new posi carrier break in ?
 

I just purchased a complete Auburn posi carrier with Motive gears. It has been a long time since I have had new gearing. If I recall correctly a break in period is required. Any suggestions on the best process to follow for break in?

Thank you
Burt

Drive your car down to Raynham, MA and I will break it in for you! :)
Actually, I'd give it a couple of hundred easy miles before hammering it if I were you. Me? I'd be hammering it now.

Rob...

I start by going to an empty lot. I do 10 tight circles to the left, and then 10 tight circles to the right. I don't do much break-in after that.

X2 on the couple hundred easy miles. Make sure there's no clunking or whining coming from the rear end. Make sure there is posi additive added with the gear oil. Then after the easy miles check to be sure the posi is working. Best way. . . Burnouts :D

What OMT said is for the posi but you still have to break in the gears. Check out the Motive website and they should have the procedure. Some you have to start the car on jackstands and run the gears for 30 min, allow a cool down and then repeat except driving on the road.

check out richmond or yukon websites for break in, definantly need to do more than just drive it or doing circles. as AG said, you need to run it at idle with tires off the ground for for a short time, let cool down. yukon then says to do a few easy 15-20 mile drives at lower speeds & let cool down. then avoid heavy acceleration for 100 miles, then if towing or hard use (like drag racing) do a few more easier drives for 15 miles & let cool. then still avoid heavy use for 500 miles & change the fluid & wipe out any metal particles from the pumpkin. & be sure to use the proper posi additive, i prefer GM posi additive with a good conventional 80/90 fluid.

i just did this with new gears & an eaton posi, it does generat lots of heat during the break in & the fluid comes out like water & dirty on the first change. rear ends, new trannys are just like a new engine & require proper break in.

http://www.yukongear.com/Downloads/M...m=auto,-16,561

I wonder how new vehicles have survived all these years. They come off the assembly line and get delivered to Joe Blow in Jerk Water Louisiana, who then proceeds to fire her up and just drive her around like nothing and there are no problems. We change some parts and then we are supposed to go through some elaborate "break in procedure".......:noidea: I never understood that about any new parts, cams, whatever....

i agree somewhat, however, "most" new cars are not high horsepower drag raced vehicles. & most new cars do have a break in period, says so in most manuals or at least it used to... factories say to take it easy for ~500 miles, or dont go over a certain speed etc etc.

then again most new vettes & other high power cars are built different than 1960-70's technology, the engines have different tolerances & technologies than our classic cars & come factory filled with synthetic oils etc that may stand up to abuse or no break in better.

& as far as "no problems" there are 10's of thousands of problems on new cars, thats what the warranty is for, ask anyone that works at a dealership about all the recalls or customer complaints & repair issues with new cars throughout the years. there are indeed all kinds of problems & thats why many consumers pay exagerated prices & deal with depreciation... so they can have a warranty & let the dealer deal with & fix the issues.

flat tappet cams, new gears, new transmissions & rebuilt engines should be broken it, unless its a real race engine that is built different than most street engines & tore down after each race or each season or some variable in between.

exorbitant break-in procedures give the manufacturer a way to blame you in the event of failure.......

That's exactly what I think! Cam fails, "You must have done the break-in procedure wrong" want to buy another cam? :D

Engine break in
 

My father worked on the line in Oshawa in the 60's and he always said if a an engine lived off the line it should live for another couple hundred thousand miles no problem because of the abuse they got going to the shipping areas. FWIW Ed

Thank you everyone for your replies.

I looked on Motive's site and they too said to drive
Easy for 500 miles and not at a constant speed.
Looks like I will play it safe though I am dying to try
Out my new and improved GTO🚀

The owners manual for my truck (2001 GMC Sierra) specifically states not to do any towing until after the first 1000km/600 miles or that ring and pinion damage may occur before they are broken in.

& change the fluid after that 500 miles.

Cool, now you will be able to really get the power to the ground! Next step will be a really good converter (if you haven't already done that).

For what its worth the posi in my Lemans 12-bolt was really tight when I first pulled the car out of the garage. I just drove it easy around the neighborhood until it quit acting like a locker. And let it cool down before really taking out on the road. I took it easy for the first couple hundred miles or so before heading to the drag strip. It has a few thousand miles on it now and it still works great- quiet, good posi, and no leaks. Probably should think about changing the gear oil though.

The rear on my TA must have been re-worked shortly before I bought the car (milage-wise) because the posi was still tight and chattered on tight turns at first. Also the gearset was a bit noisy. I didn't run the car hard for the first few hundred miles or so while working out all the mechanical kinks and the rear gradually settled in. The posi works great and doesn't chatter any more, and the gears have quieted down. I checked the oil and it looks clear but I haven't pulled the cover off and changed it yet.

My recommendation- just take it easy and stay off the interstates for the first couple hundred miles and you should be fine.

"*i prefer GM posi additive with a good conventional 80/90 fluid.*"

x2 on the GM additive. I have had a couple of clutch type posi that would clunk and make noise with generic additives. Bought the expensive gm stuff, and problem solved.

posi
 

Drive it like you stole it, and bring bail money.

OMT has it right on getting the "juices to flow" with a new posi unit install.

When building differentials with clutch type posi carriers, that I've rebuilt, I always apply straight GM posi additive to the clutch surfaces as I assemble the stacks. seems to help.
On builds with new ring and pinions, whether I'm installing the rear, or a customer is, I always put the rear of the car up on HD jack stands, or suggest it. Next, let the rear hang free and vary the rpm of the engine for about 10 minutes, with the trans in drive. Last let the diff cool for about an hour, then repeat. Over the years, I've had a few local "in a hurry" idiot thrasher/driver owner types that wanted me to install the freshly built rear (which I can usually do fairly quickly) but once the rear was in, they "have got to go" no time to properly break the gearset in :( Nearly everyone of such idiots has been more in a hurry to get on the road so they can do a few burnouts...just stupid. Have flat told several of them, thanks for buying a built rear off me, but am sorry without observing a proper gear break in, I'm not warrantying the gear set-up.