Transmission Shifting Hard After Swap

**walkure** · 06-27-2016

My GT trans gave up and I swapped in a spare trans from a GTP. After this swap I copied over the stock trans tables from the GTP and also calibrated the speedometer. On the test drive the trans slams into each gear and shakes the whole car. Is there something that I missed or is the spare trans also done for?

**WarStryker13** · 06-27-2016

did you swap the TC as well? I know the two have different stall speeds...

**Scottydoggs** · 06-27-2016

what did you do to calibrated the speedometer? ive not seen that in dhp.

**walkure** · 06-28-2016

WarStryker13:
I did change the TC to the larger GTP one because I think that is what failed.

Scottydoggs:
I am using HP tuners. It is Changing the drive sprocket ratio.

**BrandonHall10** · 06-28-2016

Here's the settings from my GTP:

**walkure** · 06-28-2016

That is exactly what I have. I'm starting to think that this spare also has issues.

**BrandonHall10** · 06-28-2016

I'm curious what your line pressure is. Sounds like you may be maxing out.

**walkure** · 06-28-2016

How do I test the line pressure?

**BrandonHall10** · 06-28-2016

https://www.youtube.com/watch?v=CNjDiPFcKuU

I don't have a picture handy showing the pressure port, but it's not hard to find. Silver hex head plug accessible from the top.

**Scottydoggs** · 06-28-2016

you sure this is a gtp tranny? you had to swap an axle right? cause only one from the na tranny is the same.

**walkure** · 06-28-2016

Pretty damn sure. I have the donor car sitting behind the shop.

I'll have to dig out a gauge and check the line pressure tonight.

**Scottydoggs** · 06-28-2016

ok, i had no idea how you came to own it. cause the wrong tranny or with the wrong tuning will also make it shift hard and then they eat them selves from it.

**Turbocharged400sbc** · 06-28-2016

It can take up to 300 miles for trans adaptives to fully learn

**Scottydoggs** · 06-28-2016

Originally Posted by Turbocharged400sbc

It can take up to 300 miles for trans adaptives to fully learn

come to think of it, when we did my tranny swap it shifted pretty firm/harsh for a while, then mellowed out by the time i got home. aka 200 miles.

**Grimsin** · 06-28-2016

The diffs are the same right? I swapped to 3.69 gears and over kill forgot to change the diff setting as I also swapped the diff, it hard shifted till it was corrected

**walkure** · 06-28-2016

I'm hoping that it is just a shift adaptation issue. But I am going to check the PCS. When I drained the fluid it looked old and neglected which leads me to consider a solenoid issue. I'm just trying to put a bandaid on the car till I can save up for a TEP trans.

**BillBoost37** · 06-28-2016

The issue is you did it in HPT. HPT doesn't show you all the tables and you are missing things. You really need DHP to copy the entire trans over and then it would be happy.

Right now..it's pissy because of tables you can't see.

**walkure** · 06-29-2016

Well I'm stumped. Found out today that if you want to check trans pressure and have headers installed you are SOL. I'm going to see my local 3800 yoda tomorrow night and see what he can do.

**Scottydoggs** · 06-29-2016

this thread came from using dhp bin to hp, i did some other stuff hp cant do, emailed him the bin file and running off it now. http://www.grandprixforums.net/threa...er-of-Bin-File

if it comes to it, i can make a na bin with the gtp tranny in dhp with the same osid # as your bin, then you need to follow that link i posted and change the vin # in the bin file so HPT will like it.

if you have the old version of hp it will open and read, then flash the dhp bin file. as long as the osid and the vin match.