jwarner801

Hello.

I'm new to this list but not to Zs. However, I've been gone for quite a long time (family stuff). Now I'm back and my son and I are getting my old 240Z autocrosser out of mothballs to go have some fun. I bought this '73 in '79. It has about 65,000 miles on it and is very solid. I also have an early 260Z 2+2 that I picked up in the early 90s that's now undergoing restoration.

I last raced the 240 in '91 and did quite well with it. The engine internals are basically stock but that's about all that is. It's got Webers, header, 3" exhaust, electronic ignition, 5-speed and Centerforce II. The body is a JCR California Z kit with modifications to the nose and hood. The suspension has performance springs, struts, and bushings all around. For street use it runs on 245/45/16 tires front and rear mounted on custom made Compomotive 3-piece wheels (8.5" front 9.5" rear). For racing I currently have an old set of Goodyear race tires mounted on custom steel wheels.

So.....

Here's the problem:

When I parked this car about 10 years ago, it had suddenly developed a wierd rear-end wiggle that just about took me off the road. It felt like a badly busted rear tire. At that time we jacked up the rear of the car and detected what appeared to be a busted cord on the right rear. Fast forward 10 years and we're looking at these old street tires and can't find anything wrong with them. No signs of bulge, put them on the car and spun them and they look fine. Wheels look straight, everything is good. Took her out for a test drive and WATCH OUT! The back end is twiching all over the place on a smooth road even at low speeds. Yikes!

I brought the car back in and got it back up in the air. Poked and prodded around the rear suspension and couldn't find anything amiss. Decided to put the race tires on to see if I could elliminate the problem. Nope! Even more pronounced with the race rubber. Spooky.

So, anybody got any ideas? I'm really scratching my head on this one. I guess I'll get it back up in the air tonight and start poking and prodding again. It sure feels like something is broke in the right rear.

By the way, anybody got a set of R160 4-bolt stub axles. I need them for a Subaru LSD I just picked up on eBay.

Thanks.

Jeff Warner
Galloway, OH
'73 California Z
'74 260Z 2+2

DrSideways

Jeff,

Glad you are getting your car back out to have some fun while spending time with your son.

You should check the gland nuts that hold the shock inserts in. Another thing... Do you have the eccentric camber bushings? If so you should check and see if one has rotated on you. This would cause massive toe in/out on one side. Something on the order of 1/4".

If the bushing has rotated switch them out to the Energy Suspension units. They are round and won't cause the problem. If camber is an issue after that then get some camber plates.

Check those two things and see what you come up with.

Alan

jwarner801

Thanks for the reply Alan. I do have the adjustable camber pieces up front. Would a problem with one of them be enough to cause what I'm feeling at the back? I didn't know they made a similar piece for the rear or do they? I believe I also have the strut spacers up front. I'll have to check all this. The front end alignment "feels" fine. I may try another known good set of tires just to be absolutely sure it's not a coinsidence.

I'll certainly check the gland nuts. Whatever is causing the problem it's certainly significant. I've got the rear towers sloted and I did check them tonight to see that they were tight but that's all I managed to do tonight. Well I also jumped up and down on the back bumper to see if maybe I had a blown out strut but they seem fine and aren't sticking.

I sure appreciate your feedback. I'll be back on it again tomorrow.

Thanks.

Jeff

tholt29

Just throwing out some other ideas Jeff... Possibly the bearings on one or both stub axles? Jack the car up and try shaking the tires and see if you can see any movement. Pay attention to the sheetmetal around any suspension mounting points... You didn't tell us how it sounded... was it clunking or grinding or making any weird sounds? Autocrossing can really stress the unibody and make some areas fatigue. I've only experienced that around the front swaybar mounts, but it could happen in other places.

Also, replace the tires. 10+ year old tires don't belong on the road or track. They are a problem waiting to happen.

Tom

DrSideways

I don't think something up front would do what you have described. However before putting the car to ANY type of real use you will want to go over it from front to back and check the condition of all of the suspension and brakes. After sitting the seals on the brakes will tend to leak after some initial use. The suspension may need more attention than you realized when you parked it.

As Tom said, look for any play in the rear wheels. Do this while the car is up on jack stands. Also check all of the inner control arm mounting bolts. There is something causing one or both of the rear wheels to do some steering of the car. Since this is not a Datsun fork lift that would be bad....

Keep looking and post what you find.

Alan

jwarner801

All good suggestions guys. I've already gone through the brakes and they're top-notch now. No "obvious" suspension problems but then we already knew that. I checked the bearings before but will certainly check them again tonight. It sure isn't a forklift but that forklift feeling is what I've got. Very much agree about the old tires thing but these are just my rollers and I'll be darned if I'll buy any new street or race rubber until I've fixed this problem. My hope is to eventually buy 16" race rubber for my Compomotives. But I can't do that until I can trailer the car to events. Anyway, I'm digressing. My great fear here is the stress cracks. I'm going to go over everything again tonight with the proverbial fine-toothed comb and maybe try a known good set of tires just for further confirmation.

Thanks again and please keep those thoughts coming.

DrSideways

Once you have checked out the suspension to your satifaction then it may be time to "call the man". Either you will need to take it to a competent alignment shop, or get "How To Make Your Car Handle" by Fred Phun. His book has a lot of basics in it and would be good for you and your son to start with. Among the basics in there he has a nice string alignment process. This can be done at home with some time and a few tools. Time being the main thing. You will need to make sure the wheels are not bent when using this method.

While you are under there checking look at the 14mm head bolts attatching the vertical plates hanging from the bottom of the car going down to the rear most rear control arm mount. Confused yet?? Just make sure every 14mm bolt on the car is tight.

What are the chances that the car got bumped sometime. This could have been done a curb hit or something like that. Maybe a midnight ride while you were away..... Not to throw anyone in front of the bus, but it has happened... hint: don't take Pop's car out and roll over the 10k mark while out... Not my most stellar moment.

Alan

jwarner801

SUCCESS!!

In retrospect it seems you basically hit the nail on the head with that last post.

Just got done spending a good couple hours under the car and all I could find was that the right rear bearing had the slightest amount of play when not under load. Like 1/8" on the edge of the tire. I couldn't even see it unless I used a 4-way to pull up on a lug nut. Pretty insignificant but it was there. On the ground you could get nothing at all. Otherwise, I could find no cracks or loose anything. What I did find was that I was able to get 2-3 more turns on a 1/2" ratchet on the 8 bolts holding up the inner transverse link arms. One of them on the right side gave me about 5 good turns. I'm not sure I ever replaced the inner bushings back in '90 when I rebuilt the suspension. I figure I probably did but then they were raced on and many years have gone by and about 8000 miles. End result was that did it! The wiggle is gone. I believe both the inner and outer bushes should be replaced but for now it feels real good and tight on the road. I also don't feel like taking on those outer bushings right now when I've got so many other things that need to be done. However, I am going to get back under there again and tighten everything. Of course this is normal prerace stuff anyway but I'm going to just get it done now so I can stop thinking about it.

Thanks a bunch for the help.

Is there anyplace on this site to put up pictures? I've got a nice digital now and I haven't taken any pictures of this car for literally more than a decade. Thought you guys might like to see her.

Thanks again.

Jeff

Spudz

Good to hear you found the problem ... I am in the process now of pulling the
rear suspension and differentia,l and putting in new bushings .

You can start your own album in the Gallery section . The link is at the top of the
home page .

Mike

jwarner801

Thanks for the photo info. I did a Duh right after my last post when I noticed the gallery link. Guess I'll have to get busy with the camera.

Thanks.

DrSideways

Glad you found what looks like the problem. Make sure and test drive to be positive you fixed it. You also want to be careful to not over thighten those bolts. A 1/2" drive can put more force than needed or intended sometimes. The nutsert fasteners in the chassis would be a real drag to repair if stripped.

No go out with some new tires and kick but.

Alan

jwarner801

Couldn't find Torque specs for those bolts. I probably put about 60 lbs. on them. I'm uploading pictures now.

Thanks.