Only left 1 black mark?
Thread Starter
Instructor
Joined: Aug 2013
Posts: 159
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From: Wisconsin
Only left 1 black mark?
So I was on my way home last night in my 84. The road was wet so I decided to have a little fun. I turned onto my road and stomped on it. It felt like my wheels were spinning a little but I never got out of control. The next day I was driving to work, and saw that there was only one 5 foot long black mark. Not 2. Why would only one of my tires leave a mark. Was only one of my wheels spinning? Does it have somthing to do with posi?
Race Director
Joined: Sep 2003
Posts: 16,838
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From: Database Error Indiana
My 87 was doing that at 80k miles. Drag racing is hard on the posi. Rebuilt the posi at 90k . All good till about 170k. Needs rebuilt again.
Carrying 100# of lead shot in the back until I decide to fix it.
Carrying 100# of lead shot in the back until I decide to fix it.
Team Owner
Joined: Aug 2005
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From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
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Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Well, if the pavement was wet, what is the possibility the single scratch may have been laid down by another car, and because of the water, you tires didn't leave any mark at all?
But, that aside, it sounds like a new clutch pack is in order. Have you changed differential fluid? AND, if you did, did you put in that little bottle of posi-track fluid from GM? (If I can find a bottle, I'll give you the part number)
But, that aside, it sounds like a new clutch pack is in order. Have you changed differential fluid? AND, if you did, did you put in that little bottle of posi-track fluid from GM? (If I can find a bottle, I'll give you the part number)
Le Mans Master
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
..... The C4 posi units are clutch style , preloaded by a Belleville washer ... clutches wear out ... don't continue to do one-wheel burnouts as it will cause the spider gears to overheat and weld themselves to the shaft they are on ... then you will need to buy a complete differential instead of just a clutch pack ...........
Team Owner
Joined: Sep 2003
Posts: 25,394
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It's not unusual for a clutch type differential to do single wheel when one tire or the other has "more slip/loss of grip". If the differential hasn't been serviced recently I'd consider fresh fluid with the limited slip additive and then do several tight figure 8's in a large parking lot to maybe decrease a finish that the clutch packs may have developed because of use. Use the gear lube of choice and if you can find the older GM # 1052358 additive on the shelf use it. In your particular case maybe two but two is generally considered "overkill"
OP mentioned WET
Does the OP have a problem? Maybe - it's a 30+ year old differential that's likely never had a "clutch-pack" and miles were never mentioned.
Last edited by WVZR-1; Sep 24, 2014 at 10:44 AM.
Safety Car
Joined: Aug 2009
Posts: 3,752
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From: Melbourne, Victoria, Australia
WOW so you guys are saying i should replace my original dana 36 that has done 170,000 miles and is trouble free even though it has coped with the supercharged engine for the last 8 or 10 years?
She still lays a couple lines of rubber if i stomp on the accelerator.
I must have got a good one
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Team Owner
Joined: Feb 2006
Posts: 23,218
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From: San Antonio Texas
Could be the mark was left by the only tire with good contact with the road and the other tire was more in the wet and didn't contact the road enough to leave any rub marks. Try it on smooth dry asphalt and see what you get. One stripe = worn clutches, two stripes = !
!
Team Owner
Joined: Sep 2003
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WOW so you guys are saying i should replace my original dana 36 that has done 170,000 miles and is trouble free even though it has coped with the supercharged engine for the last 8 or 10 years?
She still lays a couple lines of rubber if i stomp on the accelerator.
I must have got a good one
If an '84 early failed it required a case replacement with a differential assembly and also different short axles.
It's good that yours has survived and I believe that it likely should have had a clutch-pack sometime in it's life. That's just part of differential "normal maintenance". Your run it until it breaks is a personal decision. Is it a wise one? It's your gamble.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
I don't believe anyone, certainly I didn't intend on "implying" that "ALL" with high miles are suspect BUT the OP has an '84 and the D36 differential was a known "weak-link" in early production units more than others. The D36 was changed in later '84 production and all '85+ are similar to the later product.
If an '84 early failed it required a case replacement with a differential assembly and also different short axles.
It's good that yours has survived and I believe that it likely should have had a clutch-pack sometime in it's life. That's just part of differential "normal maintenance". Your run it until it breaks is a personal decision. Is it a wise one? It's your gamble.
If an '84 early failed it required a case replacement with a differential assembly and also different short axles.
It's good that yours has survived and I believe that it likely should have had a clutch-pack sometime in it's life. That's just part of differential "normal maintenance". Your run it until it breaks is a personal decision. Is it a wise one? It's your gamble.
Yes you are right it is a bit of a gamble, however it has not shown any problems so far....
I think my diff has survived because i replaced the gasket between the diff to the carier around ten years ago,cleaned the housing and also replaced the limited slip fluid and added fresh gm additive.
The damn thing is leaking at the diff/carrier join again so will be doing it all again soon, will be intersting to see how it looks. I have been thinking of going to the D44 as i have upped my boost from 8 to 14 psi, it may be the final nail in the coffin for the D36.
I don't really want to spill its guts in public, that would be embarrasing
