I finally got the reciepts on the transmission job the PO had done in the mail, which was a part of the purchase of the truck. The job was done by a shop in Yuba City, Ca., and they installed a DTT 89% TC and a DTT valve body upgrade into a new transmission. 1.Who is DTT? 2. Is 89% a good thing? I sort of understand low stall, but may need further schooling. 3. Is the valve body upgrade the reason for the overly firm shifts?

 

DTT is Diesel Transmisssion Technology, they are one of the top trans companies in the Dodge diesel business. A good shop with a good reputation.

89% refers to how tight the TC is. 89% is the more "slippy" of the TC's, but that's what is needed for a lightly modified truck. Unelss you have a lot of fuel you need the engine to rev up a little before the TC puts a load on it. It's still WAY better than stock.

The valve body is responsible for the shift feel. The firm shifts keep you from wearing out the clutches and bands, they are a good thing. Any performance trans is going to have firm shifts.

 

Don't forget that the torque converter you have will make the shifts feel even more firm as it actually doing its job.

 

I thought the job of a torque converter was to convert torque to heat?

 

That's what the stock one does.

 

A DTT torque converter and VB in a new trans should hold plenty of power, improve efficiency, and be very reliable.

 

Sounds like from all the replies that I scored on this buy...wow, lucky me! This R&R was done 40,000 miles ago. I'm tellin' ya, it is neck snappin' shifts!

 

Firm shifts are great on clutches, etc, the "neck snapping bone jarring" shifts are tough on all of the splines, pinions, and X-fer case chain.

 

First gens don't have weakling aluminum cased, chain driven t-cases. The NP 205 isn't a unit that will be upset by a hard shifting auto or a few thousand clutch dumps from a south bend.

 

That's true, the old 205!!