pcm for 4t65e runing 4t65HD?

[Z34Phoenix]

I know a PCM for a 4t65HD will run a 4t65e but will the opposite work?

i want to know for sure if people have tried this, as i am considering a swap and the only file i can use was made for a 4t65e and never had an HD option. i know that people can rung a bin for a L67 and it run their non HD trany. but will say a L36 bin run a 4t65HD?

and yes i know the gear ratio will be diff. i can adjust for that. i am currently running a gear swap from 3.43's to 3.73's in my 4t60e.

[1LoudGrandPrix]

if your talking grand prix the non-HD is 3.29 and HD is 2.93

[Z34Phoenix]

like said im not worried about the gear ratios... yes the normal non HD 4t65e is is a 3.29 some i read somewhere are even 3.05? and i know the HD's are 2.93.

I am looking to run a 97 Z34 engine, PCM, and harness so that i can run a 4t65 on my DOHC engine. there was never an option for an HD trany with that engine...

this is why i want to make sure a bin intended for a non HD trany will run a HD trany.

[FoSHO99]

Just change the gear ratio... The only thing HD really does is a different size axle and a different Diff/housing. PCM doesn't care about that.

If it helps, no mention of pcm reprogramming in this...
ZZ Performance

[Wisconsingrandprix]

you should only need a speed sen change

[Z34Phoenix]

Ok
For the gear swap I know the sprocket ratio needs changed. Shift tables obviously. Are u saying the actual speed sensor or the rev per mile in the bin?

[BillBoost37]

The only difference your pcm will see is the gear ratio. The only HD diffs are 3.29 ratio. Which when combined with the drive/drive sprockets are how you get to the 2.93 or 3.29 ratios.

HD chainsets are always 1.21:1
Non HD sets are always 1:1

[Z34Phoenix]

so if i had a trany built for 3.69 gears it wouldnt have an HD diff?

[BillBoost37]

It could.

See 4T65's are all basically the same. The differences are the drive/driven gearsets. The size of the diff HD or not (and ratio of planetaries/input sun gear) and the size of the output shaft.

So if you choose to get a gearset to make a 3.69, you'll end up with a drive/driven ratio different from either of the stock ones available from the factory. Then addin the 3.29 HD diff or a 3.29 nonHD diff to give you a final result of 3.69's.

It's the combo of drive/driven ratio plus diff ratio that will get you to 3.69. In this case, since HD and non-hd both have a 3.29 diff ratio available you could make a nonHD 3.69 trans.

Don't let yourself get hung up on the HD ve non-HD wording. The only real difference is ratio at the drive/driven gears (input side) and the size of the differential.