One last suggestion which dramatically helped on my 78 C3 was ditching the 255/60/15 tires for ultra High Performance summer only W or Y rated tires BUT you will need 17/18 rims at a minimum to take advantage of modern rubber that will ride MUCH better, have superior steering repsonse and feel, and will stick like glue in both dry and wet. I have SLP ZR1 style 17 (no longer available) with 255/45/17's in front and 255/50/17s in the rear;

 

Like those wheels a lot - bravo! I already have modern wheels and tires on the car. Went with Nitto NT555 G2 - 245/45R18 all around. I believe they're W rated.

It's weird, the car drives well in some aspects. It's super tight, steering is heavy, not too much slip in the steering wheel. You can tell it has all new suspension components. But when you get it to highway speeds, it feels less like I'm controlling the car and more like I'm trying to keep it under control.

Being an LS swap, I don't believe I can add a spreader bar, otherwise I would. Now that the adjustable strut rods and new trailing arm bolt are installed, I have a new alignment appointment for next Monday. We'll see how it works out, I'll report back!

 

Maybe I'm misreading or haven't caught something else in the thread, but rear camber is usually just slightly negative.

 

Don't want to cause a worry but sometimes the camber is too far negative due to worn stub axles in the diff. The ends ware and the axle tilts in. I've seen this more on pre 1980 diffs and when worn camber can change as the wheel loading changes Even so the heim jointed strut rods will get you there.

 

With the new strut rods, he should be able to hit ½ degree negative very easily. Run too much negative camber and with the wide 245/45R18 all around, the outside of the tire won’t grip as well as it should. You’re sort of negating the advantage of your wide tires.

The shims set the toe, the rods set the camber. But I’m sure you know that.

 

Hmm interesting, I’ll look into it. Although, as you said, the new strut rods should take care of it.

 

Yeah I know a vast majority, if not all, of that -1.5 is because of the old strut rods.

Really curious to see how this thing drives come Monday. I’m going to see if there’s any ability to increase caster in the front as well. If not…might be time for new upper control arms.

 

Before you start chasing other things, definitely get the rear alignment corrected. That’s a big culprit in making the car feel all over the road especially with the toe being uneven.

depending on how your steering box was rebuilt will impact off center feel. I had mine done by GTR1999 and it’s really nice, I wouldn’t put the effort into another option.

 

The box unfortunately isn't rebuilt, it's a new replacement. I know the quality on them is very hit or miss, but it was the best option for me at the time. It feels a hell of a lot better than original did, only a small dead zone in the middle, but I'm sure it's nowhere near as nice as the ones GTR1999 rebuilds.

 

I have been saying the same for over 15 years now^^^^^.

The borgeson option is probably a good choice for a select few with totally wrecked OEM boxes, steering system components that are a total mess, maybe, but pretty hard to beat a custom blueprinted/rebuilt hand adjusted OEM C3 box for much less money, in my opinion. Based on my experience with Rack and Pinion in various other cars and my road racing on tracks, unless you plan to race your C3 on a closed course, not sure the quicker borgeson 12.7:1 ratio is a must have. Would I like the quicker 12.7 :1 ratio in my OEM C3 box? Absolutely, but not a must have for mostly cruising on public roads.....Just my 2 cents!

 

It should be mentioned that borgeson makes 2 c3 steering options, the saganaw jeep cherokee modded setup that eliminates the 1950s c2-c3 system altogether and a replacement stock type box. this box has the 12-7 ratio and a modern variable assist feel.
I have been doing a lot of work to my car the last couple years and last year I did swap in the jeep type borgeson kit but I also put POL tubular a arms with the offset supports to allow for more castor (I can never remember the difference between castor and camber) in with poly bushings and dual adjustable coil overs. in the rear I replace one trailing arm and rebuilt the other and added a used composite spring with coil overs and homemade heim joint struts. This completel transformed the feel of the car as it travels down the road and handles.it now reminds me of my old 84 z51 vette in the handling dept. before it was scary I had a slightly bent trailing arm and the smallest pothole left me white knuckled. Now the steering actually wants to center itself like a modern car. I also added the solid rear crossmember delrin bushings from van steel which lowered the rear a bit as I like the look.

I am currently swapping in a 406 and 2004r OD trans as well as an Aces killshot2 TPI system and have everthing in but need to finish bolting on the accessories and such

To the OP I see you are on a similiar quest as I was to improve the car and I wish you luck. Ive had a lot of fun with mine learning how to do everything from body and paint to building engines and porting and assembling heads with the assistance of this forum and you tube.

 

Camber is the angle of the spindle in and out from the center of the car. Caster is its angle forward and aft.

 

Has anybody mentioned 'bump steer'?

When I updated everything including steering I installed a bump steer kit. I think it made a difference but with the car down for two years, it's hard to remember before and after. My roads locally are pretty crappy but I don't now see that the car goes "all over the place".

 

Oh ive looked it up multiple times but I always get confused on it later...I have to remember caster is like wheels on a shopping cart mounted with caster to the swivel point

 

A couple questions: (I did my own race car alignments for 30 years)

1. What is your rear ride height like? Close to stock I hope. ~27.5" at fender? If you get an inch or so high, or low, it aggravates the bump steer that the rear has.
2. Have you checked the yoke fit slop into the rear? Post '75s suffer from soft axle syndrome. Pull and push on the tire and make the yoke move in and out of the diff. Measure it. .030 to .060" or less is great. I have seen 1/4" or more. It makes the car dart badly because it moves suddenly under load.
3. Set the rear toe-in to 1/8" . No other value. Definately not a fraction under. A hair over if necessary. Under that will make the car go in to toe-out in a turn, due to it's built-in bump steer, and that makes it suddenly dart. 1/8" is the same as 0.3 degrees. The total toe is what counts. Just try to keep the left and right close to each other. If they are not the car will crab a little. "Thrust" You are a little over that now at .45*. But the two diff R & L settings you have will make the car crab walk to the left, and the steering wheel will not be centered. With a C3 changing the camber has a huge impact on the toe-in, so set camber first.

Like others said, take new stainless steel T/A arm shims, and threaded strut rods with you. The alignment guy will love them!

 

Alright guys, I just picked the car back up from the alignment shop. Here’s the new specs:



The car definitely drives better, it doesn’t feel like it randomly wants to drive off the road any longer, but I still wouldn’t say it’s 100%.

It still feels like I’m constantly having to correct the car. It drives straight as an arrow when you take your hand off the wheel, but it feels like small inputs are amplified. If the car hits a bump or otherwise veers off a bit, I need to pull it back and it feels like if I do too much I could over correct and lose control.

I have a feeling this has to do with the caster, since we were only able to dial in about 4 degrees. But wanted to get everyone’s opinion. The car is otherwise super tight.

 

i don't think its caster.. how does it compare to factory reset specs? maybe more toe?

 

Ok much better!
But still not there yet.
See post #23 and #35.
Maybe hand him the Van Steel specs.

You MUST have 1/8" toe-in in the rear (.30*).

You do not, so the bump steer (tor change) makes it go into toe-out on a bump, and steer the car.
That is what you are feeling.
All 4 cambers could be less, and so could the front toe-in. But all that is just tire wear issues.
But it is the rear toe-in being too small that causes the instability.
You're close, so it is not too bad.

Just tell him it is still nervous, and hand hm the specs in post 23.

 

Hmm alright, looks like I need to bring it back to the alignment shop…again. Hopefully he throws me a bone here, as I’m not excited to pay him a third time. Not sure why this has been so difficult

 

Let us know how it turns out!
And how much of a difference you can feel.