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.

[jimkelly]

more pics of the 2 pieces I will have welded after we make a jig to keep them centered to each other and spaced correctly. in pic I have the inner section resting on a tall socket to keep it up high inside the larger outer piece, for the pic, and to should closer to what finished part would look like.

the factory machined end goes deeper in trans and the cut end goes towards the nut. so i am thinking some spacers on the tail end/nut end will suffice?