Extreme Oversteer

[ubtripn]

HI all, I need the boards wisdom on this one, I have replaced almost everything on my 68, the front end has been rebuilt and I added a saw bar and power steering. Now I know modern power steering adds more pressure or something to the steering wheel at higher speeds and the tires turn less as you turn the wheel. I think its called variable speed, anyway I installed power steering along with a new steering box but at 65 I can twitch and change lanes. Any thoughts on how to change this. I have about one and a half turns from center to lock. The truck can be a bit scary to drive.

[jjzepplin]

Sounds like you may have a high performance style steering box. I think mine has about 3 turns to center.

[Sammy]

I think jjzepplin has the answer. I recall 3 turns as being right.
Another thought is .. there is a screen /fitting on the gear box on the inlet where the pressure line attaches". It is behind the fitting and requires removal of the fitting to find it. If that screen wasn't there that may affect the gear box also. Easy to check anyway.

[ubtripn]

Will do, I will check it. What do they make the high performance ones for, 4 wheeling? anything over 40 and you almost roll when you even think about changing lanes.

Also, thank you.

[19673ontree]

I got a rebuilt power steering gear box from advance auto parts paid high money for it and mine is fine going straight if you go around a curve it has slack and you have to fight it , I've drove it several years hate to think I threw away $300 bucks but that's what I di I orderedc a new one from cpp its on my kitchen table soon as its warm enough I'm gonna pitch the advance one

[chopnchaneled]

Sounds a lot like a castor issue,, Calling Bemer Doc, Your input please?

[BMERDOC]

Someone call me? LOL!! Did you have it aligned after adding the box? You said 1.5 turns from center to lock so thats still 3 turns from lock to lock. Six of one...half dozen of another.

[ubtripn]

I did, I replaced the wheel bearings, outer tie rod ends, idler arm, pitman arm and box, spring, shocks and then did new tires followed by an alignment.

[BMERDOC]

Did you get a copy of the spec sheet?

[ubtripn]

I was dumb, I didn't.

[BMERDOC]

Well you're gonna have to get another one. Any of the angles can cause it to be twitchy. Some more than others. Excessive toe out, Caster too shallow or too much positive Camber. Toe is the worst offender. Caster would make it wander..not so much twitchy. What are your tire pressures set at? Double check the pressures to make sure they aren't jacked.

[ubtripn]

Will do, thanks.

[ERASER5]

I bought a set of 4 used tires once. I put 2 on the front of both my cars. Not long afterwards both cars started getting twitchy and tring to change lanes, both left and right. I got pulled for drunk driving about 4 times and I don't drink at all! The belts had blown in all 4 tires but did not show any outward signs untill they were deflated to get them replaced. Geeze! Those tires warped with no air! Soooo check your tires.

[BMERDOC]

Tell them to take out all the shims and start over. 1/16" per side on toe (1/8" total). As much negative camber and as much postive caster as possible. Here is a link to my last alignment and what I consider to be the ONLY way to align a shimmed vehicle of the Aligners equipment has this option.

http://67-72chevytrucks.com/vboard/s...d.php?t=582187

[19673ontree]

I know that you know EXACTLY what you are doing bmerdoc and I would gladly pay for someone to align a front end correctly but here in the sticks where I live their just isnt anyone that can or will do it , they are smart when you get a front end aligned they set it so the tires wear out on the inside LOL I figured out a hillbilly alignment technique I use with no problem have done mine myself since the 80s , and no im not gonna explain it cause you will just laugh at me LOL ,

[LONGHAIR]

Twitchy and oversteer are not the same thing....

[BMERDOC]

Originally Posted by 19673ontree

I know that you know EXACTLY what you are doing bmerdoc and I would gladly pay for someone to align a front end correctly but here in the sticks where I live their just isnt anyone that can or will do it , they are smart when you get a front end aligned they set it so the tires wear out on the inside LOL I figured out a hillbilly alignment technique I use with no problem have done mine myself since the 80s , and no im not gonna explain it cause you will just laugh at me LOL ,

I wouldn't laugh. Theres more than one way to skin a cat! The most frustrating part of this whole thing is that when I give someone advice on how to get a good alignment they have to search for someone that is capable of doing it. A lot of alignment shops have updated their equipment but the Aligners themselves are just looking for "green is good" and don't really look at the numbers. That's why I recommend pulling all the shims and starting over. Adding or subtracting shims from an already bad alignment isn't going to help much.

[brad_man_72]

It took the alignment shop 2 hours to align my truck the way I wanted it (as much camber without the mod). It wasn't too long after it started getting twitchy, the shims fell out... took them an hour to fix that side.

[68Stepbed]

Understeer & Oversteer -- AMG Driving Academy...

[ubtripn]

Thanks for the specs and the video! Let me ammend my title statement.

Basically, I barely have to move the wheel at anything over say 20-30mph to change lanes, barely is 1/4 inch. It's like having powersteering with far too much assist. I think it is the alignment, they all swear they are doing it correct because of the big computer but I am going to give them the specs that need to be hand entered. When they search for 68 it sometimes doesn't even come up and i think they go with a 73, not sure. Anyway thanks all!

[BMERDOC]

How about this. If you need it, PM me and I'll give you my phone number. I can talk to you more about it or talk with the shop and talk them through it.

[ubtripn]

Thank you, I will find the shop and then shoot you a PM. (I don't want to use the last shop again.) Thank you! I will PM you soon.

[Classic Heartbeat]

I don't know if this is your issue or not, but you can check to see if your frame is dimpled for the integral power steering gear. I know that none of the 67s were. People tend to just shim the gear out to bolt it squarely on the frame. Problem with this solution is when driving strait, you are not in the center of your gear, you are actualy turning right slightly. Not being in the center of travel in your gear leads to the same issues that you are talking about. In this thread you state you have a 68 witch I would think that this explination wouldn't apply, but hey it's worth a mention, just because I have seen stranger things. WES

[jhwkns]

I think BMRDOC nailed it when he mentioned the toe. A little toe-out will make your steering reaction very "darty" lol It looks silly typed out, but the guy who mentored me on chassis setup called it that.

"darty"meaning it would want to dart one way or the other with very little steering wheel input.

It's pretty easy to rig a bar to check your own toe. Front end alignment isn't rocket science, although most front end shops would like you to think that. Most of the difficulty comes with lowered vehicles when you are at the extremes of your adjustments due to the non stock A-arm geometry.

[ubtripn]

That's the word, darty. Definitely. I do have the dimple. I remember being grateful not having to , "make one".