Rear Brake problem

[glanrichbex]

Hi all,

I took my Terrano ( long wheel base ) 2.7TDI to the garage today because I am really scratching my head.
When I brake gently there is no problem but a little more than gentle then the off side rear wheel locks up momentarily then releases, this is particularly noticeable in the wet or on a gravel surface.

I completely replaced the shoes, cylinders, springs and adjusters 6 months ago trying to resolve this issue.

They have had the drums off again, had a good look, put it back together, re bleed , re adjust but no difference.

Today they had another look at it, the ABS sensors are picking up rotation fine so the only thing they said is that it may be the ABS pump unit?

Please please please has anyone got any thoughts on this?

Many thanks

 

[jims-terrano]

Would the load sensing alve cause something like this?

 

[solarman216]

When this happens you should feel a vibration on the pedal indicating the ABS has kicked in, if no vibration then I would suspect the ABS system, Rick

 

[macabethiel]

Rear Balancer Valve ??

I would replace the rear balancer valve before delving into the ABS.

Some years ago I had an adjustable rear balancer valve on a vehicle that had no load sensing lever mechanism. If I sent to much pressure to the rear it would always lock a wheel it was tricky getting the pressure just right.

I had fitted bigger rear brake wheel cylinders, the valve was used to reduce the pressure on the bigger rear brake pistons. Invariably it would be one particular rear wheel that would lock up first.

 

[glanrichbex]

Hi all,
Many thanks for your replies, where would I find these valves, I cannot find the restriction valve which on many vehicles reduces the load to the rear brakes. :nenau

Cheers

Rich

 

[jims-terrano]

Load sensing valve is around rear axle area, follow the brake lines back from rear wheels. It has a couple of springs on it, detects load of the vehicle. Not all Terranos have them, the early facelift around 2001 was a switchover I believe.

 

[glanrichbex]

Load sensing valve is around rear axle area, follow the brake lines back from rear wheels. It has a couple of springs on it, detects load of the vehicle. Not all Terranos have them, the early facelift around 2001 was a switchover I believe.

Ah - mine is 05 plate - I'm going to have to crawl under and have another good look

 

[luke1987]

You only have a load sensing valve with a non ABS system, Get yourself on a nice quiet road and stamp on the middle pedal. Does it lock all 4 wheels? If it does the problem lies with the ABS system either the pump or the ECU on the back of it. I personally hate ABS and have disconnected mine but for MOT's sake everything is still there and the brake lines still run through the pump, Now before I get shouted at for doing this I have never locked my brakes under hard braking even with the caravan on the back. But im used to it with my other car.

 

[jims-terrano]

I can confirm that I have and still own one terrano with ABS and Load Sensing Valves.
To be honest they’re dam useless and if they ever give trouble again they’ll be removed.

 

[luke1987]

That's quite unusual Jim, As you know the point of the load sensing valve is to stop the rear wheels locking but with wheel speed sensors and an abs pump does yours still have rear wheel sensors or is it abs on the front wheels only?

 

[solarman216]

Nissan have an odd way of addressing this as motors that I have combine ABS with a load valve but only one line to the rear brakes, but this does not address the posters problem of locking one rear wheel, so as he has a later truck I can only conclude he has dual lines to the rear and has an ABS problem, Rick

 

[jims-terrano]

Nissan have an odd way of addressing this as motors that I have combine ABS with a load valve but only one line to the rear brakes, but this does not address the posters problem of locking one rear wheel, so as he has a later truck I can only conclude he has dual lines to the rear and has an ABS problem, Rick

Yes you’re right Rick we were going off topic slightly.

How about then following the brake lines from each rear wheel and see if it goes straight to the ABS Pump. At least that will confirm no other items in the brake lines and also confirm integrity of the brake lines.

 

[Banshee]

I'd have gone with dodgy shoes or something, I've yet to have an ABS issue so can't offer any advice this time but looking forward to seeing an outcome to this one :thumb2

 

[jims-terrano]

Just a thought, several years ago I had my old truck in at a garage. He serviced the rear brakes and we also had an abs problem. He said the rear axle oil seal was leaking and covering the abs sensor with oil and muck. Sorry just remembthis, it was one of the few garages that I trusted too so I don’t doubt the bloke at all.