35 x 12.5 BFG KM3 tyre

[Gizmops]

Hi all, my hdj80 had these 35 x 12.5 tyres fitted when I bought her 3 years ago. It passed each annual mot here in Spain. Now it fails because the rear brake force numbers are low. The local Toyota dealer has changed the brake master cylinder seals and now wants to change the rear caliper rubbers. I have asked them to check the load sensing valve , but they don't agree that the lsv could be the problem. Should the calipers have bern upgraded.

 

[felix2566]

What state are your discs and pads? If they are bad will give poor performance.

 

[Grimbo]

Check or replace the flexible brake lines on the rear axle.... they can collapse internally and restrict brake force .
Often overlooked when a vehicle pulls to one side under braking .

 

[Gizmops]

What state are your discs and pads? If they are bad will give poor performance.

Hi Felix, discs and pads are in good condition. No concerns there.

 

[Gizmops]

Check or replace the flexible brake lines on the rear axle.... they can collapse internally and restrict brake force .
Often overlooked when a vehicle pulls to one side under braking .

Hi Grimbo, there is no pulling to either side, mot test shows lower force to rear brakes and no brake imbalance issue.

 

[felix2566]

Have a read of the Toyota repair manual I'm sure in there I've seen it gives the values and explains how to set up the load sensing valve, could be that yours is not operating correctly.
I'm running 35" tires on mine and never had issues come MOT time

 

[Gizmops]

Have a read of the Toyota repair manual I'm sure in there I've seen it gives the values and explains how to set up the load sensing valve, could be that yours is not operating correctly.
I'm running 35" tires on mine and never had issues come MOT time

I suspect the same but the Toyota main dealer here doesnt agree. I put it into Toyota after the 1st mot failure. They changed the brake master cylinder seals. Failed again, they then found air still in the system. They put it on a brake tester and gave me the data printout. See attached.

 

[felix2566]

From google translating and looking at the numbers, seems like they are more concerned with the difference left to right of the rear axle numbers than the difference between the front and rear axles?

I dont understand what the 'ovality' numbers mean on the right of the page, as that's what it appears to have failed on.

Could explain why they think the rear calipers, or one of them is at fault and not working as efficiently as it should.

Have they ever been rebuilt?

 

[Gizmops]

No, not in my ownership. Got another mot test in 2 weeks. Should I be concerned or return her to Main dealer for both rear caliper refurb.

 

[felix2566]

Caliper refurb is not hard to do, shouldnt need to be done at the dealer, any half decent mechanic should be able to fit new seals

 

[Gizmops]

Thanks Felix, i will wait and see what happens at next mot.
I will get a set on seals for both sides and fit them myself. Hopefully the worst difficulty, as previous reported on here before, is purging the lines of air . Lol