Author Topic: 750f Rear Master (Read 2659 times)

Timindecaturga · « **on:** March 02, 2014, 03:11:42 PM »

Doing the rebuild and this is what I find. I have the rebuild kit but getting it apart might be a problem any suggestion?

Powderman · « **Reply #1 on:** March 02, 2014, 03:36:13 PM »

This is one area where an ultrasonic cleaner would come in handy to remove all that rust and gunk. I'd start soaking that MC in PB Blaster or something for a day or so.

BeSeeingYou · « **Reply #2 on:** March 02, 2014, 04:12:39 PM »

This is what you have once you get it apart. The corroded part under the c clip is the washer on the pushrod. Lucky the access is good unlike the front MC. Once you get that soaked a bit the c clip is easy to get at. I have heard that the rebuild kits are more expensive now as they have been discontinued by the dealers. Also the F2/3 kits did not include the pushrod while the F0/1 kits did. Hopefully you can reuse that part. This is from my F1. The rubber boot is a double edge sword here...keeps out the gunk but if any moisture does find it's way in there it stays and causes corrosion.

dlhoulton · « **Reply #3 on:** March 02, 2014, 04:31:22 PM »

I like soaking stuff like that for a day in a product called "Evapo-Rust". Can get it most anywhere; Pep Boys, Oreilly Auto, Autozone and Tractor Supply. It's biodegradable, and can be used over and over again.

Blackhole · « **Reply #4 on:** March 02, 2014, 04:46:51 PM »

It will also help to boil the unit is water for a while. I have had good luck taking them apart after a good boil. Just make sure you are using a pan you never plan on cooking with again.

Timindecaturga · « **Reply #5 on:** March 02, 2014, 05:13:43 PM »

The c ring looks like it is fused to the plate below it
It's operations and looks like it has full travel I'm starting to wonder if I should even try and get it out

Jerry Rxman Griffin aka MuthaF'er · « **Reply #6 on:** March 02, 2014, 06:54:45 PM »

Soak some vinegar on it. Mild acid can work on the rust. That clip may be a #$%* though. May try an awl and hammer in the clip hole or behind the head of the clip. It may come out in pieces. We've been there before.

A GL1000 75-79 rear kit will work. Rod is slightly longer otherwise the same.

Timindecaturga · « **Reply #7 on:** March 02, 2014, 07:24:20 PM »

I've got it soaked in pb bolt break I'll see what it looks like tomorrow but I have a feeling it's not going to be god the c ring looks very disintegrated

Jerry Rxman Griffin aka MuthaF'er · « **Reply #8 on:** March 02, 2014, 10:33:56 PM »

Disintegrated can be good. Pick it/chisel out the pieces. The acidic vinegar may dissolve some of the rust that's holding it in too.

Hon3ybadger · « **Reply #9 on:** March 03, 2014, 12:11:35 AM »

Funny you have this problem, I just went through the same exact thing. I used "The Works" Hydrochloric acid to take the rust off. Worked like a charm

Mix two bottles of The Works with a half gallon of water in a bucket. Take the rubber boot off the bottom. Now hang the r master with clothes hanger wire so that just the bottom up to the body is in the acid. Do not sumerge the whole thing. Periodically pull it out and wire brush the c clip area. By the next day you will have a very clean bottom and a removable c clip.

I got lucky with mine. The internal rubbers and piston looked brand new. No moisture at all!! Just dont be stupid like me and leave the C clip in the acid for two days. It was extra crispy.

Timindecaturga · « **Reply #10 on:** March 05, 2014, 02:41:38 PM »

Well good news I managed to get the C-ring out withe a few days in vinegar and a wire brush but the assembly is still not coming apart
Is the bottom plate just held in by the c- ring and it's rusted still or am I missing something here
Thanks

Timindecaturga · « **Reply #11 on:** March 05, 2014, 03:22:25 PM »

Quick question
Are you saying a GL-1000 rear master cylinder will work on the 78 750SS or just the rebuild kit?
Thanks

seanbarney41 · « **Reply #12 on:** March 05, 2014, 03:28:55 PM »

yep, GL master bolts on and works on f3. You will have to get an adapter for the brake line. Also, rebuild kit from GL works too, internals are the same.

sixthwisconsin · « **Reply #13 on:** March 05, 2014, 06:33:02 PM »

My findings on the 750f rear MC rebuild:

http://forums.sohc4.net/index.php?topic=101126.msg1449905#msg1449905

Timindecaturga · « **Reply #14 on:** March 05, 2014, 07:34:03 PM »

@sixthwisconsin thanks I followed the entire build thread till I got to that
That's what I needed I'll post pics tomorrow to see if it's not too bad

Thanks

Timindecaturga · « **Reply #15 on:** March 06, 2014, 02:28:51 PM »

Well it's all cleaned and disassembled
The main cylinder looks fine just wondering about the internal part is it too pitted to use again
The washer as you can see is a bit concave not completely flat
Defect or not?

BeSeeingYou · « **Reply #16 on:** March 06, 2014, 09:44:19 PM »

The washer is just a retainer and guide for the pushrod, it has no "sealing" function. I don't see any problems from an operational standpoint. My only thought is that now that you have it cleaned up I am sure the plating is gone and it will corrode easily. I am guessing a new one did not come with the rebuild kit?

Hon3ybadger · « **Reply #17 on:** March 07, 2014, 04:16:13 AM »

So let me tell you a little story so you dont pull your hair out like me.

I pulled mine apart after an acid bath and the piston and rubbers looked great, no rust, like yours did. The shaft was pitted so i sanded and polished that up. But the problem I had, That you most likely will have also is the walls of the cylinder might be slightly roughed up due to being exposed to the elements. I'm only talking about maybe 5-10mm of the inside wall closest to the washer. I found the rubber on the piston glides smoothly in to full compression but on return stops short getting hung up on the slighty rougher section. Sadly the only way I could get the piston and rubber back out was to hook it up to the front master and press it out. This weekend I'll try to polish out the cylinder with my dremel and report any improvment.

eastyork1977 · « **Reply #18 on:** March 07, 2014, 05:08:11 AM »

That rear master cylinder IS a Goldwing master cylinder. All the parts are Goldwing, including the larger piston and piston seal.

If you look it up on a cb750F parts fiche its not there, but it is under the newer 750F2 parts lists.

Timindecaturga · « **Reply #19 on:** March 07, 2014, 06:11:16 AM »

@eastyork1977
Are you saying mine is from a goldwing ?

eastyork1977 · « **Reply #20 on:** March 07, 2014, 07:10:22 AM »

Not exactly. The whole back brake is a mix between Goldwing and 750F.

Master cylinder internals are the same though.

The calliper body looks exactly like a Goldwing rear calliper but its a (392) part (75-76 750F).
The piston in the 750F is a Goldwing piston as well as the seal. (371)

Here's a link to the aftermarket kits...

http://www.ebay.com/itm/HONDA-GL1000-GL1000I-GL1000A-GOLDWING-CB750F-REAR-MASTER-CYLINDER-REBUILD-KIT-/111198047956?pt=Motorcycles_Parts_Accessories&hash=item19e3eb8ed4&vxp=mtr

Timindecaturga · « **Reply #21 on:** March 07, 2014, 08:53:52 AM »

I have that kit already

eastyork1977 · « **Reply #22 on:** March 07, 2014, 09:00:05 AM »

So you need to find some GL or 75' - 76' 750F parts then?
Those damn pistons that are so expensive, hope yours looks good. Think they were 80 bucks from Honda last time I checked.

sixthwisconsin · « **Reply #23 on:** March 07, 2014, 10:01:06 AM »

Kit 43510-371-305 was $39 at SouthSound Honda.
Also, phenolic pistons from member Godffrey are like $42.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #24 on:** March 07, 2014, 12:46:04 PM »

The GL master has the brake line exit straight outward. It has an internal fitting in the internal threads to mate to the GL line. The F has the brake line fitted at a 90 degree and held in place by the banjo bolt and 2 crushable washers. It also has a built-in (tit sticking out) stop for the brake line to prevent it from twisting loose whereas the GL does not. The GL rebuild kit has a slightly longer threaded rod but will work just fine or you could cut a few mm off if you can't get the adjustment done good enough. I have a stash with at least one NOS from each so I am able to compare. And in case anyone asks, no, I'm not parting with any.

Timindecaturga · « **Reply #25 on:** March 07, 2014, 01:28:51 PM »

Partzilla 45.00 shipped so not so bad

http://www.partzilla.com/parts/detail/honda/HP-43510-371-305.html

eastyork1977 · « **Reply #26 on:** March 07, 2014, 06:10:52 PM »

Quote from: sixthwisconsin on March 07, 2014, 10:01:06 AM

Kit 43510-371-305 was $39 at SouthSound Honda.
Also, phenolic pistons from member Godffrey are like $42.

And Thank You sixthwiconsin... that will save me some cash for sure.
Will look Godffrey up.

Cheers

BeSeeingYou · « **Reply #27 on:** March 07, 2014, 09:48:56 PM »

Quote from: eastyork1977 on March 07, 2014, 07:10:22 AM

Not exactly. The whole back brake is a mix between Goldwing and 750F.

Master cylinder internals are the same though.

The calliper body looks exactly like a Goldwing rear calliper but its a (392) part (75-76 750F).
The piston in the 750F is a Goldwing piston as well as the seal. (371)

Here's a link to the aftermarket kits...

http://www.ebay.com/itm/HONDA-GL1000-GL1000I-GL1000A-GOLDWING-CB750F-REAR-MASTER-CYLINDER-REBUILD-KIT-/111198047956?pt=Motorcycles_Parts_Accessories&hash=item19e3eb8ed4&vxp=mtr

just to be clear..the GL caliper is a mirror image of the F0/1 caliper. It mounts on the left side so it does not fit the F0/1 bike as it would be backwards when mounted on the right side but internal parts may be the same.

Timindecaturga · « **Reply #28 on:** March 07, 2014, 10:29:06 PM »

I have to to say every one has been way way helpful on this post I'm pretty competent as far hands in goes and awesome replays but I have to say pictures g Really Really Really are the best

When I hit the next BBQ resterraunt I'll let every one know how it was...
Kidding and yes I'll have a ton if pics !!!!

Thank you all

Jerry Rxman Griffin aka MuthaF'er · « **Reply #29 on:** March 08, 2014, 08:10:06 AM »

Quote from: Timindecaturga on March 07, 2014, 10:29:06 PM

I have to to say every one has been way way helpful on this post I'm pretty competent as far hands in goes and awesome replays but I have to say pictures g Really Really Really are the best

When I hit the next BBQ resterraunt I'll let every one know how it was...
Kidding and yes I'll have a ton if pics !!!!

Thank you all

just send me sum hot boled pnuts

Magpie · « **Reply #30 on:** March 08, 2014, 08:21:22 AM »

I just did the rear master on my 1980 CB750F and the internals looked just like those pictured in post #2's pic. I used a kit from Tour Max, MSR-102, which cost about $35 CAN. Cliff.

Timindecaturga · « **Reply #31 on:** March 18, 2014, 01:07:00 PM »

So i have the parts and was just wondering if any type of lubrication should be used on the rubber parts to get them in easier like a drop of dish washing soap brake fluid silicone grease etc or just assemble them dry
and while were at it same deal on the front master cylinder I'm doing that one next
Thanks
Tim

Jerry Rxman Griffin aka MuthaF'er · « **Reply #32 on:** March 18, 2014, 02:07:59 PM »

I'd just wipe some brake fluid around it.

Pigford · « **Reply #33 on:** March 18, 2014, 02:26:37 PM »

Quote from: Timindecaturga on March 18, 2014, 01:07:00 PM

So i have the parts and was just wondering if any type of lubrication should be used on the rubber parts to get them in easier like a drop of dish washing soap brake fluid silicone grease etc or just assemble them dry
and while were at it same deal on the front master cylinder I'm doing that one next
Thanks
Tim

Red rubber grease is also good stuff too + a smear of DOT 4

I also have an F2 with a badly leaking rear m/cylinder. I've stripped it and the actual m/c alloy casing is badly scored internally

So a new seal kit would be a waste of time.

So I've swapped the m/c with a CB1300 unit and it fitted reasonably well - needed a bit of tweaking but its working and back on the road until I can find a decent solution!!!

I may have to resort to getting a sleeve made and fitted? Time will tell.

Timindecaturga · « **Reply #34 on:** March 18, 2014, 04:45:30 PM »

Jackpot !
It's perfect

News:

Author Topic: 750f Rear Master (Read 2659 times)