seans85vette

So my brother and I ordered some T56 Magnums from Silver Sport.

We ordered close ratio Transmissions but we swapped out the rear 5th and 6th gears to the .74 and .50 for lower highway rpm's.

Here is the picture the Hot rod shop sent me from today



My 71' was a wide ratio 4 speed and would cruse at about 3,200 rpm going 79 mph.

I will update with info from the install including price and performance in case anyone is looking into a similar swap. If anyone has any particular questions regarding the install feel free to ask.

cagotzmann

What clutch did you install ? Hydraulic Clutch or mechanical Z-Bar ?

SteveG75

I have the T56 Magnum behind my 496 big block. Using the McLeod RST clutch and mechanical linkage. Hurst Drivelines set me up with a Quicktime bellhousing setup for the mechanical linkage and the sleeve for the throwout bearing. 10k miles so far with no issues.

Only major install issue that I had was clearance for the forward u-joint on the driveshaft. Had to build a little pocket in the wall of the tunnel. Ended up with a 1310 u-joint at the front and a 1330 at the rear end yoke (Tom's 12 bolt diff).

CPTCroaker

Hydraulic clutch with the heavy duty disc plate

cagotzmann

Twin Disc RST ?

SteveG75

Yup. I read your posts. I have a 25# steel flywheel. Some rattle at idle but not noticeable at all in gear. And I can only hear it standing outside the car thanks to the side pipes. It has been great for four years and 10k miles, though. So, I just live with it. Love the pedal feel.

cagotzmann

I also don't have any noise with the GM Steel flywheel. I went back to the aluminum flywheel and live with the noise. Idle rattle and 2000-2500 RPM Acceleration rattle.

I tried the alum flywheel with the original single disc ACT Clutch. No noise, but the pedal feel was to heavy.

Next time I may look for a triple disc setup.

seans85vette

Okay so it's been it's been about 5 weeks since my car went under the knife and it has finally come out. So here are the straight forward pros and cons regarding the install and my overall opinion of the Transmission.

Pros (install)
...ummm
customer service was easy to get in touch with and did send missing parts fairly quickly
shifter offset is positioned correctly

cons (install)
nothing fit right, except the shifter offset (supposed to be a "perfect fit")
Job took about 4 times as long as it should have
wrong u-joint (ended up using a bastard joint)
missing speedo cable and connector
center console now sits about 1 inch higher(not necessarily a con, but not a pro either)
waiting for parts added a few weeks
$2,200 install cost

Overall driving impression
Wow...absolutely amazing, feels like an entirely different car. The overdrive gears are great but my 3.08 read diff needs to be swapped to either a 3.55 or 3.70 (this was already part of the plan). The shifter throws are extremely short, and take a little getting used to , but they are extremely smooth. The hydraulic clutch is a little stiff but is smooth easy to drive.

current cruising rpm at 80mph are 2200 in 5th and 1500 in 6th. For those wondering...the engine runs fine at 1500 rpm, but obviously has no power and drops to about 1300 at 70 mph in 6th which makes it pretty much a useless gear with the current set up. As stated already I already knew this was going to be an issue and was supposed to come out of the shop with new gears, but the difficult install and made me push back the gear swap.

In the end I don't regret doing the swap or spending the money, but for those that may be considering it just make sure sure you plan you finances accordingly.

Lobzila

I am looking at doing this swap in the future and am curious about the center console being 1" higher? Can you post a picture? Thanks

seans85vette

from the view you really can't tell any difference



my finger goes down about an inch before it hits the plate that the put in to cover up what had to be cut. I'm going to find a way to attach the shifter boot to the underside of the console to hide it



the black box is the lock out module which keeps you from shiting into reverse on accident. It looks a like cockeyed in the picture but is not in actuality.

cagotzmann

What year is the car. When I installed my T56 Magnum in my 78 I had plenty of room for the shifter to fit under the stock console ?

My Install notes.

https://www.corvetteforum.com/forums...-corvette.html

seans85vette

Mine is a 71