i havent seen this problem with anyone else on this site, probly a good reason for that... but anyway i need information on all possible causes of a weak high rpm shift on a COMPLETELY rebuilt transmission (94 4l60e) but a very strong low-mid rpm shift and most of the time hits the rev limiter on the shift to 3rd gear at wot. my mechanic said the mac scanner wasnt even showing the computer as commanding a shift, after i installed 3.73 gears it started doing this sometimes on the 1-2 shift and is beginning to get old because my car has been in the shop for a month with no progress beyond the installation of a trans cooler over the weekend which seems to have helped *some* its still very soft shifts up in higher rpms and i have to let way out of it for those high rpm(5k+) shifts... if anyone has any information that will help please post up!!! oh and it has the B&M trans pak installed also.

if you need any more information let me know also!
thanks for any help!

 

if the computer is not commanding the shift than there is an input data error with tps,mass air,or output speed signal that should throw a trouble code.re scann the car.the final drive ratio change needs to be put into the computer also.usually the 3.73 will make the trans shift too early and get passing gear too early by tricking the computer into thinking output speed is faster than the program tells it the ratio is.

 

oh its definately not shifting too early... i think its been reprogrammed by hypertech because my shiftpoints ddint change after the 3.73 gears, i.e. set by rpm instead of mph, and the car isnt throwing any trouble codes =/

 

Did your transmission builder make the proper modifications to keep the pressure up at high RPM's?

They obviously didn't make the proper modifications to the 3-4 clutches to make them hold at high RPM's, either...This is why you're having a rev limiter bump on the 2-3 shift.

These are reasons you should take a 4L60E to someone who specializes in building them for racing/high performance. There's many many things we change/modify in our racing transmissions. Most "generic" shops don't even know what modifications to make to a 60E. Some are content with throwing a "boxed" shift kit in one. A "shift kit" doesn't address all the 60's short comings.
I get transmissions in my shop continually that were supposed to have been a "performance/race" rebuild. They're usually nothing more than a stock trans with a shift kit.

Frank

 

thanks for your info frank, anyone else know of a cause with a detailed explanation for this problem?

 

slipping or clutch pack accumulation issues in the 3/4 clutch pack.in order to initiate a 3rd gear ratio change you must reverse the direction of the held and driven members of the rear planet and drive it up with the input shaft and compound planetary gearset .this places a large demand on the 3/4 clutch pack although the input drum is rotating with the turbine shaft unlike conventional gm 3 speed designs.the main issues with this design /trans is insufficient 3rd clutch capacity,accumulator pressure ,line pressure and band knock off to clutch pack apply biasing.those of us who understand hydraulic calibrations have left this problem behind many moons ago.I have found that using a 4l60e .100 steel for an apply and pressure plate and using 075" steels with 9 or 10 plain tan 060"plain tan paper friction plates will outperform all other methods of driving the front carrier,reaction tube and rear carrier.remember any time 2 members of a given planetary gearset are held or driven together your in direct drive.this is the key.engine power and speed,trans ratio ,final drive ratio,pressures and component weight and direction of rotation are all trying to burn the 3/4 clutch pack.its inherent in the design at work here.study the held and driven members,dont take my word for it.ckperformance.com

 

btw the z pack is junk.i tested several sent to me from frank slocum at raybestos and they were under achievers.no the theory doesnt work when your dealing with 500 plus horsepower.

 

now THAT is what ive been looking for thanks very much for the information!!!

 

ok after i showed all this to my mechanic he admited to rebuilding my trans as stock with a shiftkit... so will retuning for the shiftpoints and such help it shift at all? im retuning anyway for the 3.73 gears and new tires but im just curious while the pcm is out if it will help my trans any with the shift when i get it back, as of right now its either a soft or bouncing off the rev limiter and still soft shift at wot and neck breaking at low to mid rpms... maybe the shift points will help because it shifted pretty good last night at 5.5k but it was just half throttle 0_0... the stock clutches and steals dont seem to be slipping though because the trans fluid is still bright red and teh clutches are showing no signs of wear hotspots or slipping... still wont have the firm wot shift i want though will i?
this just gets crappier and crappier every day =/ im gonna be a lot more picky next time i do anything to my car.

 

the factory accumulator valve spring is directly related to hard shifts up to 5/8ths of the throttle and softer shifts at heavy throttle.this is because at wot the valve compresses the spring and reduces accumulator trim pressure resulting in soft shifts.we have a valve body kit that corrects this,and it is not someone elses its ours.

 

great =/ so basically the shift kit accomplishes the exact oposite of what you would want it to do, i.e. smoother part throttle and firm heavy throttle shifts. so even if the tuning does make it shift it will still be soft and still leave me wanting the trans fixed to what i payed for it to be like in the first place, which if you knew what i spent on it, you would tell me i was stupid. but i feel like being pointed at for ignorance on this one, $1200 for a fully stock rebuild (which the time hes had my car has cost him much more than this by now) and the only hard parts replaced were the shift plate itself and the piston that applies pressure to the clutches because it was cracked. but live and learn i guess, im sure he learned a lot from this too, mostly im a pest to deal with if you dont build it like i want lol. thanks again for the information chris, learned a lot in the last few days.

 

since i forgot to mention it you wouldnt sell that in a kit would you?

 

feel free to visit the site or call in.in kit form .www.ckperformance.com