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I was amazed that the rearend clunk......


CarolinaTZ

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was simply loose nuts where the diff attaches to the mustache bar.  My 260Z has 63,000 miles and had a horrible clunk unless I synchronized the throttle/clutch/shifter with surgical timing.

 

I did searches and most of the topics pointed to the so-called "flawed" design of the diff setup on the S30.  I was convinced I needed to install the RT front diff mount.   I started with a floor jack under the nose of the diff....I expected to see a lot of lift and a deteriorated front mount.  The front of the diff lifted probably 1/4" before it started to lift the car and the bushing mount looked new.  

 

To my surprise, when I reluctantly crawled under the car with a torque wrench to hit all the fasteners around the diff/suspension, there was some loose hardware.....and this car has not been driven hard.  I almost forgot about it 'til the next time I drove the car.  Wow!  The clunk was gone!  Yeah, I can feel the normal backlash but, instead of clunking it is quietly absorbed by the "springy" metal parts and bushings.  

 

I'm pretty sure the diff was rotating and the studs were wracking in the mustache bar holes.  Checking for loose fasteners should be the first thing to do....and some of the message threads said to do that first.  But overwhelmingly the threads immediately addressed the front mount issue......and the fact that I convinced myself a low mileage car would not have any loose hardware.....not true.    

 

If you have a clunk, check your fasteners.....you may be pleasantly surprised.

Edited by CarolinaTZ
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If you don't want to check them again soon, make sure you put some blue lock tite on the bolts. I found lots of mine rattled loose over time. 

 

And there is a design flaw with how the diff mount is setup, it is more suited to driving the car in reverse then forward. An RT mount with poly rear diff bushings is going to make the car feel much more connected, and you won't have to revisit the strap or ripped rubber mount every few years.

Edited by seattlejester
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Yes, I plan to put loctite on them the next time I'm under there.  After being in so many that clunked, I was convinced they all did it without the upper style mount.  That would be a design flaw.  But that's not the case.  As long as everything is tight, the design works fine on a stock powered car.

 

I'm just excited I don't have to alter the stock diff setup on my 260Z that I want to keep original.

 

As far as the RT setup...I'm not saying it's not an improvement....it is.  I'm using one on my 72 turbo car w/ 3.90 clsd.  

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If you don't want to check them again soon, make sure you put some blue lock tite on the bolts. I found lots of mine rattled loose over time. 

 

Also, if you don't feel like dissassemling everything to do this, Green Loctite works similarly to penetrating oil and can be applied to assembled joints.  It's a medium strength theadlocker too, similar to blue.

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Also, if you don't feel like dissassemling everything to do this, Green Loctite works similarly to penetrating oil and can be applied to assembled joints.  It's a medium strength theadlocker too, similar to blue.

 

Great advise Tim.  I have a large bottle of it and use it often .  It's also great for "wicking", where it pulls itself into the threads...

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Thanks for the input, guys.  I don't mind some disassembly to add loctite. I only have 263 red on hand...my concern is that if I ever had to take it apart, it would back the studs out of the diff cover.  Do y'all agree?  If i'm wrong, I'll just use the red. 

 

Otherwise, I'll get some 243 blue or 290 green....I may lean towards the green since it's hold is similar to blue with the added benefit of not having to disassemble.

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And on the other hand, we use red on everything we don't want to vibrate off the racecar. The axle nuts take a big breaker bar to break loose, but they come off. Blue is probably sufficient for a street car, but I wouldn't say red is an absolute no.

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And on the other hand, we use red on everything we don't want to vibrate off the racecar. The axle nuts take a big breaker bar to break loose, but they come off. Blue is probably sufficient for a street car, but I wouldn't say red is an absolute no.

Same here. Not permanent, just stronger locking than blue or purple. There is a green loctite that the diff shop I used to work for used to keep races from spinning when housings were worn. Apparently that stuff was a lot stronger than the red, so yeah, best not to just go by the color apparently...

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