Clutch failing on Champion 720, HELP!

[Southbus]

Dear friends, I have a 1988 Champion 720, it has an 8400 transmission.
The clutch is starting to fail .
Sometimes I press the clutch pedal, it feels soft, I move the selector lever forward or backward and the machine jerks as if I had not pressed the pedal, this happens sometimes and in some moments everything works fine.
I have had a friend depress the clutch and watch the slave cylinder work and have noticed that as my helper holds the pedal down the slave cylinder slowly begins to release...
Checking the clutch master cylinder reservoir, I have noticed that some brake fluid has escaped from the side of the master cylinder container cover, however there seems to be enough fluid inside.
I had my friend press the pedal several times and also noticed that the slave cylinder does not seem to activate simultaneously with when the pedal is depressed or released.

I appreciate any help, I am in Chile, South America and the spare parts for these machines do not exist, however with some guidance from you I think I can solve this problem.

Cesar
Chile, Southamerica

 

[cuttin edge]

Try pumping the clutch until the pedal gets harder. Slave cylinder failed on our 730 once. There was no leak that you could see, but the fluid was in the rubber boot. Is that the same machine you rebuilt the engine on?

 

[Delmer]

If you pull the boot back on that slave cylinder, and it's not full of fluid, then the slave cylinder is fine, and the leak is in the master cylinder. If there's no air when you open the bleeder on the slave with the clutch pedal pushed, then the master cylinder is the issue. I'd take the master cylinder apart, and take the parts to a local auto parts place if it looks like an automotive style, or a hydraulics shop if it looks more heavy equipment style. The other thing to be very careful of is if it uses brake fluid, or mineral oil. If you leave the slave cylinder there, use what's in there already, hopefully it's not a mix.

 

[Blue-Fox]

I have 3 champions and they all get/ have this problem at some point in time.
1) the large cap (auto style) gaskets get attacked by fluid over time and fall apart letting it burp out some fluid and also suck in contaminates, and water. Then the main piston in the master being on bottom like a sump starts corrosion and gets sticky where it does not fully retract when you release your foot from the clutch so when you go to push in the pedal the piston only moves a short distance and barely moves the slave. I have made new gasket out of cork that I smear with a good quality rtv on one side to prevent it soaking with fluid until I can find the correct gasket.
2) A new master cylinder is the best place to start, you can recon the one you have sometimes but often fails soon after when the old pits grow new corrosion and cut the rubbers. I always replace the hose at same time and bench bleed it first then install. I use the style that has the single hole in the top with a threaded cap. Avoid that car style formed sheetmetal cap unit because they are problematic.

 

[Welder Dave]

It looks like I have the same problem on my 86 730A. It looks a little different though. The master cylinder is bolted to the slave cylinder. Thankfully it would go in gear without grinding and I could clear snow off my oval track. It looks like it leaks at both ends of what I assume is the slave cylinder. The end close to the master cylinder looked the worst. I'm guessing the fluid is from the master cylinder or does the bigger slave cylinder also hold fluid? I did notice last fall the machine tried to move a little with the clutch depressed but the brakes would hold it. Today the clutch didn't do anything to slow the drive so I just shifted to neutral. Reading above I guess the first thing to do is remove the master cylinder and get it repaired? Does the slave cylinder go bad? Here's some pics. of the oval track I cleared.

 

[Welder Dave]

Looking at the parts manual it's not the slave cylinder I was referring to. It's the booster attached to master cylinder that is leaking. Should I take the whole assembly off to get re-sealed or just the master cylinder? Never worked on anything like this before. Hoping it isn't too expensive to fix.

 

[cuttin edge]

Looking at the parts manual it's not the slave cylinder I was referring to. It's the booster attached to master cylinder that is leaking. Should I take the whole assembly off to get re-sealed or just the master cylinder? Never worked on anything like this before. Hoping it isn't too expensive to fix.

Everything Champion is expensive. If memory serves me, I think the clutch slave was over $400

 

[Welder Dave]

Hopefully the master cylinder and booster just need to be resealed. I think I'll take it to a brake and clutch shop instead of going to Jade. That's what I noticed was leaking and I think explains why the problem got worse. Hopefully the slave cylinder is fine.

 

[cuttin edge]

The booster and master don't share fluid. Same as a booster on a car, so if it's just the booster leaking. Do both masters have a booster? I can't remember.

 

[Welder Dave]

Pretty sure only the clutch has a booster. The brake master cylinder is by itself. Could the master leak into the booster and both are leaking or can just the booster leak? I imagine if I pull them out might as well get both resealed.

 

[Welder Dave]

I called Jade today and the repair kits are available. $235.90 for the master cylinder and $278.60 for the booster. A new master cylinder is $797.00! I asked the parts guy what their labour rate was and he couldn't tell me. He said it changes all the time which I thought was odd. You'd think he could at least know the current rate. Maybe it depends on the customer??? Another brake shop said the prices for the kits didn't seem too bad. He said if they're Mico they are expensive. He would need some numbers off the master and booster in order to get a price. He said it's about an and a half to R&R them and they use different fluids. If the booster leaks it can take out the master seals. I'm going to see if my mechanic friend could install the kits. I'd rather pay him.

 

[Blue-Fox]

I called Jade today and the repair kits are available. $235.90 for the master cylinder and $278.60 for the booster. A new master cylinder is $797.00! I asked the parts guy what their labour rate was and he couldn't tell me. He said it changes all the time which I thought was odd. You'd think he could at least know the current rate. Maybe it depends on the customer??? Another brake shop said the prices for the kits didn't seem too bad. He said if they're Mico they are expensive. He would need some numbers off the master and booster in order to get a price. He said it's about an and a half to R&R them and they use different fluids. If the booster leaks it can take out the master seals. I'm going to see if my mechanic friend could install the kits. I'd rather pay him.

Looking at the parts manual it's not the slave cylinder I was referring to. It's the booster attached to master cylinder that is leaking. Should I take the whole assembly off to get re-sealed or just the master cylinder? Never worked on anything like this before. Hoping it isn't too expensive to fix.

The booster on these machines functions exactly the same as GM hydro boost used on diesel pickups, diesel cars (like olds toronado) and still used today on 3500 series pickups to increase braking power.
I have no idea if parts are common but I’d be willing to bet they are. Your machine is back in the pre - DOT3 M/C era so yours should use Hyd fluid so the booster fluid should not be a prob against M/C seals. That should be just fine. Now on the later models like mine with DOT3 fluid in the clutch def cause big mess if you get Hyd fluid in past the m/C seals.
I have a $80/ea master cylinder ordered from Napa if it’s the right unit when it gets here I’ll share the number.
Jade is high on their own supply. But nowhere else to go if you need Champion specific parts.

 

[Welder Dave]

My machine uses Dot 3 brake fluid and is a series II. Series III and maybe late series II went to the mineral fluid. In the service manual for series II and series III it mentions early machines use Dot 3.

 

[Blue-Fox]

My machine uses Dot 3 brake fluid and is a series II. Series III and maybe late series II went to the mineral fluid. In the service manual for series II and series III it mentions early machines use Dot 3.

Sorry It's in my head otherwise. Im 700 miles away from my manual right now. Not the first time I've got something crossed up from a well reused 30+ year old manual that has several updates and misc pages stuffed in the back pockets detailing so many crazy switcheroo deals on their machines that every single page must be followed exactly by serial number whether or not it applies to your specific machine. My biggest point being if you mix them up youll have a mess on your hands.
I will be happy to see all my Champions going out the driveway this summer to new homes. They aren't a bad machine when they been maintained properly, just IMHO too much like an Audi or other european foreign car.

 

[Welder Dave]

They are a pretty reliable and affordable machine from most things I've read and heard. I think the early models might have been more of a challenge because there were so many different powertrain options.

 

[Blue-Fox]

They are a pretty reliable and affordable machine from most things I've read and heard. I think the early models might have been more of a challenge because there were so many different powertrain options.

Thats very true, you can buy one thats in great shape for 20-30k USD. like I say, these are great machines especially when they are kept in top shape. Mine are all cummins motors and run like a swiss watch. But I broke a throttle pedal part the other day, and Jade wants $1400.00 USD. For a new pedal. So with only a few options for parts availability?? And being 2500 miles away, in a foreign country ?? And prices that rival CAT? Without the service life of a CAT? I'm no longer going to rely on them for my contract income. I got a Deere 872, and its working great. I'm still mulling over keeping the 740, but likely let it go. I have an old 12G that is a good back up machine and super easy to find parts for it.

 

[Blue-Fox]

Pretty sure only the clutch has a booster. The brake master cylinder is by itself. Could the master leak into the booster and both are leaking or can just the booster leak? I imagine if I pull them out might as well get both resealed.

The booster operates at the steering pump pressure, so I'm pretty sure the master fluid cannot leak into the booster. The booster leaking would create an external leak between the master and its mounting flange on the booster. I have booster rebuild kits in my parts, that I havent needed to use yet. I have replaced a master with parts from Jade in the past and it was stupid expensive. I have two machines with failing masters right now (DOT3) and Napa is searching for a compatible master. Im sure there is a common part out there...

 

[Welder Dave]

I'm hoping just the booster is leaking.

 

[Welder Dave]

I managed to get my camera close enough to take a pic. of the tag. The model number is a Mico 02 461 120. Hopefully a brake shop will be a little better on price than Jade. I also noticed the brake master cylinder has a booster as well. I'm guessing that taking the panel off the bottom of the cab gives better access to get at the hoses so the unit can come out. Still doesn't look too fun.

 

[Blue-Fox]

I managed to get my camera close enough to take a pic. of the tag. The model number is a Mico 02 461 120. Hopefully a brake shop will be a little better on price than Jade. I also noticed the brake master cylinder has a booster as well. I'm guessing that taking the panel off the bottom of the cab gives better access to get at the hoses so the unit can come out. Still doesn't look too fun.

I found a crossed over replacement unit from Auto Brake and Clutch, #M100135, @$350 USD but it's on backorder until Oct-23, and says no repair kits available. So probably best to get with Jade and see if you can get a kit for yours while you still can.