Need suggestions for Chain-driven diffs

[Hiro]

UTS used a rav-4 front lsd diff last year, but only because it was free (sponcered), and they are imported.

I dont think it matters if its a live axle because of racing limitations, but the point of building this is to achieve a well constructed and planned car. IRS defiantly gets you more points. (if this is for what i think this is?)

Uni of Newcastle SAE team used a Rav4 Torsen LSD for the last few years, I think it was the rear diff though not the front. Made up our own sprocket and housing, and it was all good. Easily handled the punishment that the CBR600F4i put out, although the axles didn't (thats a whole story of it's own, by the way)

[Ben Wilson]

As this is an experimental car, and the objective is to get it racing ASAP, we have taken the suspension from a Formula Ford as it is a given quantity.

Then go for a spool, simple, light, reliable and consistant. With LSDs you get preload adjustment, heat variation, wear and added weight.

[julzy_quads]

Just weld a cog or gear onto the flange of the diff and have a chain from that to the engine. I have done this on my 450cc trike and works a treat. Need to be very precise when you weld the cog on though.

[Hiro]

Just weld a cog or gear onto the flange of the diff and have a chain from that to the engine. I have done this on my 450cc trike and works a treat. Need to be very precise when you weld the cog on though.

Our sprocket was CNC cut and bolted on, thus was removable which is very desirable in case you lunch a tooth into the chain and need to replace the sprocket (this DID happen to us, although only on the much much smaller crank sprocket)

[julzy_quads]

yeah probably a much better way to do it. especially if your going to be changing the sprockets around for different tracks and the such

[DigitalPho3nix]

Our sprocket was CNC cut and bolted on, thus was removable which is very desirable in case you lunch a tooth into the chain and need to replace the sprocket (this DID happen to us, although only on the much much smaller crank sprocket)

This is basically what we were thinking, plus using a tensioner as the chain will run a fair distance from the engine to the diff.

[SillyCarS]

just design it an get your techs to machine it at uni, you do have a workshop right?

[DigitalPho3nix]

just design it an get your techs to machine it at uni, you do have a workshop right?

Yeah, we have a workshop. But we will probably outsource it because our CNC lathe hasn't come yet (which would be really handy). We have a CNC mill which I can use, so I could do up a proto when I have a spare sec.

[datsik]

there is a company that makes these diffs for formula SAE cars... Of the top of me head I can't think of it??? its a torsen type diff and sells for about $3000 US ?? I'm pretty sure that The Curtin motorsport team used this diff.. (Curtin University) maybe you should get in contact with them.

Why are you building a hillclimb car when you could build a formula SAE car and actually compare your engineering skills against those of other UNI's.?????

[DigitalPho3nix]

there is a company that makes these diffs for formula SAE cars... Of the top of me head I can't think of it??? its a torsen type diff and sells for about $3000 US ?? I'm pretty sure that The Curtin motorsport team used this diff.. (Curtin University) maybe you should get in contact with them.

Why are you building a hillclimb car when you could build a formula SAE car and actually compare your engineering skills against those of other UNI's.?????

A Formula SAE car would take 5-6 years to design from scratch and another 4 years to become competitive.

Since my course is very new (I am 2nd year, and in the pioneering group of students) we don't have many resources yet. A Formula SAE car is probably going to be bought from another uni and then the essentials will be redesigned. But this will not happen by the time I leave uni.

As for the US$3000 diff, why not get a Quaife that is about 1/3 of the price and will probably suit the hillclimb car better?

[Hiro]

A Formula SAE car would take 5-6 years to design from scratch and another 4 years to become competitive.

5-6 years? Get a dozen committed people, money and sponsorship, and you can get a reasonable car in about 8 months

[DigitalPho3nix]

5-6 years? Get a dozen committed people, money and sponsorship, and you can get a reasonable car in about 8 months

Yeah maybe, but try telling that to the Head of School who won't spend money on anything until our new huge workshop is built.

[RobertoX]

Doh, stupid comp logging me off, I just typed a response

anyway the gist of it was: keep your car simple and reliable, use a spool now and think about upgrading to a diff later on. You can use suspension to account for the spool (such as droop limiting etc).

You can get off the shelf sprockets that are very well made and in many tooth combinations. The rear ones come very light out of 7075. (large dia rotating mass =bad)

If you do want to go a diff later on the torsen ones are ok but lack a lot of tunability, the clutch one are pretty good imo

[RobertoX]

ps. you can build a fsae car in scratch in a year but you are right in that it will take 3+ years to become competitive. I think any uni with at 'motorsports engineering' degree should have a fsae car

[datsik]

A Formula SAE car would take 5-6 years to design from scratch and another 4 years to become competitive.

Since my course is very new (I am 2nd year, and in the pioneering group of students) we don't have many resources yet. A Formula SAE car is probably going to be bought from another uni and then the essentials will be redesigned. But this will not happen by the time I leave uni.

As for the US$3000 diff, why not get a Quaife that is about 1/3 of the price and will probably suit the hillclimb car better?

I'm not sure of the price (thats why I put ????) but I know its more than $1000...that included not only the diff but the housing and possibly other bits..it may indeed be a quaife.