Rear end expert needed

[greenXpress]

Expert not required, just some one more knowledgeable than me. (won't take much) Just got back from a 50 mile test drive with my new 3.73 gears (12 bolt truck) and yes I set it up myself. (Maybe a big mistake, but certainly not my last) Done many on tractors, but never automotive. Set the pinion preload at 0.004 which gave me around 25 to 30 in. lbs. rolling torque. No wrench so I got inventive with my breakover bar. Tempature got to 180F so I pulled the rear cover to have a look see. Gear mesh comes to within 3/16 of the outer ringgear edge and pinion wear looks good. pulled off wheels and drums and it turns good and free. Question: Is 180F about right and does synthetic gear lube run cooler? I used Castrol 85-140 for limited slip to break in the gears. Hope someone is left on-line and not at BG already.

[whichdoctor]

Expert not required, just some one more knowledgeable than me. (won't take much) Just got back from a 50 mile test drive with my new 3.73 gears (12 bolt truck) and yes I set it up myself. (Maybe a big mistake, but certainly not my last) Done many on tractors, but never automotive. Set the pinion preload at 0.004 which gave me around 25 to 30 in. lbs. rolling torque. No wrench so I got inventive with my breakover bar. Tempature got to 180F so I pulled the rear cover to have a look see. Gear mesh comes to within 3/16 of the outer ringgear edge and pinion wear looks good. pulled off wheels and drums and it turns good and free. Question: Is 180F about right and does synthetic gear lube run cooler? I used Castrol 85-140 for limited slip to break in the gears. Hope someone is left on-line and not at BG already.

I have had very good luck with royal purple synthetic lube in SEERED.

[Swede4]

Jesse, I run a Currie 9" Ford in my Chevy truck - for what it's worth Currie is very clear and states Not to use synthetic gear lubes in their units.

I'm getting close to BG, in a hotel in Russellville, AR for the night. See you in BG on Sat.
Hardy Handshakes - Swede

[BBO Javelin]

I wouldn't think so as I've seen near 230 in my dodge diesel pulling my camper,close to the same on the 6 speed manual in the same truck.

[38P]

See you in BG on Sat.
Hardy Handshakes - Swede

Bringing my log book containing my 0.00 reaction time timeslip from DW '12 that you believe does not exist . . . and my "J.C. Penney's railroad engineer overalls" . . . .

(Yes,I remember . . . .)

[38P]

"Stand on it until you smell stink." (Courtesy of WBAP-AM's parody of Sir Jackie Stewart)

[Orange65]

I don't remember how hot mine got but your temp sounds close on the same length drive (12 bolt with a spool). I say if it isn't whining or smoking, drive it! I have no experience with Posi's + synthetic, sorry.

[quick 52]

you should only drive them 20 miles let cool then 20 more and cool for a break in ... 180 is not hot

[greenXpress]

Thanks guys. I'll put er back together when I get off the bus and we will be headed that way after Cameron gets out of school (and I get off the afternoon route)

20 miles then a burger.......20 miles then pizza.........20 miles then a shake.......(Cameron's gonna like this trip)

Quick 52 I drove about 4 or 5 short (5-6 mile) trips during the week, no whines or sounds. Think I'll do a couple of 20 milers headed toward BG then let er rip.

[BlueCuda340]

I feel the synthetic lube is not the way to go with a posi rear end. The posi works off friction and synthetic does its best to eliminate friction.

See you at BG!

[Lilracr]

I tend to think 25-30" lbs of rolling torque on the pinion is a bit much. I am no expert either, but as long as the rear runs free it should be good.

hard to relay the feel, but I typically tighten pinion until all forward backward movement is gone and tighten to get a slight rotation resistance from there. So I run very little bearing preload, but after very long drives the rear is never more than warm to the touch.

I always ran Amsoil but lately went to Mobil 1 and so far so good with no posi clutch chatter.

[BlueCuda340]

I tend to think 25-30" lbs of rolling torque on the pinion is a bit much. I am no expert either, but as long as the rear runs free it should be good.

hard to relay the feel, but I typically tighten pinion until all forward backward movement is gone and tighten to get a slight rotation resistance from there. So I run very little bearing preload, but after very long drives the rear is never more than warm to the touch.

I always ran Amsoil but lately went to Mobil 1 and so far so good with no posi clutch chatter.

He mentioned inch lbs. I am sure it was ft lbs it would have been a little more than 180*

[Lilracr]

He mentioned inch lbs. I am sure it was ft lbs it would have been a little more than 180*

I agree, but typically the 12 bolt pinion preload is something like 14" lbs, I like mine in a 7" lb area from what I remember and locktite the pinion nut.

I like the pinion preload loose and the backlash a bit tight.... On performance based applications.

[LAGNAF]

When I saw" rear end expert needed" I was ready to chime right in.....

Well that is until I read the posts and the OP..... wrong subject..

See you in BG!! Safe travels everyone!!

[wacky mick]

help from across the pond

they call me last minute mick ,so your later than last minute jeese just built 8.8 with posse ran it up with sx75/90 +slip modifer runs fine what load on plates if to high (set hard for strip) only get very hot if working at high speed bends