8 3/4 break in procedure.....

[challenger71]

I just put a brand new sure grip center section in the rear with 3:73 gears. I have added all the fluid and now it is time to break it in. What is the process of breaking these in. The car is still up in the air as I am assuming I need to run it with no pressure on it. Please let me know.

[Chryco Psycho]

10 minute burnout !!!
 Ok kidding you could run it on stands for 10 minutes or so couldn`t hurt , I would just taje it easy on it for 50 miles or something , keep the slicks off for 100 miles or so !!

[tactransman]

From Randy's Ring and Pinion:

What is the break-in proceedure for a new set of gears?
All new gear sets require a break-in period to prevent damage from overheating. After driving the first 15 or 20 miles it is best to let the differential cool before proceeding. I recommend at least 500 miles before towing. I also recommend towing for very short distances (less than 15 miles) and letting the differential cool before continuing during the first 45 towing miles. This may seem unnecessary but I have seen many differentials damaged from being loaded before the gear set was broken in.
I also recommend changing the gear oil after the first 500 miles. This will remove any metal particles or phosphorus coating that has come from the new gear set.

[challenger71]

Thank you. You guys rock and so does this site. Check out my restorations page on here. It will show what my car looks like now.

[longgone]

Just got my new dana 60 in and am glad I saw this post.  I've been taking it easy and not laying into it too hard but I should be safe at this point, I've got a few hundred miles on it.  Know how hard it is not to lay into a 440-6pk?

Blueglow

[challenger71]

Tell me about it. I would just love to take mine out and go .... .... I guess I will have to wait until I am done restoring it.

[nivvy]

i took mine out and jammed the pedal to the floor..... 

[mopardave]

Just put in a new 8.75 3.91 and they told me in there version is not to go over 45 for the first 100 miles, on the Dana 60 I did DTS said 45 to 65 mph max for the first 100 miles and at 500 change the fluid. NO prolonged stop or hard accelartions

[bb71challenger]

Is it true that you need to put the sure grip additive in there even if you use synthetic gear oil? 3.73 sounds like a nice ratio, especially if you have overdrive  Good luck on the break-in.

[Chryco Psycho]

with synthetic you can try without additive , if it grabs or chatters around corners add additive

[challenger71]

The guy that built my rearend told me not to run synthetic oil in my case, but to make sure I run the additive. He told me the synthetic is too slippery for the clutches to engage and will wear the case down quicker. I believe him too as he owns many Mopars plus he has a 1000 hp Barracuda for the track.  He said he tried synthetic but ended up with the rearend failing on him.

[bb71challenger]

The guy that built my rearend told me not to run synthetic oil in my case, but to make sure I run the additive. He told me the synthetic is too slippery for the clutches to engage and will wear the case down quicker. I believe him too as he owns many Mopars plus he has a 1000 hp Barracuda for the track.  He said he tried synthetic but ended up with the rearend failing on him.

Kind of weird you say that. I had a strong cone type 3.23 sure grip in my Challenger and I changed to oil over to synthetic thinking I was doing a good thing. I had heard not to worry about the additive and just use the synthetic oil. Well, it was not long and the pig up and died on me after chattering a few times. I just thought it was that third members time. I ended up putting a 2.94 sure grip out of a Imperial and thats what is in there now. Not many miles on it and yup, it has synthetic only in there. I will drain that sucker and put in conventional 90 wt. with the whale sperm when I get it ready to drive.

[challenger71]

That is why I posted that reply. I figured that there is so much debate on that topic so I would tell people what I have learned and hopefully save somebody their rearend....literally. They aren't cheap.  This guy has got more mopar parts and cars than anybody I have seen. Literally a few large garages full.  And he runs his own shop too.