Aluminum Torsen Housing

[Dave Cook]

I'm considering making some alumninum dif housings for the Torsen provided 'University Special' It would be a 7075 forging that is heat treated, turned, machined with the features to hold the gears and then hard anodized.

It would take 5 weeks to have them made so this might be more of a next year item. I am interested in comments on the usability of the current iteration and how many people would be interested in buying one if it were available.

I'm still looking into the tooling and manufacturing costs, my goal is to keep the cost under $375.

For comparison The yield of the 7075 should be 73ksi and the original SAE D5506 Ductile iron is 55ksi. The original housing was nitrided with a .0003 case at 65Rc, the hard anodizing should be the equivelent.

A 2 page pdf with more info is available at http://www.paradigmmotorsports.com/html/torsen_housing.html

Please post any comments or send me an email.

Dave

[Dave Cook]

I'm considering making some alumninum dif housings for the Torsen provided 'University Special' It would be a 7075 forging that is heat treated, turned, machined with the features to hold the gears and then hard anodized.

It would take 5 weeks to have them made so this might be more of a next year item. I am interested in comments on the usability of the current iteration and how many people would be interested in buying one if it were available.

I'm still looking into the tooling and manufacturing costs, my goal is to keep the cost under $375.

For comparison The yield of the 7075 should be 73ksi and the original SAE D5506 Ductile iron is 55ksi. The original housing was nitrided with a .0003 case at 65Rc, the hard anodizing should be the equivelent.

A 2 page pdf with more info is available at http://www.paradigmmotorsports.com/html/torsen_housing.html

Please post any comments or send me an email.

Dave

[Ian McMurdo]

That would be seet. UVic would definitely be interested, especially if you could make it happen before West this year.

[Mechanicaldan]

Hi Dave,

Great idea, but it looks like you'd just be providing an aluminum housing instead of steel. How about provide a more complete solution? I'd like to throw some ideas out to help this be a customizable "university housing" to help you sell a complete differential. It's a complete differential that could be installed and wouldn't require any more design. You could also sell this to the SCCA Formula C & D car builders.

I would propose you design it in 4 pieces consisting of one center section, one center section cover, and 2 outer sections. Make sure the center section has provisions for o-rings so it won't leak. One outer section would have provisions for a sprocket. Teams could specify the overall length to fit between their bearing supports, and could specify the offset from the center for the sprocket. You could do something simliar on the other side for a brake rotor. Personally I think the brake rotors should be mounted to the inboard tripod housings.

Similar to this:
http://sae.stuorg.iastate.edu/albums/finaldrive2006/000_0073.sized.jpg http://sae.stuorg.iastate.edu/albums/Final-Drive/DSC01198.sized.jpg

[Bill Kunst]

Dave,
Is that a one piece housing, or two? The pitcute in the link show it as two, the drawings as one.

I have seen some that are a two piece housing for the original. think of it as a bucket and lid, each having a shaft tube coming out of them. For the original housing, they machine it down until it looks like the Al housing in Dan's first pic. The bucket and the lid "clamp" an o-ring and the drive gear. Bearings in the shaft tube stabilize the cv's. Brakes go outboard or mounted to the tripods inboard. Just another idea as sealing these things seems to be the devil for a lot of endurance problems. How would the outer housing on your design seal?

Nice work,
Bill

[TG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dave Cook:
It would be a 7075 forging that is heat treated, turned, machined with the features to hold the gears and then hard anodized. </div></BLOCKQUOTE>

What kind of forging is this going to be? will it just be a wrought extrusion or will you get some sort of near-net-shape?

Also, what kind of accomodations will you make for attachment of the sprocket? I see in your website it mention that there will be a sprocket drive flange, but there isn't much detail. Will it be a certain bolt-on pattern, a custom way where we give you the specs, or will it just be a blank piece where we would be able to make it our own way?

[Mechanicaldan]

The teams could build their own differential stub shafts, or you might be able to supply them also. If you used a standard flange with the bolt pattern to the Taylor Racing Tripod housings, I think you'd have a real winner. The teams would just have to make the differential support brackets and supply the bearings.

Here a picture of the differential in the frame. The inboard discs float on the flanges of differential stub shafts.
http://sae.stuorg.iastate.edu/albums/finaldrive2006/000_0211.sized.jpg

This is the picture of the Taylor supplied tripod boot. Small, clean, and protected. http://fsae.com/groupee_common/emoticons/icon_smile.gif
http://sae.stuorg.iastate.edu/albums/album24/DSC00832.sized.jpg

[Mechanicaldan]

Check this post out for the the outboard tripod: http://fsae.com/eve/forums/a/tpc/f/125607348/m/73560899...696087005#6696087005 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/7356089994?r=6696087005#6696087005)

http://www.cosic.org.uk/misc/tripod%20housing%201.JPG

http://img516.imageshack.us/img516/5887/rhubzl8.jpg

Sorry to drive the post a little off topic.

[Dave Cook]

Dan, I like your concept and it has me thinking. The idea for my part is to 'not' provide a built differential solution, but more of a starting point for schools to do there own. Kind of like my splined bars, I'm trying to just do the 'high' overhead stuff that shouldn't be a financial or time burden on people who have better things to do like design a car. When I first recieved a Torsen diff in 1997 I wasted about 2 months hoping to find a shop that had a hob that would cut the goofy Audi spline. We ended up hobbing 30 deg splines that just fit, this was time I could have spent doing something else. A custom hob is $475 and takes 10 weeks. You can learn to machine it one spline at a time in an index head, but again you have better things to learn and design and risk scrapping more hardware over what should be a simple process

In this case to make a single unique diff housing with a drive flange you'd have to start with a 6" Billet of 7075, completely machine it in house, get a custom reamer and then have it hard anodized to the right thickness. Individually these processes cost much more than $375 and you also risk scrapping it all if you don't get the gear pins machined right.

The part will be provided as shown on sheet 1 of the pdf, sheet 2 is a suggestion for all the new teams that haven't seen the inside of one of these. With a major diameter of .904 on the splines; using off the shelf 1.000 inch bushings and seals is an easy suggestion. Flange thickness, bearing ID and location, final housing OD, sealing are all things that should be left to the teams.

The large bearing boss on one side of the forging is so that there is enough material to drive the differential through the bearing. That is if the sprocket is not on the diff, but on the other side of the differential mount.

The forging is near net, as forged it has all tapered faces for the forging dies. It needs to be cleaned up to do the gear windows and pin holes.

Any comments on the size of the part are welcome. This is a work in progress and I will need refundable deposits on 10 of them to consider buying the forging tooling. If I take deposits there will be a timing guarantee on them and scheduling updates.

Dave

[drivetrainUW-Platt]

You are having a wet dream if you you think you can price out a differential custom cnc'd outa a chunk of aluminum for under 400 bucks. Ours came out to $1200, part of which was the cost of the actual torsen internals...maybe you discovered something we didnt.

Cost is part of the reason I went with an atv setup last year, could be bougth with cv's for under 600 with minimal modification needed.

[~~J~~]

Any update on this custom housing? it seems like a good direction for us to head towards next year...

I'm also considering switching to a clutch type diff...