Suspension Benchmark

[Gonvin]

Hi all,

We are a new team and I am one of the guy that deals with suspensions. Even after doing a considerable amount of literature survey on suspension we still couldnot find any data that we can set up as our benchmark. As in, nobody tells you what should be the ideal camber change graph with wheel travel or what should be the upper limit on roll center travel?

I understand that different cars will have different requirements and some of the factors are very subjective in nature(the suspension feels good or handling is difficult etc) but how should a team which has no previous experiences set its benchmarks.

I am sorry if I have reopened a topic which has been already discussed. Your help will be much appreaciated.

Govind

[Gonvin]

Hi all,

We are a new team and I am one of the guy that deals with suspensions. Even after doing a considerable amount of literature survey on suspension we still couldnot find any data that we can set up as our benchmark. As in, nobody tells you what should be the ideal camber change graph with wheel travel or what should be the upper limit on roll center travel?

I understand that different cars will have different requirements and some of the factors are very subjective in nature(the suspension feels good or handling is difficult etc) but how should a team which has no previous experiences set its benchmarks.

I am sorry if I have reopened a topic which has been already discussed. Your help will be much appreaciated.

Govind

[Mike Sadie]

When designing a suspension system, you always want to start with the tires. Check out the thread regarding TTC Tire Data if you dont already have it. From the data, for instance, you can plot lateral force vs vertical load for a range of camber angles. This in turn will tell you how you want your camber to change with load transfer. The TTC Data is invaluable when it comes to designing a suspension system, so I would definitely recommend it.

[Gonvin]

The tire data will give me what is the optimum camber angle that is required but what about roll center height. Do we accept whatever comes out from optimizing the camber or are their similar parameters involved?

I have read up about jacking affect and others but again there is no such bounds on these.

[LU-Bolton]

Gonvin,
Here is a great article which should help you a lot with trying to understand what you should focus on with your first suspension design. This article would have helped a lot if I had it when I designed my first one. If you don't know of him, Bill Mitchell is a well respected man in this field and I have encountered him several times in the Design Tent myself.

Aaron Cassebeer

Roll Center - Myths and Reality (http://zzyzxmotorsports.com/library/roll-center-myths-and-reality.pdf)

[J. Vinella]

Govind,

The best suggestion I could give would be to make your suspension parameters adjustable. Castor, Swing Arm Lengths...etc. Your system will not be as stiff as it could be and weigh more than a non-adjustable one would have. But you will have a good base to go off of for the next year with tuning. The weight addition might be offset by the ability to pull back some performance if you get the ballpark wrong with your initial design.

As for the ballpark parameters of what is good and not that is for you to decide.

Make sure you think of the entire system in your design. How soft can I make the springs and then how stiff will the ARBs need to be to ensure the roll angle I want. What is the trade off in soft springs and stiff ARBs compared to the alternative.

Let me put my F1 Spy cap on and suggest looking at fast teams and measuring some of their parameters. This can be done with as little as, dare I say it calipers and a computer screen. From this you would gain little self knowledge but have a ballpark of what other teams are running. You will surly find that not one suspension will get the job done. Also many fast teams have more hidden up their sleeve then their car would suggest and the suspension is not the only factor.

Your initial research has no doubt given you a good understanding of what you want from your system. Now is the time to sets your parameter goals, design the system, test it and then iterate for next year.

I wish you the best of luck,