Shockers without Push/pullrod in rear suspension ??

[sid_iitd]

Due to space constraints, we are not able to accommodate push/pullrod in rear suspension ( which was planned earlier in the design ). We are using anti roll bars. We need suggestions regarding the options available to us. How can we maintain the same motion ratio?

[shark.ashwa]

Originally posted by sid_iitd:
Due to space constraints, we are not able to accommodate push/pullrod in rear suspension ( which was planned earlier in the design ). We are using anti roll bars. We need suggestions regarding the options available to us. How can we maintain the same motion ratio?
I'l try to take my poke at this...
"Due to space constraints", unless you show us the space contraints, we wont be able to help.
"push/pullrod in rear suspension ( which was planned earlier in the design )", there is either a pushrod or pullrod, please take ur pick then we continue.
"We are using anti roll bars", not really helping us out as it makes packaging more complex.
"We need suggestions regarding the options available to us", we cant suggest anything with the info you have provided.
"How can we maintain the same motion ratio?", by iterating.

Hope that helps and next time please have more information regarding your problem.

Cheers,
Sharath

[Tom Wettenhall]

For what it's worth:

First, which competition are you competing in, and how far away is it? That gives us an idea of how much time you have and how much of your car is, or should be, complete by now.

Second, I assume by not being able to fit push- or pullrods you mean that you are restricted to outboard suspension mounting. As far as I know, there is only one way to do this, which is to mount the dampers directly between the upright and the chassis. You have no control over motion ratio in this situation except to mount your dampers as close to vertical as is reasonably possible. This solution will most likely require different dampers to an inboard solution in order to meet the travel rule, with a longer stroke.

Third, one of the key advantages of inboard suspension is that you can put it nearly anywhere you damn well like. Are you *sure* you can't fit it in? Take a look at what everyone else is up to, there are a great many solutions around. GFR's is a good example of a solution using otherwise unusable space, although it may be difficult to triangulate properly with a spaceframe.

[kcapitano]

Tune to Win, Chapter 6: Rates and rate control - springs and anti-roll bars.

Find yourself a copy, someone on your team probably has it anyway.

[nowhere fast]

Originally posted by Tom Wettenhall:
You have no control over motion ratio in this situation except to mount your dampers as close to vertical as is reasonably possible.

Not true. Different damper angles and positions can give different motion ratios.

[Tom Wettenhall]

My apologies, I assumed that you'd be after MR=1 or close to it which is why I said 'close to vertical'. Position and installation angle can indeed give you a range or MR and rate gain properties. My original statement was incomplete/downright false.

[ahilto3]

https://picasaweb.google.com/l...O9Bw?feat=directlink (https://picasaweb.google.com/lh/photo/1VOmZhYC4FXvLTSVayO9Bw?feat=directlink)

I wish i could find a better pic without the body, but the coilover for the right side is mounted on the left side of the rear box and the opposite for the other side. We ran into the same problem in 2009 and came up with the mega aluminum rockers that you can see on each side. Ill try to see if i can find a better pic

Austin Hilton
LSU FSAE 2012 Ergonomics Lead

[Shebert]

If you have packaging problem with pull/push-rod interfering with driveshaft, you can always considers upper a-arm push-rod.The new guys at ETS did it this year and it was pretty clean.

If you don't have space for inboard suspension, you can acheive a wide range of motion ratio with outboard damper by varying the attachment points (but you will induced bending stress in a-arm).

Another solution that I seen on IMSA Lites is outboard push/pull-rod. Its the damper reataching to the push-rod making the complete systeme outboard but with a rocker.

https://2624702595670964123-a-...t0%3D&attredirects=0 (https://2624702595670964123-a-westracecars-com-s-sites.googlegroups.com/a/westracecars.com/west/wx10-high-downforce-package/Fence%202%20West%20WX10%20High%20Downforce%20Packa ge%20May%205%2C%202011%209-43%20AM.JPG?attachauth=ANoY7coBKsVW-IjXJam5yDiqVpUXIcnoH-Llz9eg1idX9TLLMIkwHdLlaPY1H_0h_i8bkRiVtjCtbpLhN1-ocLPH-XX2rPx33eNglsz6wb-UZBGc_7nhK6NA7DtscvzO4xjb8glQo_y28SUHBAsN2usRkKmUF W2jMEJCy3dJN6biHomEBaU6nmY2fXq2ztyOgLpLdU3hi2cuphJ tINw2i4wF1IrqVNWjqVXRnc5Qt5GnwdUPC9FCRbjlFa-YUEthDXHSSXKysoRB8VvxuTEst-jlnqRhw9g2-r-wFlld12e-q4q3dSF8ot0%3D&attredirects=0)

[Big Mo]

That looks like a Stohr DSR suspension...which has no front ARB... Also, pushrods on those cars have been known to break due to the bending load from the shock being fed back into the pushrod.

Overall, a possible solution, but will probably bring more problems than it will fix.

[Tom Wettenhall]

That's also similar to what you get on a Radical:

http://www.roebuck.eclipse.co....421/139-3904_img.jpg (http://www.roebuck.eclipse.co.uk/pics/photos030421/139-3904_img.jpg)

The difference is that both ends attach to the A-arm, and the anti-roll bar is, well, a bit different... Wouldn't that kind of system have a large amount of unsprung weight though, as the whole shock body is partially unsprung, proportional to the gain of the rocker?

[Big Mo]

Originally posted by Tom Wettenhall:
Wouldn't that kind of system have a large amount of unsprung weight though, as the whole shock body is partially unsprung, proportional to the gain of the rocker?

I've worked on a few Stohr DSRs, and these are my thoughts on this system...Also, that weight is further from the centerline. And, yeah, that ARB sure is "different."