Chrome moly transmission cross member'

[karolko]

Hey guys,

I thought this would be the place to post this.

there is a thread on here from 2002 about someone thinking about making a transmission cross member out of chromoly. but it didn't seem to get anywhere.

I too am thinking about this as i have too much time on my hands and some extra chromolyas well.

Has anyone done this? what size tube did you use?

Also, i am debating on how to mount it the cross member. I was thinking i use the factory location mounts, and the next question is should i use poly or factory rubber mounts there? Any opinions on that? I will be using an HnR transmission mount but i still want there to be a little flex so it isn't a rattlecan.


Thanks guys,

Adrian

 

[prostreetdrag]

Just my two cents.........Im am very sure this type of mod can be done very easily if you have acess to the material. That material is very strong and about half the weight as mild steel. If I were to use that material I would suggest useing no less than 1 5/8-1 3/4 diameter I would say anything larger would be over kill and possibly innerfere with Exhust or ground clearence. I actually custom built one for a prevouis G-body I own'd made from solid 2X3 Alum stock it was replicated from a doulble hump crossmember that got from jegs at the time. I was able to get the material from my prev job and I brought home and tig welded. It turned out very nice. I used poly bushings with it and had no problem. Depending what your useing the vehicle for stock rubber bushing will be completely fine. Poly bushings will not make it sound like a raddle can but they are stiffer than rubber but unless your useing poly on your motor mounts I would just stick with stock mount... However i would suggest somesort of bushing either way unless you are useing it strickly for drag raceing then keep it solid or poly because rubber will wear faster over time with the hard launches. My personal exp I would keep it consitent with your motor mounts. You dont have to use the rubber pads on each end of the crossmember you can have it just bolt to frame as long as your useing a poly or rubber mount on bottom of trans where it connects to crossmember

 

[prostreetdrag]

Also I would agree with you to use the stock location mounts the frame has more support in that area. There are actually 2 diffrent xmember mount locations on the g-body frames depending which engine/trans combo was used with those frames all the frames were made alike so you should notice a couple diffrent mounting locations under your frame. I would use whichever one will give you the best exhust clearence

 

[karolko]

i am running the HnR poly motor mounts so i think i will also be buying some polycross member pads too.

I do have a tubing bender, but i think having so many right angle bends in such a smal area would look bad. If i could get my hands or a tubing roller that would be really nice.

It would just be a matter of the ends. i am undecided as to how i should build them. I do not want to do what factory did, that is just squish the ends of the pipe and be done with it, but cannot hink of anything else either.

Any ideas?

 

[prostreetdrag]

Here's how i would do the ends if I was doing this which I think will make tubeing stronger and look more profesional....If you basically cap off the end of the tubeing and what i mean by that is basically would look like a solid rod but would be hollow of course and on the end of the tube cut a notch in the middle of the tube and slide in a peice of flat 3/16 or 1/4 inch plate and weld on each side of the plate where it slides in the end of tube that will give you a flat mounting surface rather than smashing end of tube......OR Instead of cap-ing off the end of the tube do the same thing with the plate steel by basically cutting your slit in the middle of the tube side to side and then sliding in your flat plate steel and just kind of crimp the gap and weld....Does this make since I have it pictured in my head but want to make sure you understand what im trying to say..lol I can prob draw a quick sketch of what im talking about useing microsoft paint shop program. I did somthing simalar on a crosmember support i made for my rear frame rail along the rear bumber and I can post a pic of what i did basically boxed in the end of tube instead its round and i grinded it smooth all the way around the tube so it would look like all one solid peice of tube or bar

 

[karolko]

i know what you are talking about, and i think it's a good idea, both looks and strength wise.

Where and who sells the poly cross member rubbers that connect the frame to the cross member?

My car is on the boarder line of a street car, but i plan on driving it on the street more than at the track, so i just want to keep this in mind when choosing bushings. That being said, i can't see there being any side effects of running stiffer bushings on a car with poly mounts and a cage. Do you?

Adrian

 

[prostreetdrag]

Absolutly no side effects at all. In fact with you running a cage that is the entire purpose of it is to make the car stiffer that is exactly what the cage is for which is to tie the frame to the body and make the body stiffer and eliminate chassis flex and for driver safety....Since you are running a cage I would definatly recomend only useing the poly bushing..The only thing I would be sure to do with your poly bushing is to rub some greese or bearing greese on them or in the bolt holes. The only negative thing I have everheard with poly is somtimes they are squeaky. However, I have never had that problem with them and have been useing them for about 4 years but ofcourse i use a little greese on them or on the bolts before sliding through bushing same concept as useing caliper greese on brake pins. As far as where to buy those xmember frame pads you would have 2 options I would first check with the major poly bushing makers like energy suspen's website because if anyone would make them for our cars it would definatly be them...That is where jegs and places like that get them from...Second option is if they do not make the poly pads for the frame part on the crossmember, they do however carry many many diffrent types of universal poly bushings..It dont have to be a pad so to speak you could use plain round bushings and sandwich them on each side of the crossmember(same thickness or slightly thicker as the stock pads) for each bolt that would serve as the same purpose and most likely be a cheaper route

 

[karolko]

come to think of it, there is a local company that sells bulk polyurathane. i know i can find a 1/2 to 3/8 think sheet of it and build my own like you mentioned.

Thanks for all the ideas.


Adrian

 

[prostreetdrag]

Your welcome anytime....I would consider makeing few extra sets with the left over I'm sure theres alot of Buick and G-body guys on here that would be interested in a set. I'm not 100% sure that they even make them or not for our cars, could be wrong but either way would still be cheaper for you to make

 

[karolko]

i would love to do that, but i hardly have enough time for my own car. Chromoly isn't cheap as i just bought a bunch of it for the cage recently.

 

[Slow91z]

HR sells poly frame pads.

I have a X-member like what you are talking about...I'll see if I can get the courage together to go get a Pic...It's COLD outside.

 

[Slow91z]

Ok here we go.

 

[karolko]

i would really love to see some of your photos of your cross member for research purposes of course.

If it makes you feel any better i too live in a cold climate: but where i am from we sometimes use dog sleds to get to work

Looking forward to the photos.

Also how and what did you use to mount the transmission to the cross member? The HR transmission mount?

Adrian

 

[Slow91z]

Pics are right above your post.

It has a regular old chevy tranny mount, don't know the brand but it is poly.

Just FYI this was on the car when I bought it so I wasn't involved in the making.

 

[charlief1]

Not trying to be mean but if some fabrication of something isn't posted I'm gonna send it to the General section. This section is "How to Fabricate" after all. I was hoping some one would post how it was done.

Nice work btw Collin. Can you post more on how you made it?

 

[Slow91z]

Nice work btw Collin. Can you post more on how you made it?

Oh I didn't make it, the previous owner got it from Excessive Acceleration one year at BG.

 

[Scott Atk]

This is the one I have. Fits fine but it has flex. I would go a little bigger, maybe 1.5 inch or so. HTH, Scott
http://www.maliburacing.com/iceman/