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MG Midget and Sprite Technical - Front Wishbone Modification (?)


O.K. - now this seems a little weird...Described as a MG midget A-arm and spindle set on eBay (USA)

Here is the text from the eBay listing:
"...Up for sale are a pair of A-arms (wishbones) and spindle set up off a SCCA midget race car. This set up will eliminate the need for kingpin. Uses 7"-8" springs. Offers better steering control. These are used and will fit any MG Midget or Sprite..."

eBay Item number: 140489450993

My question is - has anyone else seen anything similar to this across The Pond? Can you achieve sufficient strength using something that looks like a rose joint welded onto the side of a wishbone pan where the fulcrum pin used to be? Is this modification common on the race circuit? Inquiring minds want to know...

Thanks for any technical insight or interpretation...

Mike P.
Buffalo, NY




Mike Pelone

Wow, that looks frightening!

I don't think that rose joints are designed to take loads like that, and as flex on the threaded rod they slip onto...
Will Munns

"I don't think that rose joints are designed to take loads like that"

They aren't - that is downright bloody dangerous!

Another (similar) idiot mod pushed by Mini Mania is to replace the damper bush with a rose (heim) joint.


And people wonder why their suspensions fail?
Deborah Evans

Threads in bending are never good but can be made to work as the original Ford GT40 used a specially designed threaded joint for the upper wishbone connection with a large diameter fine thread. That being said the upper wishbone connection is subject to much lower loading than the lower wishbone connection in this case, I wouldn't touch the mentioned item with a barge pole, especially for road use.
David Billington

oh lord no!
Chris Edwards

As David says it could be made to work, but not like that. It would need the rose joint triangulated as the loads are onto the thread in shear. Not nice as it is, don't touch it.
Brad 1380

Agreed... I'm not worried about the forces on the rose joint itself (most modern suspensions have some form of ball joint at the bottom of the strut); as mentioned above, it's the force/stress on the bar as it joins the wishbone, and the strength of the wishbone itself as:

- the original attachment of the fulcrum in the wishbone has low leverage / multiplier of the forces on the joint

- putting the same suspension forces on the end of a 2" bar greatly increases the force on the join with the wishbone.

Better to adapt a design, e.g. Westfield for such a mod.

A
Anthony Cutler

Man that is really scarey
I think I'll buy them just to stop anyone using them and getting smashed up------ Willy

I've just looked again and it looks worse the second time
WilliamRevit

The acceptable side loading on such a joint is a very small fraction of the rated radial design loads; usually the races are retained only by some staking, and I've seen them come apart when loaded a lot less than this one is. And any one sided mounting calls for failsafe washers so the joint cannot completely separate - I see none. The bending load on the shank is appalling. There's stupid and there's criminal - this guy score a double. I very much doubt any SCCA Tech guy would allow such, so you can add lying and make it a triple score.

FRM
FR Millmore

THAT IS IN-SANE!!!

I dont know what worse some idiot did this not as a joke, or some moran slapping down $150 for em on buy it now
Prop

well for good or bad i hope i did the right thing.

This just looked to scary and you know some of the hair brain things Ive done... so thats saying something.

I sent the guy a nice note, just saying in MY Opinion that these look dangerous and to please reconsider selling these and if not to make sure he has the SCCA full backing and support for this modification.
Prop

This is how Huffaker Engineering (well known US race shop) modifies the Spridget front suspension. Note they use a rose joint on the bottom, but only the spherical bearing portion housed in a fully enclosed solid A frame and allow the adjustment to be made on the top side by a rose joint there.


Bill Young

Back off heathen dogs...LOL

Im pretty sure what Bill meant to say is if your going to go this direction then the huffaker design would be the more approperate design, Im sure bill isnt supporting the ebay design
Prop

Wow Bill, that Huffaker stuff looks brilliant.
Is that for racing only or also for roadcars?
No grease-points anymore so probably race only or can a setup like this do a 8000mls a year without maintanance?

Cant see how this specific antirolbar is connected...
Arie de Best

Given that it's all rose jointed, I'd suggest it's not intended for road use. Service intervals would depend entirely on where and how you drive, although I doubt they'd do 8,000 miles. They will transmit every bump and lump in the road straight into the shell and make the ride uncomfortable. You could always polybush (or similar) the inner end of the wishbones and that would make them much more usable, albeit less adjustable.
S Overy

UPDATE...AND Please dont call her chief! LOL.

If you recall I sent what I thought was a "nice" note asking that the ebay seller refrain from selling these modified spindles ...I just got a note back, and There none to happy, here is what "she" wrote...


For starters, you insulted me by calling me Chief. Next, if you don't know anything about this type of conversion, then ask, instead of insult. Further, I didn't state they were SCCA approved, only that they came off a race car. In fact, the car used them, my husband took them off the car himself, and the car actually was a winner at the Road of America races many years in a row. Share this information with your FORUM FRIENDS. You get a ZERO for your assinine assumptions, mister!

I wonder If I can earn any points for addressing her as "Your John Wayne-ness" LOL.
Prop

It sold.... $100 !!!

Hopfully someone will film the Possiable Aleaged future crash and put it on youtube.

Im curious tho... can she face criminal or civil prosection if someone is severally injured or killed as a result of this conversion. If so what are the odds of that happening? She is claiming the parts are "AS IS" and that it was on a SCCA race car, But never approved as a SCCA modification... I just cant belive stating "AS IS" is a free licence to make and sell what ever you want and avoid all lieability .... Im still scratching my head on that one

still some of the parts look Brand new (rose hiem joint) certianly not would Id expect from a high end race car for its class that wins almosts ever race at road america that it participates in over the past several years, youd think there would at least be some tooling scratches... obviously vary well cared for.

kinda makes you wonder why the car was disassembled
considering its a constant winner.

Prop

.
Prop

Another version of that design used two heim joints bolted into a flat plate that replaced the front section of the A-arms. A threaded /machined rod went through the heim joints and the bottom of the king pin. I think I saw this at Import Carlisle or possibly on eBay. Is two better than one? Twice as strong? Or still dangerous?
J Bubela

This thread was discussed between 14/12/2010 and 22/12/2010

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