Min. tv pressure ???

[Lee Thompson]

Shouldn't all 200R4 trans have a min. of 90 psi, no matter what VB is in it? I've got one that has 60 min. tv but 250 max. tv. Shifts way too soon and way too soft. I can take the tv cable tighter and fix it but goes back to soft once I go to WOT. It's a BQ trans but the VB has no markings on it altho it does have both pressure switches.I am open to any and all suggestions.

 

[mikestertwo]

That is a little low. Should be in the 70-90 psi range. Sounds like it needs a different spring on the pressure regulator valve in the pump.

 

[77 cruiser]

Is it at 60 even with a few more RPM, say 1500 or so?

 

[jakeshoe]

Sounds like the TV geometry isn't correct or the TV plunger spring is too short.

 

[Lee Thompson]

Thanks to all who replied

I put a known good BR vb on today--still 60 psi @ min.--have to go to 3000 plus to get it to move up any--I'm sure that is enough to stroke the valve making it go up. RPM alone don't make it go up. Put in a stronger PR spring --picked up 10 psi of min . Actually the one that I took out is the one I have always used. I can't see where the geometry would be off but not ruling it out.

 

[jakeshoe]

Lee,
What type of car is it in?
OEM linkage setup or aftermarket conversion.
I'm sure you know all this but the geometry can be seen here:
700R4 Info Page 1

1.125" from the throttle centerline to the center of the TV cable pin is very critical. Yours sounds like it may be more than this.
Many carbs are setup for a longer throw for a TH350 detent linkage and this won't work with the 200-4R.

You could also have a TV valve sticking. I had a 700 do this recently but it would stick in the middle of the travel, it bench tested good 95% of the time, but every now and then it would hang up even with the TransGo TV springs to prevent that.
I would have middle of the range PSi readings, about 125-135 at all throttle angles.

 

[Lee Thompson]

stock

This is my 85 T (OEM linkage)---stock floor shift. I took my billet trans out to try this one.So nothing has changed. I am wondering if something could be wrong with the bracket (the one on the vb that the tv cable hooks to). All the parts in this trans is stuff I had laying around. Not a trans that was working so there is no history. I'm going to drop the pan again tomorrow morning and take a look @ the tv setup with pan off. Maybe find the problem. Thanks for your effort.

 

[jakeshoe]

While you have the pan off I would go ahead and pull the TV plunger and measure the spring length. Look for 2.10" or so.
Use a screwdriver to be sure the TV valve moves back and forth freely.

 

[gsgns4me]

For what it's worth, here is the stock specs from an '87 service maual.

 

[Lee Thompson]

dropped the pan

Nothing--travel is good on the plunger as it is on the known good vb. Spring is 2.000 but shimed so there is only a few thousands travel before it strokes the tv valve. I have about come to the conclusion that it is a pump problem. Coming out later today. Thanks for all the suggestions.

 

[Lee Thompson]

got it !!!!

Pump problem--WAY TOO MUCH clearance between pump cover and rotor and slide. 90 psi @ Min. now and 260 @ max. Shifts are great. Thanks to all who replied.