View Full Version : HELP QUICK!!!!!! Carrier Preload?

11-19-2010, 05:33 PM
I'm installing motive 4.10's, and I don't know what the preload of the pinion and carrier is supposed to be. My carrier and pinion preload is 40 in/lbs. Pinion preload is 28in/lbs and backlash is .008. Are all these measurements good? I searched but everyone seems to say different stuff.

11-19-2010, 05:49 PM
Someone help quick I want to get this crap done tonight. Just wanting to know if all my measurements are within the tolerance.

11-19-2010, 06:48 PM
you didn't state if you're re-using the bearings or have gone with new ones,it makes a difference.
pinion bearing preload w/the used bearings should be about 10 in.lbs.
pinion bearing preload w/ new bearings should be about 20-25 in.lbs.

carrier/pinion preload- pinion preload x ratio = carrier preload
40-28=12 x 4.10 = 49 in.lbs. carrier preload

11-19-2010, 07:12 PM
I'm using new bearings, so is the 28in/lbs for the pinion bearing bad. On the writeup I used it said to do 24-32in/lbs. And what is carrier preload supposed to be is 49in/lbs good.

11-19-2010, 07:23 PM
28 is OK
49 is 'tight',but setting carrier preload properly sometimes requires a shim(s) that is not 'on hand'. if you got shims to loosen it slightly,I would but that's gonna change the pattern,if it's good now.
IF it was me and I was getting a good pattern with those preloads and a lash of .008,I would run with that. how's the pattern ?

11-19-2010, 07:40 PM
I will post pics of the pattern but I think the preload of the carrier is like way to high because it is hard to turn by hand. I used the stock shims, but I switched the carrier shims because there was absolutely no backlash with the setup I pulled out. Left shim was .024 and right shim was .023, then I switched them to get the backlash of .008.

11-19-2010, 07:54 PM
I used the stock pinion shim of .030. I guess the carrier shims are actually .23 on left and .24 on the right. Not .024 and .023

11-19-2010, 08:20 PM
compound too thick which causes smearing and hides the true pattern,you don't need a lot,a light coat will do.
carrier too tight or too loose,that's the problem with using the original shims and not having a variety on hand to be able to vary them.
4 OEM shims I pulled measured .2315,.2375,.2415,&.2435
you really need a variety of shims to set up a rearend,any change in carrier bearing lenght from the originals will change carrier preload(either looser or tighter) and sometimes you get lucky and it's perfect.

11-19-2010, 08:25 PM
I have tons of shims, I bought a richmond install kit. I just didn't think I needed them. So what do I need to do?

11-19-2010, 08:43 PM
assuming your .23 left and .24 right is actually .230 left and .240 right,I would try for shim combinations of .228 left and .238 right and see how that loosens up the carrier preload.
.002 off each end should keep the lash where it's at.

11-19-2010, 09:02 PM
Ok I guess I will go try it right now even though its pitch black outside. How easy should the carrier be to spin. I realize that is a hard question to answer but as of right now it is almost impossible to spin it by hand, when I checked the pattern I had to spin it by the ring gear bolts. Thanks for all your help!

11-19-2010, 10:15 PM
Ok, I took .002 off of each side, and the shims were pretty easy to push in. I was able to just push them in with my finger(isn't this a no no), with the stock ones I had to hammer them in. Anyway and it was still just has hard to turn the carrier.:bang: What I don't understand is why it feels about perfect when i spin it from the yoke, but it won't budge when I try to spin the carrier. Is it possible i need to add a little to each side of the carrier instead of taking away.:confused:

11-19-2010, 11:02 PM
spin it from the yoke, DO not spin FROM the carrier
it is a differant ball game

11-19-2010, 11:52 PM
It's always gonna be hard to spin from the carrier,if your pinion preload is 28 in.lbs.,that's gonna show up as 115 in.lbs.(because of the 4.10:1 ratio operating reverse)=9.5 ft.lbs.
looks like you gotta go in between what you have and what you had,.229 & .239.
you don't spin carrier,you spin pinion.
when you get a 'final',I take a drill motor with the pinion nut socket in the chuck(lot of step down adaptors) coat the gearset with some lube and drive it at drill motor rpm,if something isn't right,you can hear and feel it,such as ring gear not spinning concentrically.

from a GM 7.5 10 bolt manual

11-20-2010, 03:02 AM
I have always seen 20-25 for the pinion preload. I have always run 25 with no issues.

11-20-2010, 05:23 PM
So it's normal that I can't spin the carrier by hand. How come I could spin it relatively easy when I first took it apart, is it because there is no oil on the gears?

11-20-2010, 06:20 PM
No, bearings wear in and get loose. The specs change once the bearings are used. You expect used bearings to spin very freely. New bearings are very tight, as they wear the first few times you drive it, they will loosen up. This creates a lot of heat so drive short distances the first few times.

11-21-2010, 02:34 AM
Well I put it all back together, I decided to paint it to so it won't be on the road till tomorrow. I stuck with the stock shims switched around setup which gave me .008 backlash and the pattern in the pics above. I was tired of switching shims and checking the pattern just to find out it was screwed up. I figure if it whines like a son of a bitch, I will just buy a fab 9 when tax time comes.:D

11-21-2010, 05:16 PM
Well I took it for a drive and suprisingly it is dead quiet.:D Thanks for all your help guys.

11-22-2010, 12:36 AM
Good deal :thumb: Sometimes they will develop a little whine after a few miles but it shouldn't be much if any.

11-22-2010, 01:17 PM
Well, if it does start to whine a lil bit I probably won't care because it was extremely loud with the previous setup. I can't believe I actually built a quiet rear end, it seems like everyone always says you should let a professional do it. I am only 20 years old, and the most mechanically inclined thing I have ever done is put a water pump on an old ford truck with plenty of room to work on. I'm just sayin screw all that u need a professional crap, do it yourself.:nod:

11-22-2010, 03:27 PM
congrats ! Yes,rearends are one of those things left to the 'knowledgeable',but they really are simple,not many parts,just gotta have a decent setup,that's why there is so many complaints and dissappointments. You just didn't slap it together,you played with shims,felt preloads,checked lash and pattern,you learned about rearends.

11-26-2010, 08:35 PM
Good thread. subscribed...