200r4 1 to 2 upshift RPM Flash
05-24-2017, 01:49 PM
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200r4 1 to 2 upshift RPM Flash Looking for some ideas / help. I have a 200r4 - really long story - in my 70 Monte. Was supposed to be a fresh - well built trans for my Monte.
First test drive, it blew the front seal because they forgot the seal retainer. When I got the car back, in drive cruising normal throttle position, it would flare RPM between 1st and 2nd. Took it back, adjusted the TV cable, they messed around with it, I picked it up - left the shop - all worked fine - but - kept getting worse as the trans warmed up.
Took it back - they messed with it for 2 weeks and said - its as good as it's going to get - still had the flare between 1st and 2nd. I went to another shop for a "second" opinion. They tore the trans down and found worn out bushings, old clutch discs mixed with new and several other issues. I spent a ton of money buying all the "hard parts" - the second shop put it all back together - first test drive - shifted perfect under different throttle postilions - until it warmed up. Flare is back between 1 and 2. Soon after that I moved out of State and have been "fiddling" with it ever since.
Can someone point me in the right direction for trouble shooting this flare? I'm thinking it's the bore of the case for the 2nd gear servo? Maybe as it warms up, the servo is sticking - rpms go up (like shifting to neutral) until the pressure gets high enough to overcome the "stick"?
All the hard pieces, bands, seals, clutches have been replaced - same case? Trans shifts great when shifting manually and pushing hard on the throttle but once in awhile - even shifting manually, it has the flash between 1 and 2. It's always there in auto after it warms up. Severity of the flash changes with throttle position - light throttle - it's not as noticeable as it is at hard throttle or WOT. When it does shift to 2nd, it's a solid shift - no slipping. Upshift to 3rd and 4th are fine.
Thanks in advance.
Pat
First test drive, it blew the front seal because they forgot the seal retainer. When I got the car back, in drive cruising normal throttle position, it would flare RPM between 1st and 2nd. Took it back, adjusted the TV cable, they messed around with it, I picked it up - left the shop - all worked fine - but - kept getting worse as the trans warmed up.
Took it back - they messed with it for 2 weeks and said - its as good as it's going to get - still had the flare between 1st and 2nd. I went to another shop for a "second" opinion. They tore the trans down and found worn out bushings, old clutch discs mixed with new and several other issues. I spent a ton of money buying all the "hard parts" - the second shop put it all back together - first test drive - shifted perfect under different throttle postilions - until it warmed up. Flare is back between 1 and 2. Soon after that I moved out of State and have been "fiddling" with it ever since.
Can someone point me in the right direction for trouble shooting this flare? I'm thinking it's the bore of the case for the 2nd gear servo? Maybe as it warms up, the servo is sticking - rpms go up (like shifting to neutral) until the pressure gets high enough to overcome the "stick"?
All the hard pieces, bands, seals, clutches have been replaced - same case? Trans shifts great when shifting manually and pushing hard on the throttle but once in awhile - even shifting manually, it has the flash between 1 and 2. It's always there in auto after it warms up. Severity of the flash changes with throttle position - light throttle - it's not as noticeable as it is at hard throttle or WOT. When it does shift to 2nd, it's a solid shift - no slipping. Upshift to 3rd and 4th are fine.
Thanks in advance.
Pat
05-28-2017, 07:12 PM
#2
Should have already been addressed but the 2004r with the stock slide spring in pump is bad to collapse itself at high rpm worse when hot causing the line pressure to drop at high RPM under throttle just when it needs to be highest,
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09-03-2018, 11:09 AM
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A little late to the party, but here goes anyway. Once your trans lost the fluid you ended up with some smoked clutches and band. It sounds like the original shop were buffoons but hard to know for sure. You are probably using a stock(read: SMALL) 2nd servo(562 casting?). For any kind of snappy shift you need a larger one. A 692 or 694 factory one would be the minimum, but a sonnax is a nice addition to any 2004r. Next as pointed out above you need the pump to make pressure and your boost valve, rev boost valve and spring to get the internal pressures up, way up from stock. The pump needs some unbreakable rings and a sonnax slide spring and a real good inspection to replace worn parts if there are any(rotor, rotor guide, vanes, pump cavity and cover need a close inspection).
Next come the tear down, and inspection of the components. Particular attention to the drum surface where the band rides, the band pin and hole it lives in the case, and the bashings. All the other parts need looked at for wear, cracks etc... This trans wasn't designed by GM for high hp and even the stock GN/Turbo regal is putting twice what the original engineers designed it for through it. And he go those GN guys upping it to the stratosphere.
The assembly phase has its challenges as the last new one of these installed by GM on the assembly line was 1990 so cores and some of the hard parts are becoming more difficult to obtain. This can be overcome but gets expensive if you have to buy multiple cores to get the stuff you need.
Careful assembly with attention to detail including setting up the clearance on the internal trans sections as well as the clutch packs and band all play a role in how the finished unit shifts. Those original guy(s) who assembled it probably just took it apart and put it back together and this is what you ended up with.
There are several places around the country who can put one of these units together but not many. I wouldn't trust the local "race" trans guy to look at it if they don't have a list of happy customers you can contact. And the local trans shop is just going to cause you headaches as you've already experienced.
Next come the tear down, and inspection of the components. Particular attention to the drum surface where the band rides, the band pin and hole it lives in the case, and the bashings. All the other parts need looked at for wear, cracks etc... This trans wasn't designed by GM for high hp and even the stock GN/Turbo regal is putting twice what the original engineers designed it for through it. And he go those GN guys upping it to the stratosphere.
The assembly phase has its challenges as the last new one of these installed by GM on the assembly line was 1990 so cores and some of the hard parts are becoming more difficult to obtain. This can be overcome but gets expensive if you have to buy multiple cores to get the stuff you need.
Careful assembly with attention to detail including setting up the clearance on the internal trans sections as well as the clutch packs and band all play a role in how the finished unit shifts. Those original guy(s) who assembled it probably just took it apart and put it back together and this is what you ended up with.
There are several places around the country who can put one of these units together but not many. I wouldn't trust the local "race" trans guy to look at it if they don't have a list of happy customers you can contact. And the local trans shop is just going to cause you headaches as you've already experienced.