Can anybody Identify this part?

[bob1179]

Hi Gents, I (along with my mate in the garage) are both a bit confused as to what this cylinder is under the brake master cylinder in my '89 GMC pick up truck.

It has a bleed valve on it but we aren't exactly sure what it is. I was hoping maybe somebody here might recognise it.



Any ideas would be appreciated as we are drawing a bit of a blank.

[VidalBaboon]

I reckon it's the clutch master, mate. As said in an email about it possibly being split brakes, you have the two outputs on the BMC which will probably T-off to do the diagonal split.

That reservoir on the right looks like it has a pipe running to it, I would imagine it's the reservior for the clutch. What does it say on the label of the cap?

Edited by VidalBaboon on Wednesday 24th October 10:49

[paintman]

Manual or auto transmission?
If manual, clutch master cylinder
http://www.partsgeek.com/catalog/1986/gmc/c3500/cl...
and
http://www.redlinemotive.com/replacement/gmc/clutc...

[VidalBaboon]

Is that an ABS module too? All t' mod cons!

[bob1179]

I believe it actually has ABS, but it doesn't work and only acts on the rear wheels to stop them locking under heavy braking.

Though I can lock the wheels up quite easily...

I have to agree with it possibly being the clutch master cylinder. It makes sense.

[bob1179]

paintman said:

Manual or auto transmission?
If manual, clutch master cylinder
http://www.partsgeek.com/catalog/1986/gmc/c3500/cl...
and
http://www.redlinemotive.com/replacement/gmc/clutc...

Cheers for the information paintman.

It has a manual gearbox so this makes sense.

[PaulKemp]

I'm thinking rear brake bias
Limits braking to the rear to compensate for load, light load the rears would lock first which is dangerous