anyone running a tremec 6 speed?

[Possmguts]

I'm saving up to buy a tremec 6 speed for the 67... is anyone here running one? If so can I pick your brain on the install and how you like it?

[NC_John]

Originally Posted by Possmguts

I'm saving up to buy a tremec 6 speed for the 67... is anyone here running one? If so can I pick your brain on the install and how you like it?

I put one in my '70. Install was a pain in the ass and I love it.

[Possmguts]

Originally Posted by NC_John

I put one in my '70. Install was a pain in the ass and I love it.

What gear ratio are you running and what RPMs are you at at 70 MPH? Is the speedo correct? Was it a kit made for these trucks or did you have to fab everything to make it work? Did you go with hydraulic clutch or mechanical? Any links to an install thread by chance?

[NC_John]

Originally Posted by Possmguts

What gear ratio are you running and what RPMs are you at at 70 MPH? Is the speedo correct? Was it a kit made for these trucks or did you have to fab everything to make it work? Did you go with hydraulic clutch or mechanical? Any links to an install thread by chance?

I am running 4.56's and still can't get into 6th gear until 75-80 mph without lugging it. I could probably get away easily with 4.88's but am not sure what that would do to my 1st gear. Right now it remains very useable. I think my rear tire is 29" tall.

I bought a used early gm f-body (maybe a 93?) t-56 on c-list (I had been looking for months and got this one an hour after the guy posted it). I took it to Tick Performance in NC (google them) and had them do their stage two (built for a very conservative 700+ hp/lb-ft). They had to replace a few major components so by the time it was done, I could have bought a brand new magnum. Oh well. They guys promised I could bounce the engine off the rev-limited and side-step the clutch and it won't break.

I am using the factory bellhousing, ram aluminum flywheel and clutch (needs a conversion from LT-1 to gen 1 with 2 piece rear main), aluminum clutch slave cylinder and wilwood master cylinder. I bought the shifter relocation kit to go midway and an f-body short throw shifter which I used to build mine from an old 4-spd shifter I bought here on the parts board. I am using a big truck shifter boot and an original 4 spd boot trim ring. High hump tunnel was required and I had to trim even more out of the floor behind the hump at the rear of the transmission for it to clear.

I am using a CPP transmission crossmember with a performance suspension mount. I haven't seen anyone else have to trim as much metal as I did but my transmission is super tight and not visible below the frame rails.

I still have to figure out what to do about my speedometer. The original gauge doesn't get along with the electronic output of the t-56. The conversion kit (electronic to cable) costs so much that it tempts me to just upgrade the gauges too. I use a phone app for a speedometer but want my odometer back for maintenance.

I have more money in the transmission than the engine I built but it was worth it. It is a bad-ass setup for sure and changes the entire personality of the truck. Now I want to take advantage of the overbuilding of the tremec and make more power in front of it.

I don't think I covered it on my truck build thread but there is a pretty good one on here already that a lot of used as reference.

[davepl]

I've done two of them now (TKO-600s, not the 6 speed). Love the trans. Ensuring zero runout with adjustable bellhousing pins wasn't much fun... do that on a stand, not in the car, if you can!

The top right bolt on mine was bear, I wound up making a tool out of an old allen key and a tiny wrench welded to a bigger wrench! There's probably a "right" too for that.

Otherwise, I thought it was all pretty straightforward.

[Possmguts]

Originally Posted by davepl

Ensuring zero runout with adjustable bellhousing pins wasn't much fun... do that on a stand, not in the car, if you can!

What does that mean?

[LS short box]

On the TKO 600 you have to dial in the bell housing to the center line of the crank. The T56 you don't if you use the stock bell housing.

I had a TKO 600 in LS swapped 1973 Camaro and liked it.

I have a T56 Magnum in a 99 BMW E36 vert LS swap. I much prefer the T56. Shifts much smoother. LS7 clutch. 2000 Camaro throw bearing. Zero problems.

I ran 3:73's in the Camaro. 285/40/18". LS3 with a small cam an it would pull down 22 mpg at 75 mph all day long.

The BMW with 3:91 gears will do 25 mpg. If I was to do it again I would have 3:64 gears in the BMW. It's great swap. Think of it as a 2000 Camaro that weighs 700 lbs less. Or M3 with another 175 HP.

[davepl]

Ensuring zero runout...

Originally Posted by Possmguts

What does that mean?

So the TKO trans is a "fixed" input shaft, it doesn't float or wobble. It's solid. So it needs to be DEAD CENTER relative to the engine centerline or it'll be off center. That'll cause a bad vibration at a minimum and probably much worse.

You'll have to research the exact steps, but you basically put a magnetic dial indicator on the clutch/flywheel assembly and then rotate the engine with the dial indicator measuring the distance out to the edge of the bellhousing. It can't vary more than a couple of thousands (I forget the exact spec). If it does, and mine was, then you have to get offset dowel pins in the amount of the error to "walk" the trans around in whatever direction you need to fix the offset error.

Then when you're done the center of the engine is aligned with the center of the trans. This isn't important, I'm told, on the old M-21 and similar transmissions but is critical on these.

[Lattimer]

I looked at the 6 speed, added up the cost of everything I would need, and went with the TKO 600 5 speed. Very happy with it.

But I can see where the 6 speed would have been more useful, at least for the way I drive. The overdrive requires me to be be doing about 55-60 before I can use it at all without lugging the engine. I really want to be doing 65 before I use it. IIRC 5th gear on the close ratio 6 speed would be in between 4th and 5th on my wide ratio 5 speed

[NC_John]

Originally Posted by Lattimer

I looked at the 6 speed, added up the cost of everything I would need, and went with the TKO 600 5 speed. Very happy with it.

But I can see where the 6 speed would have been more useful, at least for the way I drive. The overdrive requires me to be be doing about 55-60 before I can use it at all without lugging the engine. I really want to be doing 65 before I use it. IIRC 5th gear on the close ratio 6 speed would be in between 4th and 5th on my wide ratio 5 speed

I figured for the money and effort I was going to spend, I was going to get what I really wanted (the 6). I was worried I would do the 5 now and regret not getting 6 later. I almost need some more rear gear to make 6th more useable. Right now, even with 4.56's, it's my "go-to-jail" gear.

[Lattimer]

Originally Posted by NC_John

I figured for the money and effort I was going to spend, I was going to get what I really wanted (the 6). I was worried I would do the 5 now and regret not getting 6 later. I almost need some more rear gear to make 6th more useable. Right now, even with 4.56's, it's my "go-to-jail" gear.

I have 3.73's and 29" tires. 5th gear at 70 mph is right about 2000 rpm.

I thought the same as you, I really wanted the 6 speed. I was stretching the budget pretty hard to get the 5-speed. Going with the magnum was almost $1000 more for the trans, plus I would have had to buy a bell housing, hydraulic throw out, speedo kit, etc. Probably modify the low hump floor also. It took a $3k swap kit up to almost $6k. then to really use it I'd need to re-gear also. Whole thing became overwhelming to my budget, especially since it was a driving truck, not a torn down project. Letting it sit for months disassembled while I saved for something I needed wouldn't fly.

I did it at the same time as my crate motor swap, and I bought the trans kit from American Powertrain. Everything bolted in nice, all I had to do was flatten the pinch weld at the firewall and cut the floor for the shifter.

Like I said, I'm happy with it. It drives nice, its fun, and the cost only almost broke me.

[Possmguts]

I haven't really even started pricing the whole thing up yet and what I'm reading from you guys is that I'm gonna need a bunch more that I thought... I was thinking around 3500 or 4000 for everything. But with that 6 speed you're saying my final gear at freeway speed will be around 2000 rpm with the 3:73 gear? I guess that's ok but I was thinking it would be a little lower.

I do really want the 6 speed... you just don't see that in a 50 year old truck much. I want to be able to head out on the road for hours and not have to stop for gas every 100 miles... But want the low end get up and go for that occasional tire frying session...

[Lattimer]

Originally Posted by Possmguts

I haven't really even started pricing the whole thing up yet and what I'm reading from you guys is that I'm gonna need a bunch more that I thought... I was thinking around 3500 or 4000 for everything. But with that 6 speed you're saying my final gear at freeway speed will be around 2000 rpm with the 3:73 gear? I guess that's ok but I was thinking it would be a little lower.

I do really want the 6 speed... you just don't see that in a 50 year old truck much. I want to be able to head out on the road for hours and not have to stop for gas every 100 miles... But want the low end get up and go for that occasional tire frying session...

Using my stock bell housing, the kit with everything else from American Powertrain for the TKO 600 5 speed was $3900 with free shipping (2 years ago, prices may have increased). Thats clutch kit, shifter, shift lever, trans, crossmember, driveshaft, u joints, trans yoke, speedo cable adapter, hardware. I had to add in a shift boot and a flywheel for my install.

IIRC, the Magnum 6 speed was like $900 more, then you need the hydraulic throwout setup at $700, and I would have needed to buy a new bell housing at $400.

My truck is a low hump, so I would have had to find a high hump to install (or make one--which is really beyond my ability), and change the carpet.



As for RPM, it depends on which trans. There are 2 different ratios you can get.

One is .63 OD in 6th, which is about the same as my 5-speed in 5th at .64. The other is .5 OD, which would turn a lower highway rpm.

Keep in mind if your engine is carbureted, cruising below 2000 rpm won't get you very good performance or mileage. Carbs don't work well at really low RPM. 2000 to 2200 at cruise seems to work pretty well. I think it has a lot to do with the vacuum signal.


Take a look here and punch in your numbers:

http://americanpowertrain.com/p-7584...-analyzer.html



My small block made 382 hp, 402 tq on the dyno. I run a StreetDemon 625 carb. 3.73 rear, cruising mostly highway, I see about 13.5 mpg. Mixed driving it drops to 12. Too much playtime it turns into 8-9.

FWIW, my daily driver is a supercharged Toyota Tundra 4x4 CrewMax. It gets about 12.5 on the highway.

[NC_John]

Originally Posted by Lattimer

I have 3.73's and 29" tires. 5th gear at 70 mph is right about 2000 rpm.

I thought the same as you, I really wanted the 6 speed. I was stretching the budget pretty hard to get the 5-speed. Going with the magnum was almost $1000 more for the trans, plus I would have had to buy a bell housing, hydraulic throw out, speedo kit, etc. Probably modify the low hump floor also. It took a $3k swap kit up to almost $6k.

I bet I have $5-6K in my 6 spd..... Ouch. The transmission itself is just part of it- all the other stuff just keeps adding up....

[Possmguts]

Originally Posted by NC_John

I bet I have $5-6K in my 6 spd..... Ouch. The transmission itself is just part of it- all the other stuff just keeps adding up....

Damn it man.. you guys are not doing a very good job of helping talk me into this...

[Lattimer]

The other way to do it is to find something in a junkyard, which is probably cheaper. I wasn't willing to go through all that effort for a used trans that I would probably have to rebuild and wind up at the same cost, plus spend a lot of time piecing together everything I would need.

[Possmguts]

Originally Posted by Lattimer

The other way to do it is to find something in a junkyard, which is probably cheaper. I wasn't willing to go through all that effort for a used trans that I would probably have to rebuild and wind up at the same cost, plus spend a lot of time piecing together everything I would need.

Yeah, I'm not into the whole junk yard thing when it comes to things like this.. I like knowing I have some sort or warranty on the high dollar parts.

Now I just have to decide on the 5 or the 6... but I really want the 6. Ill have to weigh how much Ill actually be driving on road trips I guess...

[bronze 72 super]

After reading about all the mods. required, money, labor, parts searching, etc. I'm staying with the original 4-speed in my '71 Cheyenne Super C-20. Does what I want it to. I don't get in a big hurry going down the Hwy. Easy to work on, and all the time and money saved, goes towards another '70 Chevelle!!

[Lattimer]

Originally Posted by bronze 72 super

After reading about all the mods. required, money, labor, parts searching, etc. I'm staying with the original 4-speed in my '71 Cheyenne Super C-20. Does what I want it to. I don't get in a big hurry going down the Hwy. Easy to work on, and all the time and money saved, goes towards another '70 Chevelle!!

Thats one way to look at it.

[Possmguts]

Originally Posted by bronze 72 super

After reading about all the mods. required, money, labor, parts searching, etc. I'm staying with the original 4-speed in my '71 Cheyenne Super C-20. Does what I want it to. I don't get in a big hurry going down the Hwy. Easy to work on, and all the time and money saved, goes towards another '70 Chevelle!!

What I got with the truck was a th350... I have 3:73 gears... its not a freeway friendly set up. If I'm going to build something to have fun in before I kick the bucket, I'm gonna put what I want in it, and I want it to hold together when I'm sticking toes in the carburetor

[Ruscal]

I am in the process of switching out a TH400 for a magnum. I'll take some pictures along the way to share. Rear ratio is 4:10 with 28.4" tires and close ratio T-56. Engine is stock 350 crate at this time.
Russ

[slowcpe]

I have a t56 mag sitting on the garage floor. No experience with it yet as its a complete tear down project. In for other people's experience.

[30 a truck]

I ran a 6 speed in this 30 A truck . Engine & trans were from a 2001 Camaro. 373 gears, 1400 RPM at 70. Hardly ever ran 6th gear. Loved it.

[NC_John]

But wait, there's more ($$$). I forgot I also had to buy a new starter (to work with the new flywheel since the tooth count changed) and get the exhaust tweaked since I changed crossmembers and the way it had to be run for the original three-speed was dumb.

And or course, the 3.07 gear wasn't compatible with the 6 spd... 6th gear would have been numerically good for something like 300 mph when I calculated it. So the cost of the rear-end needs to be in there too.

Yeah, its not a cheap upgrade, but probably one of the best you will do.

[Possmguts]

About to head back out on the road for the week, and thats when I do my best thinking.... Thank you guys for all the input. Each one of you gave me some things to ponder.