DTSFab.com (Desert, Trail and Sand)
Automotive Powered Off Road (AKA: Buggys, Jeeps, Trucks, Etc,Etc. ) => Chassis and Suspension => Topic started by: fabr on March 24, 2013, 06:05:39 PM
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OK,tell me why I should not consider using torsion bar front suspension with bypasses instead of conventional coilover shock and bypasses on a 3000 pound car,45% front weight . I can get bars with enough twist capability. I can think of several positives. Need to know any negatives.
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I will probably be the only one to say this but a spring is a spring and a tosion bar is a spring.
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I would think the lower arm, the one bar would attach, would have to be way over built from typical A-arm. But yeah, mounted close enough to frame you could get plenty of travel. Bar could weigh less than coilover shock? And definitely be lower center of weight.
But it be different, and cool. So do it!
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I will probably be the only one to say this but a spring is a spring and a tosion bar is a spring.
Yes and no actually. A coil spring can have a progressive rate where a torsion bar is strictly linear.
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I would think the lower arm, the one bar would attach, would have to be way over built from typical A-arm. But yeah, mounted close enough to frame you could get plenty of travel. Bar could weigh less than coilover shock? And definitely be lower center of weight.
But it be different, and cool. So do it!
The arm would need be no stronger either way. It takes the same force applied to the same point to suspend the car. I would use a lever on the end of torsion bar connected by a link to the same similar lower shock mount location as with a coilover. Maybe I need to try to sketch something up to explain.
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a torsion bar is strictly linear.
Not always. There have been many makers of bars over the years that have made progressive units. They put an extra set of splines somewhere in the bar and you have a arm with an adjustable stop to time when it kicks in. Mickey Thompson was a big fan of these and used them on many of his desert racers.
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Fmttorsionfingers_zpsabe72b9b.jpg&hash=6bc85c7121c20a232bee281f4253347678539996)
Downside is, they are expensive if you don't get the rate right the first time. Also, exploding torsion sockets. Ask any guy that's beat on an older 4X Toyota about that, the adjuster bolt goes through the floor and nails you in the ass. All the old 7S trucks had steel plates weld to the floor to prevent this........
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Isnt there a guy on RDC building one of these right now?
Dump?
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I see whats in your head. :o :o
What are the positive things to using them?
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Not always. There have been many makers of bars over the years that have made progressive units. They put an extra set of splines somewhere in the bar and you have a arm with an adjustable stop to time when it kicks in. Mickey Thompson was a big fan of these and used them on many of his desert racers.
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Fmttorsionfingers_zpsabe72b9b.jpg&hash=6bc85c7121c20a232bee281f4253347678539996)
Downside is, they are expensive if you don't get the rate right the first time. Also, exploding torsion sockets. Ask any guy that's beat on an older 4X Toyota about that, the adjuster bolt goes through the floor and nails you in the ass. All the old 7S trucks had steel plates weld to the floor to prevent this........
I see what you are saying but the bar will still be linear spring rate. The extra stop would be equivalent to the crossover collar on a coilover dual spring setup. Expense wise,so are coils if you miss it . BTDT also.
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Isnt there a guy on RDC building one of these right now?
Dump?
Many people have done it over the years. Do you have a link to the build you are talking about? I'd like to read it.
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I see whats in your head. :o :o
What are the positive things to using them?
Glad you do,the shrinks are still looking and scratching theirs.......... Positives like a lowered center of gravity. Less unsprung weight. Lowered center of gravity. Ease of changing out spring(bar) rates. Ease of changing ride height without changing spring rates. Just a few.
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I'll see if I can find it.
I think its bars front and back also.
BDKW1 knows the one I'm talking about.
Damn I'm good!
Hold on to your shorts...serious cad porn!
http://www.race-dezert.com/forum/showthread.php/48910-Something-New-2 (http://www.race-dezert.com/forum/showthread.php/48910-Something-New-2)
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While the spring rate of the bar itself is linear, your method of connecting it would make the net result progressive. That is if you watch your lever angles. If at full bump, the lever on the bar is a right angle with the link then greater than 90 as the suspension drops, the effective force the link applies to the arm will be rising rate. This is above an beyond the progressive effect you get from a coil over being leaned over. Make the length of the arm off the torsion bar variable in length.
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Personally I would not use any of Mickeys cars as an example, they were crude as hell and the only time he won something was in a Raceco VW.
The Chenowth Magnum Short Course Cars had torsion bars going down either side of the transmission and along side the seat that provided the spring rate to their 5 link suspension. In the day they were far and away the best cars running.
I drove a class 10 desert car a couple of races that had a two stage torsion bar setup with an A-ARM rear setup. Very so so. The big problem that car had was alot of odd ball ideas thrown into one car, something you should be very wary of.
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Good read,brought up a lot of good points. Thanks for finding the link.
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While the spring rate of the bar itself is linear, your method of connecting it would make the net result progressive. That is if you watch your lever angles. If at full bump, the lever on the bar is a right angle with the link then greater than 90 as the suspension drops, the effective force the link applies to the arm will be rising rate. This is above an beyond the progressive effect you get from a coil over being leaned over. Make the length of the arm off the torsion bar variable in length.
After reading the thread posted I was thinking the same thing.
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Good read,brought up a lot of good points. Thanks for finding the link.
No problem, I love this shit!
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Just took a look at the stuff on RDC and all he ever did was to do some drawings, never made a car let alone a good working car. Nice drawings thou.
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Yes ,it was not finished. It brought up some good food for thought though.
There IS a car built recently by Mosebilt that the owners love with torsion bar suspension all four corners. Like most things , there's more opinions than people.
Some people have said that the torsion bar will make for a harsher ride. How?? It is ,for the sake of argument, purely linear in rate. How can that be harsher than a dual rate coilover spring.For that matter,with bypasses ,why are dual rate springs even needed or desired in the first place when using bypasses??? Habit??? With standard coil over shocks I see the benefit of dual rate but with bypasses? Someone explain this to me.
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Another that might interest you.
http://www.race-dezert.com/forum/showthread.php/99514-my-AWD-buggy (http://www.race-dezert.com/forum/showthread.php/99514-my-AWD-buggy)
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I'll check it out now. Thanks.
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Mose's car! That guy doesn't even know there's a box to think outside of! Quite an innovator IMO.
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I guess it all depends on what your going to do with the car. The Mose car is a more of a rock car then a real off road car, like something you would take to Mexico.
My personal experience is mid-engine cars are very hard to get a good balance front to rear in any kind of rough terrain and the more one offs you build into it the harder it gets to know where you need to be adjusting to get things right.
An example would be the UMP short course cars.
Mid engine type 4 with a Hewland trans. A-Arm front and rear suspension with torsion bars front and back with rising rate linkage. Absolutely beautiful workmanship thru out. Very much one off cars with all kinds of little tricks, tons of money spent.
On the race track they were a real hand full. I talked to Don after the first race and he thought maybe the raising rate was off and they were going to fix it for the next race. The cars didnt run many races but every time I saw them they had cut them up to try something new to get them to work.
Never did.
The class 10 car I mentioned earlier had A-Arms and 2 stage torsion bars in the rear with a twin I-beam torsion bar and Fox air shocks up front. Very strange handling and very hard to try to tune. Never got close to happy.
What I am trying to say is trying things that sound great on paper dont always work so well in real life and its much better to be able to make adjustments easily then having to make changes to the chassis to try and find a fix.
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I guess it all depends on what your going to do with the car. The Mose car is a more of a rock car then a real off road car, like something you would take to Mexico.
My personal experience is mid-engine cars are very hard to get a good balance front to rear in any kind of rough terrain and the more one offs you build into it the harder it gets to know where you need to be adjusting to get things right.
An example would be the UMP short course cars.
Mid engine type 4 with a Hewland trans. A-Arm front and rear suspension with torsion bars front and back with rising rate linkage. Absolutely beautiful workmanship thru out. Very much one off cars with all kinds of little tricks, tons of money spent.
On the race track they were a real hand full. I talked to Don after the first race and he thought maybe the raising rate was off and they were going to fix it for the next race. The cars didnt run many races but every time I saw them they had cut them up to try something new to get them to work.
Never did.
The class 10 car I mentioned earlier had A-Arms and 2 stage torsion bars in the rear with a twin I-beam torsion bar and Fox air shocks up front. Very strange handling and very hard to try to tune. Never got close to happy.
What I am trying to say is trying things that sound great on paper dont always work so well in real life and its much better to be able to make adjustments easily then having to make changes to the chassis to try and find a fix.
I agree that the Mose car is a dual purpose car and has all the compromises needed to be pretty decent at both. As for 2 stage torsion bars,IMO,that is just BS in the first place. As for a rising rate linkage I'm not ,at this point,even considering it. 4 stage bypasses,yes.
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This paragraph from an F-1 article give some real insight to why progressive rate springing is needed if you think about it a bit. It has finally sunk in,I think. See what you see in it.
"The springs or torsion bars are the parts of the suspension that actually absorb the bumps. In simple terms, the softer the suspension on the car, the quicker it will travel through a corner. This has the adverse effect of making the car less sensitive to the drivers input, causing sloppy handling. A harder sprung car will have less mechanical grip through the corner, but the handling will be more sensitive and more direct, ideal for circuits such as Monaco where the drivers must be inch perfect between the barriers."
So ,if I go torsion bar,I need to design a lever/link that would approximate the progressive rate of a coilover. Gotta give this a bit more thought. eyes ;D ;D
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OK,tired of thinking about it. eyes Just want to keep the progress going so 4 shocks and 4 bypasses it is. ;D ;D If I had more time I still feel that torsions can be made to work. Just too much going on right now to put the extra time into it. Thanks for all the replies ,they really helped me sort out some things. I appreciate it.
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So is this thing gonna make spring trip or not. rofl rofl
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Doubtful but it may well be sitting on it's tires waiting for body then. A good friend ,the other day, bought a new 4x4 Torchmate CNC plasma table. About a mile from me. Next/same day turnaround for me now. A real timesaver for sure when some my parts don't need be laser or waterjet precision. ;D ;D ;D ;D ;D ;D ;D I so happy!