Lotus Elan

Lotus elan bump limiter

PostPost by: Dieschelan » Sun Nov 28, 2021 10:45 am

Hi

I’m rebuilding the rear suspension of my S3. I will buy the rear bump stop rubber and rebuild the classic Koni shocks.
I have read about the bump limiting spacers. Are these parts really neccesary? Where can I buy these parts?

Cheers

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PostPost by: Elanintheforest » Sun Nov 28, 2021 11:13 am

Diego, spacers are used on shock inserts that are used to limit the travel of the rear suspension so that solid shafts won't lock up. The only reason they are needed is that the travel limited insert is shorter (by 15mm or so) than the standard insert. If you put spacers in with your standard inserts you wont be able to screw the tops back on.

I've just fitted the TTR 'comfort' inserts to the rear of my S3, and without the spacers fitted into the bottom of the tube, the inset would rattle around .

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PostPost by: rgh0 » Sun Nov 28, 2021 11:23 am

I think its the spacers that Lotus added to later plus 2 to bring the Aeon rubber spring into play earlier in bump travel. These were about 20 mm high and made from alloy with a lip on the bottom that could be peened to grip the top of the strut. They were added to assist with the suspension performance on a fully loaded Plus 2

I don't think they are available new today.

Depending on you overall suspension setup they may assist with an Elan to make the suspension work better with modern sticky tyres

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PostPost by: jono » Sun Nov 28, 2021 7:28 pm

My early Plus 2 (current resto) does not have them as they were a later introduction so, with the help of my friend, a pair were made up on his lathe using aluminium bar. Instead of peening the ends we used a couple of pointed grub screws which contact with dimples drilled into the hex nut on the strut insert (modern inserts used).

They also give the Aeons something to 'land' on - the hex heads on modern inserts are not ideal

I also used a thick washer in the bottom of each housing - as mentioned above the modern strut inserts will rattle if you don't - also, stake the tube housing to prevent them coming loose (as Lotus did).

I made mine to achieve 25mm increase before the Aeon rubbers come into play which is pretty much as I recall it from my previous Plus 2
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PostPost by: Frogelan » Mon Nov 29, 2021 6:40 pm

I'll just add an idea here if I may.

I am intending to use the spacers above and below the rubber bump springs and have had these made up in PTFE.

When I finally get the car finished I'll report back !

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PostPost by: jono » Mon Nov 29, 2021 6:46 pm

I considered nylon or ptfe but it's a bugger to turn apparently, and aluminium looks more 'original'
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PostPost by: rgh0 » Mon Nov 29, 2021 8:01 pm

Frogelan wrote:I'll just add an idea here if I may.

I am intending to use the spacers above and below the rubber bump springs and have had these made up in PTFE.

When I finally get the car finished I'll report back !

Andrew


That is what I have done and it works well. I used suitable off the shelf poly bushes of the right diameter and thickness and hole size

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PostPost by: RichardHawkins » Tue Nov 30, 2021 7:21 pm

Frogelan,

Why do you intend to use PTFE? PTFE is expensive to use as a spacer.

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PostPost by: Frogelan » Tue Nov 30, 2021 7:26 pm

To reduce friction and reduce NVH.

Yes, it is expensive, but the material is cheaper than the machining.

I'm also planning to make a steering column bearing (at the firewall) with it.

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PostPost by: nmauduit » Tue Nov 30, 2021 7:31 pm

Frogelan wrote:To reduce friction and reduce NVH.

You may then further reduce friction and improve non suspended weight by attaching them at the top of the rod...
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PostPost by: Frogelan » Tue Nov 30, 2021 7:39 pm

Interesting idea (that I had considered) but to start with I'm using the TTR top bearing type top mounts.

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