspection the front suspension bushes were totally knackered.

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PostPost by: johnsimister » Mon Apr 27, 2009 3:52 pm

In my experience it's quite common for the rear dampers not to damp for the first couple of strokes when the car has sat for a while. Three Elans owned by friends all do it and so does mine, fitted with brand new Spax (which are a bit on the firm side, by the way, although I've covered only about 30 miles on them so far so they might ease off). Still doesn't explain why they do it, though. It is indeed odd.

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PostPost by: paddy » Mon Apr 27, 2009 11:16 pm

Update after taking everything apart:

The play at the top is because the lotocones are perished. Typical of PO to replace the dampers but not the rubber.

The play at the bottom was because the nut retaining the insert was happily working its way loose :( Good job I investigated. No loctite, no peening - what's recommended?

The upright was full of water - I guess that's probably not uncommon.

Anyway, it turns out I have very new looking Spax Krypton Gas adjustable dampers. It's ironic because when I had my first cars I would dream of having those yellow spax (yes, sad) and I've had them on the Elan this while without even knowing. They seem smooth although there were set close to the hardest setting ( = rock hard). They do require several strokes up and down to get going, and will revert to that state after standing for some minutes.

I'm committed now to having someone's surplus Konis (thanks) which I will probably fit now anyway (unless the collective opinion says otherwise). I get the feeling I'll be taking the front apart next ...

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PostPost by: ebc699 » Tue Apr 28, 2009 12:59 am

Hi Paddy,
I replaced the original Armstrong dampers in the Plus 2 with Spax Krypton adjustables and find, like John, that they take a bounce or two before they become effective. For some reason this only happens at the rear, the front, also on Spax is always firm. At the rear,the old dampers did this as well which is why I changed them.
As a matter of interest, after much tweaking I have finished up with both front and rear set quite close to the softest setting which suits the car really well.
Don't be in a hurry to discard the Spax's, I suspect that they are perfectly OK.
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PostPost by: elj221c » Tue Apr 28, 2009 8:21 am

Paddy,
Perhaps the upright was full of antifreeze instead of water? The fitting instructions for my Konis say to use 50ml of antifreeze in the strut housing before installing the insert.
Do the Spax adjust easily? If so they may be the better bet as the downside of my old Konis is that you have to take everything apart to adjust them.
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PostPost by: rgh0 » Tue Apr 28, 2009 8:22 am

I have also seen that spax's take a few strokes to become operational once they have been sitting for a while - this seems normal and must relate to the oil draining away from the piston when it sits.

It does not seem to affect the shocks performance

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PostPost by: steveww » Tue Apr 28, 2009 10:46 am

As you have found the big nut that holds the dampers in to the tube can work loose. Originally they were held in place by punching the thread. When I replaced the rear dampers on mine I used locktite to ensure they did not come undone.

As has already been mentioned the Elan is a very light car and as such only needs light damping. The fronts on mine are set at their lowest setting and the rears are only one "click" up from the softest.

I have poly bushes on mine and do not find it harsh but each to their own.
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PostPost by: paddy » Tue Apr 28, 2009 11:06 am

steveww wrote:As has already been mentioned the Elan is a very light car and as such only needs light damping. The fronts on mine are set at their lowest setting and the rears are only one "click" up from the softest.


The other day I replaced the rear dampers on by 2 ton Volvo estate and those seemed to be about the same stiffness the spax (on the setting they had been on).

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PostPost by: paddy » Mon May 04, 2009 7:40 pm

So with new lotacones and the Konis I have to say the behaviour is transformed. The rear end just sticks instead of skipping over the bumps.

Now on the mini roundabout test it's the front that can't keep up so that's the next thing to look at.

Thanks again for all the advice.

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