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Mumford Suspension


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#16
Greg Gauper

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That's one of the advantages of the Mumsford over a Watts linkage...since the bell cranks are connected to the frame and not the axle, they don't add to the unsprung weight. The only unsprung weight you have are the hollow links and the rod ends, plus the brackets. Since the links are connected to the axle at one end, the effective unsprung weight is approximately half, since the other 'half' is sprung weight. The unsprung weight is probably not much heavier than a conventional Panhard Rod.
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#17
toxicshit

QUOTE (Greg Gauper @ Dec 6 2006, 08:53 AM)
That's one of the advantages of the Mumsford over a Watts linkage...since the bell cranks are connected to the frame and not the axle, they don't add to the unsprung weight.  The only unsprung weight you have are the hollow links and the rod ends, plus the brackets.  Since the links are connected to the axle at one end, the effective unsprung weight is approximately half, since the other 'half' is sprung weight.  The unsprung weight is probably not much heavier than a conventional Panhard Rod.


yes just like i thought i thought of it like 2 panhard rods that are a little shorter.. so the weight is something i can live with. iver stripped the hell out of my car but im a rather heavy guy my self so ill start with a diet before removing more weight of the car whaha laugh.gif

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#18
jsgprod

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QUOTE (toxicshit @ Dec 6 2006, 11:20 AM)
yes just like i thought i thought of it like 2 panhard rods that are a little shorter.. so the weight is something i can live with. iver stripped the hell out of my car but im a rather heavy guy my self so ill start with a diet before removing more weight of the car whaha  laugh.gif


You gotta be careful around Greg with those kinds of comments! He has ways of sliding in little implications of corpulence tongue.gif !

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#19
toxicshit

QUOTE (jsgprod @ Dec 6 2006, 11:35 AM)
You gotta be careful around Greg with those kinds of comments! He has ways of sliding in little implications of corpulence  tongue.gif !

Jay


Thanx for the heads up Jay, i allready seen that happen wink.gif thats why i say it myself im a 200 pound motherfucker on a diet and i can laugh about it thats why i told it that way he cant point it out ph34r.gif

and im dieting because i could not remove annymore weight out of the car and keep it legal huh.gif

but lets get back on topic....

Greetings Erwin.

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#20
Greg Gauper

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QUOTE (jsgprod @ Dec 6 2006, 11:35 AM)
You gotta be careful around Greg with those kinds of comments! He has ways of sliding in little implications of corpulence  tongue.gif !

Jay

Geez....you make an innocent comment about somebody's ride height changing when he sits in his car.......... tongue.gif
In my case, it would definitely be a case of the pot calling the kettle black biggrin.gif
I definitely want to lose 10-15lbs over the winter before next season.

BTW Jay,
Vern found some old RA paddock photos from 20 years ago when I ran my first CRX in Showroom Stock. Looking at that scrawny 'kid' in the photos..... what I wouldn't give to be back down to that weight again (140lbs). Also wouldn't mind being that young again either cool.gif
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#21
Buford

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Good link with picks etc.

http://www.fordcapri...ksuspension.pdf
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#22
gtpilot

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More Mumford Pics - if you work out the lengths of the arms and the bell crank lenghts, you can get the roll center to remain in the same place in bump/droop/roll...you just have to iterate the parts of a while to find the right lengths.

I do know someone who has the plans for making the parts in the picture form the link above...

Kirk

#23
toxicshit

QUOTE (Buford @ Dec 6 2006, 03:42 PM)


that was the one i allready posted the info and pictures from biggrin.gif small world after all wink.gif

QUOTE (gtpilot @ Dec 6 2006, 05:39 PM)
More Mumford Pics - if you work out the lengths of the arms and the bell crank lenghts, you can get the roll center to remain in the same place in bump/droop/roll...you just have to iterate the parts of a while to find the right lengths.

I do know someone who has the plans for making the parts in the picture form the link aove...

Kirk

if someone decides to make a set of bars and the bellcrank etc im defenately in for a set. Jay allready pm'd me.. so i hope his setup works and doesnt bind up etc.

Greetings Erwin.

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#24
Buford

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I'd buy the set up.
Buford Out

#25
toxicshit


This was the drawing posted by D Jaws II


This is a drawing i just made using autocad2007 ( i also have the DWG for people that want it ) but when i use the correct sizing and an angle of 30 degree than i get a difrent link size for the left link. the link from the first diagram is 35 and mine is 34.64 ( i multiplied the sizes by 2 ) so i think its a little bit more accurate.

Greetings Erwin.

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#26
phatboycrxhf

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what do you mean by there not being not very much insprung weight ??? the stock panhard bar weighs like 3 pounds tops and all that stiffining stuff that guys did to the panhard bar mount is crazy ohmy.gif There has to be like 15 pounds of just sheet metal on thereand im not even counting all that square tubing and do you need the cage in your car to make sure this thing doesnt bow or just plain crack right off from stress ????

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#27
toxicshit

QUOTE (phatboycrxhf @ Dec 8 2006, 02:56 AM)
what do you mean by there not being not very much insprung weight ??? the stock panhard bar weighs like 3 pounds tops and all that stiffining stuff that guys did to the panhard bar mount is crazy  ohmy.gif There has to be like 15 pounds of just sheet metal on thereand im  not even counting all that  square tubing and do you need the cage in your car to make sure this thing doesnt bow or just plain crack right off from stress ????


Search this board or google for the therms Un-sprung and Spung-Weight

All the weight that issnt caried by the springs is unsprung wieght.. you want tot keep that to a minimum. because 1kg (2.2lbs) unsprung weight is aprox 10kg (22lbs) Sprung weight.

so if you remove 10kg (22lbs) of weight from the unsprung weight ( Wheels , Brackes, Axles, panhard set up etc.. everything mounted under the springs.. ) it will feel the same as if you had just removed 100kg (220 lbs ) of weight from the car. so its like you would be driving with or without a rather fat guy next to you. and im shure you know the diffrence.

The square tubing and stifening of the panhard is sprung weight.. 1 kg there doenst matter as much... the only unsprung weight wil be 2 x a half link.. and that will weigh almost the same as half a panhard bar thats normally there.

QUOTE
That's one of the advantages of the Mumsford over a Watts linkage...since the bell cranks are connected to the frame and not the axle, they don't add to the unsprung weight.  The only unsprung weight you have are the hollow links and the rod ends, plus the brackets.  Since the links are connected to the axle at one end, the effective unsprung weight is approximately half, since the other 'half' is sprung weight.  The unsprung weight is probably not much heavier than a conventional Panhard Rod.
just like greg told here wink.gif

this is one of many reasons why racers like light weight callipers wheels.. disks.. alluminium wheel suspension arms.. etc etc.. and remove the internal sway bar.. thats all unsprung weight.. and if you get that to the minimum the handeling will go up alot !!

Removing 10 kg unsprung is doable.. but removing 100kg sprung weight is allot of weight.. thats why i diddnt install the NSX callipers they weight aprox 9.5 kg and thats a lot more unsprung weight. than ITR Callipers.

I hope you get it now.. if not try to search for some good tech info about it, my english issnt all that good biggrin.gif.

Greetings Erwin.

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#28
Greg Gauper

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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.

Just to repeat what Erwin wrote....Sprung weight is all of the weight supported by the springs. This would be the chassis, engine, tranny, driver, etc. Unsprung weight is everything on the other side of the spring, such as the tires and wheels, uprights, brakes (if outboard..some cars use inboard brakes at the rear to reduce unsprung weight...like a Jag XKE or an Alfa GTV for example). Things like the springs, shocks, swaybars, and control arms generally are treated as 50%/50% or thereabouts since one end is connected to the chassis (sprung weight) and the other end moves with the unsprung weight. BTW - some gas shocks can be mounted upside down, by design and still function properly, yet the unsprung weight decreases since by doing this, the heavier part of the shock is connected to the chassis so the lighter part that moves helps reduce the unsprung weight. Certain models of Bilstein shocks can be mounted in this manner. Hollow sway bars that mount to the chassis are preferred over solid bars that mount to the rear axle (compare the OPM design to the Lightspeed or Jackson Racing design for example).

Another factor to consider is the ratio of sprung weight to unsprung weight. Erwin touched on this, but let me expand on it...

A good visual example of this would be to ride in a big car like an old 70's 6-passenger sedan or a modern truck, especially a semi hauler (with and without a trailer). If the ratio is high, like a heavily loaded car or truck, the ride will be smoother compared to an unloaded car or an semi truck without a trailer. That's because the bumps effect the unsprung weight (which is lighter) and doesn't effect the rest of the sprung weight which is far heavier. Now apply the same scenario to a single seat formula car. Obviously, you don't want to add to the sprung weight since we want our formula car to be as light as possible. So in order to get the ratio higher, the engineers make the unsprung weight as light as possible. This is why a modern F1 car uses very light wheels, brakes, rotors, hubs, uprights, etc, and carbon fiber suspension arms, with pull-rod or push-rod suspensions. Although the added complexity of the bell cranks and linkages is heavier than a simple outboard shock mount set-up, it's not important since all of the mounting hardware for the pull-rod setup is considered sprung weight, including the shocks & springs themselves.

Compare a photo of a early late 70's/early 80's vintage F1 car to a present day F1 car. When they first went to inboard front suspensions, the top control arm was basically a large rocker arm since it acted directly on the shock. While the basic design worked great to get the shocks and springs out of the air stream, the problem was the upper control arm had to be very strong and heavy, in order to minimize deflection and to hold up from the loads. This heavy control arm had a lot of weight to it, and half of the weight was effectively unsprung weight. To get around that problem, push-rod and pull-rod type suspensions were developed, which greatly reduced the unsprung weight (a good thing) while slightly adding to the sprung weight (not necessarily a bad thing).

Here's something else to consider...the effect of unsprung weight on your shocks. Most people call them 'shock absorbers' but this is actually not a correct term. They are 'shock dampeners'. Basically, they are trying to dampen the motion of the unsprung weight by converting the motion, or more correctly, the kinetic energy into heat. When your car hits a bump, the unsprung weight goes in motion. Kinetic energy is basically a function of mass and velocity (ke = 1/2 mv*v to be correct). So if you have more mass in motion, you have more energy to be dissapated into heat by the dampeners. So if you can reduce the unsprung weight (mass), you reduce the work that the dampeners have to do.

Now go back and look at the Mumford design and the photos. Yes the bell crank and square tubing required to mount the device are heavier, but notice they are all connected to the chassis and not the axle. This means all of the weight is 'Sprung Weight' were it isn't as important. Also, most racecars have to add ballast to get up to the specified minimum weight per their class rules. Since the mounting hardware is down very low and is centered , it really doesn't hurt the car.

Again, this is one of the big advantages of a Mumsford device.....it has the same approximate unsprung weight of a panhard rod at the expense of slightly heavier sprung weight, but provides much more suspension tuning options.

The Mumsford device is not for all applications BTW. If you are into drag racing for example, a conventional panhard rod would be preferred since you aren't as concerned with unsprung weight or how well the car handles, you only care about acceleration in a straight line. In this case a panhard rod would be preferred because the overall weight of the car is reduced, which is more important for acceleration.
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#29
Buford

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Let's make an all aluminum (except spindles) rear axel.
Buford Out

#30
Greg Gauper

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How about Carbon Fiber instead cool.gif Since they can make RWD drive shafts out of that stuff, should be a piece of cake...right? biggrin.gif
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