Which kind of diff could be better?

[pzal15]

Hi guys!
We are a new team from Spain, and we are starting with all these FSAE. I have to choose the diff, but I still have doubts whether to choose a LSD or a Torsen.. could you any of you give me a hint about it? thanks

[pzal15]

Hi guys!
We are a new team from Spain, and we are starting with all these FSAE. I have to choose the diff, but I still have doubts whether to choose a LSD or a Torsen.. could you any of you give me a hint about it? thanks

[J.R.]

If you are a new team, you most likely don't have very much money. My question for you is, do you really need a diff? We run a Solid rear, and others run spools, and if you develop the car correctly, then you can run circles around teams who have a diff just because everyone else does.

If you decide that you still need one, you really need to ask what you want it to do, and how much you can afford. I hear LSD's ain't cheap....

[D Collins Jr]

pzal:
As far as money is concerned, a good solid axle will only save a couple hundred US dollars as compared to the internals for a differential (that's on an assumption that most teams running solid axles are using mini sprint axles, i don't know what you'd use in Europe, since I doubt there are mini sprints there. I also don't know what the savings in Euros would be). The expensive portion of a diff, as you may already know is the half shaft axles, tripods, and housings. The flip side to this is that this allows for an independent rear suspension, favorable by almost all accounts for a 'road race' style vehicle, since there are left and right turns at various radii. In all actuality, your differential will be primarily influenced by your suspension. And given the number of teams that run a diff, you may find it easier to get quick help and answers about set ups and design (in addition to more literature) than if you run a solid axle or spool.

Good Luck!

[J.R.]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by D Collins Jr:
pzal:
As far as money is concerned, a good solid axle will only save a couple hundred US dollars as compared to the internals for a differential (that's on an assumption that most teams running solid axles are using mini sprint axles, i don't know what you'd use in Europe, since I doubt there are mini sprints there. I also don't know what the savings in Euros would be). The expensive portion of a diff, as you may already know is the half shaft axles, tripods, and housings. The flip side to this is that this allows for an independent rear suspension, favorable by almost all accounts for a 'road race' style vehicle, since there are left and right turns at various radii. In all actuality, your differential will be primarily influenced by your suspension. And given the number of teams that run a diff, you may find it easier to get quick help and answers about set ups and design (in addition to more literature) than if you run a solid axle or spool.

Good Luck! </div></BLOCKQUOTE>

Torsen Diff -&gt; $1200
LSD -&gt; $1700
Solid Rear -&gt; $250
Building a car on a limited budget... Priceless

[Hector]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by J.R.:
Torsen Diff -&gt; $1200
LSD -&gt; $1700
Solid Rear -&gt; $250
Building a car on a limited budget... Priceless </div></BLOCKQUOTE>

More like:
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[D Collins Jr]

So, for less than a thousand dollars more, I can have four tires generating lateral grip? Interesting. For my own benefit JR, what do you guys you for a solid rear axle?

[Mike Macie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by D Collins Jr:
So, for less than a thousand dollars more, I can have four tires generating lateral grip? Interesting. For my own benefit JR, what do you guys you for a solid rear axle? </div></BLOCKQUOTE>

I think what JR is hinting at is using a diff, spool, or solid axle is not going to have much of a difference on where you finish when you are a new team. You might be able to say this to half the teams that register too. More important then cost is the development time saved as well. It's tough for teams to get in the groove to pop out a new car every year. The best teams have been developing there car for years. New teams should keep it simple, learn , and then use that into making the next car better. Teams now are trying to do more then they can handle. The percentage of teams that don't make it through the endurance event in the US is pretty sad.

The axle we used was a 7075 splined axle from hyper racing. When i was still on the team there was some work done on developing a lighter 3 piece axle. Not sure what the plans are this year.

[D Collins Jr]

1. My point is that your diff selection (or lack thereof) needs to be motivated by how your suspension is (or will be) set up. Failure to do this will result in poorer performance on track.

2. Teams failing to finish the endurance in US competitions is at least as much a result of how the teams are set up as anything else. I know that a lot of teams in this country only exist as senior design projects. As you know, FSAE takes more than a year to learn and get good enough at to finish. In those cases, I think that the issue is bigger than, "did we spend to much time trying to develop our diff package?" In addition, US teams more than others, in my opinion, are composed more of undergrads than grad students. You can't convince me that this doesn't help the relative quality of engineering of these cars, and thus the finish rates. Moral: Finishing percentages are more influenced by team structure than these types of decisions.

3. You guys run 10" wheels at Buffalo right? Are you maybe selling any of those off? I'm looking for some 10" splined wheels to put my mini sprint back together.

[J.R.]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by D Collins Jr:
3. You guys run 10" wheels at Buffalo right? Are you maybe selling any of those off? I'm looking for some 10" splined wheels to put my mini sprint back together. </div></BLOCKQUOTE>

Sorry, we've only got our two sets for rain/dry.

[Wesley]

Or, you could spend the time to engineer your diff package and skip that time engineering your suspension kinematics.

Probably will result in the same lap times.