'79 R65 Front Brake Locked, Can't Open Tank & Unknown part

[Rob Frankham]

I don'r know anyone who uses DOT5 in an airhead... I'd say it's safe to assume that it's DOT4. You should be able to smell the difference. DOT5.1 is compatible with DOT4 (but not with DOT5).

As far as the battery charger goes, you should be safe enough on the 2 amp setting for 24 hrs. The charge rate will drop back as the battery voltage increases. The reversed poles are more of a problem but that shouldn't stop you from trying things out.

Rob

[at1rest]

Thanks Seth

I didn't think of it before but today I had more light to see and I read the top of the reservoir cap and it's specifically said DOT 4.

The PB Blaster loosen up the bleeder nipple nicely on the caliper so I got that open after I got a little piece of tubing attached to it and into a mason jar, but I loosened it and nothing came out.

I'm done with it for this week.

Thanks for all the help!

[Rob Frankham]

That doesn't sound great. You seem to have caliper issues as well as master cylinder issues.

Good luck

Rob

[at1rest]

s.
As far as the battery charger goes, you should be safe enough on the 2 amp setting for 24 hrs. The charge rate will drop back as the battery voltage increases. The reversed poles are more of a problem but that shouldn't stop you from trying things out.

Rob

The battery cables under the seat looked very short and just long enough to connect to the correct orientation so I'm reluctant to mess with that. this is on the R80.
I'll have a better look at the charger next time over there and see if the old battery that is at 2 or so volts will charge up, and also check the voltage on the R65 battery and attempt a charge.
The might both be beyond their life expectancy but it can't hurt to try.

12.7 - 12.8 volts is for a good battery but will anything less get it started?

Thanks!

[at1rest]

That doesn't sound great. You seem to have caliper issues as well as master cylinder issues.

Good luck

Rob

Yea. Might just be clogged with debris.
I'll have a week now to think about it and do some research and will report back if I try anything else.

An other thought:
Could it be that the lack of flow is because the lid is still on the master cylinder and there's a clog up there?

Thank you!

[Rob Frankham]

I'll have a better look at the charger next time over there and see if the old battery that is at 2 or so volts will charge up, and also check the voltage on the R65 battery and attempt a charge.

Don't bother. If the battery is reading 2 volts it's finished. Even a fully discharged (good) battery should read at least 10 volts off load.

Rob

[at1rest]

I'll have a better look at the charger next time over there and see if the old battery that is at 2 or so volts will charge up, and also check the voltage on the R65 battery and attempt a charge.

Don't bother. If the battery is reading 2 volts it's finished. Even a fully discharged (good) battery should read at least 10 volts off load.

Rob

OK ... good to know. Thank you!

[at1rest]

On the part number for the MC piston that I found ... when searching the part number
3272 2302357
This site is confirming that it is the correct one and does fit the 1979 R65.
https://www.shopbmwmotorcycles.com/p/BM ... 02357.html

Hit the "show more" button under "What This Fits"

[barryh]

I might of missed it earlier in the thread but are your brakes single disk or twin disks ?

The master cylinder piston 3272 2302357 that you have is I believe for a 16mm master cylinder which is for twin disc brakes. If the bike has a single disk then the original master cylinder size would have been 13mm.

[at1rest]

Single disk.
But what about the part number look up at
https://www.shopbmwmotorcycles.com/p/BM ... 02357.html

???