Heymow - Lawnmower Racing Forum
Mower Building / Setup Help => Chassis => Topic started by: George Herrin on June 22, 2010, 07:02:22 am
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Folks this is how I setup my chassis initially. This is a base line start. Not a race setup. The race setup is for you the individual to figure out.
First off a good chassis starts with the build. I have found a stiff chassis is easier to tune and responds better to little adjustments than one that flexs. And the more HP you have the stiffer it should be for consistant chassis.
#1 be SURE when building the chassis is Square and level in every aspect of the build. If you have done this and have stiffened it properly then procede to nest step.
#2 All 4 tires 10 psi. Be sure tires left to right are as close to same O.D. as possible.
#3 be sure axles and spindles are setup up neutral.
#4 You will need 4 bathroom scales. Walmarts cheapest does a fine job.
#5 Place one under each tire. Get your pad and pencil and write down each corner weight.
#6 You want your left front tire 10 to 20lbs heavier than the right front. This is called preload. Right or wrong its what I call it. I do not care what the rear says and this is done without driver. Why you ask. Because unlike karts drivers move around ALLOT on mowers there fore you cannot get an accurate read cause you never know where you will be.
#7 if you are off on this you can raise the left spindle up or down to gain this weight difference.
#8 Once you have gained the 10 to 20lb left front heavier weight bias you now have your base setup. Now your chassis is set with slight preload. Now I will share by base setup for initial test.
CHassis intitial setup using front axle with 10* KPI.
Tire Pressures and base axle setup for ME Mind you I am 250LBS and this works for me.
LF 8lbs 0* camber 10* caster Turf master 4 ply
RF 6lbs 1* camber 10* caster Turf Master 4 Ply
LR 3 lbs Turf Pro 2 ply
RR 12lbs Turf Pro 2 Ply
Depending on how it handles determines what I do to it from here. This is a base setup If your chassis is right and build square and level to start with this initial setup will get you started in the right direction. This is the only time I scale it its all I look for and those at EC build clinics saw it on kart scales and true to my word we set it up neutral and I was right at 20 lbs heavy on lf. Then with race setup all the Kart wise scalers were kinda amazed at how all the rest of the weights fell into place. I could not tell you cross % front rear % etc etc. I use the above setup and as most have seen or experianced themselves. Its not complicated, its simple and easy to understand. I live on simplicity. I do not over complicate. I am not worried about sskid pad this or cross that. I am not a karter this is not a kart its a mower. The beauty of the mowers is the simplicity of them yet some folks continue to over complicate them in an effort to maybe prove how smart they are I guess, I don't know. Try it if it does not work for you then your chassis is probably off somewhere. I have yet to set one up and someone tell me they cannot drive it. And any setup must be fine tuned to each drivers preferances.
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Hey George,
I was wondering how I could raise the left spindle up or down for the weight distribution. I know the EC front axle is welded to the frame on your builds. I placed a big order for a bunch of parts from EC last week, and I think you are building my front axle this week. Maybe there is an adjustment I am unaware of with your axle set up???
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Hey George,
I was wondering how I could raise the left spindle up or down for the weight distribution. I know the EC front axle is welded to the frame on your builds. I placed a big order for a bunch of parts from EC last week, and I think you are building my front axle this week. Maybe there is an adjustment I am unaware of with your axle set up???
The spindles have movable spacers in them to raise or lower them.
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The spindles have movable spacers in them to raise or lower them.
ditto
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Very well done and well stated George. Its the K.I.S.S. at its best.(Keep It Simple Stupid)
Thanks for taking the time to post, Chris
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Very well done and well stated George. Its the K.I.S.S. at its best.(Keep It Simple Stupid)
Yup, its so easy to over engineer stuff.
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I read and reread all the ec front end and chassis setup posts, I can't find any intial or normal left and right caster settings. All input would be appreciated.
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I read and reread all the ec front end and chassis setup posts, I can't find any intial or normal left and right caster settings. All input would be appreciated.
CHassis intitial setup using front axle with 10* KPI.
Tire Pressures and base axle setup for ME Mind you I am 250LBS and this works for me.
LF 8lbs 0* camber 10* caster Turf master 4 ply
RF 6lbs 1* camber 10* caster Turf Master 4 Ply
LR 3 lbs Turf Pro 2 ply
RR 12lbs Turf Pro 2 Ply
He uses the EC axle.
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10 degrees is pretty common and a good place to start.
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Thanks fellas, sorry for my oversight.
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I USE 13-15 *CASTER AND 5*CAMBER. BEN WORKING FINE FOR THE PAST 14 YEARS.
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I USE 13-15 *CASTER AND 5*CAMBER. BEN WORKING FINE FOR THE PAST 14 YEARS.
Uh huh... and you said to me "I cant run the line you do"??? 10 degree in, 15 back is what we run give or take a degree or two. I cut the 1x2 tubing on a chop saw at ten degree then tip it back about 15. Tack it, check it, then weld it.
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I FIXED THAT PROBLEM. FRONT END STAYS ON THE GROUND NOW. :woo:
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i am new to this sport. i have ordered most of the chassis parts i think i will need. i have build my self a front axle out of 1 1/2 x 1 1/2 square tube, about 1/8 in. thick, is that going to be strong enough for a heavier twin?
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Should be good to go^^
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More than stout enough, Id call that too heavy but I like to build lite.
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I followed it to a "T" and was amazed at the results. { so simple }
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so for initial chassis set up i have no adjustment on my spindles so once i weld them thats it but when you weld your front axles do you welded them perfectly straight or a little down on one side of it i welded my SS straight and level just want to know if you guys do it.
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We use adjustable spindles, so we weld it in straight.
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First time I noticed this post. It's funny how to builder/racers from different parts of the country can come up with such similar setups 8). I've been racing for 12 yrs and that initial set up is so close to mine it's scary. I see you didn't mention your king pin deflection angle (or is it designed into the EC axle?). Right down to the Walmart scales. I do however swear on my jacking bolt style front axle set up. I can adjust entry with jacking and exit with air pressure without entry losing to exit or vise-versa.
Lester
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is there any websites or anything to help someone build their own mower. i have good mechanical skills, mowers and all the tools. just need the steps to get me started
thanks
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Go to the builds section of this website. Anything you need to know is there. Many many many different builds for all different classes are there. From mild to wild you have found the right site.
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is there any websites or anything to help someone build their own mower. i have good mechanical skills, mowers and all the tools. just need the steps to get me started
thanks
your on it
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I was just wondering why this is the different than the cart calculator. 43% front, 57% rear and 50% left to right.
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First time I noticed this post. It's funny how to builder/racers from different parts of the country can come up with such similar setups 8). I've been racing for 12 yrs and that initial set up is so close to mine it's scary. I see you didn't mention your king pin deflection angle (or is it designed into the EC axle?). Right down to the Walmart scales. I do however swear on my jacking bolt style front axle set up. I can adjust entry with jacking and exit with air pressure without entry losing to exit or vise-versa.
Lester
Lester sorry missed this but yes its in the EC axle.
because we are not karts center of gravity much different we dont sit in one spot we move around alot.
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CHassis intitial setup using front axle with 10* KPI.
Tire Pressures and base axle setup for ME Mind you I am 250LBS and this works for me.
LF 8lbs 0* camber 10* caster Turf master 4 ply
RF 6lbs 1* camber 10* caster Turf Master 4 Ply
LR 3 lbs Turf Pro 2 ply
RR 12lbs Turf Pro 2 Ply
George do you run tubes to get the pressures that low without popping beads?
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George do you run tubes to get the pressures that low without popping beads?
Not anymore
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Do you use bead sealer?
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generally not on the fronts on the savers though generally yes if they dont seal then I will use a tube. Tubes now days aint worth a plug nickel.... OH WAIT most now days dont even know what a plug nickel is... LOL
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Great thread! I do have a question... The class I am going to be running in only allows for a stock axle, but, I can either weld the axle straight or use "adjustable wedges" to tune it. Would this baseline setup be something about to start with considering that I can only tune the front end using the factory pivot point? Apologies if this has been covered. I tried a few different searches to come up with an answer :doh:
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Yes, use scales to get close to this set up then weld,this set up works very well adjust with air pressures at the track.
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Great thread! I do have a question... The class I am going to be running in only allows for a stock axle, but, I can either weld the axle straight or use "adjustable wedges" to tune it. Would this baseline setup be something about to start with considering that I can only tune the front end using the factory pivot point? Apologies if this has been covered. I tried a few different searches to come up with an answer :doh:
Stock axles are for stock mowers... that is why you can't find anything. Very few stock mowers have
an axle that lasts for a mower, much less a racer.
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George, I come from a background of full sized cars, I built cars and crew chiefed a dirt late model for a few years. Do you change tire starting pressures when you run tubes. When we ran them the tires would heat up much faster and more due to the friction even using powder in the tire. We would generally set up a few lbs lower. Just for example, We may start at an air pressure of 10LF, 12-14RF 6-10LR and 14-16RR. If we ran a tube (sometimes to help them get heat in the tires) we would start at 2-3lbs less in any tire that had a tube.
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No I have run both with or without, mower tires are not as sensitive as a race tire. In fact I never checked the pressures when done with a race to see how much they gained. Now that I only run Super mods with race tires there is no tubes so this is not a factor for us now either.
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Stock axles are for stock mowers... that is why you can't find anything. Very few stock mowers have
an axle that lasts for a mower, much less a racer.
I understand the limitations of stock equipment. Just trying to make the most of what the rules allow for the class I am going to be running
:)