I've been searching for a while and haven't found anything, maybe I'm a crappy searcher, but anyway; is there existing posts on here about installing a 4T65HD into a L36 engine? My stock engine/trans is about to lose the latter half of that combo and as I look for 'part-outs' I want to know if I can reasonably expect to install the HD instead of the base 4T65E. I would like to get a supercharger eventually so this might be a good start. Also, I know everyone's going to tell me to just buy an entire L67 set but my wife is not going to let that fly....at all. I know because I already tried.

Thanks for any help.

 

First things first: what year is your car? If your car is pre-2003, you need a pre-2003 trans. Secondly, the HD trans isn't worth the extra because the hardened parts in the HD trans aren't the ones that break. Plus the gear ratio in the HDs will be worse for performance. Which is partly why people think top swaps, keeping your stock trans yields more power than an L67 swap taking an HD trans.

 

Sorry for the lack of detail; I have a 2004. To your pre-2003 point, can I assume since I'm 2004 I can use a 2003, 2002, etc.? So, are the 4T65E's backwards compatible but not forward compatible?

When I started my initial searching I saw a couple totalled L67 vehicles and it raised the question in my head of whether it would work. Obviously, the bigger the base I'm looking at, the greater chance of finding something. I should do some searching, but you make a good point; obviously the people that do top swap's don't end up having too much trouble with standard 4T65E otherwise they wouldn't be advocating their mods?

 

They did something to the trans in '03 that prohibits pre-2003 cars from being able to use their stock PCMs. Also, in '03 they fixed probably the largest issue with these trans, the 4th gear shaft was heat treated to keep it from breaking.

If your car is post-2003 you can use any post-2003 tranny, but if you got a pre-2003 you'd run into the same PCM issues (you'd need a PCM from that year and then have to flash it to your car), plus you'd loose the 4th gear improvements.

 

HD conversion is a waste of money, and it is geared differently so your launch will be worse

Get a 4t65e from your year and call it a day.

If you want a stronger one, check out tripleedgeperformance.com

 

Again, back to the wife, she's not flying for the Triple Edge price, but I did check it out.

Regarding same year, all 2004 4T65E's are created equally? The implication being it doesn't matter if it's from a Pontiac or other GM product?

 

It shouldn't matter, just make sure the gear ratio is 100% the same first.

 

Actually they dont think it actually does. the gears make you feel it more. But the compression ratio is higher on na motors so when you top swap your running 6-8 psi on 9.5:1 instead of on 8.5:1. You actually have arpound 20 more hp. thats why a l67 driven right gets 32 mpg and a normal 3.8na does not. The easiest thing to do is just drop a whole l67 drivetrain in. Junkyards have them cheap saw at least 10 today lol. Cost as much there for whole drivetrain as you will find a new tranny through a shop.

 

One of my local shops told me when they rebuild they have to re-flash the PCM and teach the trans it's shift points again. This was his justification for why I can't just take him the transmission outside of the vehicle and have him rebuild then I re-install. Any truth to this? Is there truth to it if it's rebuilding an existing versus getting a used?

I'm trying to balance the likely added of cost of a shop doing a rebuild (and getting a warranty) or putting in used a transmission that I don't know the history on.

 

You shouldn't have to reflash the PCM at all.

I could see unplugging the battery to reset the tables, but not a full reflash.

Frank on the forum recently swapped his transmission for a used one and didn't require any PCM work.