Rear Suspension and Differential

[TheGreatBenny]

Hello,

I am in the process of researching different suspension set ups and while searching the forum I was not able to come across what I was looking for.

I was wondering if it is possible to use a solid rear axle with trailing arms for the rear suspension while going with the conventional double wishbones upfront.

Also, it is possible to actually go without a differential and have the chain/sprocket set up connected to the axle.

[TheGreatBenny]

Hello,

I am in the process of researching different suspension set ups and while searching the forum I was not able to come across what I was looking for.

I was wondering if it is possible to use a solid rear axle with trailing arms for the rear suspension while going with the conventional double wishbones upfront.

Also, it is possible to actually go without a differential and have the chain/sprocket set up connected to the axle.

[BMH]

What you describe is pretty much what's called a spool set-up.

Here is a pretty good document that I would recommend reading (remove spaces): h t t p : / / w w w . taylor-race . c o m /pdf/understanding_differentials.pdf

[JWard]

Do you possibly mean like this? Not sure if what he describes is necessarily a spool?

http://www.fsae.unsw.adfa.edu.au/

EDIT: sorry, his final point is definitely spool, but the initial suspension specific question is along the lies of what the unsw guys use

[swong46]

I'm pretty sure OP is talking about a solid axle not a spool. SJSU used it a years back, not entirely sure how it was. I had a conversation with Claude once and he said he never seen a solid rear axle perform well in the Formula Student Series.

[Adambomb]

Actually sounds like he was talking about both...first a solid axle with trailing arms, then going "without a differential" with a spool.

I remember there was a team a couple years back that ran a solid axle and a spool with a single, and the car was like 308 lbs. Thinking they were from the west coast; I could be wrong. Looked like a pretty good setup from a glance at least. As I recall they were having so much trouble with the fuel injection that they ran a carb. I don't see any way you could do well with carbs, so it would have been really interesting to see how that car would have run as designed.

[J. Vinella]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Adambomb:
Actually sounds like he was talking about both...first a solid axle with trailing arms, then going "without a differential" with a spool.

I remember there was a team a couple years back that ran a solid axle and a spool with a single, and the car was like 308 lbs. Thinking they were from the west coast; I could be wrong. Looked like a pretty good setup from a glance at least. As I recall they were having so much trouble with the fuel injection that they ran a carb. I don't see any way you could do well with carbs, so it would have been really interesting to see how that car would have run as designed. </div></BLOCKQUOTE>

I think you are talking about Cal Poly SLO 2006
They got third in skid pad.

They ran solid rear axle with "trailing arms" and front pushrod arms. They also ran quite a bit of front caster to pick up that inside rear.

[JWard]

Yeah, he's definitely talking about both, the link I posted is a solid axle with trailing arms, though those guys run a dif.

You say they finished 3rd in skid pan, and weighed 308lbs. Im off to find some more on this car.

[js10coastr]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by J. Vinella:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Adambomb:
Actually sounds like he was talking about both...first a solid axle with trailing arms, then going "without a differential" with a spool.

I remember there was a team a couple years back that ran a solid axle and a spool with a single, and the car was like 308 lbs. Thinking they were from the west coast; I could be wrong. Looked like a pretty good setup from a glance at least. As I recall they were having so much trouble with the fuel injection that they ran a carb. I don't see any way you could do well with carbs, so it would have been really interesting to see how that car would have run as designed. </div></BLOCKQUOTE>

I think you are talking about Cal Poly SLO 2006
They got third in skid pad.

They ran solid rear axle with "trailing arms" and front pushrod arms. They also ran quite a bit of front caster to pick up that inside rear. </div></BLOCKQUOTE>

That was the case... I wasn't there when it was run though. The overall concept was there, but was never executed properly in the two or three competitions it ran in. You give up a lot in terms of weight distribution and tuning, and a lot of the parts and systems end up being quite complex to make and work on, but the lateral performance is there, the car/idea as a whole is still unproven.

[J. Vinella]

We test a true spool (CV cups with no diff) back to back with an old Torsen II.

Initial feedback was it was driveable but not as fast. Granted the car was not set up for that type of rear drivetrain. Tire temps went way up in the rear and there was graining on the inside of the tires, as expected.

I'm not going to state lap time difference, but the weight savings and complexity was intriguing.

If I was a new team, or wanted to move resources to something like aero, I would do a spool.

[TheGreatBenny]

Thanks for all the replies everyone, my team decided to go with a differential. I was hinting at going with a set up like this, but the group in charge of the drivetrain decided they want a diff.