Chassis set up, including sting line the toe.

[Lasher 19]

The topic of chassis set up came up in a thread in the MX section and I thought I would post this here for others to see.

For starters, setting up the chassis can play a huge part in how the quad handles on the track. I follow the instructions on Walsh website http://walshrc.wpengine.com/?page_id=1154 but changed how to measure toe.

If you follow the instructions on the Walsh website, you set ride height, caster and camber before setting toe. (if you can adjust caster/camber with your chassis).

Now to set the toe, I use string and jack stands. Here is my original post on the .net site for years ago... http://www.trx250r.net/forum/tips-tricks/3368-alignment.html

But here is a cut/paste of my instructions...(with added info)

Over the years of racing, having the correct toe set on the 250R will make a huge difference in corners. I spent a lot of time researching how to set the toe and none of them were easy or even seemed correct. So I figured out via trial and error a way to give our quads an alignment, similar to how they do it on cars.

Items needed...
4 jack stands that reach up higher than the middle of the wheels.
string - I use mason string from Home Depot (prefer orange color)
tape measure
2 tie down straps
2 people (one to measure, one to sit on their butt. If you choose your wife/girlfriend, make sure they are not naked...you need to concentrate)
tape - duck tape, electrical tape, masking tape etc.
Tools necessary to adjust tie rod.
Beer - not necessary but with two people, make for a better time.

Step 1
Find a level place in the garage and make sure the tires have the proper amount of air. Have a beer if you want.

Step 2
Loosen the tie rod nuts and make sure the tie rod can spin freely.

Step 3
Attach straps to each end of the handle bars and the rear grab bar. Sit on the quad and make sure the handlebars are straight, tighten the straps so the bars will not move.

Step 4
Place a jack stand on each corner of the quad. I usually go about a 1 foot or so beyond each wheel. Tie the string to each jack stand down the sides of the quad. The string should be at the same height as the middle of each wheel (across hubs). Pull the string tight by moving the jack stands further out.

Step 5
Have your helper sit on the quad and settle the suspension to "normal" height. (the helper can get on after the string is set, allowing them to help you slide jack stands, but you will have to measure a second time to be safe)

Step 6
Setting the string line...go to the back wheel and measure out 2 inches from the rim. Depending on how good of shape your rims are, either the outside lip or the inside part where the bead sits. You want to have the string 2 inches from the front of the rear rim and 2 inches from the back of the rear rim. You will have to move both jack stands to get it perfect. Once you are done, repeat on the other side. DO NOT BUMP THE JACK STANDS ONCE SET. I don't know how many times I have set the string only to kick the stupid stand when moving around. Oh...if your 15 year old is helping, you may have to explain what a "C hair" means, both in measurements and meaning.

What you are doing is creating a line that is parallel line with the rear tire with the string extending towards the front of the quad about 2 inches away from the rear rim.

Step 6
If your helper was aiding you in setting the string, have them sit on the quad. If so, just double check the string measurements once they are settled. Now is the time to set the toe. First thing I do is to set the toe to zero to find the center. Measure the distance from the front of the front rim to the string, now measure the distance from the rear of the front rim to the string. You do not care of the actual number, just that they are the same. Turn tie rod until both distances are identical. Repeat on other side. Right now you have set the front wheels to exact direction of the rear wheels. Create a zero toe, not toe in, not toe out.

Step 7
I personally for motocross set the toe in 1/8 inch overall. That means I need to make the front of the front wheels 1/16th of an inch in from the string. (back of front rim should be out 1/16th inch). Repeat on other side.

Step 8
Without turning the tie rod, tighten the nuts to lock it down. And you are done.

Comments...
When starting out, check all measurements multiple times. Including rear rims to string after tightening down the tie rod nuts.

I use the tape to tape the string after tieing it to the jack stands. Stops the string from turning on the stands when setting the string.

I have done this at the track (after getting bumped) using chairs and tie down straps. (forgot string and stands)

Difference in handling is noticable. The R will track straight and rail around corners, not to mention the handle bars are pointing straight.

If you some part of your chassis is bent, you will now it, but this set up will not care. My 89 R the front is over to one side by an inch. While the new Walsh chassis is the same on each side.

If necessary, I can take some pics next time I set this up. But it us really easy to do once you have done it a couple times. I can have it all done in 10 minutes by myself, or 5 minutes with a qualified helper.

What I have learned and found is that toe out (front wheels from top would look like this \ /) will provide stability at higher speeds when going straight. This is because the front wheels are pulling away from each other. Toe in (front wheels from top would like this / \) will cause some wandering at high speeds but allow you to be more planted in turns. That is why I put 1/8 inch toe in because I care more about being planted in turns than high speed straightaways. You can play with it to see which works best for your riding.

[havinnoj]

Really nice write up [MENTION=1722]Lasher 19[/MENTION]

[Allison#51]

Nice write up. I was under the impression that toe out helps you get into the corners and toe in provides the straight line stability though.

[Lasher 19]

I have read where toe in helps with sraight speed in some cases and can vary between FWD and RWD cars, understeer/oversteer and even the changes in toe when under acceleration. Which is why having a partner(of same riding gear weight) when setting adjustments is important. Also why I mention "settling" the quad before measurement.

I have tried both toe in and toe out on the track and found the slight toe in give me the best feel. I posted this as a method and suggest trying different set toe in/out. Different riding (drag, sand, hardpack) probably use different settings.

My 89 frame I used to have was horrible if I set toe off the frame rather than the rear wheels. So using string off the rear wheels seemed like the best bet. It has worked for me. I used my knowledge from working on stocks cars for years and thought of how they align my car at the shop to come up with this method.

One other thing I would stress is setting to zero toe at the start. This way both wheels will have the same toe.

[JohnTabata1]

Nice write up. I was under the impression that toe out helps you get into the corners and toe in provides the straight line stability though.

Tru it does

[hickwheeler]

With sprint cars years ago we would run them toe out. With them toed in we would see the front wonder or even shake a bit.

[Lasher 19]

I used to be a mechanic on a stock car (local racing 1/4 mile asphalt bull ring) and when we set the toe the right side (outside tire) would always be set to straight and we would toe out the left side to what we wanted. I do not remember using toe in at all either.

[Skeans1]

I know setting up a semi string across the drivers axles to the steer axle, 1/16" to 1/8" toe in with a 4 to 7 degree postive caster and the wheel return to center without any wander or fight or death wobble in the front end.

[rablack21]

With a rear wheel drive vehicle (including quads), you toe in the vehicle slightly because the tires will naturally push outwards when the vehicles begins moving. So when, they are slightly toed in from the start, they will actually be tracking straight when the vehicle is moving. Front wheel drive vehicles are the opposite. The front wheels will pull inwards under speed. So they are slightly toed outwards so they will track straight when moving. On a rear wheel drive vehicle, usually only up to around a 1/4" or so is needed to get the tires to track straight. Any more than that and you start running into other behaviors, possibly desired possibly not. Camber and tire pressure tend to help you more in the turns than messing with the toe. I also agree with making sure toe starts out at zero for both wheels. It's important for both wheels to be as even as possible symmetrically.