6 Speed Swap

[courage 80]

I have the 65 step side. It has a 350 from a 74 C-10 in it from the PO. It still has the original 4 speed granny tranny. The truck is geared pretty low, as most of them are from this time frame. It has a tow package on the back so I think the PO used it to pull a trailer. ANYWAY. 60 mph on the highway is about tops for me... speed limit is 75 mph.... so I get a lot of compliments about my truck (i.e. Nice truck, get off the highway.)

I found a deal on a 6speed transmission out of a trans am/camaro with all the parts. The guy wants to put in an auto.

I need a little input on possible problems that I will incur, so I can adjust my budget.

1) is it possible to use a mechanical clutch vs a hydraulic clutch.
2) Will the trans bolt up to the engine (input shafts, bell housing)
3) Other problems / obstacles that I will have to be aware of?

I know the shifter will be back further---------
----bucket seats will probably get put in anyway as the bench is shot
I will need to put in a brace for the new transmission
-----Friend has welder or buying one of the after market braces for $160
I know the speedo sensor on the trans is electric vs mechanical
-----I will use a hand held GPS as a speedo for now

[Ham-er]

Dont know about the 6 speed you are thinking of but,
Just about ALL transmitions not using overdrive are 1:1 ratio in top gear, including your granny low (SM420?) So in top gear on the highway it wont make any difference in speed to change just the tranny unless you are changing to one with overdrive. Without over drive to get better highway speed you need to change the rear end gear ratio!!

[courage 80]

From my research the trans is a 6 speed with an 0.62:1 ratio 6th gear. That is the reason I was looking at the swap.

[Musclerodz]

If it is an LT-1 6 speed it will bolt up. You can't use it without installing the hydraulic clutch and don't know why you wouldn't. You will also need to build a crossmember for the tranny.

Mike

[courage 80]

well, I struck the deal, and pick up the trans on saturday..... It is an LT-1 and from what I can now tell it has a (.72:1) 5 gear and a (.50:1) 6th gear.

Musclerodz, I had read somewhere that I may need an adapter plate? You are saying this trans will bolt right up to the 74 350 engine out of a C-10, correct? Is there anything else that I will need to get in order to make this swap work? (I am going to build the crossmember support). I am not going to worry about the speedo right now.

I am going to use the hydraulic clutch out of the donor. I am also getting the shifter console,the pedal and hydaulic clutch, the drive shaft, the bellhousing and all other parts that are used for the manual trans (as the owner is putting in a auto)

[courage 80]

I found this on Ebay.
Item number: 250144255780

Billet Steel T56 Mounting Adaptor Plate

[[ " Auction is for a new billet steel T56 adaptor plate. Plate will allow you to remove a Muncie, T10, Saginaw or T5 transmission, mount a T56 transmission and retain the use of your original bell housing and clutch linkage. Plate has dual bolt patterns, allowing you to mount transmission straight up or at 17 degrees, as needed for Camaro and Firebird applications. Plate comes with all mounting hardware to mount plate to trans and bell housing. Fits many GM applications, Chevrolet, Chevelle, Camaro, Pontiac, Oldsmobile, Buick, and many other GM models."]]

Is this only if I didn't have the new bellhousing and hydraulic clutch or do I still need something like this?

[19GMC63]

as long as you use the LT1 bellhousing, your set.

[Musclerodz]

Originally Posted by courage 80

I found this on Ebay.
Item number: 250144255780

Billet Steel T56 Mounting Adaptor Plate

[[ " Auction is for a new billet steel T56 adaptor plate. Plate will allow you to remove a Muncie, T10, Saginaw or T5 transmission, mount a T56 transmission and retain the use of your original bell housing and clutch linkage. Plate has dual bolt patterns, allowing you to mount transmission straight up or at 17 degrees, as needed for Camaro and Firebird applications. Plate comes with all mounting hardware to mount plate to trans and bell housing. Fits many GM applications, Chevrolet, Chevelle, Camaro, Pontiac, Oldsmobile, Buick, and many other GM models."]]

Is this only if I didn't have the new bellhousing and hydraulic clutch or do I still need something like this?

That sounds like an adapter to retain the mechanical linkage but why would you want to do that? It will make shifting a chore.

Mike

[layinrocker65]

I have a t56 out of a camaro in my truck. I have to buy a special flywheel because of my 2 piece rear main seal. The bolt patten for crank on the 1 piece and 2 piece rears are different. The lt1 has a 1 piece. If you have a one piece you can just use everything from the camaro. If you have a 2 piece you can buy part # haY-10-330, HAY-20-330, OR CFT-700107 FROM SUMMITRACING.COM. These are the flywheels that will work. I suggest getting an alum. one becasue my steel one os hella heavy. You have to use a clutch for an lt1 and a starter for an lt1.

what gears do you have in the rear end and what size are your tires?

[courage 80]

I am not sure of the gears in the rear end... but I think they are pretty stout. I am running 31x10.5 15s for tires. I can only get 60-65 and the truck sounds like it is screaming. I could probably push it to 70 or 75 but it just doesn't sound good to me.

I couldn't get the CFT-700107 part to pull up.
I have a 2 piece rear main, so I will have to get the flywheel.
I think that between the two that I could see, I will probably go with the steel one for price. I am trying to maintain some resemblance of a budget.

[layinrocker65]

If you have 31" tires you are going to need really low gears. I have 3.07 gears in my rear end with a 27" tire height and on the freeway I am at 2700rpm in 4th gear at about 70mph. I can even use 6th gear. I am going 4:11 in the rear when I get the money. You would need like 4:56s. A stock camaro has smaller tires, on a lighter car, with 3:73s. If a heavy truck you need the gears. I have to ride my clutch like crazy to get started. Your truck probably has really high gears.

[courage 80]

I got the trans this weekend.... as well as everything that goes with it from the pedals to the shifter console to the driveshaft, and flywheel/clutch.

From what I read, the 2 piece rear main seal and 1 piece Rear main seal cause the flywheel to need a different colt pattern, correct?

I am going to pull the engine the beginning of this week and haven't compared flywheels yet. SO.... Is it possible to take the flywheel that came with the trans (for a 1 piece) to a machine shop and have them drill the holes to make it work with a 2 piece?

[layinrocker65]

sounds expensive and weak

[courage 80]

OK... Ordered the Flywheel (should be here in 2 days). I pulled the engine and fixed the leaks... then we bolted up the new bell housing and tranny (for mock up purposes). I cut the tunnel to allow for the new shifter, and purchased the new starter. I am going to get the driveshafts done tomorrow.

LayinRocker, how did you fab up your hydraulic clutch setup. I cant really seem to find a good position to mount the setup that came with the tranny (out of a 95 trans am t-56) to the fire wall. I would really like to see some pics if you have some.

Thanks

[layinrocker65]

I used the camaro clutch pedal and made a mount for the master on my firewall. I pulled the hydro line as tight as possible and connected the pushrod to the pedal. This was always a temp. mount for me though. I know I have to extend the ine to mount the master correctly but didnt have the time. Because the factory line is so short the pushrod had to be mounted far down the clutch pedal which made it really hard to push the pedal in. 2 weeks ago I snapped the pushrod on the master after 2 years of use. No I am finally going to mount it correctly. I am going to use a factory clutch pedal from our style trucks and mound the master on top under the dash to clean up the fire wall. I am going to take the hydro line to my local hydro supply shop and have them cut the line in the middle and crimp some fittings on the ends. I will then use hard line to connect them and make it as long as I need. The trickiest part mounting it was making the master mount straight because of the severe angle on the factory master. I will try and get a pic of my first mount soon.

[courage 80]

I found out that the HAY-10-330- and the HAY-20-330 will not work with the camaro/trans am t-56. The clutch is a 11in and the HAYS flywheel only works with a 10.5, SO i have ordered the Centerforce flywheel (CTF-700107). Hopefully it works.

I was having a hard time trying to find a spot to mount the pushrod because the steering column is pretty close to directly above the clutch pedal. And I didn't want to mount it in the fender well.

[layinrocker65]

you will probably have to extend the hydro line on the clutch to mount it correctly. I have the centerforce flywheel. Its good but really really heavy.

[courage 80]

right now we are trying to mount the cylinder so that the bellcrank that actuated the clutch before moves the plunger on the cylinder. We are going to fab a plate that mounts to the frame rail on the left side of the trans and puts the cylinder inline.

This way I will only have to extend the line that runs to the reservoir and not the sealed line.

[layinrocker65]

Originally Posted by courage 80

right now we are trying to mount the cylinder so that the bellcrank that actuated the clutch before moves the plunger on the cylinder. We are going to fab a plate that mounts to the frame rail on the left side of the trans and puts the cylinder inline.

This way I will only have to extend the line that runs to the reservoir and not the sealed line.

I am so confused, sounds good. make sure you post pics for everyone to see.

[courage 80]

question>>>>..

I had the 168 tooth starter and it had 3 prongs to connect the wires to... now I have the new 153 tooth and it only has 2 connections (and another that connects itself to the solenoid)

I have the big battery wire, a medium wire with a large eye on it, and 2 smaller wires with small eyes on them.

Can you give me a little input on hooking them up to the new starter?

OH and pics are on their way.

[hewlett2002000]

courage what year/model is your truck? i only have two wires going to my starter, one to the solenoid, the other is the battery cable. there is a third that i believe went to the coil??? or something like that because the points dident get the full 12v. somebody correct me if im wrong. i dont use it cause i have HEI and it gets the full 12v. the way i understand it is that some cars/trucks have a security system that runs to the starter. do you have one? correct me if im wrong here also..... sorry im not much help, im pretty good with wiring but unless its sitting in front of me its hard for me. good luck...
John

[courage 80]

it is a 65 c-10 stepside with a SB 350 with points out of a 74. But the starter is for a 94 trans am-- because that is what the tranny came out of.

I have the wire from the battery which goes to the large post. Then from the ignition (I think) is 3 wires. 1 is a constant power (i think the full 12) when the key is in the ON position. 1 is a momentary when the key is turned to start. and 1 is a constant (but lower power== I think 9)

The old starter had the 3 posts ( battery, an S post, and a R post) the new starter has 2 posts (battery and S). I am guessing that the S post is for the starter and the battery post stays the same. Now I don't have a R post, which I am guessing is a resisted terminal that runs to the coil which would explain the lower power.

I have the constant power from the battery and ignition to the large post on the starter. And I have the momentary from the ignition on the S post. Right now I just have the other wire taped up. The truck seems to start and run; however I have not been able to drive it yet because we are still working on the seat mounting.


Do I need to hook up the other wire?

[hewlett2002000]

it sounds like you got it all hooked up right. i dont know about that other wire, i dont know exactly how the power is reduced between the started and the coil.
good luck,
John

[Shorty Cox]

Regarding the hydraulic clutch. Let me qualify what I'm about to tell you guys. I know NOTHING about this subject. I'm just going to repeat what I heard an old time machanic say. A group of machanics were shooting the breeze at the local Chevy dealer. The subject of swapping trannies came up along with the need for a hydraulic clutch set up. They were saying to fab a bracket for the slave cyclender etc. The old machanic, said, "the mid-60 GMC's" had a hydraulic clutch, use the bell housing from one of them as well as the master cyclender and clutch peddle, they will all bolt up.

Ever wonder why it is that when we wonder what someone is thinking, we offer them a penny for their thoughts, but when they tell us what they are thinking they call it their 2 cents worth!!!

Now you guys have my 2 cents worth.

[Stepside65]

yep gotta love the hydro clutch. Not as much of a chore shifting. Only pain is the fact that switching to power brakes is made slightly more difficult due to the two separate lines.

Edit: forgot to throw in that i'm sure if the bellhousing will line up or not. That thing is freakin HUGE.