The Stovebolt Site Forums The Shop Area Engine Shop Remove Rear Engine Support Crossmember?

I'm planning to replace my 235 inline with an SBC V8 in my 1955-2 Chevy truck. Do most people leave, modify, or remove the original rear engine support crossmember in their truck when replacing the original inline six with a SBC and 700R4 tranny? I currently have the SBC with a 700R4 suspended in the engine bay on a hoist to clear the rear crossmember and the combination seems to fit in the engine compartment, although somewhat higher than normal.

Don't remove it completely- - - -it also provides very necessary support for the rear spring hangers and you'll end up with serious frame flexing if it's gone. A couple of 1/2" steel plates with a piece of heavy wall 2" square tubing like a trailer hitch uses welded to them makes a good substitute, and allows more clearance for the bellhousing without seriously compromising ground clearance.
Jerry

Most opt to cut it out. The trouble with leaving it in place is that you won’t be able to remove the trans without removing the whole works. In my opinion, modifying it to be removable is the best option. These frames already have a lot of side to side flex. Not only does it provide support for the leaf spring mounts, it provides support for the cab mounts too.

Snowman: on my ‘48, as youll see when you analyze the attached photos, I cut out the the center of that crossmember, but to somewhat retain that support, fabricated a 3/16” thick steel tie plate spaced below the bottom of my 700R4 with 7/16” coupler nuts and bolts (4 on each side) on either end of the remaining support at the lower horizontal flange of that crossmember. Plenty of ground clearance and room for dual exhaust. I’ve got 4000 miles on it with no problems...
Good luck. Dave

Thanks all for your comments!

I don't know how you got the new combo to clear the old support, but if you did and can maintain proper pinion angle, good job. You also don't say what is supporting the 700R. A pic or two would be nice.

bartomos: I’ve still got the original rear trans crossmember bolted into the frame although you can see I notched and boxed it to accommodate the tail shaft of the 700R4. And for that matter I could have eliminated it all together as it no longer supports the rear of the trans; I figured I’d keep it in place for the benefit of its original factory bracing to the side rails. The trans at the rear is now supported by one of those universal fitsall adjustable rear trans mounts where the tubular ends initially telescope onto the center section: once I got everything centered I welded the ends to the middle section. As you can see it sits just forward of the original rear trans mount. (What the h was I thinking?!) The rear axle is an early 70’s “F” body (3.73 posi). I cut off the original rear spring perches and welded on new ones once I got the axle centered and got the pinion angle correct.
Good luck. Dave

Good work Dave. You have good fab skills.
Just to continue the exploration, I am asking the same question to the poster. Bartomos Bartamos

Warning. Ignore all of the following. It only applies to ADs. Dude asked about his TF, which I looked right over.

I cut the center section of that crossmember out enough to allow removal of the transmission in the future.
I then made some 1/8" steel plate to weld on to the remaining stubs of the crossmember which dropped straight down so that I could attach the center section of crossmember back on 2" lower.
The center section also had 1/8" plates welded to the ends in such a way to mate with the plates on the stubs.
I drilled holes through the plates so that I could bolt the center section to the crossmember studs for easy removal when needed.
The attached picture is the 1st of two of this modification I have done. I recommend that the cuts be made vertically rather than on an angle as in this pic. If you cut it vertically, it will fit like a glove since the plates will take up the gap created by the kerf from the cuts when the center was removed with a cutoff saw.
Carl

s the combo is suspended, the tranny pan clears the original cross member by 3/4". I have a tubular transmission mount I will use to support the tranny from, similar to the tubular engine mount I will be using. Can you think of any issues I my have down the road if I install the engine higher than normal … providing I can get the driveline angles satisfactory?

Well, don't know what higher than "normal" is. What makes you say that? Really high? Can't go too high and still use the tubular cross member, right? Fits inside frame or top or bottom. Depending on what ends you have.

Anyway I will list a few that you probably already know.
1. The pinion angle. You have a said that will be checked.
2. Cooling fan center to radiator center. Radiator hose interference with ?
3. Hood clearance to air cleaner.
4. All Chevy V8's have a built-in 4 deg down angle when carb is level. Carb/intake must be level.
5. Trans too close to floor/firewall.
6. Distributor clearance.
7. Header/exhaust manifold clearance to body/steering/firewall/frame/inner fenders.

I de-riveted the rear cross member, which left the rivet holes in cross member and in frame so that I could bolt it back on if needed. Don't worry about taking it out that way. You are "reinforcing"/"replacing " it with the two new cross members. No big deal if you need to take it out. The de-rivet is not easy but worth the effort. I had the motor out, tires off and front clip off and had access to sit and drill and grind. One at a time. Cutting it off is not the way to go. Leaving it in when you have the chance to remove is probably a bad idea. Your future plans, if you ever do them (348), will not need this piece. Take it out now, properly (de-rivet) 1/2 day or a week, whatever.

You are getting some good feedback. Some is from AD guys. Mine is from TF experience. You have a TF.

Oops. Missed the pesky detail of "you have a TF".
My over-the-top masterful, eloquent, informative, replete with awesome picture post was for an AD.
Never mind...

Carl

bartamos's's's nemesis.

All advise is good, or at least food for thought. I very often comment on AD posts and have never had one. Most mechanical/electrical issues are very similar. Carl does good work, just not much of it. His advice is valuable and respected. He is from Virginia. It is one of our states I think.

Virginia. The State of Confusion.

Living in Arizona is just a state of mines.