Auto to 5-Speed Conversion (Silver Sport Transmission Tremec TKX) Project Plus

[MoparCarGuy]

Word of caution on exhaust selection. I found severity of angle plus length of the Tremec on a lowered Challenger left my long tube TTIs with only 2.5 inches of ground clearance at the flange. Mid car placement left it very vulnerable to speed bumps so I changed to TTI shorties. Even then the head pipes off the shorties barely got me over speed bumps. Next step would be custom bent head pipes as there is plenty of room upwards. Might not be a problem with stock height suspensions. This is not TTIs fault but rather a trans issue that could only be solved by cutting out the crossmember that crosses over from the torsion bars. They do this on the 6spd but it’s not part of the 5 speed process.

I have already finished the conversion. The TTI 3” exhaust has been on the car since 1999. TTI discussed the fitment with me before the start of this project and told me they have not changed their systems since they began selling them. I had no exhaust issues and the TTI headers fit extremely well.
The thread will continue but here are a couple of header/exhaust photos.

 

[Drivun]

Nice fit. My build was 10 years ago with a tko600. Called TTI and they said it was the fit of the tremec, so we tried the shorties. Looking at American Powertrain pictures, from the top the TKX is much narrower than the 2 forward big square access panels on the TKO, probably allowing you to get it up higher than I could. Glad the TKX solves the problem as would have preferred keeping the longtubes. Im also enjoying the TKX improved shift quality in my 83 Mercury Capri.

TKO TKX comparo

 

[MoparCarGuy]

Nice fit. My build was 10 years ago with a tko600. Called TTI and they said it was the fit of the tremec, so we tried the shorties. Looking at American Powertrain pictures, from the top the TKX is much narrower than the 2 forward big square access panels on the TKO, probably allowing you to get it up higher than I could. Glad the TKX solves the problem as would have preferred keeping the longtubes. Im also enjoying the TKX improved shift quality in my 83 Mercury Capri.

TKO TKX comparo

Yes, a very different setup with the TKX. The engine is still tilted downward about 3.45° so driveshaft angle and rear pinion angle were corrected to cancel out.

 

[Flchallenger]

So what was you angle on you trans. Was it down 3.4 degrees and did you raise the rear end angle 3.4 up to match? I have the same trans but can't get it any higher up than 2 degrees down. Factor is supposed to be 2 degrees up and the rear 2 degrees down. I have had a lot of vibration problems with mine. Have a drive shaft with double u joints to compensate. Also are you running the 3.5 inch long tube headers? Then went to the shorties? I have schumaker shorties on mine but are very close to the starter.

 

[Drivun]

So what was you angle on you trans. Was it down 3.4 degrees and did you raise the rear end angle 3.4 up to match? I have the same trans but can't get it any higher up than 2 degrees down. Factor is supposed to be 2 degrees up and the rear 2 degrees down. I have had a lot of vibration problems with mine. Have a drive shaft with double u joints to compensate. Also are you running the 3.5 inch long tube headers? Then went to the shorties? I have schumaker shorties on mine but are very close to the starter.

Sorry for late response but I don't remember angles and car isn't here. I've had no vibration problems running car up to high speeds for up to 8 hrs a day. Don't recall needing to adjust pinion angle but I have hotchkis rear springs and spring mounts that have different geometry than stock. I started with tti long tube, then went to tti shorties. I have a hi torque mini starter with no clearance or heat issues. Ill try to get measurements this week.

 

[JKCuda]

Nice! I have one of these sitting in my garage. I'm going to install it in the fall though, just didn't have time this winter/spring and I don't want the car down all summer.

 

[JKCuda]

HINDSIGHT TIP: I installed the 4-speed factory tunnel without installing the transmission. That turned out to be a problem. Specifically, the TKX requires the engine/trans combo to be tilted downward which can create clearance issues at the factory 4-speed tunnel. I highly recommend that you install the transmission and mockup the new AMD tunnel first so you can determine if the new tunnel needs to be slightly raised (above the factory location). Now is the time to find that out.

During the floorpan work, I planned for the tunnel cutouts (two areas which avoid the factory crossmember) by mocking up the new AMD tunnel. Removing the console bracket for the automatic shifter was pretty straight-forward. I used a cordless 18V Ridgid cutoff tool and cutting discs. The rear console bracket is the same for automatic or manual so it remained in place.

A printed photo of the cutouts from the Internet added further confirmation of the cuts. TIP: Check everything above and below the tunnel prior to cutting so you do not have to repair anything due to making a mistake.

My original plan was to MIG weld the tunnel in place but the thought of sparks flying everywhere in my interior was scary. I considered using a wool blanket and welding underneath it but switched gear and sprung for a panel-bond adhesive installation. This turned out to be an excellent method and guarantees a permanent seal underneath the seam sealer.

Panel bond prep was very easy and I used self-tapping screws around the perimeter as well. The screws were left in place and seam sealer covered them above and below. NOTE: The crankshaft pilot bearing and flywheel are installed at this point but I will cover that later in the thread.

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Panel bond adhesive completed:

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I have the gun for this... I thought about doing this as well but was worried about flex. I do have the USCT frame connector kit install though so I may end up just doing the panel bond as well. I have a welder, but I am not a welder haha.

Word of caution on exhaust selection. I found severity of angle plus length of the Tremec on a lowered Challenger left my long tube TTIs with only 2.5 inches of ground clearance at the flange. Mid car placement left it very vulnerable to speed bumps so I changed to TTI shorties. Even then the head pipes off the shorties barely got me over speed bumps. Next step would be custom bent head pipes as there is plenty of room upwards. Might not be a problem with stock height suspensions. This is not TTIs fault but rather a trans issue that could only be solved by cutting out the crossmember that crosses over from the torsion bars. They do this on the 6spd but it’s not part of the 5 speed process.

This slightly worries me....I have TTI long tubes.

 

[Drivun]

I have the gun for this... I thought about doing this as well but was worried about flex. I do have the USCT frame connector kit install though so I may end up just doing the panel bond as well. I have a welder, but I am not a welder haha.

This slightly worries me....I have TTI long tubes.

If your doing a tkx you'll probably be ok based on previous comments. If its a tko, then either shorties or you might have to cut and strengthen the torsion bar cross piece to get the trans up higher.

 

[JKCuda]

If your doing a tkx you'll probably be ok based on previous comments. If its a tko, then either shorties or you might have to cut and strengthen the torsion bar cross piece to get the trans up higher.

Hopefully. We'll find out come late fall when I dig into it! For this year I'm going to stick with the built 904 I put in it... (against my will haha)