Anyone else have this????
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Anyone else have this???? (Dominic Sorresso)
If you have an open differential...you will vary on 60' times because you may or may not get tire spin...depending on how the track likes sticking to your tires. Obviously, one would spin before the other.
I think it's a good idea to remove the carrier and inspect it. You will want to pull the spider pinion shaft out and inspect the teeth on the spiders. They are not easy to get out as they are preloaded by the shims under the spider gears. There is a clamp made just for compressing the clutch pack so you can unload and remove the spider gears. If you do not have one, take it to a shop that does and have someone tear it apart for you.
I think something is wedged between the spider gears teeth making both axles stay locked together.
As far as your dads 12 bolt...it may not be a limited slip unit, or even if it is and his clutch packs are worn to the point of no preload, it does not have the same weak link spider gear as our vettes do. BTW: 12 bolt limited slip posi is much easier to take apart than a dana because the preload is done by a set of springs pushing against a pressure plate assembly. It's not hard to pull the springs out so it can be dissassembled.
[Modified by BBA, 12:29 PM 7/28/2003]
I think it's a good idea to remove the carrier and inspect it. You will want to pull the spider pinion shaft out and inspect the teeth on the spiders. They are not easy to get out as they are preloaded by the shims under the spider gears. There is a clamp made just for compressing the clutch pack so you can unload and remove the spider gears. If you do not have one, take it to a shop that does and have someone tear it apart for you.
I think something is wedged between the spider gears teeth making both axles stay locked together.
As far as your dads 12 bolt...it may not be a limited slip unit, or even if it is and his clutch packs are worn to the point of no preload, it does not have the same weak link spider gear as our vettes do. BTW: 12 bolt limited slip posi is much easier to take apart than a dana because the preload is done by a set of springs pushing against a pressure plate assembly. It's not hard to pull the springs out so it can be dissassembled.
[Modified by BBA, 12:29 PM 7/28/2003]
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Anyone else have this???? (BBA)
BBA/Anyone, do you have any schematics of the rear differential. It sure would help to see an exploded veiw of one of these. :cheers:
thanks guys for all your help!
:cheers:
thanks guys for all your help!
:cheers:
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Anyone else have this???? (ski_dwn_it)
Jessie,
If your dad's diff was once posi, it is worn out like Dominic's. Do yourself a favor. After looking for loose teeth, refill the diff with new dino grease, and one, or two (for overkill) bottles of GM positraction friction modifier. If you don't find a dentists dream in there, I guarentee an improvement.
Dominic,
I you are not getting wheel spin at the track, now, a properly functioning posi will give you NO gain.
To both (and all) good luck, and...
RACE ON!!!
If your dad's diff was once posi, it is worn out like Dominic's. Do yourself a favor. After looking for loose teeth, refill the diff with new dino grease, and one, or two (for overkill) bottles of GM positraction friction modifier. If you don't find a dentists dream in there, I guarentee an improvement.
Dominic,
I you are not getting wheel spin at the track, now, a properly functioning posi will give you NO gain.
To both (and all) good luck, and...
RACE ON!!!
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: Anyone else have this???? (CFI-EFI)
CFI,
My last trip to the track, I launched at about 1300-1500rpm. Anymore than that and I'll just waste time at the line. It launches straight with very little correction needed. In fact, my best time came from coming out at 1200rpm and then nailing the accelerator. That's one reason why recently upgraded to the 17" ZR-1 wheels and am now using 315x11 Yoko's in the back. I am going to verify again my memory probably by jacking up the rear. During the upgrading of the brakes, I also remember that it was necessary to raise both wheels in order to turn them. One wheel off the ground was not enough. It wouldn't move otherwise.
My last trip to the track, I launched at about 1300-1500rpm. Anymore than that and I'll just waste time at the line. It launches straight with very little correction needed. In fact, my best time came from coming out at 1200rpm and then nailing the accelerator. That's one reason why recently upgraded to the 17" ZR-1 wheels and am now using 315x11 Yoko's in the back. I am going to verify again my memory probably by jacking up the rear. During the upgrading of the brakes, I also remember that it was necessary to raise both wheels in order to turn them. One wheel off the ground was not enough. It wouldn't move otherwise.
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Anyone else have this???? (Dominic Sorresso)
Thanks guys for the information . Looks like we have to rear ends to look at now. :rolleyes: Christ I hate the smell of that oil.
Well I will let you all know what I discover when I pull it apart. Its actually not that bad of a job. I am also going to replace all the bushings with new poly bushings, and the camber braces for racing also while its apart.
Thanks again. :cheers:
Well I will let you all know what I discover when I pull it apart. Its actually not that bad of a job. I am also going to replace all the bushings with new poly bushings, and the camber braces for racing also while its apart.
Thanks again. :cheers:
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Anyone else have this???? (Dominic Sorresso)
Dominic,
If the trans was in park, or in gear, with a stick shift, ONE wheel wouldn't turn, regardless of the condition of the posi. I have changed my launch technique. I now come out at 1500 rpms, stalled against the converter. No wheel spin on a well prepped track, and 2.05 second 60 foots, uncorrected, @ 4500' physical altitude. That is about .05 quicker than coming off at an idle. 255/50/16 BFG Drag Radials, 3.08:1 gears.
Jessie,
I am very anxious to hear the verdict.
RACE ON!!!
If the trans was in park, or in gear, with a stick shift, ONE wheel wouldn't turn, regardless of the condition of the posi. I have changed my launch technique. I now come out at 1500 rpms, stalled against the converter. No wheel spin on a well prepped track, and 2.05 second 60 foots, uncorrected, @ 4500' physical altitude. That is about .05 quicker than coming off at an idle. 255/50/16 BFG Drag Radials, 3.08:1 gears.
Jessie,
I am very anxious to hear the verdict.
RACE ON!!!
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: Anyone else have this???? (CFI-EFI)
Dominic,
If the trans was in park, or in gear, with a stick shift, ONE wheel wouldn't turn, regardless of the condition of the posi. I have changed my launch technique. I now come out at 1500 rpms, stalled against the converter. No wheel spin on a well prepped track, and 2.05 second 60 foots, uncorrected, @ 4500' physical altitude. That is about .05 quicker than coming off at an idle. 255/50/16 BFG Drag Radials, 3.08:1 gears.
Jessie,
I am very anxious to hear the verdict.
RACE ON!!!
If the trans was in park, or in gear, with a stick shift, ONE wheel wouldn't turn, regardless of the condition of the posi. I have changed my launch technique. I now come out at 1500 rpms, stalled against the converter. No wheel spin on a well prepped track, and 2.05 second 60 foots, uncorrected, @ 4500' physical altitude. That is about .05 quicker than coming off at an idle. 255/50/16 BFG Drag Radials, 3.08:1 gears.
Jessie,
I am very anxious to hear the verdict.
RACE ON!!!
CFI,
It was in neutral. It needed to be so I could rotate wheels when they were both jacked up. 1500rpm is too much for my motor. Its putting out 300lbft at the rear wheels by 2000rpm.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Anyone else have this???? (Dominic Sorresso)
It was in neutral. It needed to be so I could rotate wheels when they were both jacked up.
1500rpm is too much for my motor. Its putting out 300lbft at the rear wheels by 2000rpm.
RACE ON!!!
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Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: Anyone else have this???? (CFI-EFI)
That is confusing. The wheel refusing to turn is a sign of the preload, that wheels turning in opposite directions, indicates doesn't exist.
That's great, but do you get good power (ETs) shifting at 6000 rpms? I still have stock cam, heads, and exh manifolds, too. The new engine is on the stand.
RACE ON!!!
I may have been incorrect on the wheels turning in opposite directions. I need to verify that. But I absolutely recall requiring to lift both wheels off the ground in order to turn them
I don't shift at 6000rpm. Way past power peak which occurs at about 4900 rpm with 275hp at the rear wheels(last time on dyno). I don't have stock heads,
cam, or exhaust manifolds. Best trap speed was 102mph. and best ET 13.6.
Stock tires and rear.
That's great, but do you get good power (ETs) shifting at 6000 rpms? I still have stock cam, heads, and exh manifolds, too. The new engine is on the stand.
RACE ON!!!
I may have been incorrect on the wheels turning in opposite directions. I need to verify that. But I absolutely recall requiring to lift both wheels off the ground in order to turn them
I don't shift at 6000rpm. Way past power peak which occurs at about 4900 rpm with 275hp at the rear wheels(last time on dyno). I don't have stock heads,
cam, or exhaust manifolds. Best trap speed was 102mph. and best ET 13.6.
Stock tires and rear.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Anyone else have this???? (Dominic Sorresso)
I may have been incorrect on the wheels turning in opposite directions. I need to verify that. But I absolutely recall requiring to lift both wheels off the ground in order to turn them.
I don't shift at 6000rpm. Way past power peak which occurs at about 4900 rpm with 275hp at the rear wheels(last time on dyno). I don't have stock heads,
cam, or exhaust manifolds. Best trap speed was 102mph. and best ET 13.6.
Stock tires and rear.
cam, or exhaust manifolds. Best trap speed was 102mph. and best ET 13.6.
Stock tires and rear.
RACE ON!!!
