Recently flushed the fluid out of both front and rear systems. (1990 K100LT ex-police, ABS) Used a sucking device and all seemed to work great.

Had it done at Brisans (Newcastle, NSW, BMW dealer) about 18 months ago. They replaced the fluid with Dot 5 stuff, even though the manual stipulates Dot 4. I used Motul Dot 5.1 in the recent flush. After about 200Km, the rear master cylinder started leaking quite badly! I've ordered a replacement cylinder from the BM Shop in Brisbane. They advised that the rubber kit may not work as the cylinder walls may be badly pitted and suggested that a new cylinder assembly be installed.

The questions are: Should I keep on with the Dot 5.1, or replace it with Dot 4? Did the Dot 5.1 cause the failure of the cylinder? The caliper does not leak and appears to be working fine.

I haven't pulled the cylinder apart yet, just unbolted it ready to pull apart.

Also, the hose from the reservoir to the cylinder will probably need removal and re-attaching to the new cylinder. It has a crimp hose retainer. Is there a simple effective way to remove / replace the crimp, not having the special tool required?

Got to get this happening by Thursday, for the ride to Urunga!!!

Cheers, Rick G.

DoT 5.1 was developed for certain ABS that have mechanical cycling proportioning valves. Like DoT 4, it's glycol based. So it shouldn't be a problem.

Not to be confused with DoT 5 which is silicone based.

I'd say it is coincidence that it leaked...it's got wear out sometime!

You can hack off the crimp any way you want and install a normal suitably sized hose clamp, as the hose connection at the cylinder is not under any pressure...it just feeds the master cylinder. That's where the pressure is.

Hurry up and get it fixed!

If it isn't fixed by Saturday, we're all coming to your place!

I don't belive you should just replace DOT 4 with DOT5 unless you completly clean the system. Dismantle and clean and replace all the seals and O rings etc. http://www.gomog.com/allmorgan/brakefluids.html

You have a good case to make them pay for the extra work needed and more fluid.

You will find some sites saying they are compatible and that means they will work with the same components but they dont mix and the DOT5 floats on top. no matter how much flushing you do there will always be traces of the DOT4. The systems must be cleaned properly and new seals etc.
If you disassemble the brakes and just clean them and replace with DOT4 then all may be ok.

Ah K Freak...yes, I just re-read the thread and saw the initial change (at the Dealer) was DoT 5 and not 5.1.

Yes, dismantle and clean! DoT 5 doesn't play well with anything else...then stick in the DoT 4 or the 5.1 stuff.

You have 3 days...

good luck rick g

you better hurry up ...i bet rt will be upon you real soon huh ?

giggles

I understand that DOT 5 affects the rubber seals and hoses of the original lines and is strongly advised against. Its DOT 4 or DOT 5.1.

Just finished replacing the rear master cylinder with a brand new one, and filled the system with Motul Dot 5.1. After viewing Blakey's comments and Googling Motul 5.1 it appears as if the Dot 3, Dot 4 and Dot 5.1 are compatible.

Took it for a 20Km test ride and the brakes seem to working fine, after numerous simulated "panic" stops.

Again, this is not to say that the seals. 'O' rings etc will not fail. I've got to run the gauntlet at this stage because time is fast running out.

Thanks for your interest and assistance, lads.

Good work Rick.

We'll wait at the pub for you on Saturday and if your brakes don't work, go around the block and we'll run out and form a human chain across the road and catch you as you pass...

lol


good work rick

blakey wrote:Good work Rick.

We'll wait at the pub for you on Saturday and if your brakes don't work, go around the block and we'll run out and form a human chain across the road and catch you as you pass...

What this "We" White man?