Need help. Still having slop in diff/axles

[jt1]

Lower control arm.

 

A few more random thoughts:

 

Can you reproduce the clunk with a quick on-off-on of the throttle? With the car jacked up, can you grab a rear wheel and rotate it back and forth quickly and hear anything? Is there any visual clearance between the outer heim joints on the lca and the spindle?

 

Before I dropped the dime on a quaife, I would swap in another diff and try it. In my experience, a quaife is even noisier than other lsd's. The first time I drove my car with the quaife, I thought I had left the mustache bar bolts loose.

 

jt

[DrSideways]

I noticed you have the new AZ control arms. In the photo of the control arm mounting tube there is a bushing, but the stock bolt is missing. It looks like there are not any threads inside the tube.

 

You can check this on the lift with a hefty pry bar. You will be trying to move the inner control arm mounting tube fore and aft. This would be part of the original control arm when stock. If this moves fore or aft you will need to do some engineering to get it acceptable.

 

Back in the day when the offset bushings were the hot tip we ran across a clunk as you described. The bushing was sliding fore and aft while driving. In the photo of yours you can see where the grease from the bushing has left a witness mark on the tube. Stop this for/aft movement and see what you get.

 

You can tap the tubes for the stock bolts. You may end up making another set of bushings with a shoulder on it to get where you want to go. An Energy Suspension rear kit may have what you need:) You can use some VW or Porsche fan shims to make sure and load the tube instead of just tightening the bolt into the hole.

 

Nice car.

 

Good luck,

 

Alan

[Blakt Out]

JT:

 

Thanks much. I'll check that out. But as for the moving the wheel back and forth, I think that's what my mechanic did and concluded that there was "axle slop" and that I needed to send them back to the place that rebuilt them.

 

Alan:

 

Thanks SO much. You're talking about here, right?

 

 

I also have this picture. Does it help any?

 

Edited December 20, 2010 by Blakt Out

[DrSideways]

JT:

 

Thanks much. I'll check that out. But as for the moving the wheel back and forth, I think that's what my mechanic did and concluded that there was "axle slop" and that I needed to send them back to the place that rebuilt them.

 

Alan:

 

Thanks SO much. You're talking about here, right?

 

 

I also have this picture. Does it help any?

 

 

 

Yep. That is the spot. In the upper photo you can see where the grease has been pushed up the tube due to the shaft/tube/control arm moving fore/aft. Since this is a known knock causing source I would make a repair or re-engineer the part. Then move on to the next item.

 

Getting a tap is easy. If you do go that route you would be advised to tap it in a lathe. The tube also looks to be a bit too long. You will also need to weld the large flat washers on the tube so you have something to tighten against. Look at this end of the stock unit. Duplicate and install.

 

Dave makes some cool and appreciated contributions to the Z Car community. Sometimes the designs need some help to function well in real world applications.

 

You know why they call them Sports Cars? Because stuff like this will make a "Sport" out of you. Take it in stride and work along to the next thing.

 

While I'm on the wisdom horse...... Motorsports is a study in desire and problem solving. It will test your desire to solve problems. If you don't desire to solve problems, then motorsports may not be for you.....

 

Alan

[Blakt Out]

Alan:

 

Thanks for all the ideas and wisdom. They are much appreciated.

 

I don't mind at all to do this. I enjoy it. This is Z car #14 for me, although easily the nicest I've had. I've also had quite a bit of real motorsports experience, and totally agree with you. You can see some of the other stuff that I've done by clicking the link in my sig.

 

Thanks again! I'll let you know how it goes.

[dsommer]

K, so I'm just reading up on everything I can find here... I'm not going to assume that the shop that built the car flipped the end cage of the CV shafts around to shorten them up the necessary 3/8", as noted in other posts (by Ross at Modern Motorsports too). Thing is, I don't know what they looked like before. So, can you guys tell from any of my pics if this has been done or not?

 

I'd take it apart and measure the two axels side by side. I don't know if you have to flip the cages on the 300 zx axels but you do on the 280zx turbo axels. Also on mine (280ZXT) axels we had to cut the cup down (from the outter axel retainer) that mates inside the flange adaptor (MML 280zxt adaptors) granted these were early production units but if they were just squeezed together you'd get a hella lota noise out of them IMO. Also you may want to consider running a RT front dif mount with a GM trans poly bushing.

[Blakt Out]

Thanks much. What's an "RT" front diff mount? I mean, I know what a front diff mount is, but what's an RT? Thanks again.

[ezzzzzzz]

Seems that a couple of decent set screws could be installed into the caps of the down brackets to keep the tube from moving back and forth...maybe. I'd looked into that control arm but never realized that flaw(?). This tube is suppose to remain stationary unlike the OEM LCA. Tightening the clamping force by using a thin split tube over the bushings might provide the forces needed to keep it in a fixed location. As for the CV axles, these can be rebuilt BUT if there is wear in the tulip housing it can't be repaired only replaced. I always thought that custom axle shafts should be produced to use the OEM CV's instead of flipping parts around to provide clearances. As mentioned by another, that solid diff mount will transmit horrible noises into the cabin Not that the heim jointed LCA won't do that too!). The RT mount is designed to fit over the top fo the diff nose. A GM transmission mount attaches to the diff nose and the RT mount. This keeps the diff from lifting under acceleration. Just search the forums for the RT mount to see it installed. Also, try to get this up on a two ramp lift so the vehicle is sitting in it's normal ride height. It's easier to notice abnormalities that would cause problems (e.g. things that could contact but shouldn't).

 

LASTLY, Please clean that car up. It is an attrocity underneath and an abomination to our eyes! HAHAHAHA

Edited December 21, 2010 by ezzzzzzz

[mark]

If I remember correctly, those control arms are designed with a set screw as ezzzzzzz suggested. Make sure they are there and tight. I'm betting on crappy CV's. Check out Wolf Creek Racing's set up.

[cygnusx1]

RT mount is a MUST. It may not be the solution your clunk, because you already have the solid mount. However, the RT mount is very solid, and transmits far less NVH to the chassis, than your solid mount will.

[Blakt Out]

If I remember correctly, those control arms are designed with a set screw as ezzzzzzz suggested. Make sure they are there and tight. I'm betting on crappy CV's. Check out Wolf Creek Racing's set up.

 

Mark:

 

Just talked with Wolf Creek. Great guy and was very helpful, but his kit will only work for diffs that have the U-Joint flange. My diff didn't come in a car that came with CV shafts. Oh well. We'll keep tryin!

[Blakt Out]

Just ordered the RT mount. Searching for the part number for the GM mount part number. I saw in one place that they could be bought at Summit, and in another thread I saw a part number. However, that part number did diddly on summitracing.com. I'm getting there.

[ezzzzzzz]

The Wolf Creek setup can be modified to use with your Diff. BlueovalZ and I both designed and run a Porsche 930 CV jointed axle in our cars. These are damn near identical to what Wolf Creek sells. You'd just need to machine an adapter to fit between your R200 output flanges and the Porsche 930 CV. That may require shortening the halfshaft axles but I'm thinking you could make the adapter the same thickness as the Wolf Creek part. It is doable if you want to run a really stout halfshaft. The only other thing that comes to mind with your problem is the nut retaining the flange to the stub axle may have loosened. That will create enough slop to cause the noise you've described too.

[Blakt Out]

Well, with the car on a two-ramp lift and in gear (so the suspension is commpressed as on the road), I can rock the car back and forth and listening closely, it seems like the clunk/sound is coming from the CV. It's more inward than the hub, and more outward than the diff. Also, with the wheel hanging (no weight on it) when I do the same exercise, the clunk isn't apparent. This makes me think that the CV is binding when the suspension is compressed. Maybe it's too long. Maybe the end wasn't flipped over. Dunno.

 

 

So, here's my plan of attack. Let me know if it makes sense.

 

1. Put the RT Mount and GM Mount in. Even if it's not the cause of my issue, it'll be nice.
   
2. Take the CV out and see if I can twist it and feel slop. If so, I'll have it rebuilt or look into stronger CVs (350ft/lbs should be ok though, right?)
   
3. If the CV is ok and hasn't been damaged from the binding, then see about shortening it.
   
4. Be sure to check all connections with the stub axles and adaptors.
   

 

Do I have it all, you think? Seems that all these steps need to be done, and if it's still clunking, then I proceed to keep looking.

 

I ordered the RT mount yesterday from RoostMonkey. The part numbers that I've found on the forums for the GM mount aren't accepted at Summit or Jegs. I think this is it though. Can someone confirm or deny? http://www.summitracing.com/parts/ENS-3-1108G/

Edited December 22, 2010 by Blakt Out

[ezzzzzzz]

The RT mount will require some massaging to fit a 240Z unless Rooster has modified for a 240Z. Not a big deal. How much lateral play do you have in the axle shaft when the car is sitting level? You may pull the halfshaft and check it for binding under compression in the back of the CV housing. Reversing the inner CV knuckle may be the only problem you have to resolve. Others have done this conversion with success.

[RB26powered74zcar]

I ordered the RT mount yesterday from RoostMonkey. The part numbers that I've found on the forums for the GM mount aren't accepted at Summit or Jegs. I think this is it though. Can someone confirm or deny? http://www.summitrac...ts/ENS-3-1108G/

 

 

That mount looks exactly like the one needed (I'm using on my RT part). PICTURES>> Diff mound album

Edited December 22, 2010 by J. Soileau RB26zcar

[deja]

The part numbers that I've found on the forums for the GM mount aren't accepted at Summit or Jegs. I think this is it though. Can someone confirm or deny? http://www.summitracing.com/parts/ENS-3-1108G/

 

That is the one I used. In fact I have one I did not use (bought it for my tranny but went another direction). Its been opened but never mounted. I can send it to you for $25 including shipping.

[Blakt Out]

I very much appreciate it guys. I've been waiting to hear about that. Deja, I totally HATE to negotiate on something of that cost, but your price will be within $1 of the price shipped from Summit, and if there's something wrong, I can send it back to them. Can you do better? Honestly, for the buck, I'd have to get it from Summit. I hope you understand. Sounds stupid.

 

If you want to take this off-forum (either way is fine with me) you can email me at jared@jaredcullop.com.

Edited December 22, 2010 by Blakt Out

[Blakt Out]

By the way, guys, I can't find ANY pics of the axle shortening flip-thing. I really appreciate the photobucket link that you provided J. Soileau. I'll be sure to use that when I'm doing the install. But, has anyone got something like this to show how to shorten the axles as needed for the setup that I have (that others have too)? You guys are awesome, by the way. I hope to contribute to the rest of you whenever I can.

[Blakt Out]

Found this... a VERY old thread. Going by it, I could just extend the bottom of the LCAs out a bit and be done.

http://forums.hybridz.org/index.php/topic/50334-cv-axle-install-advice-needed/page__p__440882__hl__%2Bshorten+%2Baxles__fromsearch__1#entry440882

Edited December 22, 2010 by Blakt Out