Advise on which tunnel mod kit for LS3 w/T56 Magnum in 1st Gen?

[Nativefx]

Okay I've been searching all day on all the forums that i can think of trying to find a thread I remember reading a few weeks ago talking about the advantages of one of the tunnel mod kits. I'm going to swap in a T56 Magnum so I need to mod the tunnel for clearance. I know Speedtech and Chassisworks have pre-fabbed metal for this, I'm just looking for people's experience with either one?

If you have already modded your tunnel, did it also provide the necessary clearance for the bellhousing, or did you still need to massage the front of the tunnel for clearance? How much additional clearance do I need in order to fit the T56 magnum and get an optimum driveline angle? What kind of angle should I be shooting for?

thanks, Jake

[ADiCarlo]

I just went thru this. Let's start with the crossmember, have you purchased one or decided to fab your own?


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[Nativefx]

Hi AdiCarlo, no I have not purchased a crossmember yet. I figured the answer for the tunnel mod kit would lead to the correct crossmember? I was also hoping it would then lead to the right motor mounts to use.

FYI - I will be using a full length TMI center console, if that will matter for anything.

[ADiCarlo]

Ok that's great then! I would recommend a custom tunnel cap and crossmember similar to what Stielow or DSE is doing. I say this because to obtain the proper driveline angle your really going to have to tuck the transmission into the tunnel and I can't see a all for one cap truly being the solution.

Just FYI I purchased an off the shelve crossmember and ended up with 8 degrees of angle even when fully adjusted. We had to scrap that and make our own to get the needed 1 to 3 degree ratio we wanted.

I feel that because there are so many variations of engine mount set ups a lot of companies don't want to make crossmembers because there is too much variables in the mounts.

Here's our tunnel cut with a f body style trans mounted on a DSE subframe with DSE set back engine mounts:
https://www.flickr.com/gp/48011683@N07/Y83ii2


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[Nativefx]

Hmm so are Steinlow or DSE offering these custom caps and crossmembers? What crossmember did you end up using with your tunnel cap to get the driveline angle? Was it enough to clear the bellhousing as well? Are you using full size subframe mounts or half?

I've been reading through your build thread and see you are also using a Restomod Air AC system. I haven't read completely through yet, but did you end up with the Haymaker evap unit? If so, were you able to mount and space it away from the firewall so it doesn't hit the top portion of the tunnel? I need to figure out something because I'm mounting speakers in some Screamin Performance enclosures that will go in the kick panels. Right now due to the size of the evap unit, I don't think I'll have enough clearance unless I space it away from the firewall and then slide it towards the middle of the car a little more.

[ADiCarlo]

They make there own and are not for sale off the shelf. I would call DSE direct maybe they can make you a one off.

We ended up making our own similar to what Mark Stielow did but mounted it off the subframe where he did his off the body and reinforced the metal. This required us to raise the floor panels to get optimal clearance and tucking.


Check out this thread:
https://lateral-g.net/forums/show....php4?p=617961

We had to cut a little farther forward into the tunnel to get the best clearance for the bellhousing but this wasn't required.

We're using half inch body mounts.

Haven't fitted the haymaker yet but it shouldn't interfere with the tunnel. The kicker panels with speakers may be a different story. Once I mount I can try and take measurements.




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[Vega$69]

I used the Speedtech tunnel cover.

Worked perfect and it is for sale

My last car a fabbed my own cover. Cut the hole in the tunnel as required to position the tranny correctly, made a cardboard mock up and made the sheet metal cover.

Which is why I went with the Speedtech this time. I do have the Speedtech sub and X member.

[wiedemab]

Here is another option for you.

http://www.bbclassicsinc.com/product...-tunnel-patch/

I talked to Billy last week and ended up ordering one for my '67 Chevy II project. I'm building the floors from scratch, but this is worth it in time savings. I'll post pics in my build thread once I get it.

[Nativefx]

I was hoping to be able to use a pre-formed tunnel cover, but I'm concerned about what actually works. It seems there are a number of factors that could come into play such as body mounts being used (full or half), stock subframe compared to aftermarket, space available for exhaust, correct motor mounts, etc. I'm using my stock subframe so I'm hoping I don't have to fab a one off. The main thing is if I have to cut the tunnel I want to make sure it will be sufficient to get the correct drive line angle. I haven't bought the x member or motor mounts yet so hopefully I can figure everything out and get the right parts that will work together on my stock sub.

Originally Posted by Vega$69

I used the Speedtech tunnel cover.

Worked perfect and it is for sale

My last car a fabbed my own cover. Cut the hole in the tunnel as required to position the tranny correctly, made a cardboard mock up and made the sheet metal cover.

Which is why I went with the Speedtech this time. I do have the Speedtech sub and X member.

[Musclerodz]

Speedtech make a complete kit to make this a very simple deal.