Tranny Builders 2-3 Shift ?
Tranny Builders 2-3 Shift ? I have built 2 trannies including mine with a full PB kit and is vac modded,max line press at WOT is at 230 psi on the dot everything works great except for the 2-3 shift.If you leave it in OD it shifts into 3rd perfect nice and firm but if you manually shift it for some street action to save you a little time for the down shift it will hit the limiter on the 2-3 everytime.I cant seem to figure this out,I can build these things but just dont really understand how alot of parts in the tranny work.I know a lot of builders dont use the vac-mod and was thinking about putting the PC solenoid back in and giving that a try.I have also seen where alot of the other tranny builders use only 7 or 8 clutches in the 3-4 and this kit came with 9 B/W clutches.Do you think this is generating to much heat within the clutch pack?The other one I built did the exact same thing and lasted about 3000 miles and died,but it was hard miles with it nailing the rev limiter 2-3 times a day maybe more.Mine has about 400 miles on it so far and wanting to last so if any of you guys have any info on this problem any help would be appreciated.
Joe
Joe
Last edited by ssmoov1; Oct 6, 2006 at 06:17 AM.
Ok of note manually shifting causes the pcm to raise the shift points,This is my understanding fixable with tuning ,
www.performabuilttransmissions.com
www.performabuilttransmissions.com
joe (ssmoov1) built them both he is referring to mine as the other one that died and his but the kit is from probuilt automatic. i have and the same thing happened to mine as is happening to his and about after 3k miles the hole car started to shake at part throttle and i could tell something was wrong and than the next day it wouldnt lock up and would slip all the way through 3rd and 4th. had the tranny pulled apaprt and the 3-4clutches where toast
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Mine did does something very similar to this. I posted it sometime back. With a pressure guage installed and the fluid temp about 175 deg., WOT shift into third with OD selected was fine. Line pressure was at 235 psi just before the shift. When 2-3 shift occured, there was momentary pressure drop (a quick bump) of around 25 psi and a very quick recovery to full line pressure of 235 psi. Pretty much the same as the 1-2 shift. With the gear selector in third, 1-2 shift was 235 psi with a quick pressure bump, 2-3 shift was somewhat different. About a full second just before the 2-3 shift, the line pressure goes from 235 to 110 and stays there thru the shift, with a recovery to 170 psi. Of course with those pressures, 3rd would start to slip. Have to get out of it right away to save the 3-4 pack. If I leave it in OD, no problems. Not to the point experience wise where I know what the problem is, so I just dont select manual 3rd when doing full throttle upshifts. Over 20 passes this way. (OD selected) No problems. Hope this input helps.
Mec
Mec
Last edited by Greaseymec; Oct 6, 2006 at 11:49 AM.
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Verdad Gallardo I have read about and heard about the line drop on the 2-3 shift when in the drive position. Im not sure what causes it , I do know the overrun clutch comes on simultanious to the 3-4 clutch when in D but it does not in OD , but I dont really see how that would have such a drastic effect on line preasure ,
Has anyone watched the pcs current when one is used to see what is happening there live during this shift ?I mean with both clutches coming on togeher of course you have to supply more volume , but not enough to account for a loss like your speaking of so there must be another reason ,
www.performabuilttransmissions.com
Has anyone watched the pcs current when one is used to see what is happening there live during this shift ?I mean with both clutches coming on togeher of course you have to supply more volume , but not enough to account for a loss like your speaking of so there must be another reason ,
www.performabuilttransmissions.com
These pressures were with a vac mod. WOT is pretty much 0 vaccum so the line pressure should stay at the max regulated psi. But in this case, it does'nt. Not that the line pressure drops because of a problem with regulation, the pressure is being tapped off for use somewhere else. Agreed, loss of volume. But where?
Mec
Mec
Well as i said its does turn on the overun clutch ,since the preasure dosent recover fully .its possibe there could be a leak in the overun clutch circuit , cracked piston or something like that , I will study on it some , See what I can come up with
www.performabuilttransmissions.com
www.performabuilttransmissions.com
I have checked my vacuum at WOT also and it is at 0.Is it possible the feed holes in the seperator plate for the 2-3 got drilled out to big and that the 10 vane pump cannot catch back up after the pressure drop between shifts?
Joe
Joe
No trust me the ten vane pump can keep up with any normal situation you should see how much it can pumpm out of the cooler lines while still maintaining full presure ,
www.performabuiltautomatics.com
www.performabuiltautomatics.com
my tranny is stock with a converter.. and if i go from a low roll and i pull it down to 1st to get a nice jump..it sometimes will hit the limiter on the 2-3 shift once or twice but sometimes it wont i dono what the deal is if i go from a 2nd gear hit..and i leave it in OD it shifts fine...the shift points are at 6100 and limiter is at 6250 i believe...again it happenes 1 time out of 6-8 races...and its a stock tranny with a fuddle 3200 and a tci deep pan... just thought i would join as well...