XJ Mods VSB 14

[alexbrown64]

OK, a bit more work and a bit more progress. Some of this info may help fellow Jeepers.
My pedal was really low and the brakes felt weak. The expensive EBC pads were only 200k's old and the pedal and brakes felt great at first, but were now lousy.
Today i pulled everything apart again. I was surprised to see the pads were very worn and worn unevenly. Further inspection revealed i had the wear grooves in the mounting ledges. A bit more research led to this... (i cut and pasted from another site)...

"Those mounting ledges are really rails that the brake pads ride on. They take all the force of the brake pads trying to spin with the rotor as they clamp the rotor. The caliper is a floating caliper, meaning its just mounted on its own sliding rails/pins to fit over the pads and squeeze them like a vice, the caliper doesn't have to fight spinning with the rotor, the pads are on rails to counter that.

As the pad wear and become thinner, they have to move along that rail closer to the rotor so they can still make contact with the rotor, even though they are thinner. The caliper, having only one piston, has to also slide along its own rail/pins as the single piston extends to take up the difference of the thinner pads and pull the pads. This set up is far cheaper and more reliable, then other set-ups where you have to have multiple pistons on each side of the caliper to equally squeeze and move the pads and the caliper has to take up all the force/torque of wanting to spin with the rotor as it squeezes the rotor. The floating caliper has 1 piston, and its able to slide around over the top of the pads, which the pads are mounted solid on the rails around the rotor."

Here are mine below. The top and bottom rails were worn like this on both sides of the Jeep...



When the rails are worn, your pads can't slide properly and get jammed and twisted causing low pedal, uneven pad wear etc..

So, i got the welder out, and with a little dab of weld and a bit of grind i got a nice smooth surface for the pads to run along.

Next job was to replace the pads. The new ones were so unevenly worn due to them getting jammed on the rails and twisting, that i chucked them even though they have only done 200 k's. The local auto shop had some cheapies for $39 and it was worth me grabbing them just to trial everything out. I also believe my calipers are knackered. They are 20 years old and a bit of wear here and there and even with the rebuild kits i put in, i think they are sticking, which is also wearing the pads.

Anyway, replaced all the pads, did a bit of bleeding and all of a sudden i had a nice pedal again. Just a small touch of the brakes and they are grabbing again, so there you go!! I still have some new calipers and top of the wazza pads coming from the U.S

However, i got my pedal back, which helped me diagnose and confirm my next problem. The ABS is activating under medium braking conditions. When i put the new pads in, the bed in process was to get up to 50 kph and lightly apply the brakes to a stop. The ABS was coming on and i could feel the pulses through my pedal when coming to a normal stop in dry conditions. Did this several times and same thing. Bloody ABS. This is my second HCU, but i don't believe it is that anymore. The HCU is just doing what it is told. Something is telling the solenoid valves to actuate. I can only think of 3 things. The ABS computer, wheel sensors or acceleration switch which is under the rear seat.

I have a another computer coming, my scanner reports that all wheel speed sensors are working.

Not sure what is going on here, but i think i'm heading in the right direction and will get it sorted...

Cheers,

[alexbrown64]

Update:
Plugged in my Snap-On scanner this morning and did some test driving. The scanner has a movie function so i can record what the brakes are doing for about 15-20 seconds.
Below is a pic of the scanner in movie mode at frame 19 (I get 75 frames i can scroll through). The G SW is the accelerometer showing that it is on, as i am decelerating. Motor Speed is the ABS pump (which was off, as the ABS did not activate on this run), and the wheel speed is what each sensor is detecting.
Now, the interesting thing is the rear sensors are accurate when accelerating above 10kph and read perfectly all the time at higher speeds. But when braking, the rear sensors get really bad below 20kph. Below 20kph the left rear drops to 0kph and the right drops to 11 kph. As i have the movie mode, i can scroll through the frames and look at my speed down to 0. The front sensors remain accurate, but at 17kph both rears drop down to 0. This is probably enough to activate the ABS, as it thinks the rears have locked up and the car is in a skid, so releases the rear brakes (hence no rear brakes when i was testing before).
I did about 8 runs like this and i got roughly the same measurements each time. However, the ABS only activated once or twice.

Conclusion: The rear sensors are inaccurate causing the ABS to activate and stop pedal pressure to the rear brakes. I have previously damaged both rear sensors due to wheel studs backing out of the axles. I replaced the right rear sensor with an old one from the wreckers, and fitted a new tone ring.
The left may still be damaged slightly. I do not get a warning light anymore (i did when the right was completely knackered).
On further reading of the FSM, i have the sensors set at maximum air gap. I will clean them up again and set the air gap to the Minimum to see if they give a better reading. If not, then i may need to get new sensors and check the left rear tone ring. Were heading in the right direction...



Cheers,

[alexbrown64]

OK, update on my update:
I jacked the car up, pulled the wheels and drums off. The air gap was set at the maximum of 1.4mm. I cleaned everything back up and reset the air gap between the sensor and tone ring to 0.8mm.
I then took the car for a drive with my scanner plugged into the ABS and monitoring all 4 wheel speeds. The system has now become accurate and all 4 wheels read correctly from 4 kph and up.

I now have perfect brakes.
The low pedal was a combination of worn brake pads and worn pad sliders, and sticky calipers making them sit wrong and completely unsettling the gap between the rotors and pads.
The ABS coming on was an air gap that was too large to allow a good signal between the sensors and tone rings. This was releasing the rear brakes and making them inoperable while making the front work even harder.
A test drive has the brakes now working very well with a high pedal, good boost and no ABS activation.

I am still ordering new calipers and EBC Yellowstuff pads to get more power to the brakes.

This XJ is just about ready for inspection and rego... just waiting on the engineers report to come through. It takes about 3 weeks..

Cheers,

[alexbrown64]

Well, as you know, you can never leave these things alone... a bit like a quest..
Anyway, i had a new bearing to put in the grooved idler pulley. I beat the daylights out of the pulley trying to get the bearing out, not realizing you have to grind the plastic from one side as it is molded over the bearing. So i do a bit of research and find out they are a generic part that fits loads of cars and are cheap and readily available. Being plastic, you don't want to grind and beat them.. may as well replace it as they would fatigue after 340,000 k's.
Found this thread on good old AJOR http://www.ausjeepoffroad.com/forum/....php?p=1500927 and i was down to Supercrap http://www.supercheapauto.com.au/Pro...y-38009/342119 to pick up a Gates 38009. They always have them in stock and are only $23. Came home and it fit like a cock in a sock.. perfect.



Just going around the old girl fixing squeaks, rattles and old niggles.
My new Pro Comp rims are on the way from Summit and should be here Thursday together with some other goodies that will be going on after she is registered....

Cheers,

[alexbrown64]

After seeing another thread, i decided to get one of those reverse beeper bulbs. http://www.ebay.com.au/itm/Reversing...EAAOSwRLZUEDxu . I fitted it up and it wouldn't work. In fact my reversing lights would not come on. A wiggle of the shifter and it finally all worked... but this told me it was time to do the neutral safety switch repair. AJOR to the rescue again, and between http://www.ausjeepoffroad.com/forum/....php?p=1584334 and Marcus's http://www.go.jeep-xj.info/HowtoNSSrebuild.htm i set about getting it done.

The hardest part of the whole job was getting the cable ties off the switch cable which seems to have about 5 cable ties tying it to everything all the way up the tunnel and firewall. Some f'ing and blinding later and it was all out.
When i took the switch apart, i could see my problem straight away. One of the contacts was stuck down with grease. A good clean up with degreaser, bit of a polish with some fine wet and dry, a bit of lithium grease and i popped it all back together and back into the Jeep.

Works perfectly now and will help get this Jeep over inspection. Its a job worth doing as i think they all get a bit dicky after a while. Total time for job was about 90 minutes.

I am also going to fit one of these cheap gps/reversing cameras. http://www.ebay.com.au/itm/Nozatec-7...YAAOSwKtlWqw4a . It comes with a vent mount, so the idea is to use the central vent, and plug it into the ciggy lighter which is just next to it. Pics of the install and a review when its all working.

Cheers,

[rustynuts]

Originally Posted by alexbrown64

Well, as you know, you can never leave these things alone... a bit like a quest..
Anyway, i had a new bearing to put in the grooved idler pulley. I beat the daylights out of the pulley trying to get the bearing out, not realizing you have to grind the plastic from one side as it is molded over the bearing. So i do a bit of research and find out they are a generic part that fits loads of cars and are cheap and readily available. Being plastic, you don't want to grind and beat them.. may as well replace it as they would fatigue after 340,000 k's.
Found this thread on good old AJOR http://www.ausjeepoffroad.com/forum/....php?p=1500927 and i was down to Supercrap http://www.supercheapauto.com.au/Pro...y-38009/342119 to pick up a Gates 38009. They always have them in stock and are only $23. Came home and it fit like a cock in a sock.. perfect.



Just going around the old girl fixing squeaks, rattles and old niggles.
My new Pro Comp rims are on the way from Summit and should be here Thursday together with some other goodies that will be going on after she is registered....

Cheers,

I bought one for an AU Falcon from Repco. It was packaged in a Repco box with a Repco part number and it had a steel ribbed pulley. Direct replacement. Was about $30.

[alexbrown64]

Pics below of the new GPS/Reversing camera install. I could not use any of the vent brackets it came with, so removed the ashtray and built a bracket in the recess. I could then install the 7" monitor down out of the way. I put the cables and wireless receiver behind the camera.
Very easy to connect up the reversing wireless camera. Just two wires splicing into the reverse light. I have not finished tyding up yet, but initial tests were very positive. Had a great view of the rear of the car from the screen, which automatically came on when i put it in reverse. Even though i was under a car port, the GPS booted up very quickly and displayed my street in full 3D colour. For $100 delivered it is a great little system which will help me out a lot in the future.