VY L67 T56 Manual Conversion

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rowan
Posts: 3
Joined: Sat Sep 10, 2022 8:09 pm
cars: 2003 Supercharged VY Commodore - T56 Manual
Location: Melbourne, VIC

VY L67 T56 Manual Conversion

Post by rowan »

This thread is all about converting my VY L67 from it's 4L60E Automatic transmission to the T56 Manual gearbox. I've found information from all over this forum as well as the workshop manuals and the internet as well as making my own mistakes along the way and having to figure it out. So the idea is this top can form a guide on how to do it while ensuring the vehicle runs as expected and has as many features as possible to get working.

Background: Post
Mechanical: Post
Tuning: **Coming Soon**
Electrical: **Coming Soon**

This first post is purely like a bookmark to sections in this topic allowing you to jump to what you're interested in.

**Still under construction**
Last edited by rowan on Fri Sep 30, 2022 4:55 pm, edited 2 times in total.
rowan
Posts: 3
Joined: Sat Sep 10, 2022 8:09 pm
cars: 2003 Supercharged VY Commodore - T56 Manual
Location: Melbourne, VIC

Re: VY L67 T56 Manual Conversion

Post by rowan »

Background

I purchased a 2003 VY L67 Commodore back in 2007. I prefer manual vehicles and so the plan has always been to convert this to a manual. For all purposes related to this thread lets call the vehicle stock, yes it's on FE2 suspension and lower than it should be, but the only things that have really be changed from factory specifications are an aftermarket head unit and a custom 90mm cold air intake into the factory air box.

After researching the T5 and the T56 options I settled on the T56. While the T5 would bolt up nicely the T56 has an extra gear, better ratios and is capable of higher torque. A T5-Z is rated at 330 lb-ft of torque while the T56 is rated at 450 lb-ft of torque. Bearing in mind the L67 is listed as producing 280 lb-ft of toque (from GM) both would work.

I ended up purchasing a T56 from a wrecked VY SS in 2010. I ended up ordering a bellhousing from Dellow Conversions in NSW in 2010/2011 instead of using an adapter plate. I also ended up ordering a brass button clutch and pressure plate and concentric slave cylinder from a Victorian supplier around this time too. For 11 years the parts sat on the pallet the T56 was shipped on until the 4L60E decided to lose third gear (most common issue). I'm assuming based on the smell this was a worn out clutch. Given this was the middle of COVID lockdowns in Victoria reconditioning it was very expensive and would take quite a while. The other option was having to take a gamble on a second hand unit didn't make much sense when I had the T56 sitting there.
rowan
Posts: 3
Joined: Sat Sep 10, 2022 8:09 pm
cars: 2003 Supercharged VY Commodore - T56 Manual
Location: Melbourne, VIC

Re: VY L67 T56 Manual Conversion

Post by rowan »

Mechanical

If you've come here looking for detailed instructions on how to physically swap the 4L60E for the T56 I will apologize in advance as I didn't do this part by myself as I was lucky enough to have a friend's shop do the work for me. This shop is very good with fabricating if needed, however wasn't too sure around the electrical work which I was happy to take care of anyway.

When I purchased the T56 it also shipped with the driveshaft as well as pedal box and trim which matched by vehicle's interior color so the entire changeover was relatively easy. When removing the 4L60E the Neutral Safety Switch was removed and cable tied to the rear T56 mount to ensure the vehicle would run. The bell-housing also had to be modified by creating a cutout for the hydraulic lines to get to the CSC.

The T56 was removed no less than 3 times while also trying to work out why the vehicle would run but wouldn't move. Turned out the clutch kit I had purchased all those years ago while correct for the T56 wouldn't work with the setup, so a custom Exedy clutch kit was ordered and fitted, as soon as that was in the vehicle was moving again.

At this point the vehicle would display check engine message and entered limp home mode. It was also discovered that I would need a new cat-back exhaust so this was left off the list of fixes as I have another friend's shop that specialises in exhausts. If you end up in this position expect the vehicle to do an idle seek between about 500 and 2200 RPM.
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