Miles for gear break in?

[Chuckie B]

getting my gears installed next tus/wed....about how many miles should i baby them for be-4 i go and let the car looose

 

[Wicked One]

Here you go.

1. Any overloading or overheating will cause the oil to break down and the ring and pinion will fail.


​

2. A ring and pinion installation, especially a high numeric ratio with new bearings, can cause an excessive heat build up in the rear end and cause softening of the gear teeth and bearings if a break in is not performed.​

3. To break in the installation, perform a run-in prior to driving, with the rear wheels jacked up and operating at idle speed in high gear for a minimum of five (5) minutes. Drive vehicle 10 miles at a normal speed, let cool one (1) hour, repeat, once. ​

4. Vehicles used for towing need approximately 200-300miles of normal street driving BEFORE being used for towing. ​

5. On circle track race cars, make approximately 6-8 laps at slow speed, then let cool for 30 minutes, make 6-8 laps more at slow speed, then 2-3 laps at full speed. Let cool again for 30 minutes.​

6. Drag cars need only an initial run-in since they are driven short distances and heat is not normally a problem with proper lubrication and backlash allowances. ​

7. All Just Rear Emds 9 inch differentials use a solid spacer in place of the stock crush sleeve. This is not only stronger, but facilitates the replacement of the pinion yolk and/or seal without affecting pinion bearing preload. ​

Special Notes ​

A. For Ford 8�and 9� Trac Locs, always install driver side axle first to avoid misalignment of the split side gears. ​

B. Recommended gear oil: GL-5 80-90 wt NON-SYNTHETIC. ​

C. Positractions require a Ford or Motorcraft friction modifier additive. Part number: M-19546A. ​

 

[97modgt]

Good post. I just learned something new.

 

[Wicked One]

Again, had to dip into my secret stash of info!!

 

[97modgt]

Again, had to dip into my secret stash of info!!

Don't tell me where that stash is at cause I may have to peek

 

[Wicked One]

It is just behind my medulla oblongata.

 

[97modgt]

It is just behind my medulla oblongata.

I should bring rubber gloves then.

 

[BubbaStanGT]

^ almost missed that one at first lol!

 

[Wicked One]

 

[97modgt]

hahaha

 

[BubbaStanGT]

do long distances after install cause overheating etc? IF my rear end ever gets fixed, its an hr away from me right now. So after I pick it up I plan on driving to a car wash that is about 10 miles away. Going to clean her up wait the hour, drive again 10 mins and then back to the wash to clean some more wait the other hour. So I should be good after that? Because I have about a 60 mile trip back home from there...

 

[03svt]

i have never heard of this ever. a gear break-in?? c'mon who wrote that

 

[Wicked One]

A company wrote that article, they are called "just rear ends" and they specialize in Ford 8 &9" rears. I think they would know.

 

[Chris2kGT]

i have never heard of this ever. a gear break-in?? c'mon who wrote that

I guess the "500 mile take it easy so your rings seat on the pistons" is make believe too right?

 

[BubbaStanGT]

so I should be alright doing what i mentioned above? car better be done tomorrow or im blow n er up!

 

[Wicked One]

You should be fine. What they are saying is they want you to heat cycle the rear, not go balls out until things properly seat themselves in.

 

[BubbaStanGT]

ya i didnt know if a long distance @ 65-70 mph would cause the heat. IF she gets fixed tomorrow im not burning out or launching for LONG TIMEEEEEE! thanks Gregg!

 

[Jimmerz]

i can honestly say i never broke my gears in, i got them installed and beat the snot out of the car... never had a problem.. had the fluid in the rear changed last summer and other than smelling rank all was well.. im either lucky or ford makes a damn good product.