Now for the rear end

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Slipcased
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First Name: Ronald

Now for the rear end

Post by Slipcased » Sat Aug 31, 2019 3:00 pm

I started to swap my rear end from my black 76 124 to the white 76 124.
The white one leaks everywhere except the drain plug and the diff to housing gasket. The black one has zero leaks.
I got the black 1 pulled out and the white one half way out before I noticed that both ends of the black rear is rotted,1 spring perch was rotted then broke and then welded, it is near failing again.the other side the spring perch and shock bolting mount is rotted through, the only welder I know that does anything with fiats says the housing is the only thing worth saving.all trailing arm mounts spring and shock mounts are rotted and fatigued beyond repair.
the welder says only way to repair the black 1 is all new mounts. Both rears have a stripped out lug bolt hole on the drivers axle. I'm assuming I can take the good 1 out of the black 1 and install it in the white 1?
So my question is what does it take to fix the leaking rear of the white one?what parts do I need? I'm asking here so I dont order the obvious parts and miss anything I cant see or know about. I'm almost out of time to get a drive in this summer!
fp55scca
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Re: Now for the rear end

Post by fp55scca » Sun Sep 01, 2019 1:02 pm

Slipcased wrote:
Sat Aug 31, 2019 3:00 pm
I started to swap my rear end from my black 76 124 to the white 76 124.
The white one leaks everywhere except the drain plug and the diff to housing gasket. The black one has zero leaks.
I got the black 1 pulled out and the white one half way out before I noticed that both ends of the black rear is rotted,1 spring perch was rotted then broke and then welded, it is near failing again.the other side the spring perch and shock bolting mount is rotted through, the only welder I know that does anything with fiats says the housing is the only thing worth saving.all trailing arm mounts spring and shock mounts are rotted and fatigued beyond repair.
the welder says only way to repair the black 1 is all new mounts. Both rears have a stripped out lug bolt hole on the drivers axle. I'm assuming I can take the good 1 out of the black 1 and install it in the white 1?
So my question is what does it take to fix the leaking rear of the white one?what parts do I need? I'm asking here so I dont order the obvious parts and miss anything I cant see or know about. I'm almost out of time to get a drive in this summer!
-------------------------------------------
--"the white one leaks everywhere [except the drain plug and the diff to housing gasket]" ?? That really only leaves axle seals as a leak source? Are you seeing a lot of oil on the insides of your rear wheels?

--In any case, the usual leak from the early diff (68-78) is the hogshead-to-housing gasket. It is normally retained by eight (8 x 1.25mm) bolts. Some will loosen in time. When installing the bolts, it helps to use Loctite. Under severe driving conditions, you can replace the 8 bolts with 8 x 1.25mm studs, heavy washers and locking nuts.

--The axles will inter-change between these differentials. You need to pull them out anyway to remove the hogshead to replace the gasket. Clean the faces of the hogshead and the diff-housing, and use a non-drying RTV on the gasket (I like Permatex Ultra-Copper). Be sure to torque everything evenly.
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 CSA Abarth Replica
1981 Fiat Spider Ratrod
Slipcased
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Last Name: LaRocque
First Name: Ronald

Re: Now for the rear end

Post by Slipcased » Sun Sep 01, 2019 11:29 pm

Yes there's oil from both wheels and leaking from where the drive shaft bolts to the differential.
Differential Oil Seal x1, Rear Axle O-Ring Seal x2, Rear Axle Oil Seal x2, this should cover my needs?
And the axel bearings are checked before or after I pull the axles?
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MikeGreer
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Re: Now for the rear end

Post by MikeGreer » Sun Sep 08, 2019 9:11 am

I very recently rebuilt one of the old style rear ends to go into my '79 spider. If the hogshead from the black one doesn't leak near the drive shaft, pull it and use it on the other rear end. Once the axels are out, you've done most of the hard work, just go ahead and replace the bearings, ultimately you'll be glad you did. I had a bad one that you couldn't tell until it was off the axel. Add two axel bearings to your shopping list.
45 years with a spider, that's a long time
Restoring the '79 for the second time, you're never finished ;)
fp55scca
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Re: Now for the rear end

Post by fp55scca » Sun Sep 08, 2019 12:19 pm

Slipcased wrote:
Sun Sep 01, 2019 11:29 pm
……...And the axel bearings are checked before or after I pull the axles?
----------------------------------------------
--Ron, actually you will want to check bearings both before and after pulling the axles.

--Before: With a rear tire off the ground, and the axle preferably on a jackstand, grab the wheel at the 12 and 6 o'clock positions, and check for any lateral play. Repeat at the 9 and 3 o'clock positions. There should be no noticeable play.
--With the axle removed: grip the axle and roll the bearing in the plam of the other hand. The feel should be smooth... no crunchyness.

--Note: removing and replacing rear axle bearings requires a press, and some special half-shells. If you don't have access to these, then best to leave it to an appropriate machine shop. If you do replace the axle bearings, be sure to replace the bearing collars as well. Collars should not be reused. Some manuals call for heating the new bearing to install it. I used to do this, but not necessary, IMHO. Bearing to axle is an interference fit.
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 CSA Abarth Replica
1981 Fiat Spider Ratrod
Slipcased
Posts: 43
Joined: Sat Mar 23, 2019 11:40 am
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First Name: Ronald

Re: Now for the rear end

Post by Slipcased » Sun Sep 08, 2019 10:48 pm

Good to know I just got my axle kits yesterday!
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