My 87T Differential

[Jaysun]

Today I wanted to see what kind of differential I had on my recently purchased Z31, open or LSD. My car is a turbo Z31 manufactured in March of '87. Knowing that turbo cars produced 4/87 or later had LSD I was initially expecting to find that mine was open. I jacked the car and found that:
-When passenger side wheel spins, driver side wheel does not spin
-When driver side wheel spins, passenger side wheel spins same direction (ie, both would spin to propel car forward)

But... the rear driver side wheel is hella hard to turn, I mean so hard that it's like the parking brake is on! What does this mean??

[Firehawk]

Sounds like a stuck parking brake cable. As for an lsd, they have a finned cover.

[Jason84NA2T]

Stuck cable, or even seized caliper slides.

[Jaysun]

OK, I was thinking along those lines too...

Question Part 2:
About the parking brake cable, if anything, I would say it is way too loose. I mean, it will keep my car stopped in a parking lot but it barely slows the car down if I engage it while driving. If I pull the e-brake, say at 20MPH, it is the equivalent of *lightly* touching the brakes (ie, it slows the car down just a tad quicker than letting off the gas and coasting to a stop). I would never be able to lock up the rear wheels completely.

So I don't think the hard-to-turn-by-hand rear driver side wheel and parking-brake-cable-being-loose are related. This leads me to believe that the rear driver side caliper is the culprit. But since many of you have way more hands-on experience w/ this let me know what you think. Am I looking a two unrelated problems or the same problem? Do you want me to test something out for more information? …I have the keys right here.

[G-E]

support the car and rear subframe, loosen the diff and pop off the halfshaft from the poorly spinning wheel .... probably won't show anything but play around with it in mid-air, wiggle it, turn it... then remove the caliper of course and repeat....

btw according to the fsm you should be able to turn the wheel/hub by pulling on the studs with a 5lb weight or fish-scale... when newly packed it's supposed to be higher but I'm assuming old bearings

[OR-Zman]

Just for one more idea since you said the e-brake cables are loose, then I would say check the e-brake lever on the caliper. You could have a bad caliper and either the cable is sticking and not retracting properly or the caliper is sticking and keeping the pads clamped to the rotor.

I have been through the cable and the caliper scenario. Calipers= buy an new one. Cable = PM or e-mail me and I will tell you how I was able to resurrect the old locked-up cable to be smooth as silk. :wink:

[Jaysun]

OK, so I have some information. During my big suspension upgrade [http://www.redz31.com/forum/viewtopic.php?t=1085] I got a chance to look at my parking brake problem. The driver side caliper was sticking...I sprayed the spring with some stuff and now it moves like the passenger side does. But I definately have a stuck cable too. So I searched and searched for a fix like a good boy but found no help. OR-Zman, you seem to have the answer...what's the trick?

[Firehawk]

A cheap way to fix the cable is to soak it in oil. I just stick the cable in a container of used engine oil for a a day or so. It will fix some, others are just too far gone.

Come on OR-Zman, share the info :P

[Jaysun]

The parking brake dilemma seems to be fixed although I'm still not to happy with the parking brake...still a little sticky. BTW, PB Blast is good stuff...that helped unstick the cable and the caliper spring but, again, it's still a little sticky.

Anyway, so my differential is definitely a LSD. My turbo Z31 was made 3/87 and apparently it's not supposed to have one...and I *highly* doubt that the previous owner(s) added an LSD...this car was like a garage queen with absolutely no modifications for it's entire life.

And it has the finned cover. But if these differentials were that easy to tell apart why wouldn't people just say "look for a finned cover" instead of the whole "4/87" thing?

[Jason84NA2T]

Jaysun wrote: The parking brake dilemma seems to be fixed although I'm still not to happy with the parking brake...still a little sticky.
Use some spray lithium grease, it will GREATLY help the cable not stick.

Jaysun wrote: And it has the finned cover. But if these differentials were that easy to tell apart why wouldn't people just say "look for a finned cover" instead of the whole "4/87" thing?

Because then you could easily put a finned cover on an open diff and try to pass it off as an LSD. I have two open diff's with finned covers on them. Just as many V8 owners have learned from racing my car: just because it looks like one thing from the outside does not mean you know what's inside.

[Butter]

Swap to Z32 brake system and install CNC hydralic hand brake.

Worked wonders for me.

[Benedict]

hey Butter...

when are we gonna see some video of the Z in action?