pancake

Car was originally a '78 L48 with the saginaw 4 speed. I just wrapped it up and wanted to post a short parts list since people are always asking how to do this.. this is just one way to cut it.. Here's what I used:

- Borg Warner T-56 out of an F-body (lt1 style)
- Mcleod 1400-22 hydraulic throw out bearing (to eliminate pull style clutch)
- 12" push style flywheel and ram clutch (that was in the car before..)
- Master cylinder out of an 85 chevrolet pickup (you have to cut the rod and make it adjustable. I used all thread and a rod coupler. The rod will also need bushed so it fits without a mile of play on the stock pin on the clutch pedal)
- VSS Reverse Lockout solenoid controller from Accutach (Mark is very helpful)
- GM reverse lockout solenoid, VSS, and reverse lamp connectors
- Offset shifter from Qwik Stick (2" to the left, 1.3" forward)
- Shortened driveshaft from 29.5" to 26.5" (you better measure yours!!)
- Cut cross member to make it removable, then cut out the middle of it and boxed it up to fit T56 mount
- Pulled the tailshaft housing and sent it to Dan @ t56cablespeedometer.com to have the tailshaft housing machined to fit a cable speedo gear
- 80" Speedo cable (mine needed replaced, anyway, from laying on the header)

I had to create a shim for between the bell housing and the transmission to get the required .100" - .150" that Mcleod calls for. I traced out a pattern on a piece of steel and used my plasma to cut it out.. then drilled it out. It worked surprisingly well.

I suspect I was lucky enough to pick up a t56 with reverse pop out problems so I'll be pulling it again to fix that. I've done it so many times for fitment that it's really not that big of a deal. It's either that or I have to adjust the stops on the shifter.. it goes into all other gears just fine and shifts smooooooooth.. So much better then with the saginaw crap box.

cv67

what did it cost to have dan do the speedo housing deal? Anything difficult for a trans novice in removing it guessing it couldnt be done in the car

Bigeddie

where can i get this offset shifter?

pancake

It's $325 plus return shipping to get the tailshaft housing machined for the cable speedo drive. His website is www.t56cablespeedometer.com Though I don't know if he is a supporter or not so the mods may trim this out. He's on here, though. The hardest part about removing the tailshaft housing is knocking the roll pin out of the machined piece where your shifter lever connects. Otherwise, it's as simple as unbolting it and lifting it off. Reassembly is a little harder. The bearing race and plastic spacer for the extension countershaft are a pain in the butt to get back together. I used grease to stick them in place and then carefully cursed and swore up a storm as I put it all together. Tremec has a 48 page assembly book on their web page that is free and has a complete breakdown and assembly including torque specs. I never pulled on apart before.. but I am an idiot and just tear into everything blindly and hope I can get it back together.


And the shifter is on ebay.. go search t56 offset shifter. I initially bought the wrong offset and they let me send back just the offset piece to swap it for the correct one.

cagotzmann

I am looking at making a change from the TH350 auto to a manual. But I am not sure I will see much change in performance with the change. I know a manual adds the fun factor but driving on road tracks I am not convinced it will be a possitive change. My car is also a L48. Do you have any track time with before and after results ? 1/4 mile or lap times ?

pancake

I have never run it on a track and received a time slip. I did run it on the oval at Texas Motor Speedway and around their infield course... but no slips. I went from the saginaw four speed and 3:36 final drive to the t56 with 4.11, so my final drive is considerably lower in first through fourth gear...

3.36 4.11
1st 2.85 9.576:1 2.66 10.9326:1
2nd 2.02 6.7872:1 1.78 7.3158:1
3rd 1.35 4.536:1 1.3 5.343:1
4th 1.00 3.36:1 1.00 4.11:1

So it'll come out of a corner or out of the hole better (if there is traction) and still have 2 over drives for cruising.

And the l48 is sitting on my shop floor on a pallet. I've got a little more weeeee! under the hood.

MIKE80

Nice! Done a bit different from others, including myself. Cool to see someone else converted the LT1 T56 to a hydraulic throw out bearing. Good work. Thanks for sharing. If you have any pictures of the swap post them up.

pancake

The hydraulic throw out sure saves a lot of cash vs swapping in the longer input shaft and going to the ls1 bell housing.

Here is the master cylinder mounted:


Top shot of the cut and boxed cross member:


Side shot of the cut and boxed cross member:


The bellhousing spacer:


Fitting it 1 of the 1,000 times:


Up and installed:


Another view:


Modded master cylinder rod:


Measuring clearance between pressure plate and throw out with playdoh.. (Not enough clearance here):


And that's pretty much all the pics I took.