Technical Need Pre- war race car handling help! Understeers badly

I built the car in my avatar to race in a pre-war race group on road courses. The front end is Model A with 1/4 elliptic springs, split wishbones, and Armstrong lever shocks. The rear is banjo on Model A transverse spring, same shocks and radius rods (made from front wishbone) located at outside of frame rails. I just raced last weekend and the front tires show a ton of rubber rubbed into the grooves in the tread where there is none at the rear. A ton of squealing coming from the front on hard corners. At the moment I'm thinking the rear radius rods are not allowing the car to roll in the rear causing the under steer. Anyone been here before? If it matters; the tires are 7.00 Excelsior tires which have been shaved to have about 3.5" tire patch. Thanks

 

What engine?

 

Pictures of the suspension would be helpful.
Have you considered toe in/out and caster/camber?

 

nice car Guy...

 

Ford spent a lot of time and effort creating a suspension system that is cheap, durable, yet handles fairly well. The wishbones do more than locate the axle, it is an essential pivot point. Splitting the bones and attaching them to the frame rails kinda sorta works on the front because a beam axle will twist, but it certainly won't work on the rear. Quite frankly, I don't see any justification for not staying with the original cross-spring wish-bone system because it was very successful in a number of vintage race cars, most notably Duffy Livingstone's "Eliminator".

 

Red text seems to indicate either ton of tow in/out or severe ackerman deficiency.

Pics would help.

 

Assuming your tire selection and shock absorbers can't be changed, you should:

• Raise front TP.
• Reduce rear TP.
• Stiffen the front spring by adding one or two short leaves.
• Soften the rear suspension by removing a short leaf.
• Move weight rearward.

 

I don't think the quarter elliptic springs on the front are doing you any favors. Do you have anything to hold the front end in place side to side?

 

Too much grip on the front. ie tire tread with and could be just one thing switch to a narrower tire and don't cut it.
JMHO

 

In addition to the other comments, since this is a road-race setup, you might consider having the front axle reformed to give you negative camber (maybe Okie Joe can do this???). This should increase your contact patch size in the corners.

It sounds like you're just rolling the rubber on over into the tread. On our modern road-race cars, we run quite a bit of negative camber - negative 4 degrees or so. I've never done this on an I-beam axle setup, but I can't see any real reason it wouldn't help you as it does our modern Mustangs.

Other things to consider is how good are the brakes (and driving style) - are you able to effectively use the braking zone before you roll into the corners? Where in the corners is the car getting loose? My guess is that it is upon entry to mid-corner?

Give Joe a call to discuss:

http://www.joesspeedshop.com/joesproducts.htm

 

Morning,

Going to need a bit more information, this is not meant to be rude, did you engineer the system? If so can you share your math.

No real starting point, but lets have a go...

1. Scales: do you have an un/laden weight distribution
2. Spring rates?
3. You jacked everything up and down and no contact or obvious binding? Did you get 2 fat friends to jump up and down on various part of the fame with the body off? (not joking)
4. Painted or polished or Teflon inserts on the springs?
5. Unbolt Armstrong lever shocks and run it? (can they be adjusted?) if not, try double sided plumbers tape and wrap the springs.
6. Lateral control (panhard bar)?
7. Do you have a local round about on ramp you can play on?

All else aside, sounds like the to much sprung in the front. Remove the second to largest leaf and then try, if still too stiff remove the second to the smallest leaf. Even better, have a set made.

Please reach out to Old Dawg here on the HAMB, he probably has forgotten more about road racing a banger than most of us will learn.

Good Luck,

Doug

 

I realize my description of what I have is vague. I will put up some pictures shortly when I get my camera to work. In the mean time...I do have a panhard bar front and rear. 1.5' Neg camber up front and 1/8" tor out. I do know the original Ford system with torque tube and radius rods works very well (I have that on my A roadster with flathead), but in this car I have an open drive shaft.

 

Not rude at all! I'm looking for suggestions. You and others have brought up some great points. Sadly I won't be able to try any thing on track until mid July at Road America and that track is nothing compared to the twisty thing I raced last weekend.
I did scale the car early on and surprisingly had close to 50/50 front to rear and equal side to side. I do have panhard bars and I wish now I had tried disconnecting the rear to see what that would do.
The front springs are Speedway 1/4 elliptic and the rear is they're T spring. Rates unknown.
I did recently move the rear radius rods to the outside of the frame rails and I think this screwed me good. I don't think I'm getting and roll in the back and am unweighting the front because of it..
Old Dawg are you out there?

 

Thanks for the chart!

 

Thanks Randy! As ill handling as it is; I still managed to get a win on Sat. at Blackhawk.

 

You mentioned panhard bars - do you also have sway bars? If so, front or rear . . . or both. Is the rear bar "softer" than the front - I hope so.

 

No sway bars. No sway now.

 

Is there a place here that explains how to put pics up?

 

Infinite stiffness is bad. If you think something is binding, get your jack out and start watching/listening.

50/50 with you and gas in the car?

Did you use heim joints or bushes?

Grab the plates from something and go find a freeway on ramp round about, down hill is best on a quiet Sunday morning and play around and also do the fat kid bounce test. Failing that go find your local cone dodger club and see if they will let you run.

Did you do the math on how to set the panhard rod heights? Do you think you are getting rear jacking?

If you jump on the front of the frame does it go up and down? a lot? a little? like a f@cking board? Does the rear move more? just for grins, how many leafs and how thick is each leaf in those speedway quarter ecliptics? Is the rear a stock T spring (how many leafs) ? Do you have a good spring shop in town? Think you should be able to take the car there or just the springs and get the rates.

I'd disassemble all the spring packs, polish the every living shit out of them until they are smooth as a babys bottom end and reassemble with a light oil coating/grease, wrap them in something if you need too. NO PAINT. Do you have spring clips, if so, remove them for now. Then drive the car, no shock absorbers, see what it does. Then start adding spring clips, talk to the spring shop about how to do that. then add shock absorbers.

Spring clips create inclusive moments of spring movement. Springs leafs move in time, one at a time, and sometimes under full load all together each resisting the other. A clip encourages two to try and move more as one.

Since you are running front quarter ecliptics, see if you can find someone in the Frazer Nash/GN club in England who can recommend reading about how to set up those front ends. Those guys rare prodigious racers and might be able to offer a lot of pointers.

What books are in your library about setting up suspensions?

Springs, if Jim was here, he would tell me get nice and hot on the race track and stick. sticky springs don't spring, they bind and binding is bad. binding leads to learning about where other things flex and break. He liked to have his leaf springs Teflon coated which helped reduce the generation of heat.

Did you build a frame from scratch or use an existing?

 

https://www.jalopyjournal.com/forum/threads/how-to-post-images-on-a-thread.922350/

have fun!

 

I'm willing to bet the separation of the rear radius rods to the outside of the frame rails is inhibiting rear roll of body/frame as you have said. Like ladder bars, great for straight line acceleration but all sorts of bind up on hard turns. If you can bring your radius rods forward end in close together and pivoting at a fore and aft point the same as your front U joint I think it will help. My "A" roadster has wishbones on the rear about 12" apart at the front.and in line fore and aft with the front U joint and you can feel it is free to roll side to side in hard turns. No rear panhard bar in my setup (transverse spring). The height relationship between the axle mount and the frame mount on a rear panhard bar can definitely affect understeer/oversteer, and that's on of the favorite adjustments used by the NASCAR teams during a race with mounts that can be quickly adjusted up and down.
Now for a comment on terminology: I don't like the term "sway bar" as it can cause confusion between a bar to reduce side sway (panhard bar) and a bar to reduce roll (anti roll bar}. Not a big thing but it can cause misunderstandings.

 

See if this tutorial will help you get the hang of posting pictures. If there's any problem, it's that there's too many ways of doing it...

Sometimes it's helpful if you don't upload full sized images direct from your camera. Somewhere around 1600 x 1200 pixels or smaller is usually more than big enough.

https://www.jalopyjournal.com/forum/threads/how-to-post-images-on-a-thread.922350/

 

It would depend on the length of the split rear bones and where the front pivot of the rear radius arms is in relation to the centerline of the first u-joint pivot on the drive shaft (think it is less important on non-torque tube cars, on a torque tube it being critical to not make something exceptionally vile handling and prone to breakage). He did build a race car, I'd expect he was trying to build a stiffer rear end control system. He just has to get all 10 pivot points in that back end to work in harmony.

PS. grease fittings.

 

Good panhard bar write up.

http://kb.fmiracing.com/caster-camber-setup-document/roll-center-explained

 

Got a bunch of Steve Smith books; not much in them for antiquated tech. Got to read up on picture posting. Thanks again.

 

Here is an example of rear bars.
https://www.peteandjakes.com/parts/...13-16-inch-housing/6011a-rear-ladder-bar-kit/

Phil

 

Calling @Old Dawg for help. Thanks.

Phil

 

If you can, post straight on photos of the tire tread left and right. I ponder why you would want toe out on a rear wheel drive car. I'm thinking rather than helping that is causing you to drag the outside tire sideways though the turns.
That said some of the things you read for an independent front end or a front wheel drive aren't going to work for an I beam. Also what the local dirt track boys are using won't work on a road course car.
Someone always throws the Akerman thing in to sound cool and knowledgeable but if the wheel base is within an inch or two of stock for the chassis the front suspension is off and you didn't tweak the steering arms out of the way the factory built them it shouldn't be an issue. Driving though a puddle in a parking lot and turning in a circle will show if that is the issue if the lines of the tire tracks. aren't evenly spaced while making the circle.

 

Panhead -

Study the chart in post #7.

There are MANY ways to accomplish any given thing. Don't put a ton of thought into any ONE thing, it'll just confuse you more.
Just make small changes to your existing car/suspension per the chart.
If nothing works, then make larger (parts changes) to the car to effect the given changes, per the chart.
It may cost a bit and take some time, but unless you have someone that KNOWS your suspension, cost and time it's gonna have to be..!
Experiment, experiment.

Mike

P.s. - There seems to be posts that didn't really read your original post (as always !), be careful, read answers carefully. Some might take you in the wrong direction..!
If common sense tell's you it seems wrong...it probably is.

 

It would be nice to see the front suspension setup. It's normal to expect tire wear during racing especially after a hard day on the track. Tire pressure is critical for sure and may need to be adjusted. Tires look wide for that type of speedster, but depends on overall weight. Does inner front tire lift off the ground during hard cornering?