i have to build a custom tranny crossmember for my 85 f150. i need to do it because im putting a 2wd 4 speed in it with a divorced 205 case. main reason is for the mount and also for the front driveshaft to pass through it. i got all that figured out just wanted to know what yall think about where it mounts to the frame, i was gonna run a peice of c channel across the frame and bolt it in with the 2 bolts at the bottom and leave it at that, do yall think that would be ok or do i need to figure out a way to make some braces like the stock one has?

 

What are you going to be doing with the truck? How much stress are you going to be putting on the motor and by extension the transmission? Most times you can find transmission crossmembers on Jegs or Summit racing that are bolt in.

 

its a street truck i drive it everyday but its got 40" mud tires and a 600hp built 460

 

It's hard to beat the stock crossmembers. When they stamp them out, it makes them strong and lightweight also. And tying the upper part of the frame to the crossmember keeps the frame rail from twisting.

Why can't you use a regular 2wd crossmember designed for the tranny you have? It should bolt right in if you are using one of the stock 4 speeds.

 

Take a factory cross-member for the transmission you plan on running, and then cut the driver's side ear off of it. Once you do that, you can fab up a custom ear that should give you more room for your pinion angle.

 

dude, thats the saddest thing I have read all week...

 

I am guessing you want to do this divorced to reduce driveline angles in the front. If so:

I would just use the factory 2wd crossmember, cut the drivers side like mentioned above, and make a driveshaft loop into the crossmember for the driveshaft to go through. Or just a hoop to go over the driveshaft.

The stock braces add lateral stability to the crossmember and the framerail. Keep em.

 

why is that dude?

 

'cuz your truck is a mall crawler bro. No homo.

I second the idea for modifying a stock cross-member.

(All of this was in good jest, no offense intended.)

 

its a mall crawler? thats funny cuz we aint even got a mall around here hell we just got a walmart. i dont really understand how u think you know what i do with the truck if you dont know me but seems pretty stupid to me for you to assume things like that. anyways is the frame gonna crack right there if i dont put them extra braces on it or what?? thats the only reason im askin about it in the first place

 

Relax, man. They are just messing with ya.

Modify the stock crossmember and keep the braces as much as possible.

 

Mall crawler is a popular term in the Offroad section of FTE for a truck that has a nice shiny paint job and is all decked out with lift, tires, rims, suspension, motor, you name it... and it not be used off road or hardly hit the dirt for that matter. But yeah, it was all in jest.

So, hows the gas mileage with a truck like that as a daily driver? 6 mpg with a tail wind and wax while pushing? And yes, this was a joke too.

If you're concerned with the frame cracking around the cross-member, you could always do some strengthening with some 1/4'' angle iron or plate steel. Either beef up the cross-member, the frame, or both, and you shouldn't have much trouble.

Is the frame boxed?

 

gas milage is horrible its about 3-4 to the gallon so yea it sucks, but this truck sees woods and mud as much as it sees streets so thats my case lol but anyways i was thinking that bein that im gonna have a divorced tcase with its own crossmember that about 120lbs off the tranny crossmember so thats what i was thinkin it would be ok to not have those extra brakets that are aggravatin everytime i drop the tranny lol

 

With a big block, the crossmember needs the braces due to the torque.

They may seem like a pain, but you should not have to take the crossmember out that much..... Tranny issues?

 

+1 on torque. 600 horsepower with a 460 is followed by PLENTY of torque. I don't have to see any more numbers to know that.

The reason I ask if the frame is boxed, frame flex can cause a frame to crack or bend pretty easily. When you get a truck that's as big as what you've got, and if you start horsing it around, you can break things pretty darn quickly. It looks like you've got most everything taken care of regarding strength, so I would just go ahead and modify the cross-member.

You could always go to the Offroad section and see what the guys there think. They do a pretty good amount of welding to frames. Bumpers, suspension modifications, boxing the frames, crossmembers, etc.