Lotus Elan

Adjustable rear control Arm

PostPost by: gjz30075 » Thu Oct 29, 2009 12:15 am

I've been looking at adjustable rear arms and their various designs and saw this one from Kelvedon Motors. How in the world is it adjustable? By tweeking the metal?? What am I'm missing here?
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PostPost by: memini55 » Thu Oct 29, 2009 1:44 am

Greg,

Your guess is correct! The a-arms are reasonably flexable and you are only moving them a very slight amount. I made my own set out of some stock Moog parts and they work great. I am autocrossing an Elan and wanted to dial in the rear toe. Going to make another set this winter for my sons +2.

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PostPost by: stugilmour » Thu Oct 29, 2009 3:35 am

These appear similar to the one's I got from Spyder. Adjustment is fairly easy to do.

http://www.spydercars.co.uk/adjustable_ ... hbones.htm
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PostPost by: gjz30075 » Thu Oct 29, 2009 12:19 pm

So I guess the adjuster in the middle of a solid tube really does work :?

Mark, I'd love to see pics of your modifications. I'm trying to come up with something for my arms. Actually, my arms are fine, its the car's control arms that I want to mod..

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PostPost by: rcraven » Thu Oct 29, 2009 12:46 pm

What's a solid tube?
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PostPost by: andyelan » Thu Oct 29, 2009 3:36 pm

Hi Eveyone

This design looks a bit scary to me. I would have thought the idea behind the frame being fully triangulated was specifically to prevent it flexing. With this arrangement I can't see how adjustments can be made using the turnbuckle without putting a lot of stress into the welds. Still I suppose the designer has done all the appropriate stress calculations and is satisfied it's all ok

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PostPost by: gjz30075 » Thu Oct 29, 2009 3:51 pm

rcraven wrote:What's a solid tube?

Sorry, yes the tubes are hollow. In this context, I meant solid to mean no flexibility
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PostPost by: ceejay » Thu Oct 29, 2009 8:42 pm

If you have lathe turning skills (IE, you are able to cut right hand & left hand threads) you will be able to machine the adjusters from bright mild hex & round stock, the threads can also be cut with hand taps & dies, but left hand taps & dies are expensive to purchase. As the Spyder page say's... this is the best way to make the rear W'bones adjustable.

As we all know the elan was supplied EX factory with virtually no adjustments anywhere front or rear, that is all very well if everything with your chassis specs are absolutely spot on... but how many really are... even new replacements.
I am a great believer in having the the flexibility of adjustable wishbones both front & rear, as well as adjustable spring platforms front & rear. The bench mark is the standard spec settings, but if you wish to adjust + or - from the std bench mark you can do so without to much drama.

Having a fully adjustable setup allows suspension fine tuning to find the handling characteristics you desire, especially if you are involved in competitive track work, the next thing you should source is a suspension aligner/tuner who can set the car up using accurate laser or beam alignment equipment, that takes all of the guess work out of stuffing around with strings, home made gauges etc. Some may disagree with that, but suspension tuning is a specialist field.
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PostPost by: memini55 » Thu Oct 29, 2009 9:10 pm

Hi Greg and Col,

I sould finish with a little more detail on how we made our a-arms adjustable. I bought two tie rod ends with long threaded ends, one lh thread and one rh thread. Then a bought an adjustable threaded clamp which is used for suspension adjustment and is locked in place with two clamps with a bolt and nut arrangement. We cut the rod ends off the threaded portion and cut a section out of the a-arm and welded the threaded rods in place. This is a little hard to discribe but I will post a picture later tonight when I get home.

Now for the important step, as Col said I took the car to an good alignment shop and we set up as I wanted. Stock arms can be all over the place and can really cause the car to wander anywhere.
These work very well and have made a huge difference on the Elan we are autocrossing.

Mark
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PostPost by: Galwaylotus » Thu Oct 29, 2009 9:16 pm

rcraven wrote:What's a solid tube?

A bar!! :lol:
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PostPost by: Galwaylotus » Thu Oct 29, 2009 9:21 pm

gjz30075 wrote:I've been looking at adjustable rear arms and their various designs and saw this one from Kelvedon Motors. How in the world is it adjustable? By tweeking the metal?? What am I'm missing here?

Rose joints, also called rod ends. I'd have thought a better solution would be to replace the ends of the frame with rod end bearings for adjustment.
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PostPost by: andyelan » Thu Oct 29, 2009 9:54 pm

Hi Again Everyone

I too would tend to go with the solution suggested by Galwaylotus. If there were any concern about the use of hard rod ends (i.e. "Rose" joints) in a road car suspension, one could always substitute screw in eye which take the standard rubber bushes

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PostPost by: elancoupe » Thu Oct 29, 2009 10:04 pm

andyelan wrote:Hi Again Everyone

one could always substitute screw in eye which take the standard rubber bushes




I use the eyes with rubber bushes on my adjustable arms, have been very happy with them. I would think the rod ends would have limited life in normal street usage.
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PostPost by: memini55 » Thu Oct 29, 2009 10:27 pm

One thought on rod ends or rose joints, to make the adjustment you have to remove the bolt. With the other type of adjustment everything stays in place and the adjustment is realtime.

Just food for thought.

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PostPost by: gerrym » Thu Oct 29, 2009 11:11 pm

Andy, I have a pair of the Kelvedon adjustable toe-in rear wishbones.

The turnbuckle system (LH and RH threads) works very well. One adjusted, one tightens the locknuts and the whole assembly becomes very rigid. The welds only see a tiny strain as they are located a long way from the turnbuckle. In practise, works just the same as an adjustable track rod.

Only warning is to get plenty of lubrication into them before they seize up. Then cover with favorite denso tape or what ever works for you.

Note, using the same principle I've machined up a LH/RH turnbuckle system for an engine bay brace to run between the upper towers of the chassis.

Try these guys for all the parts you should need
http://www.mcgillmotorsports.co.uk/inde ... t&catId=19 except a LH/RH male threaded stud which you should be able to get machined by a local shop for a reasonable sum

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