Differential broken

[dmg36054]

Hi guys,
I'm looking for my first spider, and I think I may have found a potential candidate. It seems like a really good vehicle, except for one small issue. The differential is toast. Seller says it "clicks and won't move". Everything else is OK. Anyone rebuilt or replaced one of these? Any advice?

[So Cal Mark]

no difference from any other differential as far as repair, but new parts have gotten fairly pricey. Most owners opt for a used unit

[Exit98]

Busted my 76 diff early Spring. Swapped it out with a later used diff assembly. Its a chance you take but worse to worse you'd just have to try again with another one off a parts car.

Bonus for me was improved gear ratio with the later diff. Very happy with the switch.

Where are you located, what year is the Spider?

Anyway if you decide to go this way, and can get/find a used unit let me know and I'll give you the rundown on the swap.

Key issue to understand, up to 79 I think the ratio is 4.10. With 2 liter cars 80(?) and up the ratio is 3.90

[124JOE]

Busted my 76 diff early Spring. Swapped it out with a later used diff assembly. Its a chance you take but worse to worse you'd just have to try again with another one off a parts car.

Bonus for me was improved gear ratio with the later diff. Very happy with the switch.

Key issue to understand, up to 79 I think the ratio is 4.10. With 2 liter cars 80(?) and up the ratio is 3.90

so now you have the 4.10? it has more tourque but has to screem at higher speeds.
or the 3.90?i think you get to use 1st gear a little longer.joe

[MIGHTY 8]

I understand that the differential is considered one of the weakest links in the Fiat's drive train.

I can attest to that, having replaced not one.....but two of them!

It's a fairly simple remove/replace process, that is by the way, described in the official shop manual.

I believe IAP sells new ones, albeit a bit pricey.

Good luck

[dmg36054]

Thanks guys. I'm in Alabama. I hope to check out this spider in a few days. If it is as nice as it looks, the differential issue should not be a deal breaker. I guess I won't be driving it home, though, huh?! As I've mentioned, I don't mind mechanical or electrical work. But I'm not getting into rust repair. Well, maybe a minimum amount if the rest of the car is in good condition.

I drove my first spider today. Rather enjoyable, I must say. Brings back memories of the Honda S2000 I had. However, the car I drove needed too much body work. It really had way too many problems for what the gentleman was asking for it.

BTW, for those of you that replaced your differential, did you replace just the chunk? the entire differential? the entire rear end, brakes and all?

Thanks for all the help and guidance.

[htchevyii]

You might check with Matthews foreign in Birmingham for a diff. They have always treated me fair.
http://birmingham.citysearch.com/profil ... _part.html

[jimincalif]

I replaced the entire rear end. Had never done anything like this before, but it was pretty much a nuts and bolts process. I was able keep the brake system intact, took a little care to support the calipers and R&R the brake line along the axle housing, but it all worked out.

[Exit98]

so now you have the 4.10? it has more tourque but has to screem at higher speeds.
or the 3.90?i think you get to use 1st gear a little longer.joe

Joe, I have a 76. Went from 4.10 to 3.90. Amazing difference. Used to be I was in 5th gear at the bottom of the driveway. Now I cruise around in 3rd and keep forgetting to shift to 5th.

Dennis, I replaced the whole rear end assembly and because I went from earlier to later you need other stuff off the donor car. Just PM me and I can fill you in if that's the way you're going.

[dmg36054]

Thanks Doug. I haven't purchased the car yet, but I will either go look at it today or tomorrow. It sound like it may not be that big of a job, no matter which way you go.

The car in question is a 1981, so I'm assuming it has the 3.90 rear already?

[124cso]

Main things to remember that an auto will have a different ratio rear axle to a manual 5 speed car and that the diff type and housings changed in about 1979 from the conventional "Banjo' type diff to a "Salisbury" type.
Probably easiest to swap the whole thing over. Some yards will just sell you the bare axle, others will sell as they took it out (with brakes etc )
Probably better to get one out of a car where it is dusty and dirty in the car, but dry (outside) rather than one that is nice and clean but oily (shows it was leaking)