solid mount rear ends

[flatheadgary]

i know this is a street car site, but i value alot of you guys knowledge and i just can't figure this out. i am also not sure if this goes in the frame or suspension section, seeing as there isn't any.
i build alot of drag altereds and i was wondering, if the way you mount the rear plates to hold the thing, will have any effect on torque on the frame when it launches. i have always made them straight up and down. my altereds don't go any faster than 10 seconds, so that may have an effect on it too. now there is another thing, is it "affect" or "effect". anyway i digress, here is a little drawing i made to explain it better. please don't laugh at my artistic endeavor or lack there of.

 

[Baby Huey]

Gary I don't see any difference in the end result as they are all Solid mounted. The launch force is going to be the same, at least I would think so....
I have been involved in two Altered builds back in the 60's and later in the 70's.
The car we built in the 70's had the rear axle mounted solid, kinda like the top one in your "CAD".....
I bet George Barnes could put a little little light on this subject.
"BH"

 

[Youngster]

I guess if it was me I would go with something like the top sketch. I wouldn't kick the frame unless you need it for mounting something such as a fuel cell etc. A cross member with a drive shaft loop just in front of the rear end would be needed. If the body has a sub-frame in it this should work OK.It's been a long time since I was involved in quarter mile stuff and I'm sure...no make that I hope the engineering has changed since then.

Ron

 

[Martin]

Torque on the frame has nothing to do with mounting position, it is an equal but opposite reaction to torque applied to the axles. How the frame reacts to the torque being applied to it can be influenced by mounting position.

An effect is the result of an affect.....or my high school diploma aint worth the paper it's printed on.

 

[donsrods]

I had at one time an Austin Bantam altered, and the rear was solidly mounted like the bottom drawing. Most of the old drag cars that I have seen from that era were done like that too.

Don

 

[der Spieler]

I have the blueprints for the Mark Williams Funny Car/Altered chassis and his are mounted like your top example.

Mark Williams Enterprises - Detail

Steve

 

[Baby Huey]

Yup, thats the same blue print we had when we built the car. I still have that drawing in the shop archives somewhere..."BH"

 

[flatheadgary]

thanks guys for the replies. i think what keeps sticking in my head is a suspended car and traction bars. in the old days, on gassers, they had those long ones and they pulled giant wheel stands. i don't really know if that is why, but you don't see those much anymore. i also know that the science of traction is alot more understood now than then. i think alot of the mounting on the chassis is more a product of the design of the frame than anything else, as with the mw one. any bars going over the rear in that example would not have the same structural strength as the way it is. what would be needed for gas tank or battery or whatever could be made out of smaller less strong bars.

 

[Youngster]

The advantage to having the frame extend past the rear end and having the fuel cell and battery mounted back there would be for weight transfer.

Ron

 

[donsrods]

You are right, weight transfer and traction sciences have come so far from the early days when they used those long ladder bars. The idea was that the long bar would act as a lever and exert upward pressure on the car in a fairly forward position. It aided in getting the nose up.

Now we know a lot more about planting tires. When and if I build another altered I had planned on solidly mounting the rear axle for nostalgia reasons. But my Son's are trying to persuade me to use coilovers and a four bar set up because of it's tunability and better bite. So, I will probably bring myself into the 21st Century and use the coilovers I guess.

Don

 

[flatheadgary]

Don, i have always looked at altereds to see how the rear is mounted and have found other than maybe '27 T's very few run suspension on them. i know altereds have a hard time hooking up as they are so light. i think if you go to the drags and check out a few you'll find nobody has come into the 21 century. hey, if suspension would work, i feel fuel altereds would use it. other than the transformer altereds, that are built from funny car type chassis, i don't find very many that have suspension. i thought about this all when i built my flathead bantam and decided that it would be lighter(ie. faster) without it. just let air in or out of the tires or add weight to each tire to get the traction you need. simple no? besides, you don't have as many points of failer, since you don't have coils, heim joints and bars very little to break. above all this, if your under 10 seconds they go pretty straight and if you are on a track that it won't hook, just sit back and relax, it probably would kill you if it did (left or right). it seems to me at every track you go to with a suspended car, you spend the whole day adjusting everything. i would rather be racing.