More to alignment than just setting drift?

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davidwilkie
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More to alignment than just setting drift?

Post by davidwilkie »

My sons and I will (hopefully) be finishing up their cars in the next day or two. I'm curious about all the "alignment" mentions. What more to do than set drift?

They've each built standard wheelbase 3-wheel RR cars. We haven't fine tuned the weighting yet, but looks like we'll have the option for adjusting the COM down to as little as 5/8" if we wish (thinking 3/4" to be safe with standard wheelbase?).

Rear axles are drilled negative canted at 2.5 degrees. DFW is drilled positive at 1 degree. Plan to put about a 1-1.5 degree bend in DFW axle.

In the past, all we've really done is adjusted the DFW axle (start at 12:00 o'clock and rotate method) to 4" drift in 4'.

Is there more we should be looking for? I see comments on "wobble" and other characteristics to correct for. Since we are planning on using straight axles in the rear, is there any adjustments even to make?

Thanks for any tips or thread suggestions!
chromegsx
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Re: More to alignment than just setting drift?

Post by chromegsx »

davidwilkie wrote:....Since we are planning on using straight axles in the rear, is there any adjustments even to make? ....
You are assuming that you have drilled perfect holes (square to block/track and same perfect cant angle (not toe in/out) and that your axles are perfectly straight and round and that your wheel bores are perfectly cylindrical and concentric with the tread diameter at contact area...none of which is the case usually. Check em (axles and wheels) out under magnification.

So just turning "straight" axles within the "perfect" cant'd hole will give a slight different effect on how much the rear wheels migrate, how fast they migrate, direction of migration and what part of the wheel bore is getting the most friction.... etc. If given a track to tune on you will find that rotating axles will change the tune of your car and may slow you down or speed you up. Even on a tuning board you can see how fast the wheels migrate to the axle heads and whether they reach the heads at the same time or not. I can be frustrating (if not maddening) trying to get the tune close to right especially if you haven't made sure you axle holes are as close to perfect as possible.
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Noskills
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Re: More to alignment than just setting drift?

Post by Noskills »

David,
You also need to tune the rear axels first. There are plenty of good posts on this discussing the technique of putting a piece if tape under the noseof the block or a thumb tack and getting the car to run straight with wheels moving out. Once this is right you move onto adding the front wheels and setting drift. Read wheel toe problems when not correted first will be bad!
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sporty
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Re: More to alignment than just setting drift?

Post by sporty »

David,

Tuning is a general term. there our several area of tuning.

Here is a few.

many of us, try and drilled canted rears and do so with no toe in and out. many of the really good car builders, do so, with not having to tune the rear axles, because of perfect drilling. (no toe in or Toe out)..

Often, what people do is get a flat and level board, 4 foot or longer 4 to 6 inches wide and then use a level to check that the part is not twisted or warped. Some use glass. they raise that board up enough , that the car will travel strait down, with just the rear wheels. often people use a piece up tape under the nose of the car and rub some graphite on it.

Now if you have sanded or done some work under the nose of the car, then it may not work to do this test, as it can and will maybe effect how the cat goes down the board.

I use to place a center line all the way down the board and a center line on the front of the car. the goal is the car should run all the way down, strait. with not going off the board and the nose of the car center staying on that center line drawn down the board.

If the car does not, you have to try and tune the rears, now many of us, just toss the wood and start over, but others prefer to try and correct it. with turning the axles clock wise or counter clock wise to adjust, to see if this can resolve or lessen the problem, sometimes wax paper shims ares used also or a slightly bent axle to try and correct this.


If the car goes down the board and goes to the right and falls off the board. then you know you have one or two things going on, you could have the right rear axle toeing out and or the left rear axle toeing in. both or one could be happening.

usually the first thing to do is try and look and see if you can clearly see which one it is, sometimes you can tell buy the wheel going to the axle head or not going to the axle head.

there our many posts on here about this.

So, lets asume as a example, that the right rear has toe out, you would then try and turn that axle counter clock wise and give it a another run down the board. to see if it has improved it at all. start with small turns.

You will know if you have made a improvement, because the car will travle farther before going off center or vering off or going off the board.

A caution is using a proper tool to turn the axle heads, because you can wreck the axle head, and cause ruff surface and warping axle head, that effect performance of the car, due to this damage. Some use a dremel and grind a small groove on the axle head and use a small flat head screw driver to turn for adjustments.

I left out some things, as i would be typing a book and the info more indepth is here on the forum already. But Hope this gives you a start and concept of it.

Now, there is also other tuning, people with tracks and timers. will use small amount of weight to adjust the cars performance, by moving it around and placing it on different spots, and run the car. to try and eak out a little more speed.

That is a form of tuning.

Now, people with tracks and timers, also tune the axle gaps on the car. all 3 or 4 of them. by moving it out a little or in a little, it can improve the speed of the car. But a track and timer is needed to tune for this. Becuase you can not see the time changes without a track and timer, from those adjustments you have made.


Then there is rail rider tuning. Many do nto have a track and try and do the drift by a set of drift numbers out there, that people suggest are safe. However the problem is, every car is a little different and every body measures there balance point and drilles there axle a bit different and weight placement. and thickness of wood.

So its hard to give people a true set of numbers, that is going to give your car the fastest times and best running on a track, and tracks differ also,setting up of them, so forth, condition and shape of them. all variables.


So, most tuning once again, falls to trying to have a track this is close to the track at the pack, or district or council races. and often, you may run on a variety of tracks.

But, with all that, tuning the car (rail riding) is best done with the track you will be racing on. I always say, if the pack allows you to come a few hours before or the night before to run the car, thats the time to try and tune it to the track.


Rail riding, is the right front wheel just barely staying on/ the edge of the rail. to control wiggle and movement from the car, non rail riders, it use to be trait runners, wish often was narrowing the front end on both sides and having the two front wheels, hug close to the rails on both sides or touch. this way as decent.

but 1 wheel touching is less friction, compared to two wheels, coming in contact with the rail.

So since many tracks and the cars built very and are different for many reasons. I only touched on it lightly, more cant or more material removed off the wheels, axle and wheel bore prep, ect. all play a small roll here. that will efffect the best posibly drift number for your own car.

So people often tune to the track, by running the car down the track with a timer. and do less or more drift, to find the best speed for the car. Some say, the best to look for, is the car just breaking free off the rail, from the slope to the flat, right in there. look for that and then add in a tad more drift and you have the car pretty close to being tuned for that track and getting the fastest times possible with that particular car.


Now, it think this boarders tuning, but its not really a true tuning.

But you mentioned wobble and ect, sometimes people who are knew, and still learning, like many of us allways try and do, keep learning.

But a exmaple of what I mean, is when you bend a axle for rail riding, that bend, if done in the wrong place, can get into the wheel bore and cause issues. so sometimes, you have to use a new axle and learn where to have that axle bend at, I always prefer when using the rail rider bending tool from derbyworx. i add in a credit card gap, between the axle head and the tool. Becuase for me, the way we built cars, our processess, good or bad, our habits, required us to do to this, to prevent the axle bend of the rail rider axle,. from having that bend effect the inner wheel bore of the wheel.

A rail rider car, should smoothly turn and gently and nice, not suddently or jerk over to its drift. Thats usually how I cna tell somethings not right with the axle on that wheel. but not excluse to checking to see if a problem is elsewhere, if after a few different axles have been tried or wheels. Did not resolve the issues.


Enough typing 4 now. I sure hope this has helped ansswer some of your questions and provided enough detail to understand a bit more.

Sporty
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