skydude

Need to cut the trans tunnel on my 72' Chevelle to fit a 5.3/4L60e at the correct angle. Wanted to ask anyone who has done this before. Is it best to cut around the sides of the entire tunnel and splice in an extension or cut down the middle and accross the ends, pry up and then fill in? Also is it best to have the engine/trans in the car or out? Thanks for any input.

dvdswan

most tunnel work I've seen has been on the sides.

bczee

iTrader: (12)

I cut the top off down to about 1 1/2" from the floor. But I would suggest the Tee cut first. It should fit with out too much effort with the BFH..

The 4L60e isn't too much bigger than a TH350.

If you having tunnel issues, you might have you engine mounted either high or set back, which would be more likely to cause tunnel issus.

What mounts are you using ?

skydude

3/8" plate on the motor, energy suspension mounts and the original 350 frame mounts. The motor is only about 1/4" above the cross member so it can't go any lower, it actually should be raised a little.

Under the carpet it looks like the floor might have been replaced so not sure if it is setting lower than what came from the factory.

oange ss

iTrader: (50)

you should have no problems fitting a 4L60E under the stock floor

Toddoky

Fitting it under the stock floor is not a problem, but getting in with an acceptable engine inclination angle for desired U-joint working angles is. The lower your ride stance is, the worse the problem is also.The problem is a byproduct of having to raise the front of an LS engine high enough to clear the inner tie rod ends at full steering lock, since the oil pan width of an LS is approximately 1.5" wider than the older SB and BB Chevy engines and doesn't allow the front of the engine to sit down between the tie rods like they did. The engine has to come down or the tail of the transmission has to come up to replicate the engine inclination angle that GM design into the car, so you can either get the steering out of the way to enable dropping the engine by swapping to a rack and pinion, or you can cut the floor and raise the rear of the trans. You can of course choose to install it as best you can without either of these expensive fixes, as others have done, but you will know in the back of your mind that you're not providing yourself with an optimally engineered set-up.

skydude

You are so right, clearance in the front and a 3 degree angle means not enough room in the tunnel. I was just trying to figure out what the best way to cut would be. I would like to keep the top of the tunnel like it is since it already has the shifter cable hole and the screw holes for the consol, and it appears from looking under the carpet that the floor has been replaced. So I was thinking that cutting around a couple of inches up then adding an extension might be best.

I would rather do the extra work than have driveline problems later.

bczee

iTrader: (12)

Ride stance may cause a problem. But remember that getting the correct pinon and transmission output angle is somewhat a different subject. Correct angles of the pinon and output shaft and drive shaft angles are more key.. as compared to Stance (which is more of causing a problem that may trasnslate into a problem getting the correct angles)

Check your pinon angle to see what it is before trying to set the engine angle. The two should match or be close.

there are some good articals on the web. .just search for them..
http://www.4xshaft.com/driveline101.html
http://www2.dana.com/pdf/J3311-1-DSSP.pdf

But all things do come into play.. good luck with getting everything setup.

BC

Toddoky

You got that right bczee, pinion angle and U-joint working angles are different, but both are important to get right for a well engineered package.
The crank axis/engine inclination angle and the pinion angle should match each other within half a degree and U-joint working angles should be kept to less than 3 degrees, which is why I mentioned ride height...lowering the rear of the car normally increases the U-joint working angles unless you started with a car that was jacked up in the back and you had a down-angle driveshaft to begin with.

bczee

iTrader: (12)

I used to have a car that resembled that LOL. .good old California Rake !..

Toddoky

Yep, I remember seeing quite a few of those in my high school days running around with Lakewood traction bars and the "stink bug" rake (Yep, that ...oopps, I guess I've just dated myself.

dobbs187

I had to cut corners of oil pan (truck pan) and replace inner tie rods with ones that has zerks on the top not the end by pan. I also got a lower tranny mount I believe it was from a chevelle with manual tranny and only had to use hammer in one spot on driver side where main tranny meets the bellhousing (don't know the proper term for that piece for auto) not sure on engine angle I don't have tool to check it but truck intake with shield is very close to cowl hood mayby 1/2-3/4 inch I don't have it running yet but kinda worried about it torquing and hitting hood