GS1000 Master Cylinder Rebuild kit

[Duncan]

Hello All

I’m trying to get my ’79 GS1000 back on the road after seven years in hibernation (The bike, that is, not me) but the master cylinder seal has failed and I’m having trouble finding a rebuild kit that fits. I’ve been to a relatively local Suzuki dealer who looked up my frame number and said ‘what you want is a 59600-47810 piston cup set’ but when it arrived it didn’t match the internals of the cylinder off my bike. I contacted Alpha Sports and they said ‘Well, if it’s not the 59600-47810 it could be the 59600-33810 piston cup set’ but that’s just arrived and doesn’t match either (sigh).

So, either the Suzuki parts ordering system has issues, or my bike has the ‘wrong’ master cylinder on it (It looks right. Looks like a grubby old round reservoir one). Either way, I’m stuffed because I don’t know how to get the parts I need to let me ride my bike.

It’s looking like I’m going to have to order an entire master cylinder, but before I take such drastic (And expensive!) action I thought I’d see if this problem rang a bell with anyone else. Or, if there is a Suzuki guru out there who could identify the master cylinder components I have by sight rather than code number. All the dusty old parts counter men round here who could have done that have ‘gone’.

Please help – I can’t ride my bike!

Yours faithfully

-Duncan

[Nessism]

Does your 1000 have dual front disc or just one?

[Rover]

Hi, The 59600-47810 kit is meant for the DOUBLE disk GS1000
The 59600-33810 kit is meant for the SINGLE disk GS1000
(we talking front brakes)

You have the kits for either bike now.Could you post a pic of your master cylinder and give us the measurement of the bore.

[Duncan]

Thanks for the responces.

It's a twin disk setup.

I'll give you the dimentions of the plunger rather than the bore, if that's OK (It's easier to measure). At its widest the diameter is 15.8 mm (So the bore must be about 16 mm I suppose) and it's 49 mm long.

See the additional photo, attached.

Thanks again

-Duncan

[Nessism]

Your master cylinder piston/cup assembly looks identical to the one in my 1980 master.

Part# 59600-49810

I can't promise you it's the exact same part, but I'll bet you a pint.

[hampshirehog]

Looks right to me. And looks right this one on ebay (don't buy this one though - buy OEM):

http://www.ebay.co.uk/itm/Master-Cylinder-Kit-Suzuki-GS550-GS650-GS750-GS1000-GS1100-GS1150-/290731918064?pt=Motorcycles_Parts_Accessories&hash=item43b0f902f0

Why isn't the new kit right?

[Nessism]

Looks right to me. And looks right this one on ebay (don't buy this one though - buy OEM):

http://www.ebay.co.uk/itm/Master-Cylinder-Kit-Suzuki-GS550-GS650-GS750-GS1000-GS1100-GS1150-/290731918064?pt=Motorcycles_Parts_Accessories&hash=item43b0f902f0

Why isn't the new kit right?

That one is different than Duncan's.

[hampshirehog]

That one is different than Duncan's.

You're right Ed - bloody obvious when I looked at them again side by side!

Here's the right one:

http://www.cmsnl.com/suzuki-gs1000-1979-s_model13513/pistoncup-set_5960047810/

£36 at Robinsons but the p&p will be cheaper.

15.8mm is the right piston size.

[rustybronco]

Here's the guts from my 78 GS1000E master cylinder. If you need me to, I can take apart the second one I had gotten to replace the original with, which is also from a 78.

[Duncan]

OK. Good. I start to get the feeling I’m being moved in the right direction for the first time in weeks.

My learned friend Nessism, there’s only a subtle difference in the part number I believe to be wrong and the one you have given me. Could you just confirm it really is 59600-49810 that I should be after, in your learned opinion? Do you have any dimensions I could use for a comparison?

You do seem to be on the right track (I really, really hope you are) because you talk about the ‘metal encased seal’ (I think of it as the daisy shaped valve riveted to the end of the plunger, yes?) as I’ve not seen this feature on either of the kits I ordered, or any of the pictures shown on Suzuki parts websites – but you seem familiar with it (Yey!). I’m a little brought down by looking at the parts diagrams on the Alpha Sports site as the reservoir on the cylinder for this plunger is square rather than round, but I’m going to ignore that for now and live in hope.


-Duncan

[Nessism]

Please post up a close up side view of the plunger. Need to take a closer look.

[Duncan]

Is this photo OK?

Oh, and thanks to Rustybronco for the picture. This makes it clear that not all the round reservoir cylinders are the same: The internals look different to mine (The plunger on RB's looks a bit longer and the valve disk isn’t attached to it) and even the exterior is a little different now I look closely (The casting around the bar clamp is chunkier on mine). Being able to spot the external differences could be very useful if I have to resort to second hand parts, so thanks again.

-Duncan

[Nessism]

I take back what I said about your plunger looking like the 1980 type, it's different.

Yours looks same as Dale's.

What was wrong with the 59600-47810 part again? Was it the wrong size or just different on the end, where that little flapper spring valve is?

That second one posted by hampshirehog is looking pretty close...

[Duncan]

Drat

Drat. A solution seems to be slipping through my fingers again. Is Dale AKA Rustybronco? The parts from his do look similar, but not the same. Many of these ‘piston and cup’ kits look similar, but unfortunately that’s just not enough. RB’s plunger looks longer and the seal isn’t as thick as mine. As you’ve probably noted from the close-up, my seal has a furrow around it, and I suppose this makes it seal in both directions so it keeps the brake fluid in whilst keeping the crud out. Seen this distinctive feature on any Suzuki master cylinder seals?

Any other ideas? (The 59600-47810 part that I got hold of to look at was longer than mine. It could very well be the same as RB’s and the one Hampshirehog suggested. If it was just the valve that was different it wouldn’t really matter, but the seal itself seems to be of different dimensions so I can’t even transfer the new seal onto my old plunger)

[Nessism]

Are you sure the 47810 part won't work? Even if the plunger is in a slightly different position inside the master it should stroke the same. Only thing I can think of is Suzuki changed the part but hopefully the new parts will retrofit.