DIY Subaru AWD to 2WD conversion, Make your own Bremar-like kit. Options

[jpnovak]

I noticed there has been a lot of talk using the Bremar Kits for the Subaru transmission. For those who do not know, Bremar makes a very nice locking lug for converting AWD to 2WD within the Subaru transmissions. This is required for those doing the full Suby conversion where the 914 drive train location is mid-ship.

I would absolutely love to purchase the Bremar parts. However, I am building a GRM $2010 Challenge car and the budget is extremely tight. I want to show how to make your own conversion parts while spending a few hours in the garage and no cash outlay. Not all Suby transmissions are created equal. Most should follow a similar procedure.

So... Lets get started. first thing to do is remove the rear end cover. Remove the perimeter 14mm bolts. Then use a dead blow hammer and soft drift to coax the end cover off its locating pins. When you remove the end cover you will be staring at the center differential. Pull this out of the rear of the transmission and set it aside. This is what we will be doing surgery on. After removal of the differential you will have a hole and layshaft that drives the rear driveshaft. It will look something like this...

picture of removed end cover.
(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020281.1.jpg)

There are more details on removal and installation of the Bremar Kit here.
http://specificdesign.com/transmission.htm

I used this site for reference. You need to remove the end nut from the shaft. I used a pair of vice grips on the output shafts to lock the transmission against the motor mounts. The same technique works in when you are reinstalling the parts.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020283.2.jpg)


Once you have the parts laying on the bench you must disassemble the differential. Set it on the bench with the spider gears down and the female splined shaft pointing up.

There is a carrier bearing that will press fit down the female shaft section. This bearing must be removed first. It also may be left in the case. Either way, take it out. Mine was left pressed on the differential. I used two long pry bars under the bearing to pull it. My bearing puller jaws would not fit between the diff and the bearing. use what you must.

Next, locate the 8 mating spline section around the perimeter of the differential. There is a inside circlip that will be inserted in the mating splines. Use a small screwdriver or pick to pull out and then remove the circlip.

Now the top part of the differential will separate. There are three main sections of the differential. The lower spider gear carrier, a middle section that supports the layshaft and the top female section that we just pulled the bearing off. I roller bearing lets the middle section rotate within the locked lower carrier and top spline section. Separate the parts and lay them on the bench.

Start with the middle section. You must cut off the internal splines. This is an integral part of the final part. Clamp this in a vise and cut off the protruding section.


These gear sections are extremely hard. I used a cut-off wheel up against the base. Go slow and get this cut as clean and square as you can. If you are crooked you will pay later.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020285.3.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020286.4.jpg)

After the cut you must partially reassemble everything on the bench. Place the roller bearings in the groove and insert the cutoff section into the outer female spline.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020287.5.jpg)

The bearings locate and center the two spline sections. Here is what it all looks like aligned from the backside.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020288.6.jpg)

With the parts laying upright on the bench you can see the alignment. At this point you should drop in the spline section that was removed from the mainshaft behind the staked nut. All together it looks like this.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020289.7.jpg)

I assembled everything on top of the base of the middle section. there is a small roller bearing the will support everything and hold it in place. Next, run a weld bead around the perimeter making the splines one. The center most section of splines will not be attached at this point. They are press-fit. They can not come out when the whole assembly is installed back in the transmission.
(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020290.8.jpg)

Now it is time for more cutting. We must now cut off the large flange from the welded part. Same procedure as before. I made the cut about 2mm up from the start of the precision mating surface where the large support bearing was pressed. The tools.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020290.9.jpg)

The Carnage: Notice that the roller bearing will be cut and fall out. Since we welded the other side these are no longer needed.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020291.10.jpg)

The result:

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020292.11.jpg)
From the end:
(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020292.12.jpg)

Now its time for more welding. Fire up the torch and fuse these sections. I did not use any filler and setup the arc with a pointed tip for maximum penetration. Lots of heat and patience.

First the outer part line.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020293.13.jpg)

Then the inner. Make sure you do not damage the inner splines. These must be clean so that they slide back on the tranmission pinion shaft.

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020295.14.jpg)

Now you can put it back in the transmission. I used a hammer and drift to make sure that it seats on the shaft. Mine fit very tight. I suspect there was a little warping from the welding heat. I used a drop of red loctite on the threads of the nut since it was not so pretty after removing the original stakes. I also removed one spacer from behind the nut as the welds took a bit of room.

Overall the cost was 3 cut-off wheels and some Ar out of the welding tank. Total time was about 2 hours.

Next step, make a flat cover plate.

[G Man]

Very good info. As of now I don't have a 914 but am seriously considering making the plunge if I can make it work. By that I mean I need an auto trans car. I have nerve damage to my spine and can't use a clutch. Would this process work on an auto transmission?

[BIGKAT_83]

Good job and a great write up. Thanks for sharing




Bob

[Mike Bellis]

Very good info. As of now I don't have a 914 but am seriously considering making the plunge if I can make it work. By that I mean I need an auto trans car. I have nerve damage to my spine and can't use a clutch. Would this process work on an auto transmission?

This will not work for an automatic. But... You can buy a front wheel drive auto Subaru or Audi and use that transaxle.

[G Man]

Very good info. As of now I don't have a 914 but am seriously considering making the plunge if I can make it work. By that I mean I need an auto trans car. I have nerve damage to my spine and can't use a clutch. Would this process work on an auto transmission?

This will not work for an automatic. But... You can buy a front wheel drive auto Subaru or Audi and use that transaxle.

Thanks for that info. Is there any info available about this process. I have seen the thread with the Audi trans adapted to the 914 engine and I have considered going that route. Any info would be great. (IMG:style_emoticons/default/beerchug.gif)

[Andyrew]

Very good info. As of now I don't have a 914 but am seriously considering making the plunge if I can make it work. By that I mean I need an auto trans car. I have nerve damage to my spine and can't use a clutch. Would this process work on an auto transmission?

This will not work for an automatic. But... You can buy a front wheel drive auto Subaru or Audi and use that transaxle.

Ya a full FWD audi automatic (w/ tiptronic and paddle shifters) engine and trani swap is something im going to be doing in the next year.

[enikolayev]

wow, great writeup! i have been wondering how to DIY this for some time now... Thanks!

[BIGKAT_83]

I also started out building a 2010 challange car, but after working on the car found it to be far better than I thought.
I was going to do a weld on the center diff. like you did but found a locking sleeve and plate from a unfinished project for $100

What are your plans for the axles? The 914 stock axles which are the same diameter as the 911 and buss axles are long enough and a large enough diameter to be resplined on the transaxle end for the subaru joint. I've had a couple of these done and really like the way they came out. I had the first ones done at a shop on the west coast for $125 for both.
After looking around I was able to find someone local here in Atlanta that would do them for less.



Bob

[rick 918-S]

I also started out building a 2010 challange car, but after working on the car found it to be far better than I thought.
I was going to do a weld on the center diff. like you did but found a locking sleeve and plate from a unfinished project for $100

What are your plans for the axles? The 914 stock axles which are the same diameter as the 911 and buss axles are long enough and a large enough diameter to be resplined on the transaxle end for the subaru joint. I've had a couple of these done and really like the way they came out. I had the first ones done at a shop on the west coast for $125 for both.
After looking around I was able to find someone local here in Atlanta that would do them for less.



Bob

Bob,

Give us some details on the axle work. How much were they shortened when they were resplined? Start a thread like this one!
(IMG:style_emoticons/default/thisthreadisworthlesswithoutpics.gif)

More photos please. (IMG:style_emoticons/default/biggrin.gif)

[Andyrew]

I agree with Rick,

I'll have to get some custom axles done when I do the Audi trani, using the 914 shaft would be easy and cheap!

Where did you have it done at over here?? Start a thread!!

[eric914]

Very nice. Any more on the axles?

[quikshft]

Overall the cost was 3 cut-off wheels and some Ar out of the welding tank. Total time was about 2 hours.
Next step, make a flat cover plate.


Excellent post and write up! I wondered why this couldn't be done but didn't have the removed parts to inspect to see if it was possible. Should save a few bucks if I should get around to building a Suby powered car.

[jpnovak]

Thanks to everyone for the compliments.

I have all but no money left in the budget and I still have to get tires and a cooling system. Radiators are cheap. Long hoses to the front are not.

For axles I plan to cut the 914 outer and Subaru inner. Then weld and sleeve the two axle sections. I can make it strong enough to last the event and then I will look at alternatives.

[camaroz1985]

That's the same thing I'm doing for my axles.

Nice work you did on the center diff. I started with a FWD parts car so I didn't need to worry about a conversion.

[sawtooth]

(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-10736-1268020290.8.jpg)

Hey Jamie very nice work. It looks like this may require tig? I'm wondering if this can be done with a mig? It looks to me like the weld on the inner portion would be really tough to get a mig tip in there to do the job.

[rick 918-S]

Thanks to everyone for the compliments.

I have all but no money left in the budget and I still have to get tires and a cooling system. Radiators are cheap. Long hoses to the front are not.

For axles I plan to cut the 914 outer and Subaru inner. Then weld and sleeve the two axle sections. I can make it strong enough to last the event and then I will look at alternatives.

I used electrical conduit under the car and standard radiator hoses to connect the engine to the tubes and radiator. Way cheaper than Gates hose.

[Britain Smith]

Call up Renegade...I got the Gates Strip hose from them for around $120. It was plenty of hose with some extra.

-Britain

[jpnovak]

Dean,

You could probably use a MIG for the welding. Depending on the torch and gas collar you may have a tough time seeing the bead. It will certainly be a tight fit.

I did use a TIG. I setup the part to rotate such that I could get a fixed angle with the torch head. Then I rotated the part with my left hand. I walked the part rather than the cup.

Make sure you have a stout welder. A 110V will not cut it on this thick steel.

[sawtooth]

Dean,

You could probably use a MIG for the welding. Depending on the torch and gas collar you may have a tough time seeing the bead. It will certainly be a tight fit.

I did use a TIG. I setup the part to rotate such that I could get a fixed angle with the torch head. Then I rotated the part with my left hand. I walked the part rather than the cup.

Make sure you have a stout welder. A 110V will not cut it on this thick steel.

Thanks Jamie, great advice.

For anyone who might run into the same issues I did, here's how I ended up welding mine...
I only have a 110 mig which works great for everything I've ever needed, but Jamie's right it won't even begin to penetrate this thick hardened steel. I tried even just to tack things in place and the welds popped off like solder.
So I took it to my machinist and described what I wanted, and how I'd seen it done with a TIG. He said there's no way he could get his tig in the front side to get the bead like Jamie did. So he came up with a plan which I think will hold up really well. He cut an aggressive chamfer on the back side between the two main cylinders. Then he welded that chamfer using filler, with lots of penetration. The center spline did not need to be welded because it is geared to the middle cylinder and can't go anywhere. It also gets seized in place because of the heat shrinkage from the weld. And it removes any chance of messing up the spline teeth.



Thanks again Jamie for your excellent write up. For anyone who can't do the great filler-less tig work like you did, this might be the next best option. We'll see how it holds up.

[charliew]

Great idea. It looks like from the picture the inner sleeve can be ground to a chamfer with a bench grinder or belt sander and that alone would be enough for a good recess to fill with filler.

The only thing about the wire feed is the filler is mild steel that is being mixed to the alloy of the sleeve. Non filler welding changes the metallurgy but not as much. This is a twisting force though not a bending force so it is not nearly as critical.