rear steer: what's really wrong with it?

[guccieng]

hello all. first post on this site (besides the welcome wagon). wanted to get your take on the first-gen f-body change to front steer from rear steer. does it really make a difference? if you update the front suspension on a rear steer car, do the original (whatever they may be) problems still exist?

[silver69camaro]

Yes they do exist after upgrades, but the question is to what degree.

The problem with rear steer cars is the steering will enter an oversteer condition as control arm bushings (as well as tie rods, linkage, the entire system) deflect in a turn. For most people this tends to be a negative because the car will tend to "self turn" while in a turn...meaning you will have to slightly reduce steering-angle-rate-of-change as g-forces increase. Obviously this is against what your natural instincts are do to.

In a front steer vehicle, the opposite occurs. Higher G-forces require more steering input, making these vehicles easier to drive and more predictable.

Does it make a difference? Yes.

[guccieng]

to be more clear of what i meant by 'updated', i have del-a-lum bushings all around. that would take the deflection out of the equation. anything else to fix any more rear steer issues?

[David Pozzi]

If you have minimized the bumpsteer, and installed Del A Lum A arm bushings, you won't notice any problems if all the steering parts are in good condition. The Ackerman curve is better on a rear steer car, but the steering linkage is in compression when a bump is hit, when brakes are applied, or cornering, so linkage looseness or flexibility needs to be kept under control. A Camaro big block thick center link was available, and it is recommended to stiffen the linkage along with a pitman arm and idler arm that are in top condition to prevent the center link from moving up or down when compressive loads are applied. The tie rod ends just need to be in good shape. Circle track racers upsize the tie rod ends to larger car or truck parts, but are not needed for our use. I once read a great article about a first gen Camaro circle track "Dinosaur", built long ago, it had rear steer, and a trick rear sort of 3 link suspension that was still beating the new cars on a regular basis. The car was set up to do road course or short track with optional suspension holes.

Top is stock .950"
Bottom is 1.125"
https://static1.pt-content.com/images/pt/2008/06/6769draglinks-1.jpg

All the C3 Corvettes had rear steer and they did fine over the years. Some did break the center link under hard braking at Sebring, mainly due to use of very wide offset front wheels, and big block engine. This forced GM to come out with an improved BB center link that was thicker diameter for the Corvette with Big Block.

I agree with Matt that in theory the rear A arm bushing compresses and could affect steering direction, however this is far overshadowed by the bumpsteer issues of the first gen. Once enough positive caster is achieved, the bumpsteer pretty much goes away, and can even reverse if too much caster is dialed in! If the expected deflection could be determined, the bumpsteer could be adjusted to compensate for it but I think you don't need to be concerned about something that minor.

Matt also gives a clue that is often overlooked, not just bushings deflect, every part of the suspension will deflect to some degree, - nothing is absolutely solid and beyond deflection when a load is applied, but rubber surely moves more than steel. Matt's statement "to what degree" is key.
David

[pitts64]

I have my rear steer 64 Bonneville handling very well now. I'm running 2.5/3+ caster. One of the best modifications I did was to install a Lee 12 to 1 B body box through Marcus's suggestion. This box goes right back to center when the wheel is let go.

I also braced up the idler arm pad and steering box (photos).

I'm looking into weld-in 2-1/2" Johnny Joints into the lower control arms.

[guccieng]

i saw the 'johnny joints' thread on performance years, but that doesn't apply to first gens, right? i'm running the marcus's stage 2 plus that has the tall tie rod ends to correct bumpsteer along with solid bushings. i appreciate everyones response. i just want to be safe and do the best i can to enjoy the car at thunder hill in willows.

[David Pozzi]

I would think a Del-A-Lum type bushing would last longer than a Johnny Joint, and they are available to fit a Camaro, where the Johnny Joint would have to be adapted. The main benefit of the Johnny Joint is it can move in several directions, but you don't need that feature on a Camaro A arm.
David

[pitts64]

I wish they sold Del-A-Lums by size. I have to fab everything on my car.

The idler arm is a very important part of rear steer linkage. If it's a tad loose you will get all kinds of straight away steering play. I use the adjustable bearing style...

[neki67]

The idler arm is a very important part of rear steer linkage. If it's a tad loose you will get all kinds of straight away steering play. I use the adjustable bearing style...

Sorry for HJ-ing the thread but could you tell me a bit more (e.g. where can you get them) concerning the bearing style idler arm?

Thanks,
René

[David Pozzi]

Jeff, good point, the idler is very important, even on a front steer car it's one of the first things I check for play.

David

[guccieng]

Sorry for HJ-ing the thread but could you tell me a bit more (e.g. where can you get them) concerning the bearing style idler arm?

Thanks,
René

HJ-away! i'm intrigued...

[pitts64]

I bought mine from Rare Suspensions. E-mail them and ask if they sell one for your application.
http://ecomserv.bytedesigns.com/rp/

The Rock auto site lets you cross reference parts to some degree.
I just found out my 64 Bonneville has the same control arm bushings as the 67-71 Chevelle. But the high was short lived, they don't make a Del-A-Lum for the oval Chevelle bushing lol....
http://www.rockauto.com/catalog/raframecatalog.php?a=G-partdescribe2

[derekf]

they don't make a Del-A-Lum for the oval Chevelle bushingThey do, however, make steel racing bushings with a nylon insert - basically the same thing as Del-A-Lum but steel instead of aluminum.

[ProTour69GTO]

i dont mean to hijack the thread but how would all wheel steering like in monster trucks handle?

[Twin_Turbo]

Not because how the rear wheels steer needs to differ at speed, at low speed when turning left the rear wheels should turn right to reduce turning radius, at higher speed they should turn in the same direction so the car mvoes sideways evenly. Kinda hard to expain. Takes electronics to control properly.