So I went to pick up the 1998 XK8 from getting the transmission rebuilt because of a faulty A Drum that nobody around here would replace.....

and now the brakes barely stop the vehicle, no squeaking, I just have to force my foot really, really hard down to the floor to get the car to stop??

The car was perfectly fine when I dropped it off...

The guy who did the transmission said he went back and looked at everything and it is all put together right....

He thinks it could be a throttle body problem as something with the vaccuum hose or something of another?

The car is NOT in limp mode etc.

I need to go pick up the car in the morning, anyone have any ideas?

 

Pads seized in the calipers after the layup??

 

If it was OK when it went in and the difference now is that it still stops OK but you have to stand on the pedal to get it to stop, a vacuum hose could be disconnected or leaking. Alternatively, if the pedal feels soft / spongy, it could be hydraulics.

You need to determine whether it's a hydraulic or a booster issue. To find out which:

1. Check the hydraulic brake system for correct fluid level and for leaks (to confirm or eliminate hydraulics as the cause)
2. With the transmission in PARK, stop the engine and pump the brake pedal several times to exhaust all vacuum in the system.
3. With the engine switched off and all vacuum in the system exhausted, apply the brake pedal and hold it down. Start the engine. If the vacuum system is operating, the brake pedal will tend to move downward under constant foot pressure. If no motion is felt, the vacuum booster system is not functioning properly.

Graham

 

I did step 2 and 3 and the peddle does not go down on start up.

I asked him if maybe the lines were somehow disconnected or crimped or unplugged he said no, that there is no vaccuum coming from the throttle body?

He is not a mechanic but he did rebuild my trans...

What should I do or try next?



What else can I try?

 

Anyone have any suggestions? Thanks!

 

Only one I have is to check the hose from the booster to the throttle body and see if it's okay. Maybe remove it and see if it's plugged or collapsed. You could also get a vacuum gauge from Autozone and check that at the throttlebody. Also check the vacuum at the booster end of the hose. If you have vacuum, then probably the booster is shot.

 

Here is the JTIS Diagnosis & Testing sequence for brake faults on the 1998 Model Year XK8:

JTIS - 1998 XK8 Braking System - Diagnosis & Testing.pdf

Go to Section G: EXCESSIVE BRAKE PEDAL EFFORT on pages 11 and 12 for the logical troubleshooting sequence.

Graham