3rd to 4 th shift rpm

[rayruner]

i got a 02 3100 malibu, with cam, wot heads rsm blower pumping 8 lb, and headers and a few other things, in the stock file, it shows the wot shift rpm at 8100 from 3nd to 4th, i got my other shift rpm at 5700, whats everybody setting there 3 to 4 shift rpm at. thanks

[3400-95-Modified]

Um I wouldn't expect 4th gear to withstand a power pull for one, and second... Where on earth do you expect to be shifting into 4th gear at WOT?

4th gear is an overdrive gear which is only 2 fiber clutches vs the others which are at least 6-8 fibers IIRC...

I don't use 4th in the 1/4 and I am running the highest gear set possible and also running 12.6's @107mph.

[rayruner]

Just asking, thanks

[rayruner]

Like i just said thanks, If you would, could you tell me how you have the trans set to shift, and also the tc.

[3400-95-Modified]

What do you mean? how it's set to shift? There are many tables regarding that... regular driving, wot, and so on... Also my tables may do you no good if your not running a 3.69 final drive ratio.

[rayruner]

sorry i asked

[3400-95-Modified]

No reason to be sorry you asked, you just need to clarify your statement and give more info on the trans your running before anyone can really answer that question, Or see if it's worth it looking into giving that info because if the setups are very different then the numbers would just make thing's more confusing for you with the way it would shift.

[robertisaar]

an 02 Malibu would be a 4t40/45, right? I'm not seeing any kind of 4th clutch in them... they appear to engage/hold 4th gear via the intermediate/4th band/servo? I'm certainly no transmission expert, but this baffles the hell out of me. grabbed charts for 4T40, 4T65 and 4T80.

http://imgur.com/BGSArPB,PdAvFvG,xWB2sTq

4T40 and 4T80 appear to be very similar while the 4T65 seems considerably different.

[3400-95-Modified]

my bad, I was thinking of my 60 when it comes to the 4th clutch... I overlooked this was a 4t40/45e which changes everything even more.

[robertisaar]

GM's official word on the 4T40/45 shift speeds is a max of 6500RPM for any gear. a torque limit of 200lb/ft for the 4t40 and 215 lb/ft for the 4t45.

I don't know how much torque the 4th gear band would hold up to before it starts slipping, but the direct clutch looks to be 6 plates, so I don't think that will be the limiting factor. forward clutch appears to be 7 plates.

[Will'sFiero]

Is it hydraulically capable of shifting into 4th at WOT? The TH700, for example, isn't capable of shifting into 4th at WOT.

I rented a Cobalt a few years back and it would hit 125mph at 6500 RPM at the top of third... Where will you be needing to go to 4th? Also, the V6 chain ratio will put that speed even higher. Have you had an experience running 3rd to redline?

[robertisaar]

I would be amazed if these couldn't be shifted into 4th at any throttle position/speed. it's not like there is a TV cable moving stuff around that could block off fluid paths the way the older automatics locked out high throttle top-gear operation.

[Will'sFiero]

I figured that the 8100 RPM 3-4 WOT upshift RPM was the way to prevent a 3-4 WOT upshift in the electronic age.

There's no hydraulic pressure available for converter lockup in 1st gear... but I'm not sure how a hydraulic or mechanical interlock would work unless high line pressure by itself could prevent the shift.

[robertisaar]

i'm thinking the PCM is the intended way of preventing it as well, with a trans so heavily dependent on the PCM it's just too easy of a solution to not pursue it.

high line pressure would be present for all shifts at WOT. I can see a way or two to cause a high line pressure condition from allowing 4th gear, but they add unnecessary complexity and more points of failure compared to just using the PCM.