66 swerves BAD under heavy throttle!

v8only

Active Member
Jul 3, 2003
2,378
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Took my 66 for a 15 minute drive. Longest ever so far.

First off, the suspension had a complete do-over with stock stuff, front and rear very recently. they did NOT however replace the steering box. I know my box is shot, as I have nearly a half rotation in the steering wheel where the shaft meets the box, but no movement out the other end.

However, it's easy enough to drive while just cruising..

I have a fairly stout engine...325 horse aprox with a t5 manual, but nothing drastic. However when I nail it, not even full throttle, the thing starts to pull hard to the left and right and left and right. It just starts swerving dangerously.

Would this be the steering box?? Tires are balding, but worn evenly...245/45/17 tires.

why would a car pull so hard like that under acceleration?
 
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you have an issue known as torque steer. what is likely happening is you have an open differential and the power is going to one wheel. that wheel is then pushing the car to the left where in you catch it by steering to the right, but because of the worn steering box you set up an oscillation where you are constantly trying to catch the car. the torque steer problem can also be caused by the rear end not being square to the car.
 
"as I have nearly a half rotation in the steering wheel where the shaft meets the box, but no movement out the other end."

and you are still driving this car?



Just got it running for the first time ever as me being an owner with this engine and trans.

So far I've been around the block twice and up and down the street.

fixing this issue is my #1 priority. I've driven vehicles with tons of steering slop. This one is bad, but it's not THAT bad while cruising and driving. it's good enough to drive around, turn corners and be fine. It's just when I romp on the gas the car breaks out a can of whoop ass on that front end.
 
you have an issue known as torque steer. what is likely happening is you have an open differential and the power is going to one wheel. that wheel is then pushing the car to the left where in you catch it by steering to the right, but because of the worn steering box you set up an oscillation where you are constantly trying to catch the car. the torque steer problem can also be caused by the rear end not being square to the car.


Damn, I was wondering if that was the case.

I just have come out of (and am still in) the world of fox mustangs. This kind of stuff doesn't happen.

This could make sense though. I drove this 66 when I first got it with the original old school slow 289 that was in it (ripped te motor and trans out the very first day) and it had NONE of these problems at all.

Not until I dropped in this engine that had double the hp of the original or more, now it won't go straight to save my life when I'm on the throttle.

I'm guessing that fixing the steering box will help a lot, but ultimately I've got to take care of my one legged rear end problem.

I've got a 3.73 fox 8.8 that I want to adapt, perhaps that's my best option.

I've been under the car a million times and damn, every component on the front end is brand new. I've driven cars with bad steering box's (but not this power level) and never seen this happen so you've got to be right with the torque steer/steering box/rear end combo :(
 
i had a similar problem and it ended up being a shot bushing on one of my lower control arms. acceleration would cause it to jerk left or right as the LCA shifted forward or back, then do the same thing under breaking.

could it also possibly be an alignment issue? under acceleration the front wheels extend as the weight is transferred to the rear, possibly throwing the alignment out of whack?
 
you might also check and make sure the ubolts which hold the axle to the leaf springs are tight.

I had an issue once where one of these was a little loose so under hard acceleration it would always pull to the right. Tightening them up fixed it!
 
4 wheel drum FTW!!!!!

I jacked her up today and moved the front wheels. the entire front end is super tight, except at the shaft coming out of the steering box. the shaft has rotational play and has slop as you're wiggling the wheels left to right. not only does it have rotational play, but it has left to right slop too. the shaft is actually moving side to side!

this box is so shot I don't dare drive it again. ****, I'm broke.

I appreciate all the help from everyone!
 
I had 245/45 17's on all 4 corners of my 65 and it was a handfull! I went to a narrower tire in front and the problem is gone, it made an amazing difference.
 
manual steering, and my box is coming out tomorrow finally.

what size tire did you go to up front?? i'm thinking a 225/45 or even skinner may work well.

what's the smallest tire you can put on a 17x8?