Problem with Sensa Brakes

[goona]

Hi All,

In the process of fixing the trailer up. New gal discs, New bearings, new stainless steel pistons to the calipers along with seals. So I put new brake fluid into the Sensa brake resivour and connect it to the truck. Sensa Brake compressor fires up and pumps up to presure and turns off. I put the bleed line on open bleed valve and press brakes and fluid comes out along with air. Keep doing the process until no air. Go to the next one and repeat the process. Finish all of them and press the brakes and noothing happens.

Does anyone know what is going on?

[ShaneC]

System is probably still pressurised. Turn the gain up and pump the brakes. The pump only operates when it needs to.

[goona]

Thanks Shane did as you suggested and still nothing. Took it for a drive and got some spasmodic results. All discs seam to have new wear marks on them and on one occassion 2 discs got warm then on the last two test all were cold again as if they they didn't enage at all. We even pulled the pump unit down to have a look and every thing appears to be in good nick.

Any suggestions? I need to get this thing going this week as we are doing our annual Stanage trip as of next Satuurday.

[MoffattC]

I don't know the actual names of the internal components but I would be looking at the cylinder (master / slave)? this has a piston with two seals from memory. When activated by the relevant solenoid is forced forward by the stored compressed air pressurizing the hydraulic lines, if one of those small seals is damaged will not hold it's pressure as was the case with my failure. Easy to confirm by jacking up one the wheels fire up system turn car off which should bring on the breakaway fail safe (brakes should lock on for a period) check to see if you can spin wheel. Also check that the solenoids are operating correctly. Leo from United Brake and Clutch (Coorparoo) was great help and has stock of the spares kits.

[goona]

I don't know the actual names of the internal components but I would be looking at the cylinder (master / slave)? this has a piston with two seals from memory. When activated by the relevant solenoid is forced forward by the stored compressed air pressurizing the hydraulic lines, if one of those small seals is damaged will not hold it's pressure as was the case with my failure. Easy to confirm by jacking up one the wheels fire up system turn car off which should bring on the breakaway fail safe (brakes should lock on for a period) check to see if you can spin wheel. Also check that the solenoids are operating correctly. Leo from United Brake and Clutch (Coorparoo) was great help and has stock of the spares kits.

Thanks Moffat,

I am pretty sure thats what is wrong with mine. When your seals failed did you have any fluid coming out of the main housing?

Regards

Goona

[goona]

Pulled it appart and found the seals were leaking so got a whole new kit from United Car care. Excellent to deal with and really know there stuff. Posted up the kit in an overnight bag. Just finished putting them in and pumped up and no more leaks. Step in the right direction. Bleed the whole system and took it for a spin and still nothing. Had a look after the application of the brakes and noticed the resivour viewing window went down quite a lot. Is this normal or do I still have air in the lines?

Thanks for the PM's guys much appreciated and will give them a go tomorrow. Any more tips are very welcome as I am running out of time very fast.

[goona]

Pulled it appart and found the seals were leaking so got a whole new kit from United Car care. Excellent to deal with and really know there stuff. Posted up the kit in an overnight bag. Just finished putting them in and pumped up and no more leaks. Step in the right direction. Bleed the whole system and took it for a spin and still nothing. Had a look after the application of the brakes and noticed the resivour viewing window went down quite a lot. Is this normal or do I still have air in the lines?

Thanks for the PM's guys much appreciated and will give them a go tomorrow. Any more tips are very welcome as I am running out of time very fast.

Dont I feel like a dummy.

Worked out what it was. After re kitting the calipers we swapped calipers from front to back but in doing so also swapped from right to left thus putting the bleeder valve to the bottom which then left air in the piston. As soon as we swapped the calpiers around and pumped up they worked straight away.

Thanks all those that gave advise much appreciated