Put some motive gear 3.40 gears in my comet with new bearings. Backlash .008, pinion bearing preload .015 inch lbs, grease pattern looked OK. Gears turned easy no binding felt really good. No gear noise while driving but the housing is getting warmer than it should. A lot warmer than it was with the old 3.00 gears. This is after a 20 minute drive. Cannot leave my hand on it very long. Should this disappate after gears get worn in or could I have a problem.
Is it a posi or limited slip? If so, did you put some friction modifier in it? That might be heating it up.
Correct me if i'm wrong but isn't the backlash a little tight? I was always told it should be around 11-12.
Hi, i own a gear shop so i feel qualifyed to answer this corectly for you. A new gear set needs to brake in. the black coating on the gear set is there to finish polish the teeth faceings. it will run hot for a while. We give a brake in procedure to every customer that gets new gears. We recomend doing 3 inital trips of approx 20 min of freeway speed driving then alowing for 2 to 3 hours for cool down between trips. After about 20 min of driving on a new gear set the temps start geting to high for the gear oil to provice the nessary protection to the gear set. After the three trips it is strongly recomended that for the first 100 miles that you baby the diff. That means no burn outs, no towing and no racing. A diff will run at 150 to 200 degrees under normal opperating conditions. So being to hot to touch is not abnormal. Your best to use a inferred temp gun to check it. If you have driven well over the 20min brake in times when you initally finished the install then you might want to change out the oil. Once it brakes down from over heating its not any good any more. Usually you can smell a burnt smell in the diff from the fill plug if its been over heated. .008 is the most common back lash that gear sets set up at. .010 is about the max i would like to see.
Yep, when I installed my Richmond gears they recommend putting the car on jackstands and running in the gears for awhile with no load. Then do the short trips as Bryant stated.
Definitly dont run synthetic gear oil in a diff. Its too slipery and ends up squeezing out from between the gear teeth. Ford puts it in every thing now. they started doing it around 97. All the f150s started makeing gear noise in about 20k miles. They exchange the whole third member in the irs exlplores because they transmit the noise really well. Its all because the synthetic does not stick to the gears. We use schaeffers gear oil #209a 140 wt. That suff is awsome. Ive seen people not do the brake in and over heat the schaeffers oil to where it smells burnt and the gear set survives. So on oil, dont use synthetic. Stay away from Stay lube brand, you might as well just run water instead of stay lube. Lucas (SP?) is good. The best out there that ive come accros is LE oils. Its very expensive, that why we dont use it. I hope this helps.
My xp is it depends on the application. Used gear sets can get by with 11-12 but new should be set up as explained by Bryant. Also Drag cars can be set up tighter to keep the shock factor down on Launch and they only see short times of use.
Thanks,i no "gear man" by along shot it was just somrthing i was told and for some reason it stuck with me.
