Hard to explain this feeling, but here goes:

I bought a D2a V8 with stock suspension and (probably) the factory shocks with about 75k miles on them.

Sometimes when I drive on very bumpy roads and apply brakes, it feels like the brakes give out. It feels like I slightly slide forward more than expected, and need to apply brakes even harder. Happens especially when there's a series of bumps in a row.

Is that normal? And because the wheel is temporarily in the air for a bit?

Or something coming loose or not working as it should when vibrating or whatever?

Booster issue? Vacuum hose connector coming loose (I've got a small vacuum leak coming from the plastic bit connecting to air intake, see video here from other post)? Or just old shocks? Old coils?

Already done:
- New Falken tyres
- Front rotors and pads replaced (Bosch)
- Brake master cylinder replaced (aftermarket; factory was leaking)
- DOT 4 fluid replaced, bled
- Upper and lower ball joints replaced

 

What you describe sounds quite a bit like the anti-lock braking system kicking in.

 

Interesting! Is it supposed to show a dash light when it kicks in? Which one?

 

No. No dash light under normal operation.

A crude explanation....When the wheel hits the bump it has traction. As it rebounds vertically there is less traction because inertia is headed away from the ground. In order to prevent a locking of the wheel, the ABS system reduces pressure on the line to that wheel. I suspect both your fronts were experiencing this.

The result is a 'bumping/thumping' sensation at the pedal and reduced breaking power. All this is an effort to retain steering. If the wheel is locked up, you become a sled (though arguably a faster-stopping sled).

 

Our roads in south Carolina suck. My significant other drives her D2 like it's a sports car. With the 3 inch terra lift and 10 ply tires, it's not exactly a sports suspension.

She was constantly losing her brakes and complaining due to the abs doing what it's supposed to do.

Then she started driving more conservatively and the issue magically went away.

This is the same lady who wonders why I don't like her driving my 4 ton 7.3 excursion on 35s.


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Very normal operation as others above said. I’m on/off road a lot for work in the disco and experience what you’re describing all the time. Congrats on a functioning ABS system 👏🏼

 

Folks, thanks so much for the replies! Puts my mind at ease. At least this is one thing that ain't broken

Some questions:

When you say, "in order to prevent a locking of the wheel," why would it lock in that situation?

Interesting story about your girlfriend! Funnily I'm not really driving it hard in those moments, if anything slowing down to adapt, but point taken! It happens when going like 20-30 mph, still OK right?

I had another thing happen twice, but a while back with the old tyres (must have been 10 years old):

- When braking there was a loud, almost metallic "crghhhhhh". Happened once when braking going over bumps on level road, and the other time going a steep downhill paved road in the wet and braking. Was that also TC?

 

What year is yours? You say D2a so I'm guessing 2003 / 2004?

I have personally felt this happen on D2's, both pre and post facelift 99-04 - it's somewhat characteristic of the brakes. But the early ones were notably worse in doing it.

Anyway, this is actually one of the customer symptoms that led LR to recall most early D2's and the fix was a revised SLABS ECU. I wonder if your car was eligible for the recall and never had the recall done. But if you say D2a then maybe not.

From another forum: "The a263 recall involved replacing the SLABS ecu with the SRD000070 part which has better tolerance to metallic particles attaching to the abs wheel sensors. The SRD000070 ecu's are pretty common at wreckers and the changeover is fairly straight forward, although I'd look for a srd000150 or srd500070 if I was going to go to the trouble of doing the swap."

January 22, 2002 NHTSA CAMPAIGN NUMBER: 02V022000
LAND ROVER/ABS ECUTHIS CAN LEAD TO AN INCREASE IN BRAKING DISTANCE THAT IS UNANTICIPATED BY THE DRIVER.

NHTSA Campaign Number: 02V022000

Manufacturer LAND ROVER NORTH AMERICA, INC.

Components SERVICE BRAKES, HYDRAULIC

Potential Number of Units Affected 55,505

Summary

ON CERTAIN SPORT UTILITY VEHICLES, CONTAMINATION OF AN ANTI-LOCK BRAKING SYSTEM (ABS) SENSOR CAN CAUSE THE ABS ELECTRONIC CONTROL UNIT (ECU) TO INCORRECTLY INTERPRET THE SENSOR SIGNAL, RESULTING IN INAPPROPRIATE ABS ACTIVATION.

Remedy

DEALERS WILL INSTALL A NEW ECU. OWNER NOTIFICATION BEGAN MARCH 6, 2002. OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT LAND ROVER AT 1-301-731-9040.

Notes

ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S AUTO SAFETY HOTLINE AT 1-888-DASH-2-DOT (1-888-327-4236).

3 Affected Products

Vehicle

MAKE MODEL YEAR
LAND ROVER DISCOVERY II 1999-2001