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Mumford Suspension


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#46
impalanut

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At the autocross events my inside rear tire is anywhere from just barely to 10" off the ground. I would love to be able to keep all four tires on the ground!

#47
jsgprod

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QUOTE (impalanut @ Dec 11 2006, 08:47 PM) <{POST_SNAPBACK}>
At the autocross events my inside rear tire is anywhere from just barely to 10" off the ground. I would love to be able to keep all four tires on the ground!



A set of 31mm torsion bars might help that a bit...interested?

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

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#48
toxicshit

how high did you set your front roll center jay ? and how thick are your current torsions that you are using ?

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#49
jsgprod

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Not exactly sure. I know that it is above the ground level but I'd have to go look at the measurements I took prior to my last race and calculate it. I think it's around 1" to 2" above ground level, the rear is currently about 6 1/2" to 7".

I am currently using 29mm torsion bars with the Integra front antiroll bar. I may be experimenting with an additional front bar at my next race in January. Not sure since it's at Sebring again and some sections of that place (the old WWII concrete) will shake your fillings loose...while other sections are incredibly smooth.

Jay

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

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#50
impalanut

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So heavier springs/torsion bars will keep the tires on the ground better? Are there many people running larger than 29 mm bars in autocross?

#51
savestheday

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I've heard of one set of 30 or 31mm bars being used on an autocross car. This is the biggest diameter that will fit in the stock housing, after that you start shortening the bars to get more spring rate.
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#52
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All this talk about different rear setups is great!!! I think after this year, we are going to move our rearend further back to increase wheel base. Also do a trick setup like a 4 link, or something like you guys are talking about.

Randy

#53
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QUOTE (impalanut @ Dec 12 2006, 01:47 AM) <{POST_SNAPBACK}>
At the autocross events my inside rear tire is anywhere from just barely to 10" off the ground. I would love to be able to keep all four tires on the ground!



There is a lot more involved in fixing that problem than changing the rear roll center. If your rear tire is getting that much air, then you need to increase the front roll stiffness by adding more spring rate, sway bars, and/or raising the front roll center. All of these changes will reduce the amount of weight transfered to the outside front tire, which is what is causing the rear to lift.

Changing the rear roll center is going to change the ratio of side force vs down force acting on the rear tires. A high RC has higher side force and lower down force than a low RC. This is exactly why these cars handle so well. They are naturally a little loose on turn-in, but once you lift the rear wheel, they get more stable. This is generally good, as long as it is controlable.

On my car, with the 30mm super short torsion bars, I have enough lateral grip to actually lift the front inside tire on a good surface (which can be a little scary). I would like to add some more rear roll stiffness to help keep the front more planted, but my car is already too loose on turn-in, so adding rear spring or sway-bar would not be good right now. By lowering the rear RC, I should be able to use a stiffer spring and get back to the same or better turn-in while reducing the total roll in steady state cornering.


I guess the short answer is that there is no one single magic part that's going to fix all handling problems. There are a lot of well proven CSP type setups that use stock Panhard bar mounting points. Adjusting the rear RC is probably one of the last things on the list of what to do to make one of these cars handle well, following springs, dampers, bushings, sway bars, ride height, corner weights, etc.

-Chris

#54
toxicshit

QUOTE (jsgprod @ Dec 12 2006, 09:04 AM) <{POST_SNAPBACK}>
Not exactly sure. I know that it is above the ground level but I'd have to go look at the measurements I took prior to my last race and calculate it. I think it's around 1" to 2" above ground level, the rear is currently about 6 1/2" to 7".

I am currently using 29mm torsion bars with the Integra front antiroll bar. I may be experimenting with an additional front bar at my next race in January. Not sure since it's at Sebring again and some sections of that place (the old WWII concrete) will shake your fillings loose...while other sections are incredibly smooth.

Jay

Thnx for your input ill be using 29mm torsions with a single Teg bar, please let us know about your experiment with the 2 bars ( what kind of 2nd bar are you planning on using ? ) And doesnt annyone use tracktion bars on the cars ? i made a set im shure they work greath.

QUOTE (savestheday @ Dec 12 2006, 12:12 PM) <{POST_SNAPBACK}>
I've heard of one set of 30 or 31mm bars being used on an autocross car. This is the biggest diameter that will fit in the stock housing, after that you start shortening the bars to get more spring rate.

Jay is planning on letting a factory make a custom batch of 31 mm bars if im correct unsure.gif

QUOTE (EPcivic @ Dec 12 2006, 06:51 PM) <{POST_SNAPBACK}>
There is a lot more involved in fixing that problem than changing the rear roll center. If your rear tire is getting that much air, then you need to increase the front roll stiffness by adding more spring rate, sway bars, and/or raising the front roll center. All of these changes will reduce the amount of weight transfered to the outside front tire, which is what is causing the rear to lift.

Changing the rear roll center is going to change the ratio of side force vs down force acting on the rear tires. A high RC has higher side force and lower down force than a low RC. This is exactly why these cars handle so well. They are naturally a little loose on turn-in, but once you lift the rear wheel, they get more stable. This is generally good, as long as it is controlable.

On my car, with the 30mm super short torsion bars, I have enough lateral grip to actually lift the front inside tire on a good surface (which can be a little scary). I would like to add some more rear roll stiffness to help keep the front more planted, but my car is already too loose on turn-in, so adding rear spring or sway-bar would not be good right now. By lowering the rear RC, I should be able to use a stiffer spring and get back to the same or better turn-in while reducing the total roll in steady state cornering.
I guess the short answer is that there is no one single magic part that's going to fix all handling problems. There are a lot of well proven CSP type setups that use stock Panhard bar mounting points. Adjusting the rear RC is probably one of the last things on the list of what to do to make one of these cars handle well, following springs, dampers, bushings, sway bars, ride height, corner weights, etc.

-Chris

allready try'd all of the above and i was always experimenting with the setup of my car's suspension. Current setup is/will be : Tein SS Adjustable Coilover shocks, 29mm torsions, RPR adjustable panhard , Welded rear internal swaybar, 350lbs rear springs, External rear Swaybar, energy suspension full bushing kit, Front Tracktion bars, and a stitch welded cassis to remove body roll / twist, Adjustable front suspension arms (prototype im currently building for adjustable camber/caster), lots of braces & 6 point cage.

Thats what will be on my car, but hey i allways need something to test and build so trying a mumford rear link setup for maximum adjustability will be the next thing on my list.

Greetings Erwin.

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#55
Greg Gauper

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Erwin,

Just curious, what tracks do you run at? I guessing Zandvoort based on your location, but are there other 'club' racing tracks near you?
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#56
toxicshit

QUOTE (Greg Gauper @ Dec 13 2006, 08:32 AM) <{POST_SNAPBACK}>
Erwin,

Just curious, what tracks do you run at? I guessing Zandvoort based on your location, but are there other 'club' racing tracks near you?


I have run at diffrent tracks ,

Zolder ( Belgium ), small but verry technical circuit, my favorite.
Posterhold ( Netherlands ), Small Oval.
Drachten ( Netherlands ), airstrip , dragracing.
Assen ( Netherlands ), verry big TT circuit.
Zandvoort ( Netherlands ), large circuit.
Nurenberg Ring ( Germany ), Verry big dangerous track but always open for all kinds of cars.

Most of them have open track days , the drag racing airstrip needs you to be in a class ( OSL/DHRA , under devision of the NHRA ). and at nurenberg you pay a little amount of money to take a piece of the nordsleife. and there are rally events on normal industrial zones etc and races on parts of not ready highways organized by the governament but that kind of thing is only once a year.

But im rebuilding my car as we speak so i have not raced those tracks for some time in my own car ( i can borrow some race cars from sponsors etc if i want biggrin.gif biggrin.gif ) . but im building the car for those tracks and all kinds of racing. so there are places enough for racing over here.

Greetings Erwin.

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2. EDM 2001 Lexus IS300 3.0 RWD - Daily Drive
cr-x.jpg


#57
jsgprod

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QUOTE (toxicshit @ Dec 12 2006, 07:51 PM) <{POST_SNAPBACK}>
Thnx for your input ill be using 29mm torsions with a single Teg bar, please let us know about your experiment with the 2 bars ( what kind of 2nd bar are you planning on using ? ) And doesnt annyone use tracktion bars on the cars ? i made a set im shure they work greath.
Jay is planning on letting a factory make a custom batch of 31 mm bars if im correct unsure.gif


Erwin, the additional front bar will be a custom one that I made, or am making as the case may be. I made one several years ago that bolted to the bottom of the front subframe and worked pretty well it just kept hitting the ground and I thought I was going to tear it off eventually. It was mounted in pillow blocks and they were getting pretty worn down.

When I figure out just how I'm going to mount the new one I'll let you know.

As for the 31mm torsion bars, yes I am going to have some made. It's just a little behind schedule right now.
This time of year is probably pretty busy for most of us and I'm trying to get race car parts made on top of all the other stuff I need to be doing!

Jay

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

scull+gif+1.gif

jsgprods Gallery


#58
toxicshit

QUOTE (jsgprod @ Dec 13 2006, 05:59 PM) <{POST_SNAPBACK}>
When I figure out just how I'm going to mount the new one I'll let you know.

As for the 31mm torsion bars, yes I am going to have some made. It's just a little behind schedule right now.
This time of year is probably pretty busy for most of us and I'm trying to get race car parts made on top of all the other stuff I need to be doing!

Jay

Thanks ill be waiting for the news biggrin.gif. And yes im trying to build some prototype front suspension arms and its christmas etc so yes a busy month.

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#59
strudel

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Erwin,
I once spoke to EPCRX and asked for the plans. He said he would send them and never did. I also have found some information on a Nissan setup that is similar to the Mumford link.
http://www.not2fast....sis/mumford.gif
http://www.bevenyoun....au/config.html

I'll try and find the info and post it. JS

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#60
strudel

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Here is the article about the Infiniti G20 and aludes to the Nissan Sentra and Maxima rear linkage.
http://www.se-r.net/...c/oct98/tb.html

Here is another discussin on linkages for a Mini.
http://www.16vminicl...opic.php?t=5242



From the Nissan manual for a 87-91 Stanza I believe or similar to 87 Maxima.




EPCRX's Mumford System

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