Leaf spring toe-in modification viability

[stuntflyr]

Since prepping my Healey chassis for road use I have come to the decision that I'll be swapping my Jamaican's BN4L frame with my unrusted bare frame I bought in the Northeast in October of last year. It's a heck of a lot more work but it's in much better shape than the Jamaican's original frame and is just the right way to go.
So, if removing the body, tearing down the chassis and building back up the new one with the straight and unrusted frame is to be done, why not toe-in the rear springs like a late model 3000 and eliminate the Panhard bar?
Any opinions on the subject and anyone have good measurements that I can use in relocating the spring's mounting points?
Thanks,
Chris...

 

[HealeyRick]

Hey Chris,

Glad to see that pristine Massachusetts frame is going to be put to good use. Marty Jule "Frameman" is the guy with the knowledge of this. Here's a previous post:

Hi Ray, thank you for your comment. Jack the car up in the rear. Establish true center of the car from front to back. Draw a line on your concrete floor or use a laser lite.Use a plumb bob to set the location of the rear springs. The front of spring should toe in one half each from front to back on each spring. The front being more narrow. If the spring needs to be moved inward you will have to remove the front spring mount from the outrigger so the spring toes in one half inch on each side. then re weld the spring mount and that is it.
If you have any questions please call
Marty 905-854-3555

 

[stuntflyr]

Thanks Rick, just a couple of outrigger repairs and one new one and transfer the bulkheads from the existing frame and I'm home free!
Thanks for the info, that helps a lot.
Chris

 

[BoyRacer]

Chris,
I think you are making a mistake in eliminating the panhard rod. It serves a very useful function, in spite of what Martin Jule claims. Secondly, it's not that easy to cut off the front spring hanger and weld it back on in a different location. And, the inside of the outrigger has an inner brace that corresponds with the present location of the outer spring hanger. Thirdly, the idea of moving the spring hangers inboard is not the best way to make your Healey handle better.

 

[DerekJ]

Just out of interest does anyone have a scientific reason as to why toeing in the rear springs would improve the handling of a car? The fastest Healeys in Europe are all prepared to FIA specs which include the original suspension set up. They don't seem to have any handling problems.

 

[stuntflyr]

Great! Thanks Richard and Derek for chiming in, I'd really like to know your thoughts on the subject and appreciate your opinions.
What would you do to best set up your rear suspension in a best case, no rules restriction situation?
Chris...

 

[RAC68]

Hi Chris,

I have been following this thread for a few weeks now. The Austin Healey chassis was never structurally sound.
I have several items I wish to address- suspension mounting bushings-these are mounted in rubber for very good reason. It is to reduce road shock and lower stressing of the chassis supports. All auto manufacturers mount their suspension components in rubber insulated bushings. Road and Track and other car magazines tested Healeys when they were brand new and found the car had handling issues and suffered scuttle shake. They also suffered from doors fly open on hard cornering due to torsional loading. sound structures do not have these issues. It was not until 1965 that Healey realized if he was to toe in the rear springs the car would be more stable in the back. On the earlier cars he ran the rear springs parallel. It utilized the pan hard rod for rear end stability but because the chassis suffered from torsional loading issues softer suspension was used to control the twisting of the chassis. The end result was a car that would spin out on a corner as we have read in many articles over the years.
Rally cars and competition cars were equipped with roll cages which added rigidity to the car. These cars suffered from structural issues as well. Applying race technology to an every day driver is not a good idea because of the different environments. A race car is inspected after every race and generally torn down and rebuilt after every race. A regular car does not have this happen.
My suggestion would be to put heavier front and rear sway bars in and toe rear springs in and remove your pan hard rod. These are low cost items. I think this would provide the most bang for your buck. Keep the insulated rubber bushings and stay away from the hard bushings.
I respect the forum's members but this is an area I have a very strong understanding and was concerned when I read some of the suggestions.
Marty

I very much respect the knowledge and opinion of the Frameman (Marty) as I do the opinions and knowledge of Derek, Richard (BoyRacer) and others and would suggest your call Marty to get the reasoning and detail behind toeing in the leafs. A track car is not the same as a street car as a street car does not have the reinforcements (i.e. roll cage, etc.) to extend the rigidity of the frame structure. Although I am no expert on this subject and do not know your overall plan to reinforce your frame, any modification not taken within the context of a total integrated plan will only yield desired results by accident and this seems to be a condition you are working to eliminate as a possibility. Call or e-mail Marty and solicit his input and then consider your possibilities.

All the best,
Ray (64BJ8P1)

 

[EV2239]

https://johnchathamcars.co.uk/

https://en.m.wikipedia.org/wiki/Panhard_rod


I think there could be some misunderstandings here:

I believe BMC lifted the rear of the BJ8 to allow extra vertical travel of the axle to improve ride and to give the new rear silencer boxes more ground clearance, but not to improve handling.

The purpose of a Panhard rod is to provide lateral location of the axle and this improves handling, not the opposite.

if handling is the primary consideration then why not email one of the most famous of the European racers, John Chatham who even knew Donald Healey. He and his workshop manager Dan couldn't be nicer or more enthusiastic and helpful. John raced DD300 for many years and it's still the fastest Healey around the Spa circuit in Belgium. Dennis Welch is the same they're building racers and rally cars all the time.

I'm afraid links are at the top because that's where they landed.

Ashley

 

[RAC68]

Ashley,

You have a good thought and it would be interesting to contact John Chatham and hear his suggestions. However, a track car is NOT the same as a street car and probably not have the prerequisite rigidity or frame stiffness John's suggestions could expect. Since I do not know John and his perspectives, I would agree he could have the suggestions we can all benefit from.

Good suggestion,
Ray (64BJ8P1)

 

[EV2239]

Just out of interest does anyone have a scientific reason as to why toeing in the rear springs would improve the handling of a car? The fastest Healeys in Europe are all prepared to FIA specs which include the original suspension set up. They don't seem to have any handling problems.

Absolutely.

 

[BoyRacer]

The fastest race Healey's in America do not toe-in their rear springs. So, why would anyone want to do it on a street car? The best mod to make on the rear end would be the addition of traction bars, also known as anti-tramp bars.
One other observation. I looked at the Wikipedia link in the earlier post about panhard bars...the illustration shows the panhard bar at some outrageous angle. That is ridiculous!!! Panhard bars must be parallel to the rear axles in order to do what they are supposed to do. The other stupid statement is that panhard bars are not good on small cars. Who writes this crap? A panhard bar is not a good idea on any car that has excessive body roll.........I mean passenger car sedans....whether it be a big car or a small car. A sports car benefits greatly from a panhard bar if you drive it like the way you should drive a sports car.
John Chatham eliminated a panhard bar on DD300 by using a bearing mounted to the rear of his diff that would slide up and down in a channel mounted to the rear bulkhead. Just another way to control lateral movement between the body and the suspension. Another way is with the use of a "watts link".....however....a watts link is impossible to fit onto an Austin Healey.

 

[DerekJ]

I might add that for normal road use, even with spirited driving, I have never noticed any real handling problems with the standard factory set up.

 

[stuntflyr]

Sounds as if setting it up stock may be a good start, thanks guys.
Chris...

 

[steveg]

I recently had Cape's "uprated" panhard bar break the stock mounting on the left side. This is where Cape replaces the rubber bushings with a heim joint which seems to put too much stress on the welded fitting. Therefore suggest staying with the stock setup with rubber at both ends.

 

[EV2239]

Sounds as if setting it up stock may be a good start, thanks guys.
Chris...

Definitely!

 

[John Turney]

I recently had Cape's "uprated" panhard bar break the stock mounting on the left side. This is where Cape replaces the rubber bushings with a heim joint which seems to put too much stress on the welded fitting. Therefore suggest staying with the stock setup with rubber at both ends.

The stock mounting on the left end really isn't that good. I broke mine with urethane bushings on the stock Panhard rod.

Chris, If you have the axle out and available to upgrade that mount, it is probably a good idea.

 

[steveg]

FWIW - I attempted to have mine re-welded in situ and it wasn't possible.

 

[stuntflyr]

It'll be a rotisserie body-off with a straight, unrusty replacement frame so it'll be exposed. I need to find a bar as neither of my cars have it installed.
Chris...

 

[steveg]

It'll be a rotisserie body-off with a straight, unrusty replacement frame so it'll be exposed. I need to find a bar as neither of my cars have it installed.
Chris...

Moss sells them new; British Car Specialists and Healey Surgeons may have used ones.

 

[stuntflyr]

Will do, thanks Steve.
Chris