Rear Toe Adjustment Cost

[moritz55]

Jon .. good observation. I did have the curve along the bottom edge of the new ones "Stretched" upward. Therefore there is about 3/8" up/down play in the slots when attached to the horizontal brace before hitting the arches.

Well I re-assembled all the hardware last night. I tripled checked measuring everything and the slotted holes on the Top of the New Rear Vertical Braces came in handy. It allowed me to "Center" the Rear Horizontal Brace nicely to within 1/16" .

I then attached the Transverse Control Arms to the Rear Horizontal Brace. This is where the "Lower Slotted Holes" in the Vertical Braces came in handy. It gave me the ability to assure my Toe-In is where it should be.

Note: Jon you were exactly right , moving the Horizontal Brace Up/Down - gave me Toe-In adjust as well as Camber. I decided to get my Toe-In as close to 0.00" as possible for each wheel. The data below reflects where I ended up before and after.

240z Stock Spec :

Toe-In..........3/32"(out)....to....7/16"(in)

Camber....20' +/-45' equals +1.08 degrees....to....-0.42 degrees

................................Driver.............Passenger

Toe-In (Before)........ - 3/16" (out)......+ 5/16" (in)

..........(After)..........+ 1/16" (in)............0.0"

Camber (Before)........- 0.3 degrees......- 1.0 degrees

.............(After).......- 0.2 degrees.......- 0.3 degrees

So .. because my rear suspension was way out of being square to the body with the old vertical braces, the Toe-in and Camber came back inline where it should be with the new vertical braces I had fab'b up. Also centering as best as I could the Vertical Braces and Rear Horizontal Brace to the body before attaching the transverse link arms paid off as it made the Toe-In adjustments easier to do by moving the Rear Horizontal Brace Up/Down.

I was hoping to get a more + (positive) Camber out of the lower slotted holes however - it gave me more ability to adjust the Toe-In better which is more important to me. To get the camber adjustments - I'd need a more exotic set of rear-end hardware as you suggested in the links embedded above.

I'll run the car for a while and re-measure the Toe-In and Camber after 1month of driving to see what they look like.

Many thanks...

Edited September 3, 2009 by moritz55

[Jeff G 78]

Very nice Mark. I'm sure your car isn't the only one that has been tweaked over the last 35-40 years. As long as you don't get any movement in the slots, it should work great. You might want to paint mark the brackets to the body and cross member so you can keep an eye on them to be sure they stay where you put them.

[moritz55]

Good idea Jeff - I'll do just that. I did use large washers on the slotted side of the flanges so that I had more surface area for attaching to. Some nice white markings on the bolt head and flange will do nicely so I can assure no movement also.

Many thanks..

Edited September 3, 2009 by moritz55

[=Enigma=]

Nice work. However I'm left wondering if you ever verified that the body was "straight' based on factory measurements. Perhaps it wasn't just the brackets that were tweaked.

[moritz55]

The only measurement I took to assess the squareness of the body was to measure the width at several locations moving from the Front to Back along the unibody frame. This measurement I took at the lowest points below the running boards using a plumb-line and 5 points on each side. I then used a 5 foot straight piece of stock Aluminum that I had for when I do construction projects. This allowed me to transfer the unibody frame lines from either side to my garage floor.

Anyway - after this was done, I had a 3/16 inch difference between Rear and Front of the car (I don't have the data sheets with me - but the width ran 53-3/8" vs 53-9/16" kind of range). My Rear measured 3/16 inch wider .. across a length of 90.75" (which is almost Front Wheel to Back Wheel. I calculated this to be roughly 1/8 degree error in squareness which was minimal. Even if I was off by 1/4 inch .. it's less than 1/10 degree out of square ...

Edited September 8, 2009 by moritz55

[jmortensen]

Congrats on getting it so dialed in side to side. That worked out really well.

FWIW I doubt you'll have trouble with the slotted parts moving. Just keep the bolts torqued. I slotted my front crossmember to adjust bumpsteer, set it and then drove my car daily and autoxed every month and did some track days and it never budged one bit, and the control arm only has one bolt.

[Jeff G 78]

True Jon, but the front transverse link doesn't get much inward force. The TC rod takes the force from a pothole type impact. In the rear suspension, hitting a pothole will try to move the tire rearward just like the front, but with the front pivot fixed and the rear pivot slotted, the rear joint is more likely to fail (slip) due to the arm rotating about the front inner pivot. I also think the joint will be OK, but the paint mark will allow him to keep an eye on it.

[jmortensen]

I don't see the difference really. If you think of the front as essentially an A arm with the control arm and TC combo, they're pretty similar. I was also running on big slick tires, so putting more lateral load on the control arm than most would, easily over 1g. Plus there hasn't been a single person on Hybrid Z stating that their toe adjuster moved, and their slots were horizontal at the bottom, not vertical, which one would think would be more likely to move. The paint is not a bad idea, I'm just saying that I think the parts are not likely to move in my estimation.

[Jeff G 78]

Hey Jon, how much can you move the front pivots out and still have enough thread engagement on the tie rods? Last night I did the inner pivot relocation for bumpsteer and camber on my LeMons car. I moved the holes up 20mm and out 6mm. The springs will be cut to lower the car about 1" to 1.5"

I really like Mark's rear suspension mod. I might have to do that on my '78 to get the alignment closer to spec. Keep us informed of how it works Mark.

[jmortensen]

The rule of thumb is 1.5x the thread diameter should be engaged. I think the prudent thing to do is to check and see where you're at, but I would guess that 6mm shouldn't be a problem.

When I raised mine I just slotted the hole and then measured with a bump steer gauge as I kept moving the pivots up until I had minimized the bump steer. I think I ended up about 1/2" higher than stock. I know JTR has their 3/4" up recommendation and others say 13/16", but measuring is really the way to dial it in and I came in well under the usual recommendations.

[Jeff G 78]

When I do my '78, I will slot them and measure bumpsteer to dial them in. This mod was for a LeMons car, so nothing fancy was needed. I don't have the time to dial it in - the race is in 3-1/2 weeks and the body is still at the cage builder. I had a spare crossmember so I did the mod while the car is away. Now I just have to make and attach the reinforcing washers like the stock crossmember had.

[Seppi72]

I'm planning to pre-empt any such problems on my rebuilt original-owner '72 by going with Techno Toy Tuning's adjustable control arms (front and rear) as well as its adjustable T/C rods (http://www.technotoytuning.com/productlist.php?vehicleid=11). I have the latter on my other '72 - the one I "bent" a year ago during an off-road excursion - and I am very happy with the parts.

The really nice thing about the TTT rear arms is that they allow adjustment of camber, caster and toe on the rear wheels using turnbuckles and (for caster) shims. I also think that the front arms will allow for even more camber range than using the typical slotted shock tower insert - and be more stable to boot.

And, yeah, perhaps the $1000 this will cost is a bit much for some people's taste, but it is at least money spent making the car corner better - something an extra $1000 in the paint job (flames and a hood mural, anyone?) can't do for me.

Edited September 8, 2009 by Seppi72