Steering Travel Issues

[Mr. Fixit]

Some time ago I posted a thread regarding the fact that my steering linkage rod hits the shackles when fully turned left or right. Now that I am reassembling the chassis/steering components after some paint and chrome, and since I have never resolved the contact/interference issue, I am wondering if anyone has ever shortened their Pittman arm to limit the travel of the steering? Thoughts??

Also, I came across an older NTBA tech article regarding bump steer which concerned me. It stated that "in order to avoid bump steer" in a conventional steering setup, the Pittman arm needs to be completely vertical when the wheels are straight and the drag link needs to be 90 degrees from the Pittman arm. Mt drag link goes up at quite an angle from the Pittman arm (reversed corvair box mounted to the frame rail) to the steering arm. Here is the link from the NTBA. http://www.nationaltbucketalliance.com/tech_info/chassis/turning/steering.asp

Is the drag link always 90 degrees to the Pittman?

Thanks..

 

[ellis8500]

If you shorten the pitman arm, you will reduce the amount of steer and you will also make it less responsive; i.e., more turns of the steering wheel for the same amount of steer. On my 27T, the tie rod hitting the spring shackles is the limit of my steering. I've thought about attaching pitman arm stops to the frame but haven't really decided yet. As far as bump steer, try to reduce it as much as you can; there will always be some. From what I've read, the suspensions on these cars are pretty stiff so you really won't get that much axle up-down movement anyway which is what causes bump steer. Some of the really knowledgable people will chime in here for sure. I only know the theory since my car isn't done yet. I've simulated my suspension setup on a CAD system and my theoretical bump steer will be very small with a two inch motion at the wheel hub. I'm guessing the shock of hitting a serious bump will be more than noticeable bump steer. I'll find out next spring.

 

[Ted Brown]

As far as the big drag link angle you have, you could lower the steering arm on the spindle, but it is mostly for looks, it should not make that much difference with bump steer, because as they say, the axle will not be moving that much, even if it did, not to worry, unless you have real short radius rods and the suspension works really nice...

 

[Duke]

One of the most important things is make sure the box is centered when driving straight.

 

[Mr. Fixit]

If you shorten the pitman arm, you will reduce the amount of steer and you will also make it less responsive; i.e., more turns of the steering wheel for the same amount of steer. On my 27T, the tie rod hitting the spring shackles is the limit of my steering. I've thought about attaching pitman arm stops to the frame but haven't really decided yet. As far as bump steer, try to reduce it as much as you can; there will always be some. From what I've read, the suspensions on these cars are pretty stiff so you really won't get that much axle up-down movement anyway which is what causes bump steer. Some of the really knowledgable people will chime in here for sure. I only know the theory since my car isn't done yet. I've simulated my suspension setup on a CAD system and my theoretical bump steer will be very small with a two inch motion at the wheel hub. I'm guessing the shock of hitting a serious bump will be more than noticeable bump steer. I'll find out next spring.

I realize that the steering will be a bit less responsive, but it may be a sacrifice that I am willing to make. When the car was completed the first time, the steering rod always hit both shackles and over time the shackles were scarred and the rod was bowed. I thought about attaching stops for the pitman arm, but in looking at my setup, I think they won't look good. Maybe I will explore putting the steering arm in front of the axle again which would eliminate all of this. Thanks for your input..

 

[Mr. Fixit]

As far as the big drag link angle you have, you could lower the steering arm on the spindle, but it is mostly for looks, it should not make that much difference with bump steer, because as they say, the axle will not be moving that much, even if it did, not to worry, unless you have real short radius rods and the suspension works really nice...

I understand. I will leave that part alone for now.. Thanks...

 

[Mr. Fixit]

One of the most important things is make sure the box is centered when driving straight.

Yes, I do have that done correctly. Thanks.

 

[Ted Brown]

Have you tried to put some new steering spindle arms to the top of the spindles?? This should get the tie rod up and away from everything...

 

[jackfordt]

I am using a short pitman arm and everything is fine. To prevent excessive travel i made some stoppers to prevent my spindles going too far.

 

[Mr. Fixit]

Have you tried to put some new steering spindle arms to the top of the spindles?? This should get the tie rod up and away from everything...

Nope! For now I wound up moving the set up in front of the axle where I know that you hate it. lol. I already had a tie rod the proper length for this and figured that I would give it a try since all of this is easily changed at any time with a few bolts. Thanks...

 

[Mr. Fixit]

I am using a short pitman arm and everything is fine. To prevent excessive travel i made some stoppers to prevent my spindles going too far.

Are your stopers at the spindles, or each side of the pitman?

 

[jackfordt]

I use the king pin bolt as a stopper ,instead using a refular nut i threaded a little pice of shaft just long enough to stop my spindle where i want and i screw it to the king pin locking bolt( '37 ford spindle) When iwill be able to fix my computer issue i wil post some pictures.

Are your stopers at the spindles, or each side of the pitman?

 

[2old2fast]

That's basically what I did, used a long interior allen set screw w/lock nut, then threaded on a acorn nut that the spindle stops against, 49/54 chev. spindles

dave

 

[Mr T Bucket]

What I'm planning on doing is pulling the Corvair box apart, or I guess before it's put together for final assembly, is to weld a stop in the groove near both ends of the steering (input) shaft.

 

[2old2fast]

Please,don't do that! I have never seen steering stops anywhere but on the spindle of ANY vehicle EVER. That includes around 45 years of repairing vehicles. [O.K. so I'm old] The steering box,mounts,linkage etc. are never designed to take that kind of load,i.e. hitting something at full lock. To use Ted's favorite word, that's just too much' leverage'. figure out a way to make the spindle stop against the king pin boss. if you want an idea of how much force you can generate, w/the car jacked turn the wheels hard right, then grab a tire and spin the steering to hard left, you'll get the idea,or break something

dave

 

[Mr T Bucket]

I guess I'm not quite following you. If that is correct, then you shouldn't ever be at full lock (I know we're taught that in school). And we all know how often that happens. My point is, the steering box won't know the difference whether the groove on the input shaft ends where it left the factory, or a half inch back. In other words, if I can turn 3 turns (or whatever the number is) lock to lock, what's the difference if it's modified to only go 2 3/4 or 2 1/2"?

 

[2old2fast]

The steering box should never be forced to full travel, LorR, hence the need for stops. at least that's always been my understanding......
in otherwords, the steering box should NOT be the limiting factor

dave

 

[pete rallis]

I had the same problem hitting the shackles..I bought the deep drop steering arms which put the the linkage below the radius arms..AND put long set screw into the back of the spindle boss on the axle and put a nut on it...this limits the turning and gives me a tighter turning radius...