I'm thinking of swapping out my 5.7L in my '85 Z28. It currently has a 5 speed in it, and I'm wondering if the 5.3L LM7 will work with the 5 speed? The 5.3L currently has a automatic trans, will I need to change the computer for it to run right with the 5-speed?

 

Welcome aboard thirdgen.org.

The LM7 is in the LS1 family, so read the LS1 swap sticky, paying particular attention to the part about using a truck engine.

Plan on needing to reprogram the PCM.

If you use the T5, plan on frequent replacement (unless you baby it).

 

Thank you very much for the help! I will definetly check out the LS1 swap info. I'm not sure if it's the T-5 that I have, or the T-56. I will have to check on that. Thanks again for your help!

 

T5 = 5 speed trans

T56 = 6-speed (six forward gears), not original 3rd Gen equipment.

Unless a previous owner has done a T56 swap, you have a weak T5.

Research, research, research. Its free!

 

A good t5 should last a while behind a stock 5.3 if you don't hammer it. My t5 is holding up just fine behind my high 13 second 350, but I don't speed shift, or do dumb stuff with it. That said, nobody does an lsx swap and leaves the motor stock for long, so plan on upgrading the trans before you upgrade the motor.

 

Im curious to see how the T5 would even work behind a LSx engine. You'd have to use a T56 flywheel and PP, but what disk and does the input shaft extend far enough into the pilot bushing? Would the TOB still line up?

Slave cyl would be in the way for exhaust, so youd be stuck with manifolds or custom headers

 

IDK what year LM7s begin and end, but the 2007 up 4.8 and 5.3s all have cranks too long to use a T56, they are .250-.280 too long over a LS1 crank or older GEN III(asides from the 99 LQ4).

But in the case a regular crank did not allow a T5 to work since it was too far out, a newer motor might help the situation as long as it is not a T56.

 

Where did you read that?

Only oddball cranks Ive seen are FWD LS4's, early iron headed 6.0's and specialty engines i.e. LS7/9

 

when i was building my rx7 there was a guy that was running a T5 behind a 5.3l he replaced it a couple times and then finally found right/strong enough parts that it stayed together for a while.

actually heres a video of his car

http://www.youtube.com/watch?v=zWYw79L9Q1s

 

Nowhere, i just know from experience. All the newer 4.8 and 5.3s i have bought from the junk yard(2007 up) all have cranks that are .270 or something like that longer than the older motors and LS1s, pretty dumb since there are folks that want the GEN IV and cannot run a 6 speed with it.

The flex plate that comes with it is different as well to accommodate the difference.

Hardly had to shim my TH400 with the 08 5.3 in the TA:

 

I have actually been doing a lot of reading on the T5 to 5.3 and it will work. You would need a 621 bellhousing (BBC) and an LS1 clutch/pressure plate/flywheel, an LS7 pilot bearing, and a Howe racing throwout bearing. The transmission will no longer be mounted at the 17* angle and you will need to make a shifter to account for that. There are more and more people doing this, just not in a 3rd gen.

 

So what's a rough estimate on gas mileage for lm7's in a 3rd gen on street/hwy??

 

I just measured an 08 5.3 and 02 5.7 and the cranks are the same, i noticed a difference in the rear cover that makes it look like the crank hub (where the flywheel/flex plate bolts too), is a little bit longer, but when you remove the rear covers and measure form the #5 main cap on both engines, the end of the crank is about 7/8" on both engines...

 

I'll check that again next chance I get.

 

Sounds like more work than it's worth to run the t5...

 

I can get 30mpg highway 23.5 back and forth to work ( lots of hills and sharp corners) i would say mid to upper teens in town i have never had a tank a gas just driving around town. Also note all of these had a few WOT pulls

2002 5.3 lm7 4L60E 2.73 gears stock stall

 

You would need to account for more than the shifter being off. What about the torque arm mount? Trans mount?

 

Or a 4thgen 3.4v6 t5 + quicktime ford toploader to LSx scattershield.

 

sub'd to your swap, gonna be doing one myself, but it'll be such slow progress it'll be years before i get it in the car

 

Or this....

http://www.hawksthirdgenparts.com/pr...actory-T5.html

 

With that you lose at least one bolt. Depending on if it has provisions for the oilpan bolts you may lose three...