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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - A-pans

I gather Barry King has now run out of the strengthened pans as well as the neg camber ones, and isn't making any more batches after the stock of standard ones is gone. Does anyone know of another source of improved / strengthened ones suitable for a race car?
David Smith

Maybe it's time for someone to revive our long discussions on alternatives.

But the trouble is, most people are happy with the bog standard versions. I don't suppose there's much of a market for anything else. Probably why B King hasn't been able to find anyone to take over his kit. (Guessing).
Lawrence Slater

David

I recently wanted the same thing as you, and Barry sold me two standard wishbones plus two of the strengthening pieces separately, I will get these pieces TIG welded in when I come to use the wishbones.
So you end with the same thing but without the 'improved lubrication' which isnt really an issue.

If you are interested I have a pair of Barry's three degree neg camber wishbones that are now surplus to requirements. I am happy to sell them to a good home !

Ian


Ian Webb '73 GAN5

Ian,

May I purchase those -3 deg wishbones from you?

I am in the US, but we can work that out.

My email address is (no spaces):

norm
kerr
123
@
comcast
.
net


I was so sad when I heard from Barry that I could not get a pair of these any more, and have been looking for a pair for my own vehicle,
Norm
Norm Kerr

So ,is someone else making the standard ones ? Or are they old stock being run down....?
Andy Phillips (frankenfrog)

There is the one feller (JHL) that post here on and off and owns a race car fabrication shop.... he does a version of the midget big brake kit

Anyway he mentioned a couple of months back that he was currently in devoloping a new modern front suspension thats fully adjustable for the spridget....

He sounds promising

Ultimately id love to see tubular wishbones that would be cool

Prop
Prop and the Blackhole Midget

You can still get bog standard from moss

.
Prop and the Blackhole Midget

Norm

If David doesnt want them they are yours.

Also I now have some drawings of Aldon type neg camber trunnions for you if you still want them, so its good that you posted your email address.

Ian
Ian Webb '73 GAN5

Ian, could you email me at mgsmithy at yahoo dash co-uk, thanks
David Smith

Darn, David for the win.

I am still planning on making upper trunions for negative camber though.

I have measured the suspension on an alignment gauge to get the necessary measurements, and have made a pencil drawing of the new trunion shape, but have been too busy at work to find an aluminum die cast source to have them made for me (and too busy to make a proper drawing, or a 3D CAD model of the target shape, beyond that rough drawing with the key dimensions) .
I have a mill to finish them once cast, and am planning to have them for sale at that point.

My plan is to offer them in a range of degrees of negative camber (simple really, just design it for -3deg (or -2deg from the stock +1), and then bore the kingpin hole in even increments closer for units less than -3deg).

Just got to connect point a to point b to get the ball rolling on it.


Norm "going negative" Kerr

Norm Kerr

Norm,

Have you thought about the product liability for those upper trunions?
Trevor Jessie

Yes, I have. They will be marketed as, "for racing only", probably, to keep the weasels off my tail.

In any case, I have identified the grey cast iron they are made of, and will spec a grade of aluminum which is at or above that strength, plus some extra margin just to be on the safe side (there is a lot of room to add wall thickness to those things, without interfering with the surrounding parts, and aluminum is light weight).


Norm
Norm Kerr

Norm
Keep me a breast id be interested

Prop
Prop and the Blackhole Midget

Prop, thanks for the 'plug'.
We are investigating the viability of 'adjustable camber' trunnions, using billet alloy ,but we are also developing as you say, a new double wishbone kit which is fully adjustable and incorporates our new ball jointed alloy uprights. These also feature bolt in stub axles to accommodate the 2mm radius or 1mm radius required by different bearings. I will also be introducing a new std alloy upright but with separate trunnions using a taper fit and bolt as per track rod end fittings. I will post pics of the uprights we use in the coil over kit if folk are interested, but the coil over kit in total will be shown when finished.
J L HEAP

Here is the new upright




J L HEAP

WOW, J L, that would be the cat's pajamas!

Looking forward to updates. It sounds like you are on top of all of the areas from which the front end could benefit.

:)


Norm


Norm Kerr

Oh good grief .....That photo just made me horny (((NICE !!!!)))

Im looking forward to seeing how this turns out....move over jules vern

After seeing that photo, im starting to wish I hadnt bought all those new racer boy toys over the past few years for my big beefy front end build....this has the makings of being something very special

Thanks JLH


Prop
Prop and the Blackhole Midget

…one more thing to add to your ultimate front end design: straighten the steering arms to reduce the huge amount of bump steer the front end design is saddled with.

Unfortunately, it is also necessary, then, to increase the thread on the rack (probably the reason why the arms were bent like that in the first place), and care taken to prevent fouling on the wheel weights, as that gets tight. Both things can be dealt with.

Doing this makes a big difference in the change in toe when the suspension is compressed (like during a turn).
I was shocked when I measured the amount of change, and how it was all in the "bad" direction, on a Midget.
Straightening the arms was an involved process (including heat treatment to maintain the material properties), but if designing new suspension components a new arm can be made in any desired shape.


Norm
Norm Kerr

Norm, I'm struggling to understand how straightening the steering arm reduces bump steer.

Surely, shortening the track rod increases bump steer?
Dave O'Neill2

Hi Dave,

The problem is that the ball joint is located outboard of where it would best minimize bump steer (reference attached image).

The stock arm is curved outboard, positioning the TRE ball joint out of line with the upper and lower kingpin pivot points.
The parallax in that photo makes it look worse than it is. Measurements said it is about 1/2".


The experiment that I tried was this:
Straighten the arms to move the ball joint 0.5" inboard (heat till red, bend, cool in kitty litter or oil).
Measure the bump steer "before" and "after" and compare the results.

What I got was:

With 0.125" toe in at static ride height
At full bump, the toe was going all of the way to 0.855" toe out with the stock arms
After the shape change, the toe at full bump is reduced to 0.250" toe out.

A small amount of toe out in bump will get the car turning in well but too much and the car will be twitchy under braking.

I have not yet had a lot of driving time with this new set up (a bad o ring in my PWDA leaked out all my brake fluid, which provided me with an exciting end to my day), but as soon as I get that replaced I'll be able to get more seat time. Anyway, the measurements on the alignment machine tell me that straightening out that arm, in order to put the ball joint more in line with the king pin pivots, has changed the bump steer in a desirable way.

Norm


Norm Kerr

Sounds good to me, just one question, why is bump steer bad? Surely if zero bump steer was required then mg would have done it like that?

Just wondering out of interest :)
Rob Armstrong

Hey norm,

Qwhen you annealed the metal to make the bend, did you retemper the metal before installing....
Im no paleontologist, but id think the softer annealed metal would flex around quite a bit under extremes

I will make the assumption you did

Btw... what did you use to heat the metal... forge or acetylene flame thrower.

Both I wish I owned

Prop
Prop and the Blackhole Midget

Hi Rob,

When the car was designed, very little was understood in the industry about what made independent suspensions handle well. Heck, major advances were being made all of the way up through the '80s, as, finally, computing power allowed thorough study of all of the factors involved and compliance could be designed IN, and used to improve handling, instead of the engineers being at the mercy of it.


Many Fords in the '50s still had solid front axles, making them sometimes handle better than the IFS GM products which floundered over bumps. Even Ford's early McPherson Strut designs in England, superbly modern in concept and the staple of the industry today (Porsche using them at all four corners of the 959, and at the front of the 911 ever since its inception), gave pretty awful handling to the earliest models using them.

Cars that handled well, back then, were often "sporty cars", that is, springs so stiff the wonky geometry couldn't get them very far out of line. Cars who's frame flex, body flex and seat cushion were still considered a significant part of the bump absorbing job of the suspension.


The A-30 front suspension on our cars has a lower arm that is uncommonly short, and narrow, an upper arm that is aimed away from the direction it ought to, to prevent camber gain in corners, and a steering rack borrowed from another car (Morris Minor) and packaged where it would fit. Being a rack and pinion, it provided a substantial improvement over the original A-30's parallel link setup, and that's what people noticed and appreciated at the time.

So, in answer to your question, they put it where they could, and used what they understood at the time to be good practice, and let the light weight, a surprisingly rigid body and luck give them the success that they had.

Interestingly, the mini suspension, designed very near the same time, turned out significantly better (geometry-wise). Partly because it was more of a clean slate, and partly because it was being undertaken by a much larger part of the organization, but also, partly out of luck.


Prop: Oxy-acetylene, rose tip. The key, metallurgy-wise, was in making sure it cooled very slowly afterwards (hence the kitty litter, or oil, to hold the heat in for as long as possible).


Norm
Norm Kerr

Amazing to think that the Minor has been around since 1948.
Lawrence Slater

i thought the angle on the steering arms was something to do with the "Äckerman" angle ?


Andy Phillips (frankenfrog)

Norm,
Does your suspension look like your picture when you have the springs in? (all straight and parallel to the ground)
I posted this picture of mine a while ago and people said it was quite normal for the TRE's to be sloping down like in the picture.
With the suspension like mine, and the toe-in set at 3mm in that position then i will be getting a lot of bump steer due to the angle of the TRE's......?


Andy Phillips (frankenfrog)

Is your engine in? Is the car on the tires?
Flip
Flip Brühl

Hi Andy,
That image I posted was a bit deceiving because the spring was not installed and so the arms were positioned to be parallel with the ground for the photo, rather lower than normal ride height.

The angle in your photo is much closer to the natural angle for a road car.

An interesting thing about the angle of the upper arm: notice how the top arm is sloping down at the outboard end, that means that as the suspension is compressed (like the outside corner does when cornering) that upper arm will rotate up and move the upper pivot outward in its arc. That effect is called camber gain. The result is that the tire is leaned in the opposite direction to what we'd want when cornering.

This is why getting some negative camber at normal ride height is beneficial for this suspension, to minimize that unfortunate characteristic of the design (and why race cars drastically lower the front end, to try and start at "neutral" and then as the arm moves up it will actually go more negative (good) when cornering hard.
This is also why putting spacers under the damper to create negative camber doesn't work well. Even if enough spacer can be provided to pull the upper kingpin pivot inboard into 1 or 2 degrees of negative camber, the raised damper height actually increases the camber gain, working against what was being attempted when you really need it (when cornering hard). At least, that is what I found when I tried it and measured the result.


By the way, the differences in handling, from reducing bump steer, or reducing camber gain, they are not colossal. The car handles so well to start with. These things sharpen up an already nice thing is all.

They matter much more to race cars. They will lower the suspension, stiffen the springs and adjust the geometry to optimize things, and then eliminate any flexible rubber bushings to prevent deviation, all for a few fractions of a second per lap. On a road car, using some of those things to improve the handling, and trying to minimize the tradeoffs, can be a nice thing to achieve. So I am studying and learning, and trying to see what is practical to achieve or not.


Norm
Norm Kerr

That woul explain why my rhs tyre rubs on the arch under hard cornering....an arb would help as would using less wheel spacers. But it seems that the harder you corner the more the top of the wheel sticks out, rather than tucking in as I see on modern cars on the road..... I see lots of reading and research in my near future, very interesting
Andy Phillips (frankenfrog)

Hi Flip,
Yes engine in and car on tyres. But Datsun engine which has ally cyl head ,ally radiator,and fiberglass front so at least 50kg lighter than normal
Andy Phillips (frankenfrog)

I was considering a mustang 2 rack and pinion from jegs racing...

they had one that was almost a dead ringer for the 71 midget R/P...what I loved about it was the ball joints are modern sealed unit and not a cap, cup and ball set up, but also theres a company that makes an anti pump steer for the mustange 2 R/P, that takes the place of the TRE and is supposed to limit bump steer....unforntaly I cant find the company in the past 2 days

The mustange 2 R/P is a popular hot rod rack for many cars

Prop
Prop and the Blackhole Midget

Hey norm,

Sorry to smack your injured horse agian with a baseball bat agian....haha

But when you softened (annealed...aka removed the temper) from the steel (cherry red cooled slowly in oil and kitty litter) did you after the bend, reinsert the temper / hardness back into the steel... reheat and dump in water.

Years ago in shop we used a forge to heat steel then annealed it in sand, i want to say it was green sand... sorry not just any old sand from the ocean or desert will do, but that gave a very nice consistent softening of the steel we were working...

Haha... god, how old am I, thats SO distrubing that in 1981 socity had no issues with children doing this type of work in school, oh how times have changed, hahaha, someone needs to bring back lawn darts, thats always good for a laugh at the ER... did you know theres a lawn dart stuck in your head....haha

Prop
Prop and the Blackhole Midget

Hi Prop,
No, we did not quench it. That would have increased hardness and brittleness, neither are desirable in a suspension component. We heated it to bend, and then cooled it slowly to avoid introducing any of that.

Based on our research, that was supposed to be the correct way to work with forged steel.


Norm
Norm Kerr

Thats what was so tempting about beating your dead horse a few more times...

With the metal now being softer, im just fearful that the metal will want to distort and do some more bending under load while driving..perticularly if there are sharp edges and tight radius turns in the softer metal

But at the same time in can fully understand any aversions to qenching the steel and making it too brittle as well....not a good thing

Thanks norm... id been kicking some of those same ideas around thinking about my up comming front end build so ive found your comments very insightful

Prop
Prop and the Blackhole Midget

Hi Norm

Did you receive my email with the top trunnion drawings ??

Ian
Ian Webb '73 GAN5

Yes, Ian I did!
I am such a jerk, I had meant to reply to you right away with a giant thank you, but then I thought (stupidly), "oh, I know what I'll do, is I'll work with these and see if I have any questions, or insightful comments and then reply with that, you know, in a few hours, or tomorrow morning, at the latest."

It is like the chocolate bar that you put in your pants pocket, "just for a second", about an hour ago (yuck).

Thank you Ian, for taking the time to measure those parts and for sharing it with me.

I am trying to learn how to use Catia (I had the training several years ago, and have now forgotten almost all of it, working as a manager, instead of actually working). My goal is to make a 3D cad model of that simple shape, and then work with a die casting place to make blanks that I can machine.

The update from JL Heap (I assume he is from Moss UK?) about them making a whole new suspension got me all sidetracked, and I wanted to confirm the steering arm idea was actually any good, first, then work on the trunion.

The fact is that bending the arm did improve bump steer, but it does change the ackerman angle too, so I am looking into that to see if the one outweighs the benefit of the other. Well, if Moss makes a new arm they can change its length and maybe avoid the problem I got from just bending the existing part (straightening it made it get longer).


Norm
Norm Kerr

" JL Heap (I assume he is from Moss UK?) "

Nope.

http://www.jlhmorrisminors.co.uk/
Dave O'Neill2

Oh, thanks for clearing that up for me Dave, I was wondering about that!

Norm Kerr

OK, finished the ackerman angle study and found out the stock arms are better. Considering the tradeoffs, I've decided to go back to stock arm shape and give up on this bump steer improvement idea.

My bent arms made the bump steer really good, but made the ackerman angle become no good:

Midget's 80" wheelbase and 46.3" front track, ideal ackerman angle should be
5 degrees on the outside front wheel should be 5.1 degrees at the inside front wheel. (delta 0.1)
10 degrees on the outside front wheel should be 11.25 degrees at the inside front wheel. (delta 1.25)
15 degrees on the outside front wheel should be 17.8 degrees at the inside front wheel. (delta 2.8)

The OE arms created:
5 degrees on the outside front wheel should be 5.8 degrees at the inside front wheel. (delta 0.8)
10 degrees on the outside front wheel should be 11.2 degrees at the inside front wheel. (delta 1.2)
15 degrees on the outside front wheel should be 16.2 degrees at the inside front wheel. (delta 2.2)

My bent arms were:
5 degrees on the outside front wheel should be 6.2 degrees at the inside front wheel. (delta 1.2)
10 degrees on the outside front wheel should be 10.8 degrees at the inside front wheel. (delta 0.8)
15 degrees on the outside front wheel should be 15.2 degrees at the inside front wheel. (delta 0.2)

So, back to standard arms it is, and give up on there being an easy answer.
This is not a surprising result, the designers understood bump steer and ackerman angle quite well, and not much in tires or technology has changed their story.

Camber is another thing, though, and getting some negative of that is still on my agenda…


Norm
Norm Kerr

mmm, i added 3mm thick spacers between the steering arm and the stub axle to give clearence between the wheel and the TRE due to it rubbing...
Would that be having an adverse effect do you think?

Seems like the ideal thing for the negative camber would be to move the inside pivot point of the upper control arm downwards somehow, and also move the steering rack down so it becomes more like your original picture....
Andy Phillips (frankenfrog)

This thread was discussed between 08/05/2014 and 14/05/2014

MG Midget and Sprite Technical index

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