Body Twisting?

[tlorber]

I've owned a 311 for about 16 years and have recently decided I need to add an early Z. So a the owner of one that I looked at yesterday said they tend to twist, and his had small fatigue cracks in the paint at the bottom of the A pillars and at the top of the "C" pillars near the hatch. He said that every Z he'd owned had the same thing. Has anyone ever heard of or seen this?

Thanks in advance.

Todd.

[Oiluj]

These joints are just spot welded and filled with lead on S30's, (or at least thru late 1972 production...). If they are run hard on rough roads or have upgraded, hi-torque engines, cracking of the paint in this area is not unusual.

Any good body shop can remove the lead and weld a full bead on the joints, eliminating this issue.

[Carl Beck]

Top of the "C" pillar is where the rear quarter panel meets and extends into and under the roof panel. That body seam is filled with lead from the factory, over time body flex will squeeze it up a bit. This is very common. I've not noticed fatigue cracks at the bottom of the "A"...

Body twist?? I'm not sure I would say that - at least nothing to the same extent as say you would find on the 64,65,66 Pontiac GTO's... body twist on them wrinkles the whole rear quarter. The unibody on the Z will flex a bit and I suppose if your racing the car and putting extreme stress on it via large racing tires, super stiff suspension and lots of torque.. sure it would twist.. but even that would be limited to some extent by a good roll cage...

I'd put it this way - if you are looking at a Z that shows signs of body twist - I'd pass and keep looking.

FWIW,

Carl B.

[John Coffey]

This is kinda funny. An owner of a 311 worrying about body flex in a S30... :-)

[ninja240z]

I have never known this being a issue with Z cars fitted with the factory L series engines. I know some V8 conversion recommend strut braces and roll bars to help stiffen the body. I think that if you find any car with the body out of alignment it was probably in a collision of some sort. If you come across a desirable car that does show signs of this you can always take it to a frame alignment shop. These guys have specs of the frame of most cars and use a frame alignment machine to pull body back into shape. This use to cost this speed demon about $200.00 (1 MGB 1 TR7).

[John Coffey]

C pillar cracking is common in 240Zs that have road raced or autocrossed. Suspension loads into the chassis from race tires and big springs are orders of magnitude greater then the torque from even a well built V8.

[tlorber]

Ok, thanks for the responses. We don't have that issue on the roadsters because they are built on a frame-actually a pretty beefy one. In fact, that large cross member under the tranny is why I've been living with a bad syncro for the past 16 years. You have to pull the engine to get the tranny out.

[sblake01]

I saw that comment. I owned a 311 for 20 years and don't recall body flex being a problem. Other things, yes. I had that motor in and out a few times for things that wouldn't require that on a 'normal' car.

[jmortensen]

Just as an interesting story on this subject, I was at an autox where a guy snapped the A pillar OFF of the unibody just by running the car. To be fair that guy was hard on everything though. He also snapped an r180 mustache bar in half.

His solution was to weld it back together and he added a 4 point roll bar that tied into the roof near the map light. He said that after he installed the bar he could drive into a driveway at any angle and the interior panels no longer creaked and groaned and he thought it made a seat of the pants difference when autoxing.

[Maples71240Z]

His solution was to weld it back together and he added a 4 point roll bar that tied into the roof near the map light. He said that after he installed the bar he could drive into a driveway at any angle and the interior panels no longer creaked and groaned and he thought it made a seat of the pants difference when autoxing.

I have the Autopower 4 point bar in my 71 V8 conversion. If I put my fingers between the top of the bar and the roof panel where the map light is I feel a bunch of side to side movement of the roof. I planned to attach the bar to the roof area by the light to stiffen things up more. On my Z the pillers are not showing any cracks yet.

Edited October 24, 2009 by Maples71240Z

[adamr]

FWIW, I've had 6 S30s, 3 of them had C pillar cracking at that seam.

Question:

Sometime within the next 5-10 years, I'm going to spend the money and have the typical rust areas properly fixed, have the C pillar issues addressed, and then repaint the car.

How should this area be properly addressed/repaired. I understand that lead was used to fill in the joint, but is there a better way to repair and or reinforce it? No roll cage for me. I'd hate to have to do it a second time. Consider how I drive and the following modifications to my car:

My intentions are not to race my Z, but to enjoy spirited and often aggressive driving whenever I so desire. In my scenerio, I have a mild cam, header, bored engine (all done by PO). I also installed a 3.90 R200 w/ a later ZX 5spd. With these mods, what is the best method of repair to the C pillars. Also, would strut tower braces be good preventative medicine?

Thanks,

Adamr