Help With New TruTurn Setup to Measure for Wheels/Tires

[Steel409]

Hey all,

I need some help understanding what's going on with my 1970 Nova. This winter I installed a new rag joint, power steering box, all ridetech (3 pc. MuscleBar, Strongarms, coilovers, and TruTurn). I have OEM subframe, inner fenders, and disc brakes. Now that I'm going to measure for wheels/tires, I'm running into a perplexing issue.

I rented the wheel-fit "tool" from MCB, and had things all measured out on the passenger side for an 18x9", 245/40R18, which told me I need a 5.875 BS. I set the ride-height as best I could by lowering the coil spring all the way down loose on the coilover, jacked up lower control arm, and had half the sidewall covered by the fender lip; that seemed close enough to get everything done. With the steering wheel cranked all the way to the left, the tire, on the passenger side, almost touches the Musclebar, and I have great clearance at the rear when the steering wheel is cranked to the right. For $hits and giggles, I decided to throw the tool/tire combo on the driver's side. I'm glad I did. With the steering wheel clocked all the way to the right, There is .75"-1" clearance to the sway bar, and with the wheel turned all the way to the left, the rear of the tire on the drivers side is pushed against the inner fender. It's not just "close", it actually flexed the tool mounted to the hub. While both side Tru-Turn steering arm stops don't touch the lower control arm (passenger side does at full lock, drivers side does not), I don't understand why there is a side-to-side variation like this and/or what could be causing it.

Any ideas?

I set the tie rod lengths as close to the old stuff I took off, but is that the reason for everything being wonky? I thought that would at least be close to get wheels and tires measured and ordered, and then I would obviously take the car to a shop for a proper, professional alignment. But without this, I can't really appropriately measure for wheels/tires. Not with any confidence anyways. Is there a typical tie rod length, driver side and passenger side?

Thanks in advance for the help, this site has always been very helpful.

[dhutton]

Did you roughly align the camber and caster? Too much caster can cause problems.

What caster slugs did you use? Same one in both sides?

Don

[cwylie]

Err to the (higher backspace) frame rail side, not the fender side. Its way easier to run a small spacer than to redo your wheels. Im running a 265 on a 10-inch wheel in the front with tru tun and its tight. Also keep in mid your brake kit will affect your offset. Willwood is like .38 out from factory. Kore 2 is like .25 in from factory if I remember correctly.

[Steel409]

Did you roughly align the camber and caster? Too much caster can cause problems.

What caster slugs did you use? Same one in both sides?

Don

Hey Don, I used the standard "street" caster slugs that came with the Strongarms from ridetech; yes, same on both sides. I put the shims back in, in the same spots, from the old stuff I took out. Again, thought all of this would be close enough until I could get the car to a shop for a professional alignment.

[Steel409]

Err to the (higher backspace) frame rail side, not the fender side. Its way easier to run a small spacer than to redo your wheels. Im running a 265 on a 10-inch wheel in the front with tru tun and its tight. Also keep in mid your brake kit will affect your offset. Willwood is like .38 out from factory. Kore 2 is like .25 in from factory if I remember correctly.

265/35, 40, 45? What backspace? I'm curious to know how you were able to fit those. I'm a tad disappointed I couldn't fit anything over this 245/40, but if all the other geometry is off, I can't confidently determine what will and won't fit. Thanks!

[67-LS1]

I’m wondering if the subframe is centered in the body. There always seems to be a little “slop” in these early cars. My 66 Chevelle can be bolted to the frame quite crooked.
Have you measured from the wheel hubs to fender on both sides?

[Steel409]

I’m wondering if the subframe is centered in the body. There always seems to be a little “slop” in these early cars. My 66 Chevelle can be bolted to the frame quite crooked.
Have you measured from the wheel hubs to fender on both sides?

I can check that tonight. But, even if I had all of the body panels off the car, the front of the tire on the passenger side would still hit the sway bar, and the rear wouldn't hit inner fender/frame, but on the drivers side the front of the tire wouldn't hit the sway bar, and the rear would definitely hit the inner fender/frame. All the ridetech stuff is mounted on the subframe. Does that make sense?

[dhutton]

Hey Don, I used the standard "street" caster slugs that came with the Strongarms from ridetech; yes, same on both sides. I put the shims back in, in the same spots, from the old stuff I took out. Again, thought all of this would be close enough until I could get the car to a shop for a professional alignment.

Still sounds like too much caster. Try removing a couple of shims on the rear control arm bolt.

Don

[dhutton]

265/35, 40, 45? What backspace? I'm curious to know how you were able to fit those. I'm a tad disappointed I couldn't fit anything over this 245/40, but if all the other geometry is off, I can't confidently determine what will and won't fit. Thanks!

In my experience you have to run a lot of negative camber to fit wide tires with TruTurn. -1.5 degrees or so.

Don

[Hotwire]

If it's anything like my 64 Chevelle there's a hump in the rear of the driver's wheel well for the parking brake cable exiting the firewall. I've dialed in so much caster on my car the wheels are off center in the wheel well, it's not pretty, but gets the job done.

[Steel409]

In my experience you have to run a lot of negative camber to fit wide tires with TruTurn. -1.5 degrees or so.

Don

Hey Don,

Do you mean add shims at the upper control arm bolts? Thus moving the UCAs in towards the engine? The previous suspension had two shims at the back, one at the front. In some of the pictures of other pro touring rides, it looks like there are a LOT of shims between upper control arm and frame, which I thought = lots of negative camber, and thus allowing additional tire clearance at top of fender.

Thanks for clarifying... Obviously my first suspension overhaul!

[dhutton]

Hey Don,

Do you mean add shims at the upper control arm bolts? Thus moving the UCAs in towards the engine? The previous suspension had two shims at the back, one at the front. In some of the pictures of other pro touring rides, it looks like there are a LOT of shims between upper control arm and frame, which I thought = lots of negative camber, and thus allowing additional tire clearance at top of fender.

Thanks for clarifying... Obviously my first suspension overhaul!

Yes adding shims on both bolts adds negative camber. Adding shims on just the rear bolt adds negative camber and positive caster. That’s why I suggested removing a rear shim to reduce caster. So in your case you could also try adding some shims to the front bolt to add negative camber and reduce caster.

Don