At morning start up,,, brakes act like they are not effective. Petal feels hard and high. This is happening at 1 or 2 mph and feels like it wont stop or like RPMs are very high,, they are not. After warm up they work just fine.
104,000 miles with pads about 50% front and back.
seems to be getting worse as the weather gets colder. Never real cold in Austin Texas. Please help.

 

Sounds like a bad power brake booster, or a problem with the vacuum circuit providing the motive force. There are several ways to confirm this. One easy method is to disconnect the vacuum line to the booster and plug the line on the engine side. If there is no change in the pedal feel, that means the booster previously hadn't been working. If so, the next step is to confirm proper vacuum feeding the booster while under load. I'd tee in a vacuum gauge at the booster vacuum connection. If good vacuum is present but there's still no power assist, the booster has failed.

Also, if the vacuum reads low with the gauge teed into the line, disconnect the booster again, remove the tee and take a direct reading on the vacuum supply line. If that's good, the booster has an internal vacuum leak.

 

I have absolutely no idea what you just said but you seem to know what you're talking about! Haha

 

Take to a competent place to fix it, then

 

Testing the brake booster is easy. It might make it even easier if you do this test on a friends car to get the feel:

1. With the car off, pump the brake until hard.
2. While pressing the brake pedal start the engine.
3. The pedal should go down.

If it doesn't go down is the booster and has a leak somewhere or the vacuum hose going to the booster.

Here is a link to a more detailed explanation if you still don't understand.

jaghelp.com: How to test your Jag's Brake booster

Your brake system is very important for yours and others safety. If you can't figure it out, then seek qualified assistance like somebody advised you before.

Best of luck!!!

 

ThaNKS ALL FOR YOUR HELP. My Christmas present proved to be a cracked sleeve that connects the brake booster vacuum line to the throttle body. 2 inches of tape saved the holidays for me.
Tom

 

Merry christmass to you too!

 

A cheap fix on any Jaguar is certainly a fine Christmas gift!!
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