'82 Rear Differential Question

[DeltaV]

I have an '82 Spider that I've been working on getting back into shape the last few months; I've done some work with the steering, some electrical, and just finished fitting a stock exhaust system back on the car (the prior owner had just chopped it off behind the cat...if he wasn't deaf from before, he sure probably is now). The process has been a bit delayed since I moved twice, most recently to Charleston SC.

I actually took her out this evening for a few miles and was actually able to hear myself think for the first time...it was nice. She's got some spunk in her; got up to 60 quite easily.

The next line item to be fixed is the rear differential. Specifically (and the prior owner had told me about this), the ring gear is missing a tooth or three, so makes quite the racket. I was originally thinking that I could do the work myself, but I've been researching that over the summer and I'm beginning to think that it may be more than I'd want to bite off. If it were an earlier car with the 'pumpkin' it would be easy(ier), but the unitized diff seems to require a more precise touch.

So, is repairing the rear diff something I should leave to the professionals?

If so, any recommendations for a mechanic in the Charleston SC area? I searched and found a recommendation for 'Charleston Import Automotive'; were they good (for a bunch of Brits)?

Thanks! I'll get some pictures up once I get a chance to wash her.

[vandor]

The easiest repair would be to find a good used rear end and swap it in. Finding gears for the current rear end may not be easy. Also there were 3 different gear thicknesses between 1979 and 1985 and if the diff is not original you may order the correct gear for the car, but it may not fit the diff. So it could turn into quite a PITA.

A few years ago I sold all the parts to a customer so a rear end shop could rebuild the diff in his '84 and with parts and labor he spent over $1500.

[DeltaV]

Thanks, that is what I had gathered about 'repairing' the rear end.

How involved is the axle swap? There is one that has been on Ebay for a month or so for about 500/shipped; is this something I could handle with a few jack stands and sockets, or is it more involved? Would probably be a chance to get those sport springs you list on your website as well

[djape1977]

not overly complicated. having someone who did it before nearby will help a lot

[Exit98]

Delta,

Where are you from?

Swapping out the rear is easy. You might be in an area with a vibrant Fiat community, like here in NJ or in the Baltimore area for example. There are plenty of old rears around and parts cars too.

[DeltaV]

Charleston SC

(though originally from Philly; didn't have the time to tackle the job while I was up there).

[TStark]

Its a cinch. I drove two hours one morning to buy a doner axle, by 3pm had it brushed, painted, installed and driving by 3pm. 2 jackstands and a floor jack.

[KandJinmaine]

In 2006 we had the bright idea of moving from the SF Bay Area to Maine. We decided it would be the best thing in the world to drive our Fiat across the country that summer, taking the northern route and stopping at a number of national parks etc.. We got as far as Olympia, Wa. when I heard a funny noise.....

We rented a truck and car dolly and drove back to Cal. After moving to Maine and much research we found that one vendor of Fiat parts, perhaps VAS, was importing new rear ends from Italy, minus the axle shafts. We just had to wait six months or so for the next shipment. As mentioned before, jack stands and a floor jack was all that was required, and having the bearings pressed off/on the shafts. Install was an hour or so with my brother helping. As there is some forgotten difference between years you need see if your shafts are compatible with the new parts.

Sure wish it had held together for that trip though....

[DeltaV]

So, the new axle is in my garage, and I have her rear end up in the air. Not planning on doing the main swap until this weekend, but I was poking around making a game plan, and did a search to see what I could find on here about replacing the axle; lots of people saying it is easy, but not a lot about the actual swap (unless I missed it).

Any pointers/suggestions? Can I just use a spring compressor on the suspension so I don't have to release the struts as well? The rest really does appear to be unbolt and then re-bolt, but if anyone has any hints or tricks I'd appreciate it (or a link to somewhere that does).

Thanks!

[njoconnor]

When I was uncertain about dropping the rear axle on my 72, Alan Barnes (SoFlaFiat) was incredibly encouraging. With attribution to Alan, and continued thanks, here's his procedure for dropping and re-installing the rear axle (no spring compressor needed!!)

Alan said:

Here is my step by step for getting the whole rear end out of the car, single handed in a few hours:
Spray the bolts, nuts, etc. with PB Blaster the day before you plan to do this…
1. Block front wheels (both)
2. Release the e-brake
3. Jack rear of car under the pumpkin (I use a roll of paper drywall tape between the pumpkin and the jack to avoid damaging the drain plug. It is amazing how strong the roll of tape is and it forms to the jack bowl and pumpkin nicely)
4. Place 2 jack stands under the rear jacking points just forward of the rear wheel arches (the higher you get the back of the car on the stands the easier it will go)
5. Leave the floor jack under the pumpkin supporting the axel
6. Remove the rear wheels
7. Remove the e-brake cables from their captive tabs on the long trailing arms
8. Unbolt the brake T and proportioning valve and remove any straps/clips holding the brake lines to the axle
9. Throw a rope over the car, remove the rear calipers and tie them up out of the way (with the rope I tie them to each other but you can use anything including the rafters, just make sure nobody gets in the car now and presses the brake petal. If you are rebuilding the rear calipers you can skip all this and just remove them from the car, I use this method when I don’t want to go thru the brake bleeding process)
10. Look around and make sure that all brake parts are released from the axle
11. Remove the panhard rod (you already did…)
12. Mark the flange on the rear u-joint to differential (I touch it with a grinder since pen will disappear when painting parts. I don’t worry about marking it when I am swapping either the rear end or the driveshaft since it doesn’t matter any more)
13. Remove the four bolts holding the driveshaft to the diff and hang/support the driveshaft so that it does not hang in the e-brake cable (another jack stand works well for this)
14. Remove the two bolts on each side holding the shock bottom brackets to the axle (this leaves the shocks hanging from the car and can get in the way if you don’t have the car jacked high enough. I very often remove the nuts on tops of the shocks and let them slide out when I drop the axle. One thing you will never get out is the horizontal bolt holding the bottom of the shock to the bracket)
15. Remove all four trailing arms (yep, take them out completely, all four at the same time and paint them) (still trying to figure out why someone would say only remove one end at a time…..)
16. Check around and make sure that everything is detached from the axle (I may have missed something trying to type fast)
17. Lower the floor jack an inch or two and check again that nothing is snagged up
18. Continue to lower the jack and check until the jack is bottomed out.
19. Now the car should be in the air, the springs and shocks should be falling over and be able to be plucked out of the mix, and you should be able to roll the jack out from under the car on the floor jack.
20. Clean
21. Paint
22. Replace the pinion seal!! (it is simple, costs $11.- and they all leak when they get old. People talk about how tight the tolerances are and the fact that crush sleeves are no longer available but simple count the exposed threads before you remove the pinion nut and, with a new seal in, put the nut back in the same place plus an 8th of a turn.
23. have a beer if you like…

Putting it back together is just as simple:
1. Position the axle on the jack under the car
2. Hang the shocks from their top bolts
3. Slide the springs up the shocks (new?) and set them on the buckets on top of the axle making sure to align the hard rubber end pieces which are stepped at the end of the coil and need to sit in the stepped bucket
4. Slowly jack the axle up checking spring and shock alignment as you go
5. Jack it to the point where you just start taking weight of the jack stands
6. Bolt everything, except the calipers and wheels back on, leaving the trailing arm and panhard rod bolts snugged but not tight
7. Raise the jack until you have all the weight of the car (some people weight the truck for extra measure but I have never done this)
8. Tighten the trailing arm, lower shock brackets and panhard rod bolts to spec
9. Remount brake calipers and wheels
10. Remove jack stands
11. Drop the car and go….. check the brakes maybe?


Took me (Neil) 3 1/2 hours to remove the axle (and I'd never done anything close to this before). A few weeks to replace bushings (all of them), pinion seal, clean, scrape and paint, new shocks and springs, and then the re-install took about 90 minutes (with Son The Youngest helping). Do it. I still smile when I look under the car and see no drips and shiny black paint!

Neil

[DeltaV]

Thanks a ton! That was really helpful.

I got it off in a little under 3 hours Saturday, then the new one back on in a little under 2 on Sunday (didn't get fancy with the cleaning and painting...although my prior owner of the axle painted the diff cover in Italian flag colors, so now I can say my mistress has a tramp stamp).

Haven't had a chance to test it out yet, though; I live just outside of Charleston, and we're still a bit under water in places...

[njoconnor]

Hey, stay safe and dry! Hope you're in a safe(er) area. Some of that video on TV is pretty awful.

Most of the thanks goes to Alan Barnes (SoFlaFiat). Could not have done mine without his help.

Neil

[DeltaV]

It works! Had her out for a quick little drive around the neighborhood last night.

One final question; searching online here indicated that I should fill the differential with ~1.3 quarts of fluid (90W). I was only able to get about a quart in (this was with draining as well). Is that normal (I know you never really get all of the old out), or are there any tricks to refilling, like putting the front up on stands to put the fill hole a little higher?

Thanks!

[AriK]

Refill with what fits in while the car is level even if the capacity is less. I've experienced the same thing. I drove the car around the block re-checked the fluid level with the car in the same position and it still would not take more fluid. In any case i believe it's better to be slightly under-full as less operating pressure is less stressful on the seals.