I am installing some 3.73's in my 10bolt friday, and i was wondering if I will be ok to do a little racing on saturday? Is there a break in period for gears, if so how do you break them in and how long will it take? thanks, i tried doing a search, but didnt search too hard.

 

i usually baby it for around 500 miles than change the gear oil once more.

 

I got this from another thread, perhaps another site (I don't remember):

"Originally Posted by chevystyle
Just had my gears replaced. The shop gave me a Break-In Procedure paper. I decided to post it in case somebody wanted to know. My gears were replaced with AAM OEM GM 7.625 4.10 ring and pinion set from UNITRAX.

Ring and pinion sets require a break-in period to prevent damage from overheating. Overloading or overheating will cause the lubrication to fail, resulting in damage to the ring and pinion. In order to maximize the life of your differential, please follow this break-in procedure.

1. After installation, fill the differential with only premium national brand 80w90 or 85w140 GL-5 gear oil. Also add 4-8 ounces of Dane Spicer friction modifier to the oil if your differential contains a limited-slip or posi unit. Alert: Verify that the drain and fill plugs are properly secured.

2. Drive your vehicle easy for 30 minutes or approximately 20 miles. Avoid aggressive starts, hard stops and long distances at a steady speed.

3. Let the differential cool for at least 45 minutes.

4. Repeat steps 2 and 3 once.

5. It is not recommended to tow during the first 500 miles. Also avoid wide-open throttle acceleration for the first 300 miles.

6. When towing for the first time, drive easy for 20 miles let the differential cool for 45 minutes.

7. It is recommended to change the differential fluid between 2,500 and 5,000 miles (someone else recommended 500 miles K_K). Use the lubricant specified in step 1. Subsequent oil changes should be performed every 20,000-30,000 miles.

Many differentials have been damaged by overheating, overloading, inadequate or improper lubrication. The above procedures may be a minor inconvenience, but if followed, your differential should prove to be one of the most dependable devices in your vehicles.

Again, this was a list given to me by the shop."

 

Do I need to break in my new ring and pinion gear?
A. Yes! All new ring and pinions should be broken in to avoid over heating or over loading and burning up. We recommend a specific break-in procedure that has worked for our own service shop over the past fifteen years. First, NO towing, heavy loads, or hard acceleration for the initial 500 miles. Next, for the first 100 miles you should drive 15-20 mile increments under 60mph and then let the differential set and cool for at least 15-20 minutes. At the 500 mile mark you should have the differential oil changed. This removes all the loose shavings from the new gear and phosphorus material from the oil. Small price to pay to prolong the life of your differential. Also, after 500 miles you can start towing or carrying heavy loads. We recommend that for the first 45 towing miles you drive in 15 mile increments again due to the fact this is the first real load the gear will see and as the ring gear flexes there will be contact on new portions of the ring gear and pinion gear teeth.

 

thanks guys!

No WOT for 300 miles, i dont know wtf im going to do...

 

I drove 10 miles let it cool another 10 miles let it cool and raced it the next day with new Richmonds and Auburn posi. Seems to be fine.

 

I just toasted a set of Motive 4.30 street gears because I didn't follow their break-in procedure. Putting some richmond's in now and will be breaking them in for the full 500 miles........

 

Guy broke in his 4.10s for 400 full miles and they are super quiet. I rolled into my 3.73s WOT several times before 50 miles. Mine's not as quiet as his but they are still both working.

 

i broke mine 4.10's at the track 2 days after I had them installed there is a slight whine at around 80 under acceleration, thats about it.

 

I just had a set of 3:73's put in lastnight. Installer has put in over 300 and has had about 20 (all raced cars) or so come back burned up from improper break in. He says everyone of them admitted to pounding on the gears before 200 miles. He scared me enough, so i'll baby the thing for a few hundred miles before i get on it alittle. He also said it is very important to change the fluid at or around 500 miles...the additional heat created by the gears breaking in tend to break down the gear oil quicker along with any filings.

 

thanks for all the feedback, damn 500 miles with out wot thats gonna be very hard! I also will change my gear oil at 500 miles also.

 

hmm you learn something everyday

 

Although the place i bought my gears from said no problem on WOT after 100 miles...installer said to be safe, 200 miles. I'm going to split it, 150 mile WOT runs and a 500 mile gear oil change.

 

When i read my Moser Instructions I followed it to a "T"

Fill with fluid, add diff lube if needed.

Run on jack stands, 2k rpms for a few minutes and reverse for a couple. Let sit and cool.

Then drive for 20minutes with variying speed (stop and go), park and let sit over night.

The go race it. Worked fine ever since.

You can baby it for 500 but as soon as you put any force to it, any real force, it will show a slight noise, at least in my exp of any aftermarket gear be it a 10 bolt, 12 bolt, 9" etc etc

 

Two different gear sellers said to only go with OEM for the reasons you stated above...so i spent the extra money for the OEM's.

 

good, i went with oem's also. j/w I bought a seal,gasket,red loctite,white grease, gear oil and additive. Does that sound right, I also thought about getting a dial indicator for it.

does anyone have a write up on the gear change, Im just want to be sure im doing everything the right way.