Toe in on a 1500 lb. rod

[Pigiron]

This one has me baffled. My 1500 lb. 27T roadster with a Speedway frontend and friction shocks drives just fine up to 65 mph. Over that the front wheels start bouncing like a drunk at a macarena contest. I'm running the friction shocks off the front crossmember to a link on the spring shackles (spring behind axle setup), there is no freeplay there. Hairpins from tube axle to frame, no freeplay there. 6 degrees caster with 3/8" toe in. Tires are balanced. Bias 5.60x15 Cokers. I've tried different air pressure settings. Whadda ya think? I wanna do a trip down the local dragstrip, but not with the front tires jumping up and down.

[Stevie G]

Jack up the front end, set a cinder block in front of the tire or wrap a hanger around the frame to use like a pointer(Set real close to the tire). Spin the tire and see if it is true/round. I had a Barracuda that did the same thing and after replacing all the parts that had been damaged by the real problem discovered that there was a front tire out of round. Kicked my but for quite a while.

My 2c

[choprods]

Id say 1/8" per side on toe in.......[1/4" total- was the caster calculated on the frame bench/rack or at loaded static ride height?

[Jimv]

I have 1/8" total on my T with 5o caster.what you might be getting is Bump steer. Also alot of times when a shake comes in at a certain speed its because of tire balance.
About a month ago there was apost about cker tires & the trouble people where having with them, thats another possibility.
JimV

[whodaky]

Are the tires new?
On my coupe after I had a lot of miles on my Firestone wide white rag tires I found they tended to do the same thing! They weren't much good then! Had a couple of pair do this and they were new to start with, was uusally after around 10,000 miles

[Paul]

sure wouldn't hurt to try Stevie G's suggestion.

tires may be out of round,

ballanced..

you may not notice it at a lower speed,

car's too light to..

absorb...

jounce...........

Paul

[Tman]

WHAT Pressure settings? Most guys run too much. You have SuperBalls bouncing up front? Most cars out of our shop run 20-23 lbs in the front. Even less in the rear.

[RockyMtnPits]

Hey Pigiron! Have you seen Pops' 32? Be sure to give him shit about the "you know what" sitting between the frame rails!

[Pigiron]

I saw your Pops today Trent, the Sweet Patootie and I drove the Deuce to Red Lodge. I have been giving him a hard time about that Olds valve covered brand X since he got it.
Thanks everyone for the suggestions. The tires are new and I am running 15 psi. I have another set of rims and tires I will try if the toe in change does not work. Spent today crusin' but back at it tomorrow. Thanks again.

[DrJ]

Are you running your tie rod in front of behind the axle?
If it's in front do you have the arms out far enough to have correct Ackerman?

[Pigiron]

My tierod is behind the axle. I hate to see a rod with the tierod hanging out in the wind in front of the axle. Ugly and is the first thing to get hit. Also shows lack of ingenuity. By the way my draglink at the pitman arm intersects with the hairpin frame attachment point so I avoid bump steer.
Thanks for the input, ya gotta cover all angles and it helps to have other folks thoughts.

[Pigiron]

Well after a couple of hours tweaking the frontend tonite I've come to realize that a friction shock setup on a 1500 lb rod is a lot different than a friction shock setup on a 1200 lb front engine digger. The main diff is the weight of the mass at each end of the axle. 56 Ford pu brakes and wheels weigh a hell of alot more than wire wheels with Avon cycle tires! So I am dumping the friction shocks I was so proud of and installing hydralic shocks and Ford F-1 upper mounts. More work but loving it!
By the way, before all this I adjusted the toe in to 3/16" and took a spin. Got her up to 70 and the right front started to bounce and than the left, applied the brake and it stopped while still accellerating and took it up to 90 with no bounce but riding the brake a bit. It just needs more shock absorber. And I did check the tires and wheels for trueness and they are dead straight.