crAzy95Z28

iTrader: (3)

Ok ive had this tranny for 5 years now and has been rebuilt prob about 4-5 times. All stage 3 builds. Well we cant figure out whats wrong with it. Ever since the 1st build my 2-3 shift at WOT will over rev the shift point. When the tranny is cold it actually hits at the shift point. But when warm it always over revs.

We thought it could of been the shell but it wasnt. We even switched out to a new shell and stil same problem. The shop is a good shop (been mentioned on here before) Will not name names because i dont want to start anything. But they have done all work on my car since day one and never have had problems with them.


Now my PCM was edited and i even brought down the shift points (MPH) way for the 2-3 shift and still has not worked. I havent tried to bring it down much, but figured a slight change would work. From what i remember it was brought down from like 76mph to 72mph i beleive. I wonder if bringing it down to lets say 67mph would cause it to shift right? My rev limiter is maxed at 6200 or 6400 i think from the MSD 6AL, from PCM is maxed at 7k. Also the shop has good feedback on their trannies and never has had a problem with one till mine.


Any ideas what you guys would think? It is from a LT1 car OBD1 as well. Plus it has 3200 stall in it too...Let me know what you guys can think of?

Jditlfm

iTrader: (26)

I took a look at the stock tune in my 95. What i saw was that the Normal up shift table said that at 100% tps 2-3 shift point was 93 mph and in performance mode its 98Mph. Now the thing you said with it shifting fine when its cold there is a table for that. This table is name COLD MODE UP SHIFT SPEED MODIFIER (MPH) VS %TPS. In that table there is a reduction of 2 mph. i would try playing with the shift table and if not then i would try adding some more main line pressure for the 3rd gear shift.

crAzy95Z28

iTrader: (3)

Hmm....adding more pressure along with a shiftkit would be safe? Theres not way i shift at 93mph going from 2-3... I think its somewhere in the 70's. I do have 3.73's but has been calibrated in the PCM..

Now i just need to find someone with LT1edit...

Jditlfm

iTrader: (26)

I have tunnercats. When i plugged in the 3.73 gear ratio in my tuning software it changes the shift points to 81 normal and 85 performance. What size tires do you have? All of that is going to play a role.

crAzy95Z28

iTrader: (3)

315/30/17 i think.

Jditlfm

iTrader: (26)

If thats correct tire size that makes more sense. Now that were on the same page i have shift points of 77 in normal mode and 81 in performance mode without modifying any values. Do you have the normal performance button for the trans? What RPM do you want to shift at, according to a gear tire calculator i am using, for a 6200 rpm shift you want 74-75 mph value in the shift table, I would put this value in the normal and the performance tables to ensure it shifts when you are commanding. If that does not work i would start looking into line pressure tables. The reason i say this is that when you say it works when its cold and not when its hot that tells me something. Looking at the computer tables there are only to things that change from when the trans is hot to when its cold and that is the shift point in Mph by a reduction of 2mph when cold and the line pressure is not multiplied as much when hot.

crAzy95Z28

iTrader: (3)

So what would cause it to over rev... then shift? Cause during that over rev state the car loses tremendous power. Also when it does this it revs high (like teh tranny is slipping as well) in which would also decrease the life of the clutch packs..

For example, lets say my car is suppose to shift at 6000 rpms. Well during the WOT the shift will hit that shift point then over rev to...ill say 6500/6600rpms. but then it seems to miss causing an over rev which also sounds like the car shifting into neutral (not really) but sounds like it. Then it eventually catches and shifts. During that lil default mishaps the car loses a good .2 / .3 in the 1/4 mile times.

Jditlfm

iTrader: (26)

Then i would try and increase the shift pressure on the Number 3 shift. When cold it has a value of 2 as a modifier but when it gets into operating temp that value is 0 what i would try is changing the values in that table that are 0 to 2, this would increase the line pressure on that shift. hopefully solving your problem.

crAzy95Z28

iTrader: (3)

and this if for either LT1edit or Tunercatz?

Jditlfm

iTrader: (26)

tuner cats