TH200-4R Shifts Explained?

peterkin

..it isn't rocket science
Joined
Oct 2, 2001
I've been looking at an exploded view of the TH200-4R from Xtreme Automatics, and it has sparked some curiosity. I like to know how things work, and sometimes down to the minutiae. I've been looking for an explanation of which clutch sets are used in which gears, how the band is applied, how accumulators work, and how the governor is entered into the equation. If you feel so inclined to detail this for the community here, can you put it in a scenario based on the drag strip? If you possible, please start from the burnout box to going through the traps in 4th gear. ( I know 4th isn't realistic, but it covers all shifts). Thanks in advance. I think this would benefit this section of TB.com in a big way.

I have attached the exploded view from Xtreme Automatics that I referenced in the beginning of this post.
 

Attachments

  • explodedViewTH2004R.pdf
    951.6 KB · Views: 148
there is s "Principles of Operation" book for the 200R4 which has lots of details.

in the standard 2004r (i.e. no unusual mods) first gear is slightly different if the shift is in D or OD, and the pressure control is different also.

I'm not an expert, but here are some starters, assume the shifter is in D

at a standstill, the "forward clutch" is on and the power is transmitted thru a roller clutch for first gear.

on the 1-2 shift, the "intermediate servo" is activated, causing the band to grab the drum. nothing is "released" during a standard 1-2 shift, so no overlap/bind to worry about.

on the 2-3 shift the band is released and the "direct" clutch is activated, the timing of this action is crucial to prevent a "flare" and minimize bind.

making sense so far?

Bob
 
The attached chart will show what clutches and roller clutches are used by gear range.

operation.jpg
 
X2 on the principles of operation. Hit eBay and pick up a copy. Not only does it show what clutches do which function , it has diagrams that show which place in the worm casting does what. Good info if you are interested.

Posted from the TurboBuick.Com mobile app
 
I'll get that book and do some studying. Thanks for answering my questions and steering me toward the information I'm looking for. Once I think I have it, I'll probably come back and post up for the experts to critique it.
 
Lots of info and ways that the gurus do things. Not everyone needs a billet input shaft but all need the hard pump rings, hard stator support and Sun shell.
Lots of views on pressures and where they need to be. Also plenty on what to do to the vb but much depends on what parts and such you are using and your power level. You don't need a lot of things a trans that is hitting the strip every weekend laying down 10s when you go to the track twice a year and hit some high 12s. But it does suck when you are on the side of the road with a twisted off forward drum shaft.

Posted from the TurboBuick.Com mobile app
 
Ah yes, the multi-neutral modification. Turns your P-R-N-OD-D-2-1 into a P-N-N-N-N-N-N. :nailbiting:
 
LOL, I've had that happen before...fortunately I was at a track rental with a trailer. After all of the searching/reading I've done here, I've tried to formulate my own recipe. It is hard considering the number of differences in the way that each trans guru that has shared information has done things during their career.

Thanks for taking the time to share information.
 
Might give Chris at ck performance a ring and see if he has any. He used to advertises em on his website.
 
Appears he is pretty proud of them.
I didn't pay that much but I guess I wasn't in a hurry. I'd just keep a search going on the eBay as one could pop up at any time. Your call
 
Top