Replace 405 Abs Master Cylinder With Non-Abs

[jibduh 0]

Near the end of my caliper's life, as they were failing, I mashed the pedal to the floor to get my '91 Mi16 to stop. The pedal 'clunked' like something snapping.

 

For a while afterwards, this clunk would repeat when I pressed the pedal past half travel.

 

I've had my calipers replaced and the clunk is gone, but I don't have much braking pressure, and need to pump the pedal to stop.

 

I think I need a new master cylinder.

 

It looks like there was both ABS and non-ABS offered. They appear similar with slight differences in bore size and pedal travel.

 

Can I replace the ABS master cylinder with a Non-ABS version (loads cheaper and ABS doesn't work anyways)? Would I need any extra parts to make it work?

[B1ack_Mi16 67]

I think the difference between the MC's are that the ABS one has 2 outlets, and the non abs might have 4?

Not 100% sure though.

 

If the ABS doesn't work anyways you could just as well just change the whole brake servo/pedal assembly if you find something cheap on the scrapyard.

 

It might be you still got air in your system though, as it is often very hard to bleed the rear brakes on these. You need to jack up the right rear suspension arm to open up the reducevalve so it will let fluid through properly.

 

Then you also need to take the rear calipers off the yoke and put a piece of wood inside them to avoid the piston popping out.

When that's done bleed it while holding the caliper such that the bleed screw it the top point. You can't bleed them without removing them as the bleed valve is not the highest point when mounted on car.

 

I believe air in your system might be the real problem and not the master cylinder. At least it's the first thing I would check.

[welshpug 1,646]

Which ABS system do you have? if the later non integrated system then you don't need to swap the pedal box.

[jibduh 0]

B1ck, I think you're right about the 2 vs 4 ports, browsing the non-ABS has 2 ports listed http://www.rockauto.com/catalog/moreinfo.php?pk=1622902 and the ABS has 4 ports listed:http://www.rockauto.com/catalog/moreinfo.php?pk=1621422

 

(shilling for RA because they're just about the only place that sells in North America) It looks like I'd need a splitter at the very least if I wanted to move to non-ABS. Pity.

 

One of the reasons I ask was because there was a cylinder listed as non-ABS but with the 22mm bore that the ABS seems to have, and was wondering if I might get lucky in buying it, or being able to use it even if it was non-ABS (ports not listed).

 

Swapping out the pedal box would seem easy enough, but again, being in North America, I'm a little stuck for junkyard parts since Peugeot didn't sell as well here as I'd have liked. Which brings me to another point: Is there any place that lists what parts are common between regions? I assume that there's a lot of commonality, but RA would have me believe otherwise. I'm hoping they're wrong and that there's somewhere else for me to do my research; It'd be a Godsend. Any advice for other places to part shop?

 

The mushiness would be symptomatic of air in the system. I guess I might have put a little too much faith in my mechanic and wanted to believe he did it right. New (and thus dry) calipers may have tripped up the bleed too. I'll try another bleed to see if it gets better. Thanks for the tip on the suspension arm.

 

without looking at the fronts, I assume that the bleed screw is on top, and that it'd be hard to mess up a bleed on those?

 

welsh: my system is a bosh branded system. Not sure what else to make of it, whether it's integrated or not, I'll have to poke about.

[B1ack_Mi16 67]

The fronts can definately be bled in situ, rears must come off as described above.

 

My Mi16 only had a 2 port MC and had two T-pieces to split the lines. The ABS® was removed by the dealer sometime before I bought the car.

 

The early ABR system was prone to failure.

[welshpug 1,646]

standard later cars are 2 port on non abs as well, pair of T pieces on the bulkhead, pretty sure my brothers 89 n-a non abs diesel is 2 port as well.

 

the ABR system was bendix IIRC, so sounds like you'll be fine fitting a 2 port from any other vehicle that fits.

 

 

however regarding the clunk, this could be the rear load compensator if it is partially seized.

 

also the bleeding is tricky to get right sometimes, due to the rear load compensator (if it has one) the rear trailing arms must be raised, or bled with the wheels on the ground.

[jibduh 0]

B1ack: is your ABS light constantly on, and do you have the bosch box? I finally actually took a look at my master cylinder. It was a Bendix unit, and there were only 2 copper lines coming out. I wonder if someone else had already converted to non-ABS. I wasn't able to trace where the lines went, exactly, but if ABS was removed, why would the bosch box still be there?

 

As far as jacking the suspension, only the rear right needs to be jacked up for that particular caliper to be bled? Should it stay up while bleeding the left caliper, or should I jack the left rear caliper when bleeding that particular caliper. Is it sufficient to raise the suspension by jacking at the bottom pivot of the damper where it connects to the hub?

 

welsh: I'm not familiar with the rear load compensatior. Is that a pressure bias valve or something similar? the clunk was fairly consistent in the pedal displacement where it happened before it disappeared. Given my current scenario, would it be worth replacing?