unknown_host

iTrader: (1)

Hey guys,

So I managed to find a 3 series 9 bolt carrier with 3.23 gears for $100. I told myself I wouldn't dump too much money into my 9 bolt, as I really want a 12 bolt or 9" if I am going to spend money on a rear end.

I called a driveline shop and was quoted $350 to $400 to install the used 9 bolt and 3.23's. Does this sound reasonable? How hard would this job be to do myself? Are there specialty tools required?

Thanks in advance!

big gear head

That's about the going rate for a gear swap. Setting up a set of gears can be complicated, especially used gears. There is a good thread on this in the FAQ about 10 bolts sticky.

Base91

iTrader: (1)

I just finished doing exactly that for the first time. It required a lot of reading of the various threads and articles and just following the instructions carefully. If the cones in are worn too much you'll need to re-shim inside it and get the gear pattern right. Keep the original carrier shims. There's a reasonable chance they'll work with the new carrier. Just doing the swap didn't cost a lot. Shims, a bearing, marking compound etc. Maybe $50 or so total. I didn't do a complete rebuild. Just enough to get back in action. So far so good. Just read first. BTW those would be 3.27 gears.

unknown_host

iTrader: (1)

How long did the swap take you?

subroc

iTrader: (2)

Honestly you will probably spend more than that to do it. I have only seen ONE 9 bolt that had not bottomed the cones. All the others either needed to be reshimmed and machined or replaced. That will jack the price up. Also just so you know...3.23 is a 10 bolt ratio. What you found is probably a 3.27.

big gear head

I've been building rear ends for over 31 years and an average rebuild takes me about 6 hours. Used gears are much harder to set up because the contact pattern is very hard to read. Get a GOOD installation kit, not anything that Summit and Jeg's sell. Randy's Ring & Pinion has a good installation kit for the 9 bolt.

Base91

iTrader: (1)

I've done the one 9-bolt rear end. Actual time for just the carrier part is hard to say as I added PBR brakes too but I'm guessing about 30 hours of hands on spread over a year. Add to that lots of reading. I wasn't in a huge hurry and really took my time to understand what I was doing. I also have a friend who machined the carrier steps and cone noses for free. That could cost a bit if you don't have a friend like mine. I could probably repeat what I did in 12 hours or so. But that's fairly minimum, not a full rebuild replacing all seals and bearings and so on. It all depends on how much time and / or money you want to spend and how soon you need it and how interested you are doing the work yourself. I like learning stuff. And saving money.

Eagle223usa

Dumb question but how do you determine how much to remove from the posi cone nose? I have read all the re build info I could find but have not found this. Thanks.

Base91

iTrader: (1)

Once the carrier steps had been machined I dropped the cones in and figured out how much to take off so they would be at the start of the little windows. In my case it was just under 1/8th inch off each cone nose.

Eagle223usa

How well did it work when you were done with it?

fireturd350

iTrader: (8)

$300 or so sounds very reasonable. I was quoted everywhere from $350 to $900 from various places in this area for a 3.27 gear to 3.70 swap. The highest was the GM dealership. That was with me providing everything (full bearing kit, compound, oil, etc).

If you can I would recommend checking stuff out first yourself.

Before spending several hundred in labor and having $600+ of parts put into mine I pulled it apart myself. Looked good until I looked at the window and saw cones on the ends. I didn't think it was a big deal a little big of machining and shims. I opened the case and found broken spider cross shafts. At that point the cheapest I could find used cross shafts was another $75 or so. I went with the Aussie way and just put a good weld on the cones. Now it's a spool for anytime I need it. I picked up another spare 3 series carrier for $50 in cause I ever want limited slip again.

There are articles describing the process of machining like you said, but basically you want to remove enough off the cone you have a decent gap in the "window" on the side of the carrier. It will depend on how worn your cones and case is. Obviously the cones are only so big so you remove material off the small side of the cone so the larger end rub friction on the inside of the case again put in shims to allow spiders to work still... until the cone bottoms out again then you repeat the process. Eventually the case and cones will become too thin. It also depends on your cone design. Our OEM ones look different to some of the replacement ones.

Eagle223usa

I already have the kit and a 3 series carrier. I just wasted a Zexel after about 1000 miles. Seems like a catastrophic failure. It's a bit crunchy now. I have a set of 3.23 or 3.27 gears in stock, used. I have access to a machinist. I just needed to know what needed cut. Thanks all.

Base91

iTrader: (1)

It is fantastic! No whine at all on drive or coast. Absolutely no jerking or grabbing from the posi. It's really smooth. The PBR brakes work great too especially with the rears dialed up with the adjustable prop. valve. At an auto-x meet at the weekend I span out and ended up facing the wrong way. Just before coming to a complete stop I was able to feed in the power and slide the back end round in a 180 and continue with the run. Previously I'd have had to do a 3 point turn and probably have been spinning one wheel. I've only got the v6 so I don't know if I can light up the 275 tires off the line. Don't want to risk breaking anything yet as it's still a DD as well. It really has transformed the car especially on the track and pulling out of junctions and parking lots. I don't have a lot of power but what I've got I can now used to the fullest.

Eagle223usa

Thanks Brother, I appreciate the feedback.