I bought the valve months ago with plans to install it myself but in the end I took the car to a highly recommended indy shop. The shop is a small one man operation with a highly knowledgeable owner who has worked on several Jaguars. He performed a fluid and filter change and installed the valve I supplied for just under $550.00. I think that's a bargain. The car was shifting hard, especially under under WOT, but it shifts flawlessly now. If you are anywhere near Chester County, PA I highly recommend Ed's Transmission and Auto Repair in West Grove.

 

Hi, what car is it? What is the purpose of the installation of the shift improver, is it to have smoother shifts or to have faster shifts?

 

Wondering because I remember seeing something about a new valvebody for the Mercedes gearbox, developed to increase shift speeds. The merc box of my Xkr 00 shifts incredibly smooth, but also incredibly slow. Unless the pedal is to the metal, then shifts are reasonable quick. But I would like shifts to be faster all over.

 

https://transgo.com/products/zf5hp24/

This one?

 

Yes that’s the one.

 

If I understand correctly the valve I had replaced is the main pressure control valve. If the valve binds up in the bore, as they are known to do on the model of ZF 5 speed in the early XK series, the “A” clutch drum will fracture from the over pressure.

 

97 XK8. It does shift smoother now but the main reason for changing the valve is to prevent transmission failure if the stock valve binds in it’s bore. If I his occurs the transmission can be catastrophically damaged by the over pressure.

 

on the Mercedes gearbox, the only way I know to speed up the shifting is to go to the blue top solenoids as described in other posts but I think they are hard to find and also exoensive. There was a rumour that you could drill the brown (the ones we have in our 'box) but no one ever expanded or said how or what they did.. seems a top secret..