ajrothm

I am about to finish up the install of my 9" tonight but I am getting mixed opinions on the break in of the gears. Some of what I read is:

Opinion 1:
1) Run car on jack stands in forward and reverse for 10 mins, let it cool down completely.
2) Run the car easy on the street varying speeds/rpms for 30 mins, let cool down completely.
3) Run the car easy for 500 miles varying speeds/rpms, then drain the oil and its ready to go.

Opinion 2:
1) Run the car easy on the street varying speeds/rpms for 30 mins, let cool down completely
2) Repeat the above at least 3 times(3 heat cycles)
3) Run car for 200-300 miles of normal driving(no WOT), then change oil and let it rip.

Opinion 3:
1) Run the car about 20 mins varying speed etc, park it and let it cool completely
2) 300-500 miles of normal driving, drain fluid and then let it rip.


I just want to do it right and make the gears last a long time and be as quiet as possible. It seems that Strange, Motive, Moser all have different procedures. My 3rd member is Strange but with Motive Perf. Pro gears.

Thanks in advance.

Scott@DrivelineSolutions

iTrader: (22)

OPtions 2 is the the one I would recomend and stay below 55 mph for the first 2 cycles.

Slvr00Bird

iTrader: (2)

Yea I'd go with option 2 as well.. Putting it through a couple of heat cycles is what I've heard, but there isn't really a "set" break in method. Hell there are a lot of guys around here that don't do anything as far as break in. They say take it out and beat on it and that's how it gets broken in. So I'm sure it's all personal preference but I'm going to take it nice and slow when I get my 9in..

alamantia

iTrader: (10)

Id go to the drag strip and get it done in 12 seconds.

06 SS

if the 'heat cycle' in your diff is higher than the temp used to temper/harden the gears in the first place, you have serious problems....like a melted car.

Run up to speed to ensure there are no whine/shuddering problems and if all is good, it will stay that way, hammer away as hard as you want. No problem with the gears. Now, if you want to take it easy and do a couple of figure 8's to get the lube everywhere first, won't hurt anything, but there is no way the temps in a diff are going to further strengthen the gears.

alamantia

iTrader: (10)

ive bought new cars and the rear never whined. And i assure you that when i picked them up from the dealer i did not bring jack stands.

Drive the car, you will be fine.

ajrothm

Yeah thats kind of what I figured. In years past, if I had a set of gears installed in a car, I usually drove it home from the shop, let it cool down, then drive it about 200 miles, change the gear oil, then it was open season on the bitches but...... Those were not $2700 rear ends in those days....LOL Just want to do this one right.

I will probably just heat cycle it once, let it cool over night, then drive it easy for a couple hundred miles, then change the oil and start banging gears.

It will be a while before I get to go to the strip anyway, just some street rippin on bald Nittos....

SS1875

iTrader: (34)

This was the procedure given to me by Eric @ Midwest Chassis for break in of my Fab 9" with a Strange center section and true-trac.

do 3 heat cycles with regular street cruising driving... no sustained highway speed or launches. after minimum 3 heat cycles, then do whatever you like. heat cycle is from cool to full operating temp, then back to cool. usually 1-2 hours cool time.

after minimum 500 miles change out the gear oil. use whatever you like and what viscosity fits your needs.

ajrothm

I just did my first "heat cycle" drive. I ran it for about 25 mins, all different speeds and varied the loads etc. Right now, the rear end is perfectly quiet with no noticeable gear noise. I am getting some contact noise over bumps, I am pretty sure its the torque arm hitting the floor pan in the rear. All in all, the first drive was uneventful. I did notice two things, first it requires a little more pedal pressure on the brakes to get it to slow down then it used to, at all speeds. I assume this is due to losing the ABS functions. 2nd thing I noticed is the rear of the car seems to be a little more "hoppy" over bumps etc. I guess I can attribute this to having the LCAs lowered all the way down in the lowest hole on the brackets. My car is lowered and my LCAs used to be pointed in a negative direction(inverted at the rear) now they point downward slightly and it seems to lift the car some... I am guessing its normal. I will do another ride tonight to "heat cycle" it, then this weekend I can put some miles on it. Glad to be driving it again though.