Hi all - wondering if I could get some insight into an issue I'm having with a 2002 Jaguar XK8 convertible. Whenever I am driving the car in low gears, I hear a whining sound in the lower gears. This is accompanied by rough shifting into higher gears and downshifting into lower gears. Once the car picks up speed, the higher gears shift easily. The rough shifting is particularly bad when the car wheels are turned. Sometimes there is a jolt in the car to engage the lower gears.

The ABS light is on intermittently and sometimes when I hit the brakes hard, the car throws itself out of drive, and I have to shift back to Neutral/Park then into drive again to move the car forward.

Anyone have any experience / thoughts on what's wrong?

2002 Jaguar XK8 112,0XX miles

 

When was the last time it was correctly drained and filled with the correct amount and type of fluid?

If you don't know, do that. While you're in there do the trans-go pressure regulator valve - easy peasy (but messy removing the valve body)

 

Some quick background; I inherited the car from my grandparents. The transmission fluid was very low when I got it, so I drained and filled it up last month. I did not do a filter change at the time due to the drain pan bolts being in rough shape (really easily strippable). The transmission was able to shift gears much better.

I used Valvoline Multi-Vehicle (ATF) Full Synthetic Automatic Transmission Fluid. Amazon Link:
Unfortunately, there is a change that my grandparents put ~30 miles of driving with low transmission fluid.

 

Did you do it properly - car raised evenly, adding fluid when the existing fluid is around 90-98 degrees temperature and then put the plug back in when it was just dribbling out of the hole?

That's about the extent of my transmission knowledge for these cars - hopefully someone else will chime in soon as to the symptoms and potential cause(s).

 

Sounds like low fluid - did you follow the correct procedure to set the fluid level?

 

You most likely have low fluid, but it's highly likely you have a pressure regulator problem, and/or other valve body problems.

The first thing to do is to go to FCPEuro.com (or your local BMW dealer if you like to pay triple) and order 22 (IIRC) of these:

BMW Automatic Transmission Oil Pan Bolt - ZF 24159896928

Also a filter, a pan gasket, and new pan and fill plugs. Go to Amazon and order the Transgo kit for the 5HP24 transmission. @AbnMike is correct. This should be done while the car is experiencing harsh shifts, before other things break.

Get the car on a lift or on jackstands, level. Drain fluid, remove pan, remove filter. (Get the screwed up bolts out as best you can. To avoid screwing up the new ones, get a T27 1/4 inch drive bit. DO NOT attempt to use a T25.) Follow the instructions in the Transgo kit. There are about 24 bolts holding in the front half of the lower valve body. Remove them, pull down gently (there is a dowel in the upper right corner as you're facing it. Follow instructions for replacing the failing pressure valve. Replace the bolts in the correct holes. Torque the "large head" bolts to 8nm, and the small head bolts to 6nm. You will need a 1/4 inch torque wrench. BTW, all the bolts, small head and large head, are T27. BE SURE TO GET THE SHIFT VALVE ALIGNED WITH THE PIN ON THE SHIFT LEVER BEFORE YOU BOLT THINGS DOWN! Do not ask how I know this. Replace the filter and the pan, torqueing all bolts to 10nm.

Fill the trans until the fluid dribbles. Start the car. Run through the gears. Wait until the trans is above 40 degrees Centigrade, and less than 50 degrees Centigrade. Monitor this either by using a scan tool that will show trans temp, or in a pinch an indirect-read infrared thermometer gun can be used, pointed to the pan. It's not as accurate but better than nothing. When the trans reaches temp, fill the pan until it dribbles out (probably another 1 to 1.5 liters more), then close 'er up and take 'er for a spin.

CAVEAT!!! The above is if your trans is doing the occasional harsh shift. If it's shifting hard all the time, you may have something deeper. If the pressure spike problem has gone on too long, the A drum may break but before that happens a passage in the upper rear part of the valve body may split. If the trans is shifting harshly most of the time, especially in the lower gears, you'll want to check the following while you're inside the trans.

Disconnect the electrical connector at the rear of the trans, pull the U-clip, and push the connector back into the body of the trans. Then unbolt the VB. The large head bolts are the ones that hold the VB to the trans body. The small head bolts hold the VB "sections" onto the main VB. After you unbolt the VB you can remove it from the car, but be careful. It's a lot heavier than it looks. Once out of the car, look at the rearmost half of the VB. If one of the passages has a split in it (you can't miss it), then that portion of the VB MUST be replaced. Here's a link. These parts are getting hard to find. Both of them now say "email for price." 18 months ago I paid about $175 each.

https://www.thectsc.com/catalog/hardparts-32.html

To unbolt the upper rear half, it's done from the bottom. All the bolts that attach it pass through the corresponding lower rear half of the VB. So, unbolt from the bottom, then transfer all valves, clips, springs, etc., etc., etc. from the old to the new. BE CAREFUL. TAKE PIX. Don't ask how I know this. Bolt the new ones in place, torqueing the bolts to 6nm. Using all three of your hands, hold the VB up into the trans, feed the connector back into its hole, and get a bolt started to hold the VB up. Then align the connector correctly and push it through the trans body and secure it with the U clip. Finish bolting the VB into the trans. 8nm for the large head bolts.

This seems daunting, but it's not a bad as it sounds. However, it IS messy. And removing the VB will result in you needed an extra liter, more or less, of fluid.

Good luck! Keep us posted.

 

Been there, done that.
After a start, I always wait for the revs to drop before shifting into gear. Used to have a little thunk when went into gear that disappeared with TransGo.