nexstar7

im having my diff purged. when they put the fluids back with the additives, whats the proper way of breaking it in. also im getting a dyno tune, should i do the tune first or fluids first depending if there a break in period for the fluids. thanks Ralph

GMMillwright

iTrader: (4)

Not to hijack the OP, but I'm in the same boat. Just getting ready to start driving on my new Midwest FAB9 with Detroit Locker.

Do I need to run a special "break-in" fluid? If so, for how many miles? Once that's done is it OK to run synthetic with the locker?

Thanks.

ssvert99

iTrader: (26)

we don't suggest the use of any synthetic fluids for the first 500 miles. as far as a new gear break-in, you need to do 5 heat cycles with no abuse. this is light street driving, don't go over 55mph, don't go down the highway for 20 miles at 65mph. just drive it like a grandma on sunday . no clutch dumps, burnouts, full throttle accel, etc. about 15 minutes at a time, then let it cool off for no less than 1 hour between cycles. a heat cycle is from cool to full operating temp, them back to cool. this needs to be done 5 times.

the purpose of this is to surface temper the gears. all gears are heat treated, but it is essential for the life of the gear(and incidentally noise level) to break-in the gear properly and this process of bringing the gears up to temp slowly and letting them cool slowly is what does the job. Richmond Gear told me that 95% of all warranty claims they see are from people either not doing the break-in or improper method.

GMMillwright

iTrader: (4)

Thanks for the quick reply, Eric. Do you recommend synthetic after break-in? What viscocity? 99% street driven, BTW.

02sleeperz28

iTrader: (26)

Thanks for this thread I need to break in my new rear also.

MeentSS02

iTrader: (11)

Define "having my diff purged." I'm assuming you are talking about a new ring and pinion and bearings since you are asking about break-in, but it isn't clear what you mean.

ssvert99

iTrader: (26)

synthetic can be used after break-in yes, but some diff unit manufacturers do not recommend using synthetic oils. as far as viscosity, for the break-in just any GL-5 rated or better 80/90 is fine. after the 500 mile if you do alot of highway driving or roadcourse use maybe a 85-140 type would be good. drag only cars could get away with a thinner racing type lube. any of our clutch type posi units will require a additive and we recommend the Ford OEM Friction Modifier. the Wavetrac, Truetrac, Detroit Locker, and spools do not require additives.

getusumws6

iTrader: (9)

I think the OP is just having the fluid changed, in that case you dont break-in fluid.

nexstar7

just draining the fluids and adding new fluids

nexstar7

thanks getusumws6

MeentSS02

iTrader: (11)

As stated...no break-in required for fluid changes only.

alamantia

iTrader: (10)

Just break it on the same way you did it whwn you bought the car.

slvrbackls1

iTrader: (2)

Do you mean the wacetrac and truetrac need the additives and the locker and spool dont. Im confused??

MidwestChassis

iTrader: (5)

They do not, a clutch posi is the only ones that require an additive.