? about low/reverse clutches, sprags operation.

[JDSfastGN]

Well im helping a friend out with tearing down and diagnosing his tranny. The tranny shifted really well and all of a sudden one day it would not shift at part throttle until 5000+ and they were never able to get it into 3rd. It didn't slip while in gear and it shifed very firm when it hit the 1-2. It still had reverse and acted normal. I automatically assumed it was the governor spring or a stuck TV valve in the valve body. But the trans is as clean as ive ever seen from a tranny thats seen a lot of track duty. All the valves are free, the governor spring is there. and i can't find anything else wrong. I've taken it down to the rear carrier and such. The only ? i have regaurding this is when i twist on the front internal gear (633 in the manual) the sun gear spins the opposite as its supposed to but the low/rev clutches seem like they are spinning and then slip and don't catch and spin any more even though im still spinning the gear. If i go the opposite way the clutches don't spin which i believe it correct.(is the slipping of the clutch while turning the internal gear fairly fast normal? the 3 200s ive worked on all spun right along with the gear) Does this all sound normal? What should the rear sprag cause these clutches/sun shell etc... to do? Sorry as i know this is probably not very clear so if i can clarify anything let me know. i'm hoping the not shifting problem was a gasket type problem and it will be ok when we reassemble and install. The valvebody will be cleaned etc.. but if anybody has any other ideas as to the long delayed shift let me know. It has quite a few strange mods from the previous builder. (drilled hole in case next to 3-4 accumulator hole with check ball jammed in there, no 1-2 accumulator spring etc...) but i don't want to change much in the shift calibration as it shifted very well in a 4.1 T63 car, and the clutches all look brand new still. Thanks guys

 

[Hacksaw]

There's 2 places for general 200-4R rebuild tips:

http://www.montecarloss.com/SSThunder/drivetrain.html
http://www.ptsnctb.com/images\../faq/display_faq.asp?faq_id=4
And a BRF valvebody:
http://www.gnttype.org/techarea/transmission/valvebody.html

Now, that Low Reverse (L/R) sprag locks one way, & freewheels the other way. The locking allows first gear by keeping that L/R planet stationary during Low. The L/R clutch only comes on in Reverse, and manual Low (to allow engine braking).

So, does this L/R sprag seem to slip? They do give out, but not as frequent as other parts in this trans.

While it's apart:

*Drill/check the front seal drainback.

*ALWAYS replace the: Stator support with a hardened one (PTS's site has tips in how to do this right), Pump rings with stronger ones (less fragile, will kill you trans if it fails), and the sun shell if it's looser a 1/4 of a tooth on the sun gear.

* Clean the valve body really well. A sticking TV valve (the one in the vb the sring moves around) or PR valve (in the pump) can cause shifting problems.

* Make sure the governor weights & valve are free, and that the gear is not loose.

* Don't overtorque the pump or valvebody!! Bad things can happen.

It might be nice to add an aftermarket billet servo & Alto Red band, with a PTS improved band anchor.

-Mike H.

 

[JDSfastGN]

There's 2 places for general 200-4R rebuild tips:

http://www.montecarloss.com/SSThunder/drivetrain.html
http://www.ptsnctb.com/images\../faq/display_faq.asp?faq_id=4
And a BRF valvebody:
http://www.gnttype.org/techarea/transmission/valvebody.html

Now, that Low Reverse (L/R) sprag locks one way, & freewheels the other way. The locking allows first gear by keeping that L/R planet stationary during Low. The L/R clutch only comes on in Reverse, and manual Low (to allow engine braking).

So, does this L/R sprag seem to slip? They do give out, but not as frequent as other parts in this trans.

While it's apart:

*Drill/check the front seal drainback.

*ALWAYS replace the: Stator support with a hardened one (PTS's site has tips in how to do this right), Pump rings with stronger ones (less fragile, will kill you trans if it fails), and the sun shell if it's looser a 1/4 of a tooth on the sun gear.

* Clean the valve body really well. A sticking TV valve (the one in the vb the sring moves around) or PR valve (in the pump) can cause shifting problems.

* Make sure the governor weights & valve are free, and that the gear is not loose.

* Don't overtorque the pump or valvebody!! Bad things can happen.

It might be nice to add an aftermarket billet servo & Alto Red band, with a PTS improved band anchor.

-Mike H.

Thanks for the reply man.. When turning the output shaft, the L/R clutches turn as they should it seems(only in one direction). It just seems when turning the front gear at a good rate, the clutches will not turn any more and can don't turn with the unit the faster i turn it. This is the only thing im not sure about. I have rebuilt 3 other 200s with my dad and never really noticed this about the L/R clutches before, but i wasn't sure whether it was normal or not. The valve body is very clean, but will be cleaned and double checked, all the governer weights and check balls are freely moving and clean. The tranny is outfitted with a stronger foward drum, hardened stator, 10 vane pump with good rotors, Kevlar band (i use altos in my rebuilds, but this one is not adversly affecting the drum and seems to shift well) It has 3 OD clutches and is running an extra clutch in the directs. I don't do the extra clutch in the direct usually but i don't want to change anything as it shifted very well behind a strong motor before and all the clutches look to be in great shape. I'm hoping it may be just a valvebody gasket problem, or something simple that is taken care of when we reassemble. Thanks for the help and links.
J.D.

 

[JDSfastGN]

quick ?... this tranny stopped shifting a while ago and the owner doesn't remember this when he took it out, but if the TV cable some how became unhooked in the tranny, doesn't the TV go to full line pressure automatically? Or am i thinking of something else? This would explain the high and hard shift points if this is the case.

 

[Hacksaw]

I found an article about 200-4R shifting someone had posted elsewhere:
http://www.geocities.com/smasherss/tranny.html

It's at the bottom of the page. See if this helps.

Now, the unmodified 200-4R has an "emergency" system on the TV so that if it's too loose or disconnected it will raise up the pressure. It's a checkball lifted by the U shaped wire on the TV. It's like the 200 there.

DANGER!: Some valve body kits eliminate this feature to allow a bigger TV adjustment range.

Some TV adjusting advice:
http://www.gnttype.org/techarea/transmission/tvcable.html

-Mike H.

 

[chris718]

the rear carrier remains motionless when using the rotating the front ring gear clockwise .negative loading on the output ring gear will allow it to rotate the same way it would in manual lo if the clutches werent applied.remember its the held divided by the driven in the front planet and the rear planet when operating in first gear reduction.the pinions are merely there to transfer motion and force between the two.