Ask an HDC Tech: the Transmission Conversion Q&A

[Ron@HDC]

We're here to answer any questions that you may have about installing a Tremec 5 or 6-speed manual overdrive transmission into your vehicle. What do I need? What'll it take? Have a question or concern, this is the place to post. Ask away!

[pokey64]

Originally Posted by Mike@HDC

We're here to answer any questions that you may have about installing a Tremec 5 or 6-speed manual overdrive transmission into your vehicle. What do I need? What'll it take? Have a question or concern, this is the place to post. Ask away!

Hi Mike,

We’re looking to do a T56 Magnum in our 66 Chevelle. I’d like to know “What do I need? & What'll it take?”. I’d also like to see photos of what your tunnel cover looks like when installed.

Details: BBC, 4 Speed, factory console, 3.73 gears, mechanical speedo

Let me know if you need any other details.


Ed

[whitess]

Can a rubber trans mount be used in place of the poly one, and if so which one? I'd rather not use poly motor mounts.
Thanks, Larry.

[Ron@HDC]

Originally Posted by pokey64

Hi Mike,

We’re looking to do a T56 Magnum in our 66 Chevelle. I’d like to know “What do I need? & What'll it take?”. I’d also like to see photos of what your tunnel cover looks like when installed.

Details: BBC, 4 Speed, factory console, 3.73 gears, mechanical speedo

Let me know if you need any other details.


Ed

A few more details would be appreciated.

How much power will you be making? What is the car's intended purpose? Do you prefer a mechanical or hydraulic clutch? What is your rear tire size? What speed do you typically cruise at on the freeway and roughly what RPM range would you like to be in?

[Ron@HDC]

Originally Posted by whitess

Can a rubber trans mount be used in place of the poly one, and if so which one? I'd rather not use poly motor mounts.
Thanks, Larry.

Yes, you can use a rubber transmission mount with our driveline conversions. We design all of our kits to use a standard oldschool Chevy transmission mount.

[pokey64]

Originally Posted by Mike@HDC

A few more details would be appreciated.

How much power will you be making? What is the car's intended purpose? Do you prefer a mechanical or hydraulic clutch? What is your rear tire size? What speed do you typically cruise at on the freeway and roughly what RPM range would you like to be in?

620HP at flywheel.
Main goal is for a comfortable/enjoyable car for our family to cruise in. (Our boys will be 1 and 4 this summer) Mostly cruising in town and countryside, occasional spirited driving, maybe 1 Good Guys autocross per year.
Undecided on clutch style. We have a mechanical in our Camaro with a BBC and TKO600 and it’s fine.
275/40/18 rear tire.
Highway speeds around here are 55-60 freeway are 70-75. 1800ish RPM?

[Ron@HDC]

Originally Posted by pokey64

620HP at flywheel.
Main goal is for a comfortable/enjoyable car for our family to cruise in. (Our boys will be 1 and 4 this summer) Mostly cruising in town and countryside, occasional spirited driving, maybe 1 Good Guys autocross per year.
Undecided on clutch style. We have a mechanical in our Camaro with a BBC and TKO600 and it’s fine.
275/40/18 rear tire.
Highway speeds around here are 55-60 freeway are 70-75. 1800ish RPM?

Okay. We have two T-56 Magnum transmissions that will work in your Chevelle.

One is a 2.66 first and a 0.63 6th. This transmission will turn over ~2075RPM @70MPH in 6th gear, and ~2070RPM @55MPH in 5th (Which is 0.8).

The other is a 2.97 first with an 0.5 6th. This transmission will turn over ~1,650RPM @70MPH in 6th, and ~1900RPM @55MPH in 5th (which is 0.74).


Because of the low RPM in 6th gear for the 0.5, I would suggest you look at the 0.63.

The T-56 was designed around LS motors and since you will be installing it behind a big block, you will essentially have to start from scratch regarding parts. HDC does have a parts kit which includes everything you need to put this transmission in to your Chevelle, except the driveshaft. Rather than listing all of the parts here, I'll give you a link to the page on our website. Click here to see the HDC T-56 Elite kit for your Chevelle.

Unfortunately, I do not have any pictures of our tunnel patches installed in a '66 Chevelle with a T-56.

If you have any other questions or would like to go over your driveline conversion more in-depth, don't hesitate to call us at 707-535-3030.

[whitess]

"Yes, you can use a rubber transmission mount with our driveline conversions. We design all of our kits to use a standard oldschool Chevy transmission mount."
Thanks appreciate the help and the quick response!