How hot should an 8 3/4 housing get?

[threewood]

I started getting some sure grip clutch grabbing after driving a while. No issues cold but when it is warmed up and driven several miles it will pop and grab at slow speeds. It has Mopar friction modifier in it, clutch type sure grip 3.55 gearing.

Anyway I hit the center housing with a laser temp gun and it was 140 degrees in the center, both axle flanges were at 118 and 120 degrees. And it looks like a little fluid has came out the vent.

Normal? I am going to replace the gear oil with Mobil 1 75w90 and add Ford friction modifier anyway.

 

[PP1RT]

New gears getting broke in or do you have some miles on it?

New gears getting broke in will run a little hot. You need to make some short drives and then let it cool off in between. After a few cycles change oil again and add fresh additive.

 

[69L48Z27]

The rear fluid would need to be a lot closer to 200* before I would get concerned. I'm sure your fluid level is good, not sure why it would be pushing fluid out the vent. How much are we talking about?

 

[AR67GTX]

I would say 140 F is within a normal range.

 

[moparnation74]

Sounds normal to me as well.......Oil coming out of the vent leads me to believe it may be overfilled......

 

[65-440]

How old is this unit ? I had the same issues with a new sure grip, after a few miles it would bind and pop around turns. Changed fluid, ran nothing but the ford modifier but nothing worked. After tearing it apart 3 times, shipping back and forth to the supplier I was working with(very reputable by the way) and always had the same issue I installed a Detroit true Trac and haven't looked back. I don't think I'll ever run a clutch unit again.

 

[andyf]

Might try driving in some figure 8's in a big parking lot just to see if you can work it loose or find out if you have a problem. Could have someone walk behind the car as you drive it slowly in a figure 8 to see if they hear anything unusual.

 

[Ironbuilt]

Not sure if this helps, but I have axle temp gauges in my Peterbilt and the rear axles hover right around 140 degrees. Gear oil will not start to break down until north of 200 degrees. Like others said, oil out of the vent sounds like an overfill issue.

 

[Billccm]

The vent on mine stays a little wet. I assumed it might be over filled as I cracked the plug and it leaked out easily.

 

[threewood]

Thanks for the replies!

It is an older unit with original gears. Just started grabbing again while driving slow. Can the modifier wear out? I went through this when I got it back together originally. Used Lucas w/ LS modifier but it wasn't enough so I added a bottle of Mopar Friction Modifier. Filled the rear end until it dribbled out the fill hole.

No noise or whine in the gears at all.

As long as the temp is within range I'm not concerned. I'll still pump out the old and refill with new gear oil and Ford friction modifier.

 

[Fran Blacker]

Many guys here have said to use ford friction modifier. Had a 64 Olds doing that, felt like one rear wheel going over a speed bump. Whale oil additive helped but still did it.

 

[Cranky]

Had trouble with a Trac Lok in a 9 1/4 and none of the factory type friction modifiers worked but a 1/3 bottle of STP did the trick. That was 70+K miles ago and it's still going strong. Never tired STP in either of the 8 3/4 style SG's however it did reduce the howl in my Dana 70 by at least 50%! Dumped it in 100% over 3 years ago

 

[threewood]

Does anyone know the difference between the Mopar, Ford and GM friction modifier?
I had read about the Ford being the best but I used the Mopar, because it's Mopar lol. Trying the Ford stinky stuff this time.

 

[MoparLeo]

Shouldn't make noises when driving in a straight line. Clutch type do make some noise and are somewhat grabby when turning. That is how they work.

 

[MoparLeo]

Dodge TSB on Sure-grips :
https://www.e-bodies.org/Resources/TSB/Sure_Grip_Diagnosis.pdf

 

[Billccm]

Does anyone know the difference between the Mopar, Ford and GM friction modifier?
I had read about the Ford being the best but I used the Mopar, because it's Mopar lol. Trying the Ford stinky stuff this time.

For what it's worth, my friend that runs the local brake shop uses the AC delco limited slip with every diff he services.

 

[Billccm]

https://www.forabodiesonly.com/mopar/threads/sure-grip-oil.398407/#post-1972232351

 

[1967coronet]

I started getting some sure grip clutch grabbing after driving a while. No issues cold but when it is warmed up and driven several miles it will pop and grab at slow speeds. It has Mopar friction modifier in it, clutch type sure grip 3.55 gearing.

Anyway I hit the center housing with a laser temp gun and it was 140 degrees in the center, both axle flanges were at 118 and 120 degrees. And it looks like a little fluid has came out the vent.

Normal? I am going to replace the gear oil with Mobil 1 75w90 and add Ford friction modifier anyway.

After reading your post , I took my 67 out for a cruise today. 25 miles of hyw driving at 60 plus mph and checked my 8.75 3:23 sure grip when I returned home with my temp gun.
141* housing center, axle flanges on mine were 108# and 106* I just have napa 80/90 and transX limited slip additive in mine prob close to 5yrs on the oil and additive.
I would say your temps are good going by what mine is doing. I don't have any chatter or grabbing but do know the sure grip is working fine, vent is dry on mine.
The transX is the anti chatter formula.

 

[beanhead]

How old is this unit ? I had the same issues with a new sure grip, after a few miles it would bind and pop around turns. Changed fluid, ran nothing but the ford modifier but nothing worked. After tearing it apart 3 times, shipping back and forth to the supplier I was working with(very reputable by the way) and always had the same issue I installed a Detroit true Trac and haven't looked back. I don't think I'll ever run a clutch unit again.

This sounds familiar!! I the same EXACT experience, except I was dealing with a local shop that tried every trick in the book to get the clutch unit to run right. They concluded the case just wasn't to spec and the manufacturer (Yukon) wouldn't warranty another one. They (to their credit) warrantied a complete new unit and 2 sets of spiders...then said 'no more! It's because he's out burning rubber! Well, my shop said, 'I don't care if he is or isn't these things should hold up, period..' and they COMPED me a new Truetrac AND all the labor and it's been fine ever since....no additives required. When they re-did my power-lok I used 2 bottles of ford instead of just one, no help. @threewood I'd keep a real close eye on it, if problem continues it will gouge the clutches and possibly take out the innards. Personally I think the powr-lok clutch units are having serious quality issues as I (we) aren't the only ones experiencing this..

 

[beanhead]

And sure sometimes a little chatter in turns is okay, but not pops and binding. I've been in many a mopar than made zero noise so I think unless the clutches are set up to be aggressive, operation should be smooth.