diff for project

[captain crescent]

After countless hours of pondering to my self i decided to ask the masses of Toyspeed.

I am just collecting all my parts for my current build a Hayabusa powered Suzuki CXG. i am looking for a smallish independent rear suspension diff it has to be an open diff, reasonably light (weight is my enemy) and the input has to be as close to the centre vertically as I am turning the diff upside down.
So any ideas or possibilities would be appreciated.

[Jdawg]

MX5

[strx7]

legacy/wrx

[nz_climber]

Ford sierra and Landrover freelander are both alloy case and used by many bike engined lotus 7's in the uk

I would think the determining factor would be the ratios, most hayabusa 7's I have read about tend to run a 3.2-3.6 diff (sierra ratios are 3.14, 3.38, 3.64, 3.92)

Also from the 4wd sierra's they have a separate front diff, which is a bit smaller, and saves turning a diff upside down.

Just need to search a few wreakers to find the one you are after. Plus they are cheap (I got my complete rear end for $60) Freelander diff will be harder to find.

[nz_climber]

Check out here for a gear calculator for various bikes with different diff ratios, will give you an idea on what would suit your car

http://www.locostbuilders.co.uk/forum/23/viewthread.php?tid=121319

[captain crescent]

i already had the calculator but thanks anyway . yea i mite actually go have a look at a front diff from a ford cheers for that. im not set on a gear ratio as i will be running chain drive so sprockets can change my ratios.

[nz_climber]

No worries, just had a look at a few pictures of the Suzuki CXG.. I am not sure what your plans are for it, but I would be guessing the best use of space there would be to have the engine facing east-west like in the bike, and then use a chain drive diff (that would be the most compact set up.

I imagine having the engine north south onto the diff would make the set up pretty long with lots of overhang.

Chain drive diffs are easy to build from any diff internals you wanted, and a lot lighter than a normal rwd diff, also drive train losses would be a lot lower since you don't have to transfer rotation through 90 degrees. Plus it is easy to incorporate reverse and in board brakes etc (if needed)

Anyway just an idea, you have probably already thought of it

[captain crescent]

the main problem would be if i was to run it east west with a chain drive diff is the cross member that runs across the back under the fire wall. and because of the very limited space the engine would be almost or touching the back of the seats which would not be really ideal . my current plan is to put the diff as low as possible with the input shaft facing the rear of the car mount the motor above it and chain drive around the two. i know this may sound like i will have a problem with higher centre of gravity but this is the only realistic way that myself and workmates can figure putting this in (without space framing ).

[Si]

I have a toyota G series diff here that probably weighs far too much, and is far too big, but your welcome to come check it out if you like.

http://iforce.co.nz/i/5honuf4d.jpg

[captain crescent]

thanks si but you are right far to heavy just seeing all that cast iron my poor little car starts trembling in its boots lol

[Flannelman]

early Rav 4?

[Dell'Orto]

Why not chain driven as per MR BUSA have splines either end of the sprocket, and run conventional halfshafts from it for the IRS? Mount the "diff" in some sort of heavy duty hanger bearing arrangement so it stays central.

[captain crescent]

as you can see the crossmember with the mount on it is my main problem the chain and sproket would be running pretty close to the member. and the engine would have to be sitting quite high to get the chain clear of the crossmember

[nz_climber]

What is the car going to be for? I am guessing a Track car, because bike engined cars are not so good on the road. For the best set up and handling you need to get the engine low and within the wheel base.

So I would be putting the engine in the back seat, make a new firewall around it, and chain drive diff and custom double wishbone rear end. (just like MR Busa)

[captain crescent]

it is going to be track ,hill climb and road regestered maybe.

i would kind of like to keep it semi standard so i dont want to space frame the rear end if i can avoid it. as i say its not the fire wall that is the problem with mounting the engine in the back seat it is the crossmember that is sitting at the bottom of the firewall and the distance between the fire wall and the back of the front seats seem to be a bit of a pain to i estimate around 50 mm between the back of the seats and the head of the engine so it wouldnd exactly b nice if somthing decided to part compony from the engine . the car is wider than it is tall if that makes any difference for handling lol.