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MG Midget and Sprite Technical - Midget Supesion mods Part 2

Thanks for all the info on my previous thread.

Next question.

MBG Front Lever Arms on a midget.

I hear that you can fit them and they do improve handling. Also running this set up would keep within HRCR regs.

Can you still use the top trunnions as I use Peter May neg camber trunnions. If there's a mod to fit them what is it?

I'm just wondering which way to go.

Thanks

Peter
Peter King

I dont think mgb shocks on a midget is possiable without some serious modification work, and even then, im not sure it would be worth it ....ive never seen or heard of it being done before

Have you looked at the frontline conversion...put that on barry king wishbones and you may have something

Prop
Prop and the Blackhole Midget

Prop,
this is racing/rally stuff so some rules/regs you're not allowed to break/bend as much as others

Peter,
the racey lads are around at the moment so you should get some info soon
Nigel Atkins

Nigel.

Can you give some basics for how this is done... Id think the lever would be to long to begin with

Wouldnt just a damper valve from a triumph TR6 work judt as well


Prop
Prop and the Blackhole Midget

Peter,

I'm not sure about the specifics such as the trunnion details but I can remember hearing of this mod decades ago and it has cropped up on the BBS before IIRC and it always seemed to involve an adapter plate to go between the MGB damper and the spridget damper mounts to deal with the differing hole centres or positions for a bolt on mod. I suppose you could weld in new captive nuts to take the MGB dampers directly. IIRC the adapter plate raised damper which wasn't great for the geometry but that was a trade off for better damping and a more rigid top link. I think if Prop hasn't heard of it before then he hasn't been paying attention.
David Billington

There is a pic of an MGB damper on a race car in Daniels book (older version).

Cue Daniel !
richard boobier

what david said, with a side order of richard.

I had heard that the plate under the damper brought a bit of -ve camber to the party, but I think that's only for a midget arm that would stay the same length.
Rob Armstrong

Some of you will remember David Coulthard who used to sprint a white Midget and contribute on here, I think he had the MGB lever arm conversion on that. I think it used to be fairly common. Definitely seen it before.
John Payne

As mentioned above, there is an adapter that sits between the shock mount and the shock itself.

IIRC there are two hole line up with the originals, then the inner most hole is bolted down through the adapter plate using a countersunk screw.

Two further holes are drilled and tapped in the plate to allow the fitment of the inner MGB shock mounting bolts.

I dont remember what happens at the trunnion end though, sorry, but I do believe its a standard midget top trunnion, I will no doubt be proved wrong there
PeterJMoore

I dont get how ive never heard of this, i thought i heard it all..intresting for sure.

I guess my question is why ??? Whats the benifits....im guessing this is an out dated mod, because the peter cardwell shocks are more then enough to do the job and modernday telescope shocks are alot easier to apply then would appear the MGB levers

I guess its a good mod if you are trying to pull one over for historic racing and wanted a cheating advantage

Prop
Prop and the Blackhole Midget

it solves one of the problems with the midget front suspension, which is the flexing of the damper arm, while still being eligible for racing.
Rob Armstrong

Eligible for what racing??

Not FIA Appendix K becaus that states the shock type a bit more than just a leverarm......
Onno K

******It solves one of the problems with the midget front suspension, which is the flexing of the damper arm*****

Jesus.... That thing flexes ???, HOW !!!

Wow, this is turning into a day of realising of how much i dont really know.

Prop
Prop and the Blackhole Midget

Thanks for all your help Guy's.

I can't use frontline because it incorporates telescopic front shocks.

HRCR regs say you have to use lever arms and thats why I was wondering about MGB shocks as it keeps it within the regs or so to speak.

I may have to go Peter May for fabricate myself.

Peter
Peter King

Peter,

Do the regs say you can't use telescopics or that you have to retain the lever arms. IIRC I've seen/heard of telescopics being used for the damping but the lever arms remain but non valved and with the Peter may type arms to improve rigidity. Maybe not what was intended but within the letter of the rules. Just depends on which set of rules you play by.
David Billington

David,

THe example that I have seen is what I think is a Frontline kit.

This is what HRCR say about front suspension

Front.
Lever arm.
The fitting of a front damper top link kit so as to provide an additional link on the opposite side of the lever armshock absorber to the original lever arm is permitted. The top link kit is available from peter@petermayengineering.co.uk

I've attached a picture of what's not allowed.

Regards

Peter




Peter King

David is correct... They do make a kit that uses the lever arm just as a control arm andd has a telescope shock..id think it would fall in the technicalities of the rule

Minimania.com sells the kit here in the usa, but being minispares in the uk is a sister to minimania, im sure they could get them also


Prop
Prop and the Blackhole Midget

Peter,

What you have indicated may specifically preclude the use of the FL unit but you haven't posted enough information from the regs to say whether a telescopic fitted along side a PM assisted lever arm is allowed. IE do the regs require the damping be done by a lever arm damper or do the regs just require the lever arm damper to be present but no indication of whether it needs to perform a damping function. These questions are old as I remember the same discussions about regs interpretations 25 years ago where the same questions occurred.
David Billington

I always thought that the MGB damper was 'allowed' as it was a lever arm - I've not read the regs though, so am willing to be corrected!

re flexing of the arm, I could feel it when braking hard in the dry, the same feeling you get on a steel forked pushbike when braking hard with the front brake, a sort of difference between expected and actual slowing down for the first microsecond of braking is the best way I can describe it. It's why I triangulated my top link.
Rob Armstrong

I have twin lever arm dampers on the Frog. There are several different versions but if you opt the for Austin A60 ones with the top resevoir and cranked arm there is no need for an adapter plate and the arm length gives essentially zero camber. The first pair I had lasted about 60000 miles (or 3 engines and 2 gearboxes in my case)so they've been pretty robust on the Sprite. 2 mounting holes are carry over and you need to drill 2 more - but I've only ever bothered with 1 and in 40 or so MOT's they've never attracted any comment.The fulcrun pin takes standard bushes and the Sprite trunnion is carried over but turned 180 degrees. The bottom line is they are so over engineered for a Sprite they never wear out and all the loads stay on centerline as intended so the pan is never subject to twist. They sometimes come up on eBay http://www.ebay.co.uk/itm/AUSTIN-A60-MG-MAGNETTE-MORRIS-OXFORD-RILEY-WOLSELEY-FRONT-SHOCK-ABSORBERS-/261120395187?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3ccbfd07b3
F Pollock

Wow F.

Ive not seen that before...im a fan for sure, i like that infact i like this more then the MGB levers...that just looks so stable and easy to install...not bad at all... And its double valved as well as over built
Im tempted to give that a try

Prop
Prop and the Blackhole Midget

No,no please don't. Get that thing running first.
F Pollock

I've reactivated this thread because I quite fancy the A60 front damper mod that Fergus (F. Pollock) describes.
However, Yesterday I compared an A60 damper to a Midget one and for the life of me I can't see how it can be done without a lot of work.
Fergus says that two holes are carried over. I can't see how that can be, because the A60 holes are wider apart at the outboard end and the space between the two arms for the top trunnion is much too wide for the Midget one.

If you're reading this Fergus, could you please enlighten me as to how you achieved the mod, preferably with pictures.
Or if anyone else has done it, perhaps they could advise.

(I emailed Fergus at the above address, but it bounced back.)
Bernie Higginson

Sorry, only jus pt seen this! I was about to embark on this mod for my road midget but I have decided to replace all bushes first and get the original dampers working as best I can before I do any modding.

Anyway! I was about (still thinking about it) to buy the adapter plate from mambamotorsport think it's around 100 quid. And John, the guy who makes them seems a top bloke, I have spoken to him over the phone a couple of times.

And with regards to the trunion, he makes a slightly wider upper bush to fit the original trunion to the MGB damper.

Hope that helps!
Karl Bielby

Assuming you can mount the A60 damper, could you use two Midget arms on it. 1 left hand and 1 right side. Would that leave the correct gap for the Midget top trunion?

Rob
Rob aka MG Moneypit

Bernie - apologies I was incorrect as actually only 1 original mounting hole is carry over - the others need to be drilled through. Once you have the A60 damper lined up in position it will be fairly obvious which is which. The arms are wider than the trunnion, but I added a washer each side to make an interference fit. I reverted back to standard dampers last year so can't show you any pictures I'm afraid - but if I was doing it again and to save on the drilling I'd probably shell out and opt for the Mamba plates.
Fergus

Fergus. Thanks for your reply and explanation. Am I correct in thinking that the MGB and A60 shocks have the same "footprint" and both would fit the plate? If so, would the MGB one be more suitable because the front end weight is closer to that of a Spridget than the A60, or is it the cranked arms of the A60 shock which make it the better choice?
Sorry for all the questions, but I'd like to get it right at the first attempt and you have already done it successfully.
BTW. Did you switch back to standard for originality?

Karl. Thanks for the info on the top trunnion.
Bernie Higginson

I swapped back mainly for originality along with a change to a narrower tyre. I think both bodies are the same, and it's the arms that are specific to MGB, A60 and Big Healey etc.In terms of front end weight I wouldn't get too excited about it as you'll probably need to tune the viscosities to achieve a matched pair - a bit like you do with SU's sometimes. I always found the A60 dampers beautifully compliant - the only negative being a lack of self centering. But that was almost certainly down to running 18psi on 206X60's than any alteration of caster.If you go the Mamba route it would make sense to use MGB as I guess someone there has worked out the geometry.In that way you'll be buying into an engineered package.In your boots I'd make a trip and see it first hand - or go to Olton Park if they've got a car running.
Fergus

Fergus. Thanks again for all that. It's given me food for thought and all the information needed to make a choice.
Bernie Higginson

This thread was discussed between 11/12/2012 and 08/05/2016

MG Midget and Sprite Technical index

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