• đź’ˇ Fun fact. Whenever you start a thread, TCG Mechanic 5000 (our AI bot) will reply to you to start helping. It doesn't know everything and it will struggle with more complex questions but it can get the thread going and provide valuable information. You can choose to disable it prior to submitting a thread.

Hitting the limiter in the TA. Why?

Shibby50

TCG Elite Member
Mar 30, 2008
5,005
74
Braidwood, IL
So a week or so ago I swapped the built 4l60 into the TA. A clip in a solenoid broke and burnt up a few bands. Had it rebuilt. In the meanwhile I ran the stock Trans and had no problems with it. Finally my buddy finished up the rebuild so we put it back in. I test drove it and seemed to shift fine, made a pass and did a wot 40 roll all shifts seemed fine. Fast forward to a yesterday. Finally got the new rims and tires on, take it for a test drive and now it hits the limiter on the 2-3 shift. Would putting a taller tire on it 26 to 28" make it hit the limiter? I would think that would only happen the other way around. I'm thinking the Trans is just junk and is burnt up already and I need to ditch it for an 80 and put the stock one back in for now. Any thoughts?
 

Gone_2022

TCG Elite Member
Sep 4, 2013
13,094
7,525
It changes your rotational speed. From what you are going vs what the car thinks. Also from the start a shop that I won't name, which is not around anymore did not have his speedo set correctly from the get go. Last time we cruised he said he was going like 70 and mine said 60-65. And I know mine is right. And that was before his tire swap

My vote like I told you in a text is the Trans shift points and possible gear ratio. With what the car thinks it has.
 

DNKFXSTANG

Member
Jul 22, 2014
8
0
It should be the tire change. Full throttle shift points in the Fbody PCM's are decided by MPH and RPM. It needs to satisfy both criteria to shift, and they have to occur in a pretty close timeframe (forget what it is). If you changed the tire size and didn't modify the tune, it will absolutely affect this.
 

DNKFXSTANG

Member
Jul 22, 2014
8
0
It could be his original tune happens to satisfy both criteria within an acceptable period and shifts during that particular shift. I can't say for certain without looking at the tune and a log. If the OP uploads an hptuners log and his tune, it will be easy to see if that's his problem.

The tune should have an RPM and a MPH that need to be satisfied for each shift. If one one parameter is met, and the other takes too long the car will not shift. If you bolt a 28" tire on a stock car, it will not work correctly unless the speedo is adjusted.

Put the original tires back on and that will rule this out.
 

rocket5979

Gearhead
Nov 15, 2005
6,576
18
Round Lake, IL
I don't think changing a wheel and tire would make an auto trans shift at a different rpm .



Many auto transmissions command shifts based upon engine RPM AND vehicle speed. So changing tire size without modifying the tune to compensate can screw the shifting up.


EDIT: Nevermind, DNKStang already mentioned what I said. Yep, the issue is pretty much guaranteed to rest with your tune needing re-adjustment so don't fret about a blown trans just yet.
 

Gone_2022

TCG Elite Member
Sep 4, 2013
13,094
7,525
Guess I'll swap the other tires on real quick and see if it does this. Wish u had hptuners and a way to log runs

If it doesnt do it then good. However that still leaves you needing a tune. Well at least small shift point adjustments. And I believe speed inc is quite backed up. Def would not happen by this Friday, and I dont think that would matter anyway as the rain is still in the forcast all day for the track.
 
Old Thread: Hello . There have been no replies in this thread for 90 days.
Content in this thread may no longer be relevant. Consider starting a new thread to get fresh replies.

Thread Info