I herd a guy talking about doing this "full throttle 4th-gear shift kit (costs under $20 in parts to add it) so it will not stay in 4th at full throttle even at speeds over 120mph." Wanted to know what I need and what to do? It sucks red lining at 125mph.
Thanks,

 

Do a search for b4c police package upgrade... On police packaged third gens and some other stuff i guess, they had an option for a full throttle upshift. Which means, hold the gas down, 1-2-3-4 not 1-2-3 like a normal 700r4. The kit is about 20 dollars, and comes with a different upshift valve, a booster some springs etc. You have to drop the valve body to change it over. I put it in my car, and it works pretty good. The only thing is, you should also change the kickdown valve thingie... BM and some other companies make a modified version... This will make you have like 75%throttle while in 4th gear for the car to shift down into 3rd... IE passing somebody. My trans has always been a little weird, but after i put it in, it shifts into 4th at full throttle which is what I wanted... But when lightly accelerating, It doesnt stay in 3rd gear very long, kinda switches almost like a 2-4 shift. I havent put anytime in to figuring that out yet though.

 

mine did the exact same thing. love the way it shifts into 4th at wot but unfortunately i found i had to shift it manually otherwise it just went from 2nd almost straight into 4th. but if you don't mind shifting from d to od manually, its great.

 

So Far I've found this one from , But it says not for use over 250HP
"#20. 700R4 full throttle 3-4 up-shift sleeve. Now you can have a full throttle 3-4 shift. At 80 MPH it takes 90% throttle to make a 4-3 downshift. Can be installed without removing the valve body. The Up-shift Sleeve also eliminates part throttle 4-3 downshift for less gear searching. This is an extra option on the 700 Raptor. Not recommended for motors over 250 horse power. Cost $49.00"

And a B&M one from Summit
" BMM-70249 Automatic Transmission Controller, Buick/ Chevy/ GMC/ Oldsmobile/ Pontiac, TH700R4, Each
4/29/05 $118.69 "

Do I need to just go talk to a GM Dealer parts guy to get the GM's one?

 

yup, just go to the dealer parts counter and order part #8673948. i think it was about $18 and installed with the tranny still in the car.

 

Change Kick down valve thingie? With a stock one?

 

If you want the trans to upshift into 4th gear at wot, you have to drop the valve body to change the valve inside the body. There is no way around it. Now, if you dont mind that your trans stays in third at wot, and you just want to be able to cruise a bit faster or to be able to hit the gas a bit more before the trans automatically downshifts, you can just change the tv plunger and sleeve. For that, you just have to drop the trans pan, and take the old one out and put the new one in. They are available from B&M and TCI. Do a search for b4c, and you will find the GM part number, then just order from a dealer or gmpartsdirect.com its about 20 dollars, comes with valve body gaskets, upshift valve, boost valve and spring. If your going to do it, just read on it, and take your time. When you drop the valve body, theres a few ball bearings that are gonna fall out, dont loose them. You have to keep everything very clean, and be sure that the mating surfaces between the case, seperator plate, and valve body are perfectly clean so that the new gaskets seal it. Good luck.

 

i'm looking for a solution to this also. is anybody aware of a way to make 4th gear act like a normal gear i.e. shift into the correct gear at the appropriate rpm yet also shift into 4th at wot?

 

I had a Typhoon at one time that would do this from the factory. The trans worked normally 1-2-3-4 shifts driving around but also had 4th gear upshifts at full throttle, loved that 700R4 in that truck, worked like a dream. I am unsure what GM did to that trans to accomplish it but it worked flawless and shifted hard. You might want to check out syty.net and do some searching over there. There are a couple of syty specific tranny guys on there that know this trans in and out and can lead you in the right direction. I know the syty trans was like no other 700r4 according to them and the valve bodies are hard to find. Could be of some help though, Larry.

 

You can take out the TV plunger sleeve, and plug the 4-3 downshift ports with 2 Allen screws (about $.34). This will eliminate in 90% of the cases, the 4-3 downshift problem at high speeds, & will give you the 3-4 WOT shift you want. This can be done without removing the valve body, just the 2 bolts & pin that hold the TV bell crank & TV plunger bushing. You will need to grind the Allen screws for clearance for the TV plunger & bushing. A Dremel will work for this.

 

fascinating. and does this eliminate the need for the gm 3-4 upshift valve or the b&m tv kit?

 

also, does that mean it will not downshift from 4-3 ever? im guessing you would have to shift into d from od to get it to downshift from 4th with that mod.

 

I was thinking the same thing. Hopefully the fellow from pro built will chime back in and clearify that.
I know the Typhoon I had worked flawless, downshifted out of 4th at full throttle and ran up to the shift point and went back into 4th at full throttle. It never did any of that goofy stuff everyone here describes with the B&M 4th gear kits and the like.
If you decide to check out the syty.net web site on those trannys, ask for a guy named John Waller, he is a tranny guy and knows the syty transmissions specifically and what makes them work. I do know the valve bodies were specific to that application but not sure that is the reason for the full throttle shifts into 4th. Larry.

 

It appears as though GM hasn't even fully figured this one out. A "new" 700R4 from the GM parts counter shifts into 4th at WOT, hot or cold. This 700R4 worked great... for about 4 months before I smoked it. I took it back to the dealer and they replaced the entire 700R4. This "new" 700R4 would only shift into 4th at WOT when it was cold otherwise it wouldn't go into 4th at WOT or slip out of it when the speed exceeded 110MPH. GM said they couldn't do anything about it because I'm breaking the speed limit when it happens!!! According to them, the fact the car is designed to go 150MPH doesn't matter...

 

Next time, tell them you take the car to track events and need 4th gear to hold at WOT.

 

Not sure which trans you got, if it was just a factory replacement for your vette? A friend of mine just bought a new 700R4 from GM and he ordered the police spec 700R4 which has 4th gear shifting at full throttle. His has worked flawless. I could get the part number for this trans if you like. It is the same one the police cars used in the late 80's and early 90's for high speed persuit.
Anyway, my Typhoon had this feature from the factory also, and it worked flawless, never had any trouble from that trans even after numerous boosted launches with all wheel drive. 4th gear always worked at full throttle. I am not sure what GM did to these transmissions from the factory but I do know for a fact that the valve bodies were special for these syclone/tyhoon 700 trannies, even different from the vettes of that era. It was the best working 700 I have ever owned/driven.
Anyway, the closest thing to it that GM offers anymore is the cop spec trans that I mentioned above. I am not sure what GM does to this trans either but I know it works much better than the "so called" kits out there that are supposed to transform a normal 700 into 4th gear full throttle shifts, I have not seen one of those kits work exactly right yet unfortunately.
Sorry to here about your troubles, pulling that thing in and out gets old numerous times gets old. Hope you get something figured out. Larry.

 

I ordered a factory replacement 700R4... they wouldn't warranty any other "version".

The first 700R4 sounds like it functioned as a "police version"...but the second definitely didn't... I dunno.

Ya, I can re&re the thing blindfolded now. I currently on transmission #8... and it's starting to feel sloppy.




Has anyone installed only the #8673948 GM shift valve (and NOTHING else) and personally experienced the transmission staying in 4th at WOT?

 

Wow, thats too bad. Sorry to hear that. I wasn't thinking about the warranty problem, makes sense.
Transmission #8? Man I am starting to wonder about the reliablility of these 700's As far as that shift valve you are referring to I believe some people on this board have tried that and complained about the trans shifting from second and straight into 4th gear at part throttle driving. for some reason the trans passes up 3rd gear all together when cruising around. At full throttle I beleive it worked though, maybe someone will chime in here and confirm that so don't quote me on this. Hope you figure something out. Larry.

 

yes. well, almost. i also had a transgo shift kit but that shouldnt affect the 4th wot shift. and yes, it shifts into, and stays in 4th at wot. the only downside i found to it was the part throttle 2-3-4 shift. it tends to skip right over 3rd unless you manually shift from d to od.

 

Pro-built setup my transmission the above way he described. It allows for WOT upshifts into OD, but no downshifts under throttle even at 100% throttle it stays in OD. If I want to use "passing gear" I just blip the throttle to build up some fluid pressure and manually downshift it into 3rd gear. Other than that for normal driving it doesn't affect the way the car drives at all. It still does the regular 3 to 4 and 4 to 3 when I'm driving like a grandma around town. I've been very happy with the Pro-built trans so far. Firm shifts at moderate throttle or above, but no neck cracking shifts at part to low throttle like the B&M kit I had before this trans. (That got old quick especially in the rain)