700R4 boost valve removal
- Thread starter Doober
- Start date
A couple days ago I installed a .472" boost valve & Corvette servo, made a little bit of a difference at 50-70% throttle into 2nd, and helped quite a bit in 3rd and 4th too, but I still feel what seems to be a low pressure symptom - at very light throttle 2nd shift is very soft, and when I give it more throttle after it's started going into 2nd you can feel the clutches grab, and 2nd feels normal again.
I ordered one of these today, just going down the line, trying to correct the pressure issue (looking at the 2nd accumulator and throttle valve now, this kit addresses both). The plan is to use these known new/good parts in the rebuild, whenever that happens.
I ordered one of these today, just going down the line, trying to correct the pressure issue (looking at the 2nd accumulator and throttle valve now, this kit addresses both). The plan is to use these known new/good parts in the rebuild, whenever that happens.
if your thinking it has a pressure issue, you need to put a line pressure gauge on it, it may just be on its way out, if it keeps sliding into 2nd your gonna end up glazing the input drum and replacing it as well, may be ahead of the game to go ahead and get it done before it quits on you.
ive done several 4l60e transmissions for no 3/4 or slipping 2nd, IMO, they are one of the worst transmissions GM has ever built, i have a mildly modded 99 NBS Sierra with a 5.3 and it has ate 3, first time was clutches, 2nd and 3rd was the input sprag....next time it will be an 80e
ive done several 4l60e transmissions for no 3/4 or slipping 2nd, IMO, they are one of the worst transmissions GM has ever built, i have a mildly modded 99 NBS Sierra with a 5.3 and it has ate 3, first time was clutches, 2nd and 3rd was the input sprag....next time it will be an 80e
I might be wrong about pressure, looking/feeling more like a 2-4 band issue. I'm considering trying to replace it, since 1st and 3rd gears are pretty solid as far as holding power.
Re: 700R4 boost valve removal (and partial rebuild)
I put a .472" boost valve and Corvette servo in last week, but it didn't help much. 3rd is a positive shift and 4th flares a little but not near as much. 2nd slips really bad, enough to where I try to get enough speed in 1st that I spend as little time in 2nd as possible.
Earlier today I started unbolting everything to get the trans out... converter unbolted, 3 of 4 crossmember/mount bolts undone, exhaust disconnected, etc. I'm hoping to have it out tomorrow, and do a quick look at the accumulators and other stuff inside. I may or may not install a shift kit, still up in the air about that. I'm also debating on piecing together parts for an actual rebuild. It drives fine, just 2nd slips real bad and 4th isn't great, but semi-acceptable.
I put a .472" boost valve and Corvette servo in last week, but it didn't help much. 3rd is a positive shift and 4th flares a little but not near as much. 2nd slips really bad, enough to where I try to get enough speed in 1st that I spend as little time in 2nd as possible.
Earlier today I started unbolting everything to get the trans out... converter unbolted, 3 of 4 crossmember/mount bolts undone, exhaust disconnected, etc. I'm hoping to have it out tomorrow, and do a quick look at the accumulators and other stuff inside. I may or may not install a shift kit, still up in the air about that. I'm also debating on piecing together parts for an actual rebuild. It drives fine, just 2nd slips real bad and 4th isn't great, but semi-acceptable.
yea the band is probably toast, you dont notice it as much cause the 3/4 clutches are on in 4th gear also, along with the band.
IMO, if your gonna have it out and apart, rebuild it, the 3/4 clutch packs are a known bad spot in the 700r4/4l60e, id avoid the z-packs or any of the "special" 3/4 clutch sets and just put a good original style in it with good clutches
i dunno what shift kits are out there for the 700r4, but i put alot of the TransGo HD2 kits in the 4l60s, they help a bunch, and you can tailor your shift firmness with hole size in the seperator plate and shims in the accumulator.
IMO, if your gonna have it out and apart, rebuild it, the 3/4 clutch packs are a known bad spot in the 700r4/4l60e, id avoid the z-packs or any of the "special" 3/4 clutch sets and just put a good original style in it with good clutches
i dunno what shift kits are out there for the 700r4, but i put alot of the TransGo HD2 kits in the 4l60s, they help a bunch, and you can tailor your shift firmness with hole size in the seperator plate and shims in the accumulator.
Trans is out today.
Can't remember, what does this tag mean?
~1600rpm stall
The number stamped onto the pan rail (passenger side just above the pan sealing surface) is 2CAM189C. From what I understand it's also supposed to include part of the VIN, but it doesn't, which leads me to believe possibly it's a reman?
Can't remember, what does this tag mean?
~1600rpm stall
The number stamped onto the pan rail (passenger side just above the pan sealing surface) is 2CAM189C. From what I understand it's also supposed to include part of the VIN, but it doesn't, which leads me to believe possibly it's a reman?
X2 on what Boostin said,
Stay away from Z-packs & thin steels.
High Energy frictions seem to work best with tight clearance.
Examples:
#1 -
#2 -
Stay away from Z-packs & thin steels.
High Energy frictions seem to work best with tight clearance.
Examples:
#1 -
#2 -
Last edited by a moderator:
Sounds good, I'll keep that in mind. I'm in the process of installing the "Jr" kit from TransGo, and hit a snag with a stubborn roll pin a couple weeks ago when I finally tore the trans down (have some pics, just gotta post them), and had to take it to work were someone had some good needlenose pliers. I wound up tearing up the end of the pin trying to get it out it was so stuck. Got a replacement, thiw weekend (Thurs-Fri) plan on replacing said pin after changing the spring for the throttle valve, drilling the separator plate to TransGo's specs, and getting a new band, 3-4 clutch set and new gaskets ordered. My guess is with the way $ is right now it'll be another month before I can get the remainder of the parts :x
Similar threads
