Adjustable rear control Arm

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?

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.

Mark
USA

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

spydercars.co.uk/adjustable_ … hbones.htm

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

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…

Greg Z

What’s a solid tube?

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

Regards
Andy

Sorry, yes the tubes are hollow. In this context, I meant solid to mean no flexibility

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.
Col.

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

A bar!! :laughing:

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.

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

Regards
Andy

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.

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.

Mark

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
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

Regards
Gerry

…nearly there…

Details John? Or do you fancy making a ‘kit’ for each side? and passing them round? :unamused: :laughing:

What material for the r/h & l/h ’ bobbin’ (EN8??) what dia have you gone for? 1/2’'unf?.. etc. Great if you could share the info. I have been looking at this for a wee while now. No need in doing it twice!

Well done! did you do the turning etc yourself?

Alex…

Got me a length of 1/2"hex steel EN**,chopped into 4 3/16" pieces,cut out 3 3/8" of A-frame
A bag full of 1/2" BSF LH and RH full nuts and a right and left hand 1/2" BSF die

Turned down half (in quantity and size) the full nuts to 3/4" to fit the A-frame bore, the other half (in number) being used for locknuts…

Don’t know wether to glue :laughing: .solder :laughing: braze or weld the half nuts in the tube??

John :wink:

P.S.as I’m no engineer it wouldn’t be fair of my to inflict my meddlings on other folk (elf and safety?)

Greg,

As said I am posting a couple photo’s of the a-arm mods which we have done to our Elan.
I can get the Moog part numbers if you want and provide them for you also. Just let me know.

John

Your design looks to be and should work well!

Mark


Hi All, John…

Braze or weld John. Rest looks ok. Loads on this component are either tension or compression (Mainly!)

To make the rh/lh ‘bobbin’, I thought about using two bolts rh & lh. At least 1/2’’ dia, placing back to back after machining a groove / lip on the end of the hexes then welding them carefully (Tig or Mig) together, welding down into the machined area will allow removal of any excess weld, and restore the hex for adjusting.

Basically the same as you for the ‘inserts’ into the tubes. I.E. turn down nuts. 1 l/h & 1 r/h and assemble the ‘bobbin’ with locknuts etc and press the 'inserts into the cut tube ends.Then just weld the 'inserts into place. Bingo…

I will be doing this mod over the winter months.

Thanks for the info…

Mark… This method worthy of investgation also. Please do provide the part numbers. I take it the threaded ‘stubs’ are welded into the tubes?

Again thanks for the info’… Super interesting…

Alex…