Diff Housing Desing

[simonsuarez]

Hello i'm in charge of the differential in my team and i was thinking of making its housing out of aluminum. Since we're a first year team I thought this would be the simplest way to do so or you have some other suggestions? Another thing I got the drawings from the Torsen website, what else do i need in order to begin designing?

Simon Suarez
Equipo FSAE-LUZ

[simonsuarez]

Hello i'm in charge of the differential in my team and i was thinking of making its housing out of aluminum. Since we're a first year team I thought this would be the simplest way to do so or you have some other suggestions? Another thing I got the drawings from the Torsen website, what else do i need in order to begin designing?

Simon Suarez
Equipo FSAE-LUZ

[Chris Clarke]

The easiest method of designing the diff would be to house the Torsen gears in their stock carrier, and design a carrier of your own around the Torsen carrier to enclose it. (The Torsen carrier is not sealed). Many teams do it this way.

I think there is quite a few other posts about designing an aluminum differential to hold the torsen gears.

If you do go with an aluminum diff, ensure that you dont have the gears running directly against the aluminum, they will tear the carrier up.

Other things you need to consider:

-Tensioning/supporting of the diff
-Sealing/venting
-axle retention
-Sprocket mounting
-Brake rotor mounting (if using inboard brakes)
-Cooling
-Packaging in the chassis

Also, make sure you talk with the rest of your team regarding the handling characteristics you want from the differential. They can be very different depending on which type of differential you use.

Chris

[simonsuarez]

Thanks Chris we ended up choosing a Torsen Diff now we must decide on the number of brake discs (1 or 2)

[roadrunner]

Just finished my final year report on this subject.

Most teams go with a single brake rotor, its lighter, less parts, can be mounted easily to the diff itself and reduces un sprung mass.

As for the diff itself, weve found some quite significant differences between our drawings from Torsen and the actual assembly. This caused many problems when trying to drill through the casing!!!

[drivetrainUW-Platt]

Hey,
i am really suprised that the dimensions that you got from Torsen were not correct, we took the exact nunbers and it fell together almost perfectly, had to take a few thousands out for one of the thrust washers but everything spun freely after that.

[simonsuarez]

What drawings did you have? The ones that TORSEN has in its web page or another ones? I thought that one was accurate.

Simon Suarez
Equipo FSAE-LUZ
www.fsae-luz.org (http://www.fsae-luz.org)

[drivetrainUW-Platt]

we had a set emailed to us, talk to the company, see if they will do the same.

[roadrunner]

the blue prints that came with the diff in the box it was delivered in. Were wondering if we`ve got the old style drawings with the new diff, or something along those lines.

All sorted now though as we`ve machined it to death to reduce its size and mass.

I`m sure most people wouldn`t have this problem but we seem to attract this kind of error!!!!!

[simonsuarez]

What would you say is the aprox weight of a housing? Have you tried another materials besides aluminum? Because i've seen ones in plastic?? i think, excuse me if i'm wrong but what try to say is that you can see the gears inside of it. what d you recomend for a 1st year team like us? Thanks

Simon Suarez
Equipo FSAE-LUZ
www.fsae-luz.org (http://www.fsae-luz.org)

[Chris Clarke]

The ones with the plastic windows that you have seen use the stock Torsen carrier.

The steel Torsen carrier transmits all the loads from the sprocket to the gear assembly (you have to structurally mount the sprocket to the Torsen carrier), the plastic is non-structural and is there to seal the unit.

The steel unit is fairly heavy, so I would imagine this is heavier than an aluminum housing.

[Angry Joe]

As a first year team I would not go crazy with anything. My suggestion is to keep it simple and conservative, and use the stock housing. If you try anything fancy before you get the basics you will regret it.

Drivetrain was the single toughest part of our car by far (except for 2004, when we didn't have one http://fsae.com/groupee_common/emoticons/icon_biggrin.gif)

[Denny Trimble]

How did you end up accommodating roll with the chain to that live rear axle? Very stiff rear ARB (which would also help with the spool effect)?

[Angry Joe]

We basically ran a swingarm. It was designed to flex and allow a small amount of roll but this was a big concern.

As it turned out, axle roll was just about the only thing that didn't cause the chain to come off the car...

[simonsuarez]

Do both half shafts have the same lenght? What about the tripods (or cv-joints)? i was told by a guy who raced in formula ford that since our car is a lot lighter than an actual formula car we could use comercial parts from used cars e.g shafts, tripods, and we didn´t have to test them because they are proved to work with heavier cars with double the horsepower we're gonna use. Any thoughts? Correct me if i'm wrong but shouldn't we use parts that are in the market in order to save a lot of time? Ill take any suggestions thanks

Simon Suarez
Equipo FSAE-LUZ
www.fsae-luz.org (http://www.fsae-luz.org)

[Underthefloor]

I am designing an aluminum diff housing for the first time. I was just wondering how in depth other teams analysis is. Did anyone go so far as to determine all the coeficients of friction and figure out all the internal torques caused by the gears?

[Steve Chalmers]

I too have investigated the idea of designing a lightweight diff. What I am trying to determine is; do you go for say a Quaife of Torsen then go to work on slimming the thing down. Or on the other hand do you take the internals and and manufacture a completely new aluminium housing. I have heard mixed reports stating that this can be done quite easily and other teams seem to have had no end of grief.

Where does one start? Get a diff and then concentrate efforts on producing a lightweight aluminium unit of essentially the same design?

[Cement Legs]

We are using the new Torsen diff this year and since the housing is not a rotating weight with a moment arm, or unsprung mass, we will likely use the carrier made by torsen. With the time we save by not taking a couple to a few pounds off the diff, we will hopefully be able to take more weight off of other parts of the car.

[Albatross]

Hi everybody!! I am a memeber of the new team that participated in last F-Student 2004 racing for Madrid!

I´m taking care of the drive train this year for my first time and I have a pair of questions:

Do you fasten the carrier to the rest of he housing of the diff? I mean, to seal the whole. What about torsional efforts on it?

We want to mount the brake disc on this housing. Can it heat the diff too much?

If you need anything, I'll try to help!!