Yeah, I agree you can spend alot of time if your being really accurate with the gear clearances, which I am.
Dirty Dog hit the nail on the head.
If you have the right process down, you can come pretty darn close on the first shot, or two, with really good tools, careful math and very accurate measurements (you'd have to be a robot). This takes quite a bit of time in itself.
However, it is much easier said than done, usually will take quite a bit of prep, and re-prep to ge everything just right. I build everyone one of these like it's going into my own car.
Lets just say, I've seen some pretty sloppy stuff come out of gear shops. Yet people drive down the road with a whiny rear end, and don't realize it until quite a few miles down the road during a highway trip, when they finally turned the radio down low enough to hear it, lol. I've seen gear shops turn people away, that came back correct this, or offer to check it but only if the customer pays the same flat rate again to tear it open again.
I'm doing them at a low price right now, just to show that my setups will be perfect, and take a real licking. (especially if you opt for a detroit locker).
I'd rather get them out there, and let people field test and abuse them, I back anything I build, and I'm happy to prove my builds first at a lower price.
But I'm still assessing a good average time for this job, and I won't always be doing them for as cheap as I'm bidding them now. Because all I do are 8.8's nothing else, and I do them to NASA clearances.
You won't get that outside of a really good Ford speedshop, and your not going to pay less than 350-500 for one of those shops to do it the right way. Maybe even more, many of those shops charge alteast $100/hour
So right now, if you provide all of the parts, and a new carrier, I'm only charging $120.00 to rebuild them, this is for about 6 more months. Then I will reset this fee to a larger amount, based on average time. I'm guessing I will charge at least double this price in the future, but I'm going to average this after several jobs.
If you are providing a carrier and housing, and gears. In a high mileage unit, everything needs to be rebuilt, I replace every single bearing, bolt, race in the entire unit, including the side/pilot bearings for the half shafts,
(Unlike gear shops, I'm not going to send one out with new carrier bearings, and 100,000 mile pilot bearings.) It will cost $30.00 labor for me to rebuild the carrier (for the next 6 months) if you send a new traction lock carrier or other, and don't need any build up done, then there is no additional labor for my installation of the carrier.
The parts and supplies alone for the entire pumpkin (minus the case/gears/carrier)
cost in the range of $200-250 (thats for minimum, no custom options). add 150-185 for gears, 75-150 for a case, 75-500 for a carrier (from used OEM, to wild aftermarket), and add for any custome options, e.g. one piece spacers, carbon fiber clutches, solid spacers, hd shims, re-usable gaskets, etc, etc.
Some additional options may include custom machining if the carrier used does not have grooves for circlips (if required by customer) on the side gears (for half shafts - retention), does not include 28 spline side gears, if a 31 spline carrier was provided.
I have hunted around quite a bit and the cheapest I've found a shop doing this work, was doing it to beat the local competitions price, Local competition was doing it for 200, and this shop was beating them by 20-25 bux I can't remember exactly.
They did work mostly on chevy, and dana rears, and knew very little about 8.8 IRS or specifics of Aluminum differentials.
There are special specifications for Aluminum diff's that are complete different from iron 8.8's, never mind Dana rear ends.
I asked one of them there about bearing kits for the 8.8 IRS, and he was adament that the kit that included axle bearings for a live axle setup would work fine with the IRS diff, which is totally incorrect.
Obviously, they would have charged the customer for these, reliased they wouldn't work, and left the old ones in, and sent the customer on their way.
I trust those guys to work on one of my 8.8's about as far as I can through a cast iron one.
Just my .02
It pays to work with people who have worked on a specific application and have real world results with that application. Or a Niche-professional.
I know who I'll be hollerin at come time to get a new converter,
The guy that knows the application, and the converters in and out. DirtyDog!
For any parties interested, I'm building up a detroit locker for an Aluminum diff, with 4.30's for a customer, and he's got a pretty darn powerful test bed, so he is going to poor the heat on this sucker, and see how much of a lick'n it will take.
I'll probably be installing it towards the end of February.
I'm sure he'll be reporting back with his findings sometime in the spring.
1997 Sport - Work in progress:>
MP BB 304 Teksid 4v- w IC'd / Ported M112
Eaton pulley puller (VMP or BF preferred)