1975Scamp
Well-Known Member
I have a 8.25 rear, I have done the jack up and spin wheels test and they spin opposite directions. So, it appears that I have a open rear. But sometimes I get both tire to spin why is that?
Open or Suregrip?
- Thread starter 1975Scamp
- Start date
-
If that was completely dry pavement, you have a sure grip. The clutches are probably worn. Did you do the spin the tire test in park or neutral?
1975Scamp
Well-Known Member
I was dry pavement...I don't remember park or neutral... I will retry...
Oklacarcollecto
Life is an experiment
Remove the 10 bolts on the rear cover and see what you have for sure.
Don't all 8.25 have the cone style sure grips?
Should be done in park.
The clutch types are all I have ever seen in the 8.25. I have one sittin in the driveway......although worn out.
1975Scamp
Well-Known Member
OK, Thanks, I will retest and re post!
Oklacarcollecto
Life is an experiment
I just learned something. I thought the clutch style went away in the middle of the 8.75 production.
hollywood hig
King of the assklowns
it's an open rearend..........the weight on each tire will determine whether it will hook up w/both tires, sounds like your weight on each tire is pretty close to each other.
i had an open rearend in my car for years and used air shocks, each with it's own schrader valve to balance the weight on each tire, it would hook up posi all the time.
doesn't matter if the car is in neutral or park to do the tire spin thing, if it's in park, neither tire will spin if it's a suregrip..........
higgs
1975Scamp
Well-Known Member
I forgot to mention that the rear casting is from 1969-1970 B-Body.
Oklacarcollecto
Life is an experiment
Then that would be an 8.75 wouldn't it? Picture please.
1975Scamp
Well-Known Member
It is a 8.25 rear, cover bolts to rear.
Exactly. That's why I suggested park.
Oklacarcollecto
Life is an experiment
Everyone I have had has been an 8.75 in those years but lord knows I haven't seen everything. I have never been lucky enough to score a factory Dana 60.
I know even now, the clutch type is all Mopar offers for it. Auburn does show a cone type. Also another reason why it may spin both one minute and one the next is because to my knowledge, the 8.25 sure grip never had a spring preload pack in the center. It's a torque sensitive limited slip. When power is applied, the clutches "ramp" up against each other, real similar to the cone style, but with clutches and no preload springs. That could also be why it fails the spin test in park possibly. I too have seen an open differential spin both tires before......but not as positively as in his pics. First time for everything I guess. That's why I like this hobby. You see something new everyday.
I'm like you. I didn't think it came out till after 70.
1975Scamp
Well-Known Member
Surely does spins both wheels in park, opposite directions.... Hmmm....
Oklacarcollecto
Life is an experiment
Open rear end.
Here is a good article but I have personally never seen a Mopar with a 4 3/4 bolt pattern as mentioned in the article.
http://www.hemmings.com/mus/stories/2007/01/01/hmn_feature21.html
It could well be open. Do you have a lot of power? That could explain it.....OR it still could be the type sure grip I described.......but I would probably give a little resistance trying to turn the wheels in park.
1975Scamp
Well-Known Member
I am running 350-400 Hp, Wouldn't open only spin one wheel all the time? I have also been told that open would always have 1 strip shorter than the other if both tires broke loose. When I get both to spin, they are always identical in length. I guess i will have to open it up to verify. If open, any opinions on internals to swap to suregrip?
I had an 04 F250 Super Duty. It had a Sterling 10.5" limited slip. It would fail the spin in park test badly, yet smoke both rear tires almost every time. That Sterling limited slip is the same type that might be in yours. No center preload spring pack. That's why it will fail the spin test in park. There is nothing engaging the clutches. If you remove the rear cover and there is no spring pack, that doesn't necessarily mean it's not a sure grip. You'll need to remove the spider gear shaft and gears and side gear to see the clutches if it has them. You MIGHT be able to look into the area I have circled and see the clutch pack. You can see it in the picture. The blue tang that inserts into the case holds them in place. If all that is there, it's a sure grip. I'm like you. I have never seen an open rear spin both tires as positively as in your pic. But, there's a first time for everything. Lastly, because it does not have a preload pack, even a new one of this style may not spin both tires all of the time. The one in my truck did not even when it was new.
1975Scamp
Well-Known Member
Thanks guys for all of your insight. I will just have to open it up! Thanks Again! You Guys Rock!
Post a pic when you do.
I have read that when a suregrip unit is worn badly it can exhibit the signs of an open diff. Is it possible you do have a suregrip that is badly worn, although when you put enough to it it's enough to make it work?
67Dart273
Well-Known Member
Here's the OPPOSITE that can happen with an open spider differential...............I just pulled one out of my 67 (Ford 9") was an open spider I'd put in temporarily, and quickly found that either a "mudder" or a "burn out specialist" had owned it. They had spun the axles until one spider wore a big cavity in the case!!! That not only caused play in the wheel (tip in-out) and low speed noise, but it ALSO caused the spiders to bind up in a "quasi" "posi"!!!
I thought I had a photo of this mess, but cannot find it.
I thought I had a photo of this mess, but cannot find it.
hollywood hig
King of the assklowns
-
