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Rabbit Hole Rear end questions.

Dudeland

Entry posted by Dudeland in Differential questions.

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I moved this from general discussions.  This is a better place for it. 

 

There are a bunch of questions that I am working through.  Any help would be appreciated. 

 

 

 

So here is the first rat hole.  I just made arrangements with one of the members for an open E21 diff.  The reason I got it is I know sooner or later I will need it. He also has the 320 axels ( I think).  Do I get them?  I am not entirely sure what I am looking for. 

 

 

From what I can tell there is a mish-mash of thick, thin. 8 mm/10mm options.  I would like to just swap out the end of the 320 axels with a 02 one to bolt up against the stub axel as it looks the cleanest with the knowledge that a well-used cvt of each size is in the road trip kit. 

 

So here is the second rat hole. 

I am running new gas lines, and as such I am welding tabs on the bottom of the car to hang them.   They will be soft.. for now.   The lines go over the rear diff, and some battery cables will be run in the same general area.  It would be much easier with the diff out.

 

So here is the third rat hole. 

I am suspect of the diff.  There is something getting tight, and although my 5-speed is not that great, I can see getting so tight that it would hold you on a mild slope.  I suspect the rear end as the guy who handed it to me said that it was "Tight but within spec".   To me it was different, but I have no feel for these things. 

 

The fourth rat hole. 

So I have a phantom clutch sitting on my shelf doing nothing.  Do I clean up the case, jam the phantom clutch in the E21 case, and then run that until it eats itself? I am sure that it would be otherwise loose and give me the ability to diagnose a drivetrain issue.  

 

I don't really feel like addressing driveline issues right now, but it seems like the right time to address this issue as having it out would make things easier to do at the same time.

 

Some of the stuff I have gone through is below. 

 

Thanks in advance. 

 

P.S I found an old-school guy that can work on the rear end. He is doing work on my daily right now.  He can likely install a Qalfe or other LSD option right now if I asked him. 

  

 

 

 

Article. 

 

 

Edited by Dudeland

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5 Comments

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tzei

Rh1. Get them E21 shafts - both (and you’ll have spares). Diff prolly has m10 threads so u need cvjs to match. If you can put 02 cvj on E21 axle then lenght should be ok. I couldn’t - was too tight and i bailed and used shims between diff flange and inner cvj to get lenght right.

 

Rh2. Just make hard lines at the first go?

 

Rh3. Sounds too thight. Might be short lived.

 

Rh4. Open, clean, inspect. Don’t just kill it. Might be good after little service.

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Georges

Adjusting differentials is not for amateurs. I would take it to a diff shop and just ask them to check the specs. They are expensive to rebuild so at that point you can decide which way to go.

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Dudeland
On 7/20/2023 at 9:51 AM, tzei said:

Rh1. Get them E21 shafts - both (and you’ll have spares). Diff prolly has m10 threads so u need cvjs to match. If you can put 02 cvj on E21 axle then lenght should be ok. I couldn’t - was too tight and i bailed and used shims between diff flange and inner cvj to get lenght right.

 

Rh2. Just make hard lines at the first go?

 

Rh3. Sounds too thight. Might be short lived.

 

Rh4. Open, clean, inspect. Don’t just kill it. Might be good after little service.

RH1 Why wouldn't the shafts fit?  I am lowered by about an inch. 

 

RH2 I have the bits right now to run soft lines.  I feel that they will be less prone to rocks flying up at highway speed.  I plan on taking it to the track.  I am about to reach out to see what is required from a tech perspective from the folks that organize it.   Right now it is the easiest way to get things working, and I will be changing out the EFI configuration from TBI to MS and 3 Series intake, so perhaps then I will change them out.  

 

RH3 I will have the 02 rear end looked at. I guess I will know when I take the existing one out. 

 

RH4.  I agree I don't want to grenade it.   I do have a rebuild kit from I.E (not sure if I have the correct pinion bearing).  I am really feeling like a Qualfe or Wavetrack,  I just don't want to spend the $3K cdn right now.  The phantom clutch is something I can do myself. And considering I put less than 3K Km on the car a year, it would allow me to have better traction while keeping my eyes open for a deal.   The extra tension on the bearings may be ok for now.   

 

 

 

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tzei

Rh1. E21 pumpkin is 9 or so mm narrower (output flange to output flange. You’ll be able to measure this as you have em both) than 02 unit iirc. With 02 shafts it’s enough to pull output axle(s) out of the diff which is no bueno.

 

My findings are that there is tiny amount of difference in axle bores - 02 cvj didn’t want go over E21 axle splines. E21 cvj goes on 02 axle, no issues, works fine, but this combo is just a little short to function without pulling output shafts out. Hence spacers.

 

Hope i make sense.

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rstclark

A little off topic but looking at your featured photo of the turbo set up,I see how the plumbing works with the relief valve etc. But have you actually installed this and run it ?  Looks to be a high mounted turbo as opposed to the factory turbo set up. 

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