LB75B Brake Master Cylinders Leaking

[jinman]

My LB75B has dual brake cylinders (also called pumps), and recently they started leaking. I have no idea what the previous owner used for brake fluid, but I bought and use only NH brake mineral oil. I suppose the previous owner could have put DOT3 fluid in the reservoir. If so, this is probably just the beginning of brake problems and may result in my having to have the rear axle pulled to overhaul the internal brakes. Gosh! I hope not.

Anyhow, the online parts diagrams show that really there are no internal repair kits. My dealer's service manager verified for me that the cylinders have to be replaced rather than rebuilt. Messicks has them for $268 each, but the guys in my dealer's shop give me free tips and support anytime I need them.:thumbsup: For example, one of the techs overheard me talking about the master cylinders and told me several installation tricks, to be sure and replace all copper washers with new ones (8 total), and how to adjust the brakes for best operation. He said to give him a call if I needed more questions answered. So if my parts are $300 each, I'll make up for it with free advice.

I just hope the master cylinders are all I need. I don't know that someone put DOT3 fluid in the reservoir, so I can keep hoping until I know for sure. What I do know is both cylinders are leaking and I need the best brakes I can get on my terrain.

When I get the parts and start this job, I'll take lots of photos and post them. It shouldn't be a hard job and I've done lots of brake jobs on cars and bled the brakes. This should be straight forward. Wish me luck.

 

[jinman]

YEA! Parts are in. . .will pick them up later today.:thumbsup:

 

[jinman]

The attachments are details of the brake system from the Maintenance Manual. Actual photos will follow when I start the repair.

 

[jinman]

I'm $632 lighter, but I now have my parts, new copper washers, and two quarts of mineral oil brake fluid.:thumbsup:

 

[jinman]

Today, the weather is perfect, so I decided to tackle my brake job on my TLB. The first thing I did was to spray both the pedal area and the master cylinder area with purple cleaner and let it sit a few minutes before cleaning off all that slimy residue of mineral oil, dust, and dirt. The results were amazing. Looking at my photos, you'd never know the brake cylinders are leaking. I also removed the screws on the cowling under the steering wheel so I could pull it back and work from the side instead of having to lay on the operator's platform and work up through the brake pedal cutout. The photos below show removal.

In the photos of the brake pedals, notice the grease zerks. You couldn't see these until I cleaned the area. I don't think they've been greased since the tractor was new. The right pedal was so stiff that it would stick anywhere you put it. After a bit of work I got both zerks to take grease and the pedals work perfectly now.

 

[jinman]

So, I took the crossover tube off of the old master cylinders and installed it onto the new master cylinders using four new copper washers. The tech at my dealer told me that I should install the crossover tube before putting the master cylinders back into the tractor because it would make the job much easier getting the cylinders in place and aligned. He said finger tight only unti the Master cylinders were bolted into place. Also, the plastic hose adapters from the reservoir are a pain to get out of the old hoses, so I pulled the new ones and just left the old adapters there and inserted them into the new cylinders.

Everything is back together now and I'm just awaiting my wife's return from the store to help me with brake bleeding. I sure hope this takes care of my problems with leaks. Keep your fingers crossed for me.

 

[jinman]

Brakes bled = Success:thumbsup:. . .

The End:laughing:

 

[EddieWalker]

Umm..... I had no idea there where master cylinders, or that they take mineral spirits. Guess what I'm doing in the morning?

Thanks for the infor Jim and good luck with your repair,
Eddie

 

[jinman]

I think you may have mechanical brakes on the 555. I'm not sure, but it seems someone told me once that the 555 was not hydraulic.

Edit: Yep, I just verified mechanical brakes on a 555C by looking at the parts diagrams at messicks.com.

Let me add one other bit of info for anyone who might do this job. In the photo below and just below the brake master cylinders, there is a round object with two huge wires and lugs. This is the battery disconnect switch. If you don't disconnect your batteries right at the battery terminals, this switch stays hot and you MUST be very careful not to short either of those terminals to ground or you will be in for a huge spark and a welding lesson. This switch carries the power from two 12 volt batteries.

 

[EddieWalker]

Jim,

More surprises. Your machine has two batteries. I have one. My disconnect is next to my fuel filter, on the side of my engine block. Yours is in a much easier location to get to!!!!

Eddie

 

[Kyle_in_Tex]

Thanks for posting Jim. Always nice to see a documented repair. It just pains me to see such simple brake master cylinders cost so much. Also wonder if modern synthetic brake fluid would be superior? Brake cylinders are such simple devices. If they get water in them, they will rust and if the rust is so bad, it will create pits in the bore that the rubber seals can't seal and then they will leak. As they heat and cool with the machine, they can pull water out of contaminated fluid. It is imperative to have good brake fluid to keep the system water free. It is also a good idea to bleed brake systems every few years to put in fresh fluid from an unopen container.

 

[Kyle_in_Tex]

Jim, I work with a young man who worked at a large NAPA while in college. He is the type who is a wiz at crossover and can scour catalogs trying to find a suitable replacement. I always run things past him for advice before I spend any money on my vehicles.

He helped me get a belt for my JD 350 sickle bar cutter. JD wanted $75 and NAPA was something like $47, but his former co-worker sold it too me for $28.

 

[jinman]

Kyle, had I noticed these cylinders were Bosch, I might have checked around and found rebuild kits, but I'd bet that the full kits would have been $100 each and maybe not included the rubber boots and proper pedal hookups. My rubber boots were gone too. If I spent over $100 per cylinder on rebuild kits, I still have to remove the cylinders and also maybe hone the bores. In the end, I'd have lots of time and parts involved in a repair with no guarantees the parts will work. $305 per cylinder is a bunch, but the repair was a breeze. If I had to pay for 2-way transportation, labor, and parts this would have been a very expensive repair, maybe close to $1000. So buying the new parts seemed to make sense to me for ease and overall cost. I sure can't complain about shipment time on the parts either. I ordered them on Wednesday afternoon and they were at the dealer by Friday morning. Everything bolted up and fit perfectly with no anxiety. That's worth a bunch.

Oh yes, the mineral oil brake fluid is $8.71 per quart. I've found other sources, but none cheaper than my NH dealer. Some foreign auto dealers want over $25 per quart. Yikes!