Lifting the transmission to lower the c/g?

[THEYTOOKMYTHUMB]

I'm an oval racer by trade and thankfully getting back into it after taking 6 weeks off against my will. I'm just sort of sitting here thinking about racing and a thought occurred to me. There are a lot of off-road based cars that can only be lowered so far before the drive shafts become a major issue. The rule of thumb(no pun intended)is that the drive-shafts should not go above parallel to the ground. One option might be to put spacers under the tranny so that the rest of the car can be lowered. Maybe the same with steering in some cases. Just something to think about with certain models. I may have to go down to the dungeon and look at a few models up close just to see if I'm making any sense. Thoughts?

[CamplinP]

Well I am no engineer, but unless some other angle changes wouldn't above parallel be the same as below? I am not sure what car you are talking about but any car or truck I have, with the chassis on the ground the dogbone is not at risk of poping out as if the suspension was extended too far. Worth looking into.

[THEYTOOKMYTHUMB]

Well I am no engineer, but unless some other angle changes wouldn't above parallel be the same as below? I am not sure what car you are talking about but any car or truck I have, with the chassis on the ground the dogbone is not at risk of poping out as if the suspension was extended too far. Worth looking into.

Well, I sorta deduced the same thing after thinking about it for a minute. I just did a rough bench test with a couple of cars that weren't in the dungeon and there is certainly no more drag up than down. As long as the drive-shaft isn't pinched by the suspension. I will call this yet another post that I should've thought thru before posting. Oh well, it entertained me briefly...

p.s. It was one of those things that was bred into my r/c mind. I heard it at a young age and took it for gospel. Normally a very logical person, I never gave it a second thought. I've just been too busy trying to keep my axles parallel to the ground.

[CamplinP]

Ya never know untill you think and talk about it. Some pretty good ideas have come from idle BS'n.

[THEYTOOKMYTHUMB]

Ya never know untill you think and talk about it. Some pretty good ideas have come from idle BS'n.

This is true. I can't wait to get back to the track. I just need a couple hours and I should be able to drop my line by 2-3 inches thru the corners.

[Jay Dub]

Drive shaft angle is an often mis, or not understood peramiter. Having a drive shaft angle above parallel to the ground will keep your weight and chassis higher while under acceleration. This is because the drive shaft angle binds the transmission outdrives and dogbones and resists movement. In a straight line this is not a big deal, as it will only effect front to rear weight bias which might give you a little more or a little less steering off center (there are allot of other things it might/ will do, but they are negligable).

In the corner however it offers similar effects, but they are more drastic. By keeping the weight on the car high in the corner, this means that when throttle is released, the suspension will have further to relax, and transfer more weight. This means that the car will dive or transfer weight more and harder. In many situations this can make the car more difficult to drive (typically at high speeds or in high bite situations). There are situations where this is desirable (basically the opposite of what I described before). Usually when running a "high diff" type of setup ( in a 4wd car- e.g touring cars), one will run the suspension a little softer to get back the reactivity (steering reaction) because the suspension will feel "stiffer" while driving.

Having the diffs low, will usually make the car smoother, and more predictable, albeit with slightly less traction. -Jeff

[THEYTOOKMYTHUMB]

Drive shaft angle is an often mis, or not understood peramiter. Having a drive shaft angle above parallel to the ground will keep your weight and chassis higher while under acceleration. This is because the drive shaft angle binds the transmission outdrives and dogbones and resists movement. In a straight line this is not a big deal, as it will only effect front to rear weight bias which might give you a little more or a little less steering off center (there are allot of other things it might/ will do, but they are negligable).

In the corner however it offers similar effects, but they are more drastic. By keeping the weight on the car high in the corner, this means that when throttle is released, the suspension will have further to relax, and transfer more weight. This means that the car will dive or transfer weight more and harder. In many situations this can make the car more difficult to drive (typically at high speeds or in high bite situations). There are situations where this is desirable (basically the opposite of what I described before). Usually when running a "high diff" type of setup ( in a 4wd car- e.g touring cars), one will run the suspension a little softer to get back the reactivity (steering reaction) because the suspension will feel "stiffer" while driving.

Having the diffs low, will usually make the car smoother, and more predictable, albeit with slightly less traction. -Jeff

Well, I won't pretend to understand everything you said, but the jist of it is that my car might be more forgiving thru the corners with a higher c/g? I hope that's what you're saying because it makes sense to me. The pipe is no friend of mine as anyone that has raced with me will tell you. I typically like to run a little higher and faster thru the corners. This method is not ideal as there are several freaks(great guys so I mean this in the nicest possible way)at my local track who run the pipe like they're the rabbit in a dog race. They always turn more laps even though they appear to run slower. They are essentially running on a smaller track than I am. I'm trying to come up with a method that will allow me to speed up lap times w/o making love to the pipe. Any advice from anyone is greatly appreciated.

[LTO_Dave]

I noticed that my RC10 TrackMaster and JCAR trannies have the outdrives a bit higher than the stock tranny. But when the car is drastically lowered, the universals/dogbones are almost parallel. It's just a guess, but I bet there was some reasoning behind the design.

[JK Racing]

we used to run a plastic spacer (nylon? delrin?), maybe 1/8~1/4 thick under our trannies to "lower the chassis" running dirt oval. I resisted for a while, but once I put it on, it didnt come back off...

RC10's, Ultimas & JRX2s...

[fastang]

we used to run a plastic spacer (nylon? delrin?), maybe 1/8~1/4 thick under our trannies to "lower the chassis" running dirt oval. I resisted for a while, but once I put it on, it didnt come back off...

RC10's, Ultimas & JRX2s...

Isn't the reason for lowering a car to get the CG lower? If you lower the chassis but run spacers under the tranny doesn't this just bring the CG back up to where it was considering the motor is probably the heaviest item on the car?

[JK Racing]

NiCds were heavier than the motor...overall, the chassis/arms/shocks/electronics/battery went down, but the tranny motor stayed the same height. I dont profess to understand it completely, but I do know it worked.

[Jay Dub]

What we were discussing before is more theory on drive shaft angle than on anything else. However, by raising the tranny, and then lowering the chassis to compensate, you should retain much of the on throttle characteristics of the car (because of the straight drive shafts), but with a lower CG. A lower CG will transfer less weight, and keep the car flatter. _Jeff

[Charlie don't surf]

And, to add to what Jeff has said, a higher drive cup angle than the hub angle ( especially with a high CG and high roll center ) really creates much better drive off the corners than a level setup-

I have visual aids at hand thumbs ( yes, Pun intended ) if you need-

[Jirka]

Drive shaft angle is an often mis, or not understood peramiter. Having a drive shaft angle above parallel to the ground will keep your weight and chassis higher while under acceleration. This is because the drive shaft angle binds the transmission outdrives and dogbones and resists movement. In a straight line this is not a big deal, as it will only effect front to rear weight bias which might give you a little more or a little less steering off center (there are allot of other things it might/ will do, but they are negligable).

In the corner however it offers similar effects, but they are more drastic. By keeping the weight on the car high in the corner, this means that when throttle is released, the suspension will have further to relax, and transfer more weight. This means that the car will dive or transfer weight more and harder. In many situations this can make the car more difficult to drive (typically at high speeds or in high bite situations). There are situations where this is desirable (basically the opposite of what I described before). Usually when running a "high diff" type of setup ( in a 4wd car- e.g touring cars), one will run the suspension a little softer to get back the reactivity (steering reaction) because the suspension will feel "stiffer" while driving.

Having the diffs low, will usually make the car smoother, and more predictable, albeit with slightly less traction. -Jeff

You, Jay Dub, can answer very well to these kind of questions. I still remember Your answer about antisquat a while ago and it was the best description of antisquat so far that I have read and I have read a lot of them.

Jirka

[THEYTOOKMYTHUMB]

And, to add to what Jeff has said, a higher drive cup angle than the hub angle ( especially with a high CG and high roll center ) really creates much better drive off the corners than a level setup-

I have visual aids at hand thumbs ( yes, Pun intended ) if you need-

Yes please! Not only do I like looking at purdy pitchers(pun intended), but I really do want to understand this whole concept(I'm a bit slow ). Thanks for the input guys.