I'm still in the middle of my LS427/570 swap build so the car hasn't been driven yet. I'm using a Holley transmission crossmember. The engine is mounted on a UMI Road Race K member along with UMI's LS swap brackets. I installed the transmission several months ago and I thought that everything was good. This evening, I was under the car and on the passenger side of the transmission forward of the shifter, it appears that the transmission is up against the tunnel.

From what I understand, this Magnum F is supposed to fit 4th gen F bodies. I've done a lot of research and I don't remember anyone saying/posting that their Magnum F required hammer clearancing in their 3rd gen. Am I wrong? For anyone with a Magnum F in your 3rd gen, did it fit without hammer work?

 

If you've swapped in a Tremec T56 Magnum F, did you have to massage the transmission tunnel of your 3rd gen F body?

If you swapped in a regular T56, did you have to massage the transmission tunnel?

 

The shifter tower will bump against the top of the tunnel but the rest of the transmission housing should easily fit. Most people (all?) have to open up the shifter hole in the floor pan more rearward to make room for the teansmissuon shift tower.

In my case, I had to cut it so far back that I lost the bracket that the center console bolts to.

 

I've got my tunnel cut out about perfectly for my Magnum F's shifter tower. My transmission is actually hitting the tunnel forward of the shifter. Here is a picture of the Magnum, non-F in my LS swapped Foxbody Mustang in my signature:


The part that I circled in yellow is the part that is hitting my IROC's transmission tunnel.


I was looking at my engine from the front and noticed that my motor mounts on top of the UMI K member aren't exactly even. Close but definitely not even. None of the motor mount bolts are tightened up at this point. I'm starting to wonder if maybe my engine/transmission isn't lined up exactly straight, fore to aft. Maybe it's a bit sideways causing that part of the transmission to hit the tunnel.

I've now got the transmission crossmember loosed up real good and I'm going to get back under the car and see if maybe I can move the engine/transmission to see if I can get clearance where the yellow oval is showing in the picture.

 

You have a mix of non-stock parts in mpactng fitment. You have a non-stock trans. and shifter assembly.

And you didn't clearance it.

Shim the mount for your over priced revised Borg-Warner design up. Washer, fender shim, whatever. Driver it. After time, It will self clearance perfectly6.. Remove the shim(s).

If you set everything else up correctly, that's all it takes for an ideally clearanced Install.

 

I think you've got a bit of an uncommon problem that is unique to your car. Just gotta figure it out. The more you change things the more "unique problems" you'll run into. I've had my fair share of them too -- stuff that other people never really complain about but I had to deal with on my car.

 

I had one of those bolts hitting a fuel line in my 82. Removing the fuel line gave the clearance! But what its the line 3/8th so 1/2 in OD. It was where the fuel lines crossed the trans tunnel. I was running new lines so it didn't matter. In also had to elongate the shifter hole like everyone else. I have a poly engine mounts and a spohn x member so it maybe it a little higher than some(maybe?). Yeah, the magnum f totally fits, but its tight! Ill say this too, try and get it all up as high as possible if you wanna make it over speed bumps!

make sure the bolt head isn't rubbing the body. I had a long bolt rubbing the floor of my old truck. It took months to figure it out what it was. It only made noise on certain sections of highway and it drove me crazy. It wouldn't do it 90% of the time. And then it would resonate through the body.

the magnum f is awesome, you'll be super happy w it.

 

I didn't because during my research, I hadn't read where anyone had an issue.

The car is still months away from being started and I wouldn't have even known that I had an transmission interference issue if I hadn't been under the car dealing with my Holley Dominator wiring harness. Some of the wiring goes over the forward part of the T56 and I was working with it. That's when I noticed that the rectangle part just forward of the shifter was up against the floorboard.

When I installed the non-F Magnum in my Fox coupe, I knew that part of the transmission would hit the tunnel. I was able to take care of the interference and I've never had a hint of transmission/tunnel banging in the 2 1/2 yrs that I've been driving the car.

 

I told this to my wife and she said, "isn't that the truth!" I've had issue after issue with this build. My Fox coupe build was realatively smooth but this IROC is giving me grief every step of the way.

 

I spent all afternoon dealing with the transmission/tunnel problem. I loosened the Holley crossmember along with the transmission mount and tried to move the engine/transmission slightly to the left. It's as far to the left as possible. The only way to get it further to the left is to slot the bolt holes in the crossmember.

I was wondering if my engine/transmission assembly was sitting wrong in the car. I used my laser level to check and see how things line up. Here are some pictures:


If you look carefully, you can see that my laser dot is slightly off center of the harmonic balancer bolt. I tweaked it perfectly center but didn't take another picture of it centered. The following pictures were taken after it was perfectly centered.



Pretty close to center.


Again, pretty close to center.

One thing that is very apparent looking at the engine from the front of the car is the fact that it is sitting about 3/4" passenger side of centerline. It's very apparent with the way the passenger side header is very close to the subframe rail with a lot of room on the driver's side. This explains why the right side of the Magnum F is up against the transmission tunnel and I have a ton of room on the driver's side. At least my laser level is showing that everything is lined up. I'm 100% open to some education if I'm wrong on this.

I knew that the Foxbody Mustang has its engine sitting 3/4" to the passenger side. When you know it, it's easy to see. Former Holley engineer, username Todoky on the car forums, explained all of this in his engineering threads years ago as he was developing the LS swap kits for numerous different vehicles. I just never knew that the 3rd gen Camaro has the same offset.

 

I also cut a small access hole in the side of the tunnel with direct line-of-sight to the hex fitting on the slave cylinder bleed valve.

Post #1296, https://www.thirdgen.org/forums/ltx-...ml#post6326067

You will end up having to exchange the fluid periodically because of heat from the exhaust.