Suspension design books?

[scottm]

I am looking for suspension design books that get into proper design for roll center, tire scrub, bump steer, etc. I want any good book, but one specifically about long travel off road would be great. I have heard of one called Racing by the numbers, but I can't find it anywhere. Any ideas?

[partybarge_pilot]

I don't think there are any that deal with off-road type stuff. Mostly street stuff, try Herb Adams, Carrol Smith or Paul Van Valkenburgh.

[FABRICATOR]

"one specifically about long travel off road would be great"

Good luck. The best you could do is piece one together, but there will still be pieces missing. Learning too much about pavement will leave you permanently confused about off-road.

[WoodyW]

Ditto that....and most of those books will have you guessing as to "proper" geometry for suspension with the ranges of travel encountered in off-road. But they are still good reads.

[DPpatrol]

Tune to Win by Carroll Smith is a good overall view of suspension/vehicle dynamics book. Race Car Vehicle Dynamics by Milliken and Milliken concentrates on the actual equations which govern vehicle motion. Both are my favorites, however they have nothing really to say about off-road setup. I have never seen a book which does discuss off-road. I am not saying its not out there, I just havent seen it. The problem with off-road is there are so many other factors to consider that things like roll-center movement are probably not as important as they are on road-cars. For example obtaining usable travel is probably much more beneficial to an off-road vehicle than constraining roll-center movement.

I can tell you one thing for sure though, getting a suspension system to do what you want over about 2 in of travel is a pain in the ass. When designing a suspension with 12-20+ in of travel you're probably going to have to make a lot more comprimises.

You may also want to check on Bill Mitchell's program WinGeo. You input hard points and input ride or roll changes and it calculates all neccessary suspension parameters. It is quite user friendly.

jason

[FullsizeFun]

You may also want to check on Bill Mitchell's program WinGeo. You input hard points and input ride or roll changes and it calculates all neccessary suspension parameters. It is quite user friendly.

jason[/QUOTE]


Where can you find this program? do you have to buy it or can you download it somewhere?

[Greg]

My wife got me a book from the SAE called "racecar vehicle dynamics". Its by far the best book on racecar suspension desing ive come accross yet. It was $100 though. I think she got it from amazon.

[ntsqd]

My wife got me a book from the SAE called "racecar vehicle dynamics". Its by far the best book on racecar suspension desing ive come accross yet. It was $100 though. I think she got it from amazon.
That is the Miliken & Miliken book.

I don't think you can learn too much from the pavement oriented books. But what you do need to do is temper the more extreme aspects of pavement design with experience on dirt.

[Kritter]

That is the Miliken & Miliken book.

I don't think you can learn too much from the pavement oriented books. But what you do need to do is temper the more extreme aspects of pavement design with experience on dirt.

TS cant recommend that book because they call damping...damping and not dampening.

I have M&M on my desk...its a good read.

[scottm]

Thanks everyone. I ended up getting Advanced Race car suspension design, by Steve Smith. I found it on ebay for $17. I'll let you know if it is useful. Its true that roll center will be hard to improve but some aspects are addressable. Bump steer of course, but scrub especially is a bigger factor than many realize. Some buggies and trucks out there have 3-4" of scrub per side. Reducing that by half, for example, would be a noticable improvement.

[DPpatrol]

Where can you find this program? do you have to buy it or can you download it somewhere?

http://www.mitchellsoftware.com/

jason

[DPpatrol]

Wow, I just checked the price online of WinGeo and I never realized it is a $345 program. It is installed on the computers on campus, so I had no idea it was that expensive.

jason

[ntsqd]

TS cant recommend that book because they call damping...damping and not dampening.

I have M&M on my desk...its a good read.
No, that is a reason I could recommend it. But I haven't read it so I shouldn't comment on it's content.
BTW, that's Damperening.

[Josh_K]

"one specifically about long travel off road would be great"

Learning too much about pavement will leave you permanently confused about off-road.I love it!!!!!!!!! And couldn’t agree more.

The only thing more fun that listing to pavement racers tell me how to set up a off-road chassis is listening to a drag race engine builder tell me that I need to spin my engine a 7500 rpm so it wont build heat?????????

Josh

[Kritter]

No, that is a reason I could recommend it. But I haven't read it so I shouldn't comment on it's content.
BTW, that's Damperening.

Damperening...I like that.

[scottm]

Im gona lern all bout dampenatin now, cuz I just ordered this too: Competition Car Suspension by Allan Staniforth, $25 on fleabay.

[ntsqd]

That's a reasonably good book, written by an Englishman who is mildly eccentric (aren't they all?). Can be an amusing read at times. His rubber band suspension is a mind blower and the WOB link is VERY interesting. Not sure how much of the book directly applies to off road (true of most suspension books) but it is a good background and reference book.

[ChuckH]

There is a decent amount of info if you read all the old SHOP threads.

The word "Damperening" is progress in American English, Much like Gay no longer means a happy person... im sure some tight assses held onto Gay meaning an "happy person" for awhile.

Disclaimer for the inept, definitions of words change over time, get used to it.

[ACID_RAIN28]

What was the explination on that 7500 RPM's will not build heat???

[Josh_K]

I don’t have a clue! It’s just some drag race B.S. that I can’t figure out. I was told this buy really good engine builder that specializes in drag race and oval engine. This dude that will remain unnamed is in the same building as Mark Shoaff with the Pac-West 8 truck and builds there engine. I know its his first off road engine build and was telling Mark and I that if we spin our small blocks at 7500 rpm they will run cooler. I don’t understand it. And you can’t reason with this dude because he "knows it all".

This is just an example of other types of racing having nothing to do with off-road racing and that it with permanently confuse you as to what is really important.

Josh

[SurferChris1]

Tune to Win by Carroll Smith is a good overall view of suspension/vehicle dynamics book.

I second that. I learned a lot from Carroll Smith's books.

[ntsqd]

I don’t have a clue! It’s just some drag race B.S. that I can’t figure out. I was told this buy really good engine builder that specializes in drag race and oval engine. This dude that will remain unnamed is in the same building as Mark Shoaff with the Pac-West 8 truck and builds there engine. I know its his first off road engine build and was telling Mark and I that if we spin our small blocks at 7500 rpm they will run cooler. I don’t understand it. And you can’t reason with this dude because he "knows it all".

This is just an example of other types of racing having nothing to do with off-road racing and that it with permanently confuse you as to what is really important.

Josh

That's not a case of what works for other types of racing being confusing. That's a guy who thinks he knows way more than he does, and passing it off as Gospel.

[Kritter]

its probably true on those cars since it probably makes the dry sump pump turn to have optimal flow rate, probably has the perfect amount of air coming through at that speed, etc...

whereas on a off road truck...7500 rpms is on and off and on and the ergos are nowhere near the same.

so in his defense...he may be right on for the environment his roundy round engines are in, but for dez racng he just doesnt know.

[Ryno]

Sorry to hijack-

But on the drag race note, those motors are build to run hard. When they idle, they get way too hot. At Winternationals, my brother in laws team lost a round due to a guy "burning them down". They were ready to go, fired up the car. The other guy lifted the body, blah blah blah. Meantime, the motor has no coolant, and gets too hot.

[scottm]

I don’t have a clue! It’s just some drag race B.S. that I can’t figure out. I was told this buy really good engine builder that specializes in drag race and oval engine. This dude that will remain unnamed is in the same building as Mark Shoaff with the Pac-West 8 truck and builds there engine. I know its his first off road engine build and was telling Mark and I that if we spin our small blocks at 7500 rpm they will run cooler. I don’t understand it. And you can’t reason with this dude because he "knows it all".

This is just an example of other types of racing having nothing to do with off-road racing and that it with permanently confuse you as to what is really important.

Josh

I have been thinking about this while driving around Flagstaff all weekend. Is it possible he deals with alcohol engines? Methanol evaporates with tremendous cooling. Carbs and manifolds get so cold they can become covered in frost. Its a long shot; more likely he's just misunderstanding some other aspect of the system.

[Josh_K]

I think what this guy is trying to get at is that a small block makes more HP at a higher rpm (as all engines do). So if you cam it to run 7500 rpm it will build more total hp than say 5000 rpm. Now once you have a motor cammed to run all out at 7,500 and you try to use torque to pull you thru a sand wash at 3,500 to 5,000 rpm you have a heating issue.

What wobbles my mind is that if you cam a big c.i. engine to build torque form 2k to 6k and run the piss out of it about 4,000 or 5,000 rpm, how can you say it’s the wrong set up for a off road engine? But this guy does!

Thom is right here. The real issue is that this guy thinks he knows all the correct parameters that are needed for building an off-road engine and he doesn’t. The biggest issue I see with having a 7,500 rpm engine is that it’s the last 20% of engine operating range is where it comes alive. It’s only my opinion, but I feel this is hard on drive train parts and it would cause the driver to have to be way to aggressive.

Josh

[scottm]

I don't believe an engine can't run cool at 5000. If you have enough air flow through the radiator and enough coolant flow through the engine, it has to run cool enough. A lot of people, including pro mechanics and engine builders, need a basic lesson in what is hp. Hp is the product of torque times rpm. Torque comes from cylinder pressure, and depends on the amount of air/fuel mix drawn into the cylinders. Volumetric efficiency determines cylinder filling, and varies with rpm, port shape, cam timing, etc. As long as the engine can maintain air flow into the cylinders (torque), higher rpm results in proportionally higher hp.

The more air/fuel the engine can inhale, either through forced induction or higher rpm, the more torque and hp it will make. So hp comes from burning more fuel and releasing more heat, but it will be proportional. If the engine inhales 50% more air/fuel at 7500 than 5000, it will also be releasing 50% more heat. If an engine runs hotter at 5000 than at 7500, then its probably due to mundane factors like reduced air flow through the radiator or perhaps the ignition timing is optimized for 7500, resulting in detonation at 5000.

In my experience, any car truck or buggy, racing or not, runs hotter when powering up a long uphill sand wash. Think about it: Its probably producing at or near max torque at some mid-range rpm, for a long time, maybe 5-10 minutes straight. You are moving relatively slowly, so air flow is down, plus you have time to watch the gauges. Wide open straights are different. You are going very fast, and you are not likely do it for more than a minute or two at a time. You probably won't be taking your eyes off the road. So the heat is being produced at high rpm, its just not as apparent.

Making x amount of power is always easier and more reliable with more displacement and lower rpm. A 250 hp Lycoming airplane engine is something like 540 cid, and only turns 2000 rpm. Ask your guy if he'd rather have a Lycoming 540 at 2000 rpm or a 2.5 L pinto engine turning 8000 in his Cessna.

[ntsqd]

From my experience crewing on a Super Comp Dragster turned Top Alcohol Dragster I liken Drag Racing to being Competition Engine Rebuilding. Not really the sort of time bomb I'd put in an off road racer. I'll venture that an endurance type Circle Track engine would be a closer fit.

And to bring this thread back on topic, there are some books written for the circle track crowd that presumably address gaining traction in dirt. I've not looked at them, but they are on my list. Try searching Steve Smith motorsports or motorbooks.

[FABRICATOR]

Got several Steve Smith books. They cover a lot of theory and hands on info. for sprint, modified, and pavement.

[scottm]

I just recieved Advanced race car suspension development by Steve Smith. I glanced through it yesterday and it looks good, simple and direct.

[scary fast hummer]

You know, it seems to me that there is plenty of corporate knowledge on this forum from the "godlike" members, for somebody to write a dirt specific supension primer. Something that covers long travel I beams, A arms, 3 and 4 link, mezzanine rears (whatever they are, just saw it mentioned somewhere), etc.

If not an epic tome, how about just thorough post that could be made a "sticky" in the suspension section of the shop forum?? That way, when newb's (c'est moi!) ask the same basic question for the umpteenth time, you can refer them to it rather than box thier ears or re write the history of suspension. Just a thought.

"suspension is, as susupension does!" Forrest "Long Travel" Gump