Lotus Elan and Lotus Elan Plus 2 Forums

Hi Guys,
I rebuilt the suspension of my +2 a while back and have been annoyed by a loud bang from the rear of the car (Passenger side)..
During the renovation I fitted TT sliding spline drive shafts and droop limiting dampers to match.
The noise seemed ot be linked to going over recessed drains, and was very variable..
Initially I thought It may be something in the boot (trunk), so removed everything and tightened down the battery!
This made things way worse.
Then I experimented with increasing the load (added two children to the rear seats and a wife to the front (no comments about her weight!)), and no matter how I hit those drains, no noise.
So I have concluded that on full extension the dampers are hitting the end stops and making a big clunk.
In fact I can hear it now when the car is completely empty and I push the car up and down, the noise is only on rebound!!
So anyone any ideas of how to solve this apart from the current methods which are to always travel with friends (or fat hitchhikers) or run with a bag of sand in the boot?
I am wondering about putting a strap around the springs to reduce full droop a little, or whether increasing the dampening may work to help (It does seem a little bouncy at the rear at the mo!)
Cheers for any help
Tim

Tim,
Don't know if this applies for a +2. The newer lotocones have a slightly shorter metal bushing moulded into the center. I had the special sleeved nut cinched up hard but still the strut was loose to move up and down by about 0.5mm. It made a horribly LOUD clunking noise. IIRC, I added a 3mm spacer to more than makeup the difference and the noise went away.

Unfortunately I changed the lotocone on the other side , but not this side, and it seemed pretty clamped!
Cheers
Tim

Tim i would try inceasing the damping as you suggest drain covers dont affect my sprint like this and it soaks up the bumps unless your doing 90 mph of course. When i push down on the rear wing the car rises back to it original position with no overshoot or bounce.

regards

Ian

Tim,
I know someone who fitted TT shafts to his Sprint and then found that if the suspension went to full droop, e.g. hump-backed bridge, etc. there was a binding action in the joints and a LOT of noise. This is because the shafts are primarily designed for racing and the associated shorter suspension movement which causes less deflection in the angles of the drive shafts. TT took the shafts back and he went to Spyder.
Also know someone who fixed this by relieving the offending bits with a grinder!
My MM shafts bind ever so slightly if the rear of the car is jacked right up but I don't experience any noise on the road as I don't thing the load ever comes completely off.

Cheers,
Pete.

sounds like a duff shock to me - -ed

I think I had this problem when I fitted the TT shafts - it was caused by one of the bolt heads hitting the sides of the yoke at full droop, suggest have a look and see if any evidence of the yoke being marked by a bolt head or jack up car and with suspension at full droop rotate a wheel and see if the gap between one of the 7/16 bolt heads and yoke are dangerously near!
Since fitting I lowered the car for racing and even now one bolt head is significantly nearer the yoke than the others.
You may not have the problem but if you have not checked it may be worth trying
Ear plugs are another option
Richard

Will check the bolt heads..
Originally I fitted the shafts with standard shocks and became aware of the binding of the joints. I phoned TT and he said it wasn't a problem unless you "jumped" humpback bridges!
I didn't like this solution so I go hold of some droop limited dampers.
On fitting and testing at full droop they seem to work fine without any binding.
However I guess things could have moved, I'll check.
However I now realise that droop limited dampers would also lead to the damper becoming fully extended more easily..
This could be a problem I guess.
Cheers
Tim

How high does your car sit at the rear? Can you get your fist under the arch? If it is really high (new/wrong springs?) Then you will be running out of travel sooner than you need to. If it never clonks with weight in regardless of the amount of rebound that you get (on a humpback bridge for instance) then you need to be looking elsewhere for the problem. If it clonks when empty I would put the car on ramps (or wheel off with something under the bottom of the susp leg, and while someone bounces the car to make the noise use a length of dowel against your ear and the susp leg at different points and you should be able to work out where the noise is coming from. Use thick dowel or a broom handle, NOT something that could be forced into your ear! Great techniqu for tracking down engine noises as well.

Good luck!

I don't think its too high, and the one thing that I didn't fit during the rear end rebuild was the springs...
It only seems to clonk without wieght in the back..
Have been commuting for a week with a full laden boot without any noises.
When it was empty it clonked over every manhole and on the bad ones you could hear the spring resonate with the clonk..
It doesn't clonk on humback bridges fully laden...
Next week (hopefully) I should get a chance to look it over properly..
Cheers
Tim