Choosing a transmission crossmember
 

I want to buy one of those universal bolt in crossmembers for my trans. I cut up the factory one and kinda made it work... but I'll save myself some future headaches by just buying one.

Factory 50 frame. Th350 trans.

I've never bought a universal crossmember before so I want to make sure I have this correct. I need to buy a mount pad, anchor style? I need to install the pad, support the trans and then measure how far down the bottom of pad is compared to bottom of frame rails and that's my drop right?

And to get the angle perfect, I can shim some if needed?

Re: Choosing a transmission crossmember
 

I can get this mount up the street and this is the kind of crossmember I'm wanting. Just want to make I get the right one.

Re: Choosing a transmission crossmember
 

Let us know how it works, once you do it

Re: Choosing a transmission crossmember
 

I used that one on my '55 2nd series and had to modify it extensively because I put my power brake unit in its way. Without the brake unit in the way it would have worked without a problem. On a '50 frame your mileage may vary.

I'm not sure what a "mount pad, anchor style" is. You show the crossmember and the trans mount in your picture. That should be all you need.

Someone with an AD truck can fill in...

Re: Choosing a transmission crossmember
 

I used one like that and it worked great

https://farm5.staticflickr.com/4510/...e724338a_z.jpgMessages Image(4025115421) by Joe Doh, on Flickr
https://farm5.staticflickr.com/4487/...868b8a84_c.jpgIMG_7453 by Joe Doh, on Flickr

I used the extra pieces from the engine mount crossmember to make it removable.

one thing to watch is the "drop" amount, I used a 2" drop and next time I will use a 4" drop so my exhaust fits better.

also, my trans mount had a single center bolt so I had to modify the mounting pad slightly

https://farm5.staticflickr.com/4504/...bef41646_c.jpgIMG_7408 by Joe Doh, on Flickr

Re: Choosing a transmission crossmember
 

I used a 2nd gen Camaro trans crossmember on mine. A little bit of fabbing, but the right width and bends for exhaust.

Re: Choosing a transmission crossmember
 

Google called that kind of mount, a pad and a anchor style kind... My biggest question is, how do i measure and get the correct drop?

Re: Choosing a transmission crossmember
 

universal kits need to be cut to size and welded onto the frame
if your going to cut and weld use square tube. it's cheap and just as easy to fabricate

Re: Choosing a transmission crossmember
 

mock the trans up with the right down angle and see where the trans mount sits in relation to your framerails. use a straightedge if you have to, then figure out if you need it to go up or down and how much. its literally that easy. of course it wasnt so easy that I did it haha, so learn from my mistake.

Re: Choosing a transmission crossmember
 

Ogre I don't trust my welding skills enough to make my own crossmember yet. So I went and ordered the bolt in. I put a yard stick across the rails and measured up and a 2 inch should work out. I'll post when it comes in.

Re: Choosing a transmission crossmember
 

Be sure to pay attention to driveshaft angles:

https://www.google.com/search?client...UTF-8&oe=UTF-8

Also, if you need to revert back to a welded-up crossmember, just tack it in place, then take it to a buddy that is a good welder, along with some adult beverages...

Re: Choosing a transmission crossmember
 

Lol I've had to get a welder buddy by a few times, it's just not very often. So I try to do as much as I can with very little welding mixed in. I've started getting better at it but I've got a ways to go.

I've got an angle finder and I'm ready. I'm going to level the carb and get the end of trans at like 3-4 degrees right? Same with axle... not welded to seats yet... but I need to make sure it's not perfectly lined up. Or so I'm told.

Re: Choosing a transmission crossmember
 

Just like the articles in the link will tell you -- the centerlines of the transmission and the pinion yoke should be parallel, and you should shoot for each angle being 3 degrees (optimally), to achieve that parallelism.

If you line everything up perfectly at zero degrees instead of 3 degrees, the truck will be a big tuning fork and you'll be able to take it out for a butt massage. :dohh:

Leveling the carb is a good thing but, in my opinion, not as critical as drive train geometry.

Re: Choosing a transmission crossmember
 

I'm reading up on setting the angle and I'm a bit lost. I do not have my driveshaft cut to the right size yet. So I cannot install it and put an angle finder on it. I thought I could set everything by going off of trans and diff. Am I wrong?

Re: Choosing a transmission crossmember
 

set the truck on a level surface and with wheels etc on. if you have a rake angle picked that the suspension is set up for then get the truck at that angle. long story short, get the truck sitting at the rake angle and suspension ride height it will be run at. whether that be sitting on stands or whatever. just be sure to have the stands under the axles so the suspension is carrying the weight like it will be when driving. next, put an angle finder on the engine oil pan rails and mess around with a floor jack under the rear of the trans untill you get the engine at a 3 deg "down at the rear" angle. install the rear trans mount of your choice, set a level across the trans mount to cross member surface of that mount (level it of course) and hold there with cable ties or whatever. measure up from the level surface to where you want the cross member to be mounted on the frame. that measurement will be the amount of drop member required.
pretty easy now to draw that up on a piece of cardboard from a large box and take it to any welding shop with a pic of the bought cross member for their reference of what you want. they could fab one up in no time. then bolt it into your frame. the shop will need to know the width of the frame rails at the mounting point and how much slip you want for one tube to slide inside the other (for width adjustment as per the bought member)
so 3 deg down on the engine/trans combo and 3 deg up measured on the flat of the pinion yoke if you don't have a drive shaft. d/shaft needs to be the last thing in the puzzle after everything else is finished, mount wise.

Re: Choosing a transmission crossmember
 

you absolutely dont put the angle finder on the driveshaft. you set the trans angle with the angle finder on the flat part of the trans and the axle angle withe the angle finder on the nose of the rear.

Re: Choosing a transmission crossmember
 

Ok good, article was going on about u joint working angles and stuff. As far as installing the crossmember... I need 3 degree down.


I put the angle finder here... is that Ok? Granted this is on the hacked up member I'm replacing...

Re: Choosing a transmission crossmember
 

like said. the confusing part is yet to come. leaf spring wind up factor. some guys fudge the pinion angle because they have big motors and when they "hit it" the spring wind up from acceleration changes the pinion angle a bunch and causes vibration under load due to the working angles of the u joints being so different. ask any 4x4 guy who has a spring spacer block lift kit and he will tell you all about his troubles. one reason why some guys go with a 4 link rear suspension or have fancy looking traction bars.
just set the pinion angle to be opposite the trans angle and go with it.

Re: Choosing a transmission crossmember
 

Thanks for the quick responses. So I can get the crossmember in and safely weld everything in its final place as long as I have 3 degree down on a level surface, weight on the wheels....


I'll weld and set the axle at the right angle when I'm ready for driveshaft.

Ive never been the hotrod pedal to the metal sort, so I hope I can avoid any leaf spring wind up stuff.

You said 3 down and 3 up. Some of the articles said to be off a tad but I don't understand why. Should I ignore all the different stuff I've read and simply go 3 down 3 up, put driveshaft in and I should be good?

Speaking of driveshaft... what's best way to measure to get one cut down to size?

Re: Choosing a transmission crossmember
 

3 down 3 up phases the driveshaft which some feel is bad and will wear the u joints quickly. however, the rear pinion angle is not a static measurement, its dynamic, so it will change as you accelerate and drive. even under load on the highway the leaf springs will twist slightly as the truck pushes against the load. even with a solid mount like a 4 link, the arc of operation will assure the pinion angle will not stay constant.

if you want to be suuuuuper technical about it, go 4 down 3 up, or 3 down 4 up. but I would bet almost all my money (and some of yours) that 3 down 3 up will work just fine. one of the "real world vs ideal world" things.

Re: Choosing a transmission crossmember
 

And this is why I like this forum. I can ask all the noob dumb questions I want and you guys never word a response in a way that makes me feel like a dummy. Thank you. This forum has been an amazing source for helpful advice.

Re: Choosing a transmission crossmember
 

your truck needs to be 99% together to get the correct height to get the length
with the front yoke all the way in, measure u-joint to u-joint and give this measurement to the driveshaft guy, he will deduct 1" off
this is how the shop that made mine asked me to measure

Re: Choosing a transmission crossmember
 

Just order you a new one this way it will come balanced

Re: Choosing a transmission crossmember
 

Ok guys, got it in. Had to also get a new mount, other one had bad threads.

Went in real smooth, minor trimming to fit. The center rotates in the end pieces, and I have not welded it just yet. I have a couple questions.


Where to place angle finder, each spot gave me different reading, or wouldn't real change when I jacked up or down. I put it on pan, on screws that hold pan, and on the very end on shaft.

Next, when I weld tube to keep from rotating any, I need to make sure the pad is parallel to mount surface on bottom of trans right?

Re: Choosing a transmission crossmember
 

it's a dillema for sure, where to place the angle finder. the trans shaft has some play in it because the yoke isn't in there to center it, the amount the bolts on the engine oil pan stick out depends on how thick the aluminum casting is under the bolt and the casting thickness can vary because that bolt head surface isn't machined, etc etc. you could put the angle finder on the vibe damper of the engine I guess.
to answer your question, the trans mount pad needs to be parallel to the trans mount surface. also, it may be a good idea to assemble the whole thing and have a jack under the cross member to hold the weight of the trans against the rubber mount, otherwise the angle gets skewed when the weight of the trans crushes the rubber some. personally I always leave a bit of room there so I can shim to get the angle right. \I fab a shim from flat stock and use that under the mount, between the mount and the cross member. if you put it dead on then there is not room to work with if you have a vibration, or whatever, down the road. can you use vice grips or ratchet straps to hold things on each side frame mount while you mock up?
if you have a yoke for the trans you could slide it in and put the angle finder on that possibly, depending on how nice a fit the yoke is with the trans bushing. you would need to take the rest of the driveshaft apart to get that unless you have a spare one that will fit. maybe the driveline shop would loan one knowing that is what is keeping you from having them work on a driveshaft for you. just some thoughts.