We admit it; from time to time we need to dink around on the Googles and internets just as much as the next guy. Being car guys, our random internet searches and forum chatter leads us to a lot of really neat projects and gives us a flavor of what you, members of the 'jack-stand-mafia' are really searching answers for. We've seen a growing number of questions being asked about the LT1 T56 and how it can work with various platforms. First off, the T56 is just plain awesome. Six forward gears of pure give-it-hell attitude with two overdrives, what more could a car guy want? The T56 has the ability to allow us to road race like madmen and then drive home going 75mph at 1,800rpm. In some cases, swapping over improves gas mileage to almost 15 miles per gallon on the highway and sometimes more! The T56 has been such a great transmission, that all three car manufactures in the U.S. have used it in their vehicles.
You can even find this transmission in a few select Aston Martin DB7's and Vanquishes. Dodge crammed them into the Viper as well as some of its SRT10 trucks. Ford also put them into a few Cobra and Cobra R's in the early 2000's. Of course, most notably the T56 was installed from the factory on GM's Cadillac CTS-V, GTO, SSR, Corvette, Camaro and Firebird lineup starting in 1993. The LT1 T56 saw its hay day from 1993-1997 before it was replaced by the LS1 version. Which means a lot of them are still out there, they are less desirable (and therefore cheaper), and with the M28 and M29 versions in '93 there is even the option of switching to one of two numerically higher gear sets (First to Third only, same Fourth to Sixth). As the result, a very common question we kept seeing over and over again was, "can my LT1 T56 work on an LS series motor?"
Up until recently, the simple and short answer was: "sorta." A lot of the answers we see people giving on the forums have something to do with just going out and getting an LS1 version. That of course, is the easy answer, but with good, unexploded versions of the LS1 T56 going for as much as $2,000 or more on the old Craigslist, there has to be a more economical way to do it. We gave Mike Weinberg at Rockland Standard Gear a call to see if he had a solution for us. RSG has been around for a while and supplies a lot of hardcore racers with transmission and running gear parts; he also gives seminars on rebuilding techniques and edits training manuals. We knew we were getting the real deal from Mike.
Mike put together a kit that takes all the guess work out of the process. He includes a new input shaft specifically for the LS1 T56 transmission, a new front plate and all the shims that you could possibly ever want. The part number you'll be ordering is "LT1/LS1," that's it, pretty simple to remember. The price? Even better, a scant $398 nets you the chance to make your T56 modern and up to date. Now, to be fair, you can do this at home with basic tools, but having the right tools can make all the difference in time and aggravation. We borrowed the correct transmission cradle (as seen in the photos in bright blue) from our local GM dealer. Rumor has it that every GM dealership is supposed to have one on hand and at the rate that these things break, it's rarely in use. So, you might be able to sweet talk them into letting you borrow theirs as well. We also used a fairly sizeable press and the correct bearing removal tool to complete the job. While these are not essential to doing the job, again, they make life a lot easier in the long run. You might want to head over to a machine shop and pay a couple bucks to get the job done faster and more safely.
We enlisted the help of veteran engine builder and racer Myron Cottrell of TPIS in Chaska, Minnesota for a little guidance. They normally don't do these sorts of things as part of their regular day-to-day business, but we knew we were in good hands. The job starts off fairly easily. You'll need to set up the tranny on its tail, but make sure that the output shaft does not rest on the floor; you don't want to risk damaging any of the bearings or screw up the shaft alignment when it comes time to put it all back together. Everything is straight forward from this point onward. Follow this simple guide and you'll increase the value of your old LT1 T56 by almost double.
Doing this swap should only take roughly a few hours with the right tools and knowledge. This might be a good time to start scooping up those old LT1 T56's you see at swap meets and random Craigslist ads while they are still cheap!
1 When you call Rockland...
1 When you call Rockland Standard Gear, this is what you get for your money. The kit labeled “LT1/LS1” comes with a front plate, a front shaft and enough shims to keep you happy for the long haul.
2 We set up our LT1 T56 on...
2 We set up our LT1 T56 on the special GM fixture that is specific to these transmissions. We did have to remove the reverse lockout solenoid to get it to fit properly. When doing work on a transmission it helps to have the correct tools. It was bolted to a sturdy table and is in the perfect position to remove the front plate. We used a mini-impact to break the bolts loose. A little trick here is that on each side of the front plate, you’ll find a couple slits that are perfect to use a pry bar. Over time, the front plate can really fuse itself to the case. A solid hit with a mallet will separate the two.
3 Here’s the inner workings...
3 Here’s the inner workings of the T56. Take notice of the configuration for when it comes time to put them back together.
4 The original shaft (left)...
4 The original shaft (left) from the LT1 T56 is considerably shorter than the LS1 version (right). You will have to get a new bearing or in our case, reuse the bearing that is pressed onto the shaft.
5 Removing the bearing is...
5 Removing the bearing is a major chore; we used a heavy press with a bearing removal tool. If you are going to do more than one of these swaps, this tool is invaluable.
6 The LS1 plate (left) is...
6 The LS1 plate (left) is distinguished from the LT1 plate (right) by its bleeder cutout labeled “A” in the photo and the hydraulic input line labeled “B.” On the LT1 version, the mechanical fork cutout is labeled “C.” The fork pivot is also a dead give-away that you’re dealing with an LT1 T56.
7 Using a long piece of heavy...
7 Using a long piece of heavy gauge pipe, we again went back to the press and installed the bearing onto the new shaft. You might be able to get away with heating up the bearing and slipping it on. We weren’t so lucky.
8 This procedure is a bit...
8 This procedure is a bit tricky. With the blade of a long screw-driver, we were able to pry the lower counter shaft slightly as to get the new shaft to mate inside the teeth of the counter shaft. You have to be very careful here; on the other end of this shaft is a plastic bearing that can easily be cracked or broken, use caution.
9 We lucked out here; our...
9 We lucked out here; our donor T56 only had 10,000 miles on it (according to the owner who sold it to us). We were able to reuse the races as they were in pristine condition.
10 Measuring the depth of...
10 Measuring the depth of our recesses, we figured out that only one shim was needed for each race. Tolerances here are fairly important. Ours thankfully didn’t need much messing with.
11 A very thin layer of RTV...
11 A very thin layer of RTV was enough to keep leaks at bay for many hard road racing miles to come.
12 Go slowly when putting...
12 Go slowly when putting the plate back on. A little patience at this step goes a long ways. Everything needs to be lined up properly and seated. We ran into a little interference with the reverse shaft. Things had shifted a bit while we tried to muscle things together. The front plate should fit snuggly over all of the components, do not force fit it.
13 Transfer over this plug...
13 Transfer over this plug from the old plate to the new plate, otherwise you’ll have a nasty tranny leak and that’s never a good thing.
14 All finished! You now...
14 All finished! You now have a LS1 T56 at your feet, it’s time to go out and play!