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Mumford Suspension


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#31
Omega Mugen

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QUOTE (phatboycrxhf @ Dec 6 2006, 12:05 AM)
that looks really heavy ,cool but heavy would it really make that big of a diffrence to do all this work and have all that wieght ???


You have to look at the cost-to-benefit. The cost is weight. The benefit is more control over your car. Having more control over your car can shave a few more seconds off your times than having just a couple more pounds that the engine has to carry.

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#32
toxicshit

QUOTE (Greg Gauper @ Dec 8 2006, 01:05 PM)
Excellent explanation Erwin!  Phatboy, it appears that you don't know what the technical definition of 'Unsprung Weight' vs. 'Sprung Weight' is.  Hopefully Erwin cleared that up for him.  That wasn't a slam on you Phatboy either just so we're cool  cool.gif When I first got into racing, I didn't know what it was either or why it was important.  Hopefully Erwins explanation helps.


Thanks for the bigger info and better explanation sometimes writing large shunks of english tech can be difficult for me smile.gif i know what it is but to explain it can be hard in a other language.

QUOTE (Omega Mugen @ Dec 8 2006, 11:51 PM)
You have to look at the cost-to-benefit.  The cost is weight.  The benefit is more control over your car.  Having more control over your car can shave a few more seconds off your times than having just a couple more pounds that the engine has to carry.

And like Greg and I told the weight is low down in the car and adds allot of control to the rear suspension. So it is something i can live with. but thats a thing everbody has to decide for him self.

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#33
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I still think that people are overselling the advantages of the Mumford linkage.

Panhard bars work very well, and are simple and can be made to be adjustable (to a point). Really, the only advantage that the Mumford linkage has is that it can be designed to place the roll center at a location that is not physically possible with a Panhard bar. This may be a huge advantage for certain applications, but for others, it may have limited usefullness. It all depends on where the optimum location of the roll center really is, and how much room you have to work with.

Often times, panhard bars are built with curved shapes to clear other parts, thus allowing the virtual line that connects the two mounting points to go through something. Another feature (or disadvantage) of a Panhard bar is that you can get slightly different rear tire loading by controlling the angle of the bar. NASCAR uses this as the primary tuning tool for adjusting handling - they raise or lower the 'track link', which is the height of the connection of the Panhard bar to the axle.

The Mumford linkage has a lot more moving parts, bearings, links, etc. It is also generating much higher reaction forces due to the leverage of the linkage, so it requires a more sturdy mount to the chassis. In most race cars, that added weight really isn't an issue, because you have weight minimums anyway.

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#34
phatboycrxhf

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oh i see thanks for clearing it up guys man i have lots to learn smile.gif

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#35
toxicshit

About the dimensions in the drawing i made doe annyone have the lenghts of the links they use at this moment ? EPCRX ? JAY ? GREG ? someone ? if i know the length of the links then i can draw the brackets that i need to weld to the axle and the angle they will make ! ans sort somethings out.
QUOTE (phatboycrxhf @ Dec 9 2006, 09:47 AM) <{POST_SNAPBACK}>
oh i see thanks for clearing it up guys man i have lots to learn smile.gif

whe are all here to learn something wink.gif so no problem. im sure most of the guys over here all needed to have someone to learn them stuff in the beginning biggrin.gif

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#36
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QUOTE (EPcivic @ Dec 9 2006, 06:12 AM) <{POST_SNAPBACK}>
I still think that people are overselling the advantages of the Mumford linkage.

Panhard bars work very well, and are simple and can be made to be adjustable (to a point). Really, the only advantage that the Mumford linkage has is that it can be designed to place the roll center at a location that is not physically possible with a Panhard bar. This may be a huge advantage for certain applications, but for others, it may have limited usefullness. It all depends on where the optimum location of the roll center really is, and how much room you have to work with.

Exactly...I agree.

The Mumford link may be useful if you know where the rear roll center should be relative to the front on these cars...I, for one, haven't a clue where that is. I'm sure I could figure it out, but, I not sure the gains are worth the time and hassle spent to do that and the fabrication necessary to install one that works properly.

I think that with the small amount of rear suspension travel these cars have when properly set up for track events, a height adjustable phb is more value added. To that end, I have another HF axle that I'll probably modify for an adjustable (height) phb mount.

Here's what I'm wondering: Does the Mumford link allow you to place the rear roll center such that it prevents the 1/3g cars from "three wheeling" (lifting their inside rear wheel)? If it does not, then, when the car lifts it's inside rear wheel, what does it matter where Mumford link defined rear roll center is? Wouldn't you of acheived the same result with an adj phb without the time/weight/cost associated with designing, fabbing and installing a Mumford link?

#37
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i have been folowing this diskution, and one thing that noone has mentioned is where this would be usefull? i know that in klub rallying i NEED the rear and a litle loose, so that would not justify the extra weight aded i think. and a "noob" qestion since i have never driven a racetrack: wouldn't this give a litle more understeer?
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#38
toxicshit

Wether it is or isnt usefull was something is asked myself a long time ago. but this linkage has proven its self on some 1st gen cars and thats why i started the topic to see if i could find anny help in converting the panhard suspension link to a mumford suspension link. not to find out again whats better and why.

And because my car kept three wheeling true corners and i could not get the roll center to the point where i would like to have it i decided to go for the mumford setup, and ill keep the mounts for the panhard on the chassis and axle so i can always go back when needed.

But i would like something wich is better adjustable then the panhardbar with its stock mounts. because my car was lowered -4cm and the panhardbar was parralel to the axle and i could not do annything else! because i made a flat bottom car and a real diffusor out of carbon for my car ( made a belly pan out of carbon sheets ) i need to lower my car some more and if im going to weld what is a thing that needs to be done, then i could also convert to a mumford suspension link setup.

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#39
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I was dead set on building a mumford link setup. But decided the r&d time could be spent elsewhere right now. With the roll center becoming the rear tire that is still on the ground when three wheeling it negates the benefits of the mumford. If the roll center adjustablility would aid in planting both rear tires all of the time I would start fabricating one again.

I guess the question that most people are looking for is. Will the mumford allow you to keep the car from three wheeling?
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#40
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QUOTE (savestheday @ Dec 11 2006, 08:48 AM) <{POST_SNAPBACK}>
I was dead set on building a mumford link setup. But decided the r&d time could be spent elsewhere right now. With the roll center becoming the rear tire that is still on the ground when three wheeling it negates the benefits of the mumford. If the roll center adjustablility would aid in planting both rear tires all of the time I would start fabricating one again.

I guess the question that most people are looking for is. Will the mumford allow you to keep the car from three wheeling?


There are a lot more things than just the rear roll center that control how much or if your inside rear tire lifts. Actually, I believe itís the front R/C that will affect the rear lifting more than the rear R/C will. That and the complete car set-up that you have.

FWIW, I have always strived to keep all four of my wheels on the pavement as much as possible when setting up my car. I always ask people when Iím at the track if they see any rear wheel lift or not. So far everybody tells me that all four wheels stay down, which is good.
This:


is the only evidence Iíve EVER seen of any wheel lift from my car on the track. And that was on the initial turn in. In other pictures Iíve seen from that turn that same wheel is down or at least touching the pavement.

I have seen many 1G/3G solo cars with the rear tires waaay higher than that in addition to some track cars. I probably did it too back when I had my car lowered a bunch in ITA years ago. But I also hated the way the car handled when I did that and after I raised it back up, which also raised the front roll center, it handled much better. Not to mention extended the tire life over the race distance.

Solo set-ups and race track set-ups, while striving to achieve the same goal, high tire grip, are generally different from what Iíve seen and heard over the years. There is no definitive, absolute right and wrong in car set-up. Whatís right for you may feel terrible to someone else and they still may be able to beat your time with your set-up. all the while hating your set-upÖitís happened to me laugh.gif .

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#41
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OK i'll be the oaf that blabs out and says he would prefer 4 link
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#42
jsgprod

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QUOTE (zakats @ Dec 11 2006, 12:21 PM) <{POST_SNAPBACK}>
OK i'll be the oaf that blabs out and says he would prefer 4 link


So would I! Except for the fact that itís against the rules in the class I race in.

Not only that but some 4 links still require some sort of lateral axle control. Take a close look at the trailing links in this picture, itís a four link if Iím not mistaken. Kind of hard to tell but I seem to remember that it was. Kirk? TJ?


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#43
toxicshit

QUOTE (jsgprod @ Dec 11 2006, 01:13 PM) <{POST_SNAPBACK}>
So would I! Except for the fact that itís against the rules in the class I race in.

Not only that but some 4 links still require some sort of lateral axle control. Take a close look at the trailing links in this picture, itís a four link if Iím not mistaken. Kind of hard to tell but I seem to remember that it was. Kirk? TJ?



yes it was here are some more pics of the same car and suspension linkage.

http://www.shamrockm...om/mumford1.bmp
http://www.shamrockm...om/mumford2.bmp
http://www.shamrockm...om/mumford3.bmp

Greetings Erwin.

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#44
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So jsgprod would you care to share some info on your setup? If not i'll send a pm, you know how racing is. laugh.gif
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#45
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QUOTE (jsgprod @ Dec 11 2006, 11:15 AM) <{POST_SNAPBACK}>
This:


is the only evidence Iíve EVER seen of any wheel lift from my car on the track. And that was on the initial turn in. In other pictures Iíve seen from that turn that same wheel is down or at least touching the pavement.
Jay


Jay, does this mean the photographer managed to get that picture on the only time you were pushing hard enough to lift that rear? Maybe you need to push harder and get that sucker off every lap? LOL