65 Corvair's Steel Front Diff Build

Given that the steel diff is not available from JBA anymore. I have decided to try to make one myself.

It first starts with a Dana 30 front axle, this one is out of a 1994 Wrangler with 3.07 gears. This one was found locally for very cheap, however it has had some water (and mud) in it for some time. Given I will be installing new gears, and a probably a locker, I will not be needing any of the internals. The good news is that there is no corrosion or pitting behind any of the bearing races, so after a good cleaning it will be ready for modifications.

After getting the axle home, I noticed some differences in the pinion location and learned about high vs low pinion for the Dana 30. Since this axle is from a 1994 wrangler, it is a high pinion Dana 30 where the Liberty's D30A is a low pinion gearset. Just looking at the front pinion shaft area on the Liberty, there should be enough room above the normal pinion location for a high pinion.
This other forum has a great picture of the difference between the two. https://www.cherokeeforum.com/f2/hp-dana-30-lor-low-pinion-166417/

I will try to get the high pinion to work, but if does not work out, I will have to find a low pinion.

Comparison between the two diffs. The Liberty D30A is a lot easier to move around the garage



You can see all the dirt/muck inside the housing.


But all the material behind the bearing races look good, so this diff should be rebuildable.


And then playing with the parts.
The Wrangler axle shaft will slide right into the Liberty D30A housing, and a Liberty wheel bearing will fit onto the wheel end as well.



Next up is to wash and clean the housing, and then cut off the axle tubes.

That's quite the project you're taking on! I'm interested to see how it goes. Good luck!

I’ll be interested to watch your progress also! Nice job trying this fabrication project. D30’s from solid axle Jeeps are not expensive or hard to find, so what’s the worst that can happen? Ha ha.

Can the steel D30 just be “flipped” to make it low pinion? You can tell by my question I am very unfamiliar with these diff housings.

Pass the popcorn. This will be very interesting.



The high pinion might help with driveshaft angle when the axle's installed and you should have plenty of clearance.

Thinking outside of the pumpkin!

lfhoward said:

Can the steel D30 just be “flipped” to make it low pinion? You can tell by my question I am very unfamiliar with these diff housings.

Click to expand...

Unfortunately, if it was flipped it would cause the CV shafts to spin in reverse since the ring gear would now be on the opposite side of the pinion gear.


I ordered new Liberty outer seals and bearings that are unique to the CVs to measure what size bores and depths are needed for housing modifications.

I got a majority of the deconstruction complete. Some of the deeper cuts I will fill with weld and grind flush. On the passenger side, I cut the cast vacuum disconnect housing off the steel axle tube, to keep it is maximum length.
For the driver's side, I cut along the differential housing.

Next up on the agenda is to clean both housings, then disassemble the D30A to start taking measurements.

To attach the stock 3 bolt "front" mounting bracket, I plan on using the cover mounting bolts to attach a piece of plate steel. From my measurements, a 1/2 inch place will place the CVs spot on to where they are in the stock location.

Difference in distance between the cover mount and the CV centerline.



Measurements put into 2D


Difference in Dana 30A and regular 30 cover bolt patterns.

I wonder if you could move the whole axle down to improve the front cv angles by offsetting your adapter plate and passenger side mounting holes.

The high pinion Dana 30 would allow for quite a bit of drop till you get back to the OEM pinion location. It would just depend how far down the lower control arm and strut fork would let you go. Any amount would likely help.

Just a 'pie in the sky' thought.

Antony807 said:

I wonder if you could move the whole axle down to improve the front cv angles by offsetting your adapter plate and passenger side mounting holes.

Click to expand...

I have considered including multiple mounting holes in the brackets to accommodate a diff drop. However, I need to measure the clearance between my Jeep's differential and skid plate as I believe that would be the limiting factor.

Today's Progress

I cut the driver's housing extension off the main body, so that the welds were removed. This left the remainder of the axle tube held in place by the press fit. Using a FWD (Front Wheel Drive) bearing puller/installer tool, I was able to get the last piece of the tube out.

To fit the new CV shaft bearing and seal, I plan on having a new piece machined that will press into the axle housing that mimics the original aluminum differential.

FOLLOWING

I think I have all the bolt holes measured out for the new front mounting plate.
Using an aluminum yard stick, transfer punches, combination square, and some dial calipers, I think I have pretty good measurement for the hole locations.


Here are all the hole locations I was able to measure with my bracket design.
After I get the first bracket cut and if it fits, I will upload the .DXF file for anyone to make their own.

I would add a few extra holes (4?) to drill and tap into the housing for counter sunk bolts so when you need to remove the cover the plate still holds the diff.

Looks great!

I ordered the front mounting plate from sendcutsend.com on 1/2 inch steel.
The part fits pretty good, but small improvements could be made for the next revision. (if there is one)

And with the cover on.

Hopefully this weekend I will have time to remove the front differential and try to fit the high pinion in.

The original vent connection had been broken off at some point during this differential's life, but a 1/8 NPT tap and a fitting works well to fix it.


I had the new bearing/seal mounting area 3D printed to try out for an evaluation. Overall, it works really well, but I need to get the side of the housing machined to get the correct distance from the carrier bearing to the CV seal and bearing.

I did a rough fit-up with the steel diff housing. Even with the high pinion it looks like it will fit.
For the CV pinion yoke, I purchased a used Dana 30 CV yoke (99-04 Grand Cherokee) from eBay to reuse the current driveshaft. (The axle originally had a traditional U-joint pinion yoke)

Pinion Flanges 5012444AA Link for Summit Racing Equivalent part.

Looking really good!!! Nice fab work.

Quick update, I am still working on the project, working on getting some machined parts quoted.
I hope to have this all done over the winter so I can do the swap then.

Any update? Curious how it's going.

I found a local shop that would make the bearing and seal mounting flanges for the CV shafts.
He said he will do it when he has time, but this is low priority for his business. I will update the thread once I have the parts.