How well do the brakes on your cucv work?

[jimmy-90]

I hate to be the bearer of bad news, but master cylinders seems to be one of those parts that you may buy new, but it may not be worth a ****. We're getting so much chinese junk passed off as parts and shelved in inventory of parts stores that it's a wonder we can fix anything anymore. I've read threads of guys going through a few before they finally install one that is works.

Keep in mind, that's not calling it a quality part. Only that it worked.

I hope your luck is better.

I suspected that $35.00 for a master cylinder sounded awful good lol. Im gonna see if I can spare a couple bucks next week and pick one up. Hope I don't wind up having to get like 3 of those things to get somthing to work. Heck another quart of D.O.T. 5 will cost like $20.00 or $25.00 alone. If I have to buy like 3 or 4 more of the big quart size containers of fluid that could get REAL EXPENSIVE!!!

 

[donalloy1]

my M1009 brakes like a champ! can stand on her. just hang on! prefer hard braking situations in it over my more modern vehicles with ABS! just went through rears, fronts still look good. stuck w/original silicone base. advise was to stick w/it or completely breakdown system to avoid mixing dot 3.

 

[Dave Kay]

I suspected that $35.00 for a master cylinder sounded awful good lol. Im gonna see if I can spare a couple bucks next week and pick one up. Hope I don't wind up having to get like 3 of those things to get somthing to work. Heck another quart of D.O.T. 5 will cost like $20.00 or $25.00 alone. If I have to buy like 3 or 4 more of the big quart size containers of fluid that could get REAL EXPENSIVE!!!

If you don't mind me pointing out; no matter WHAT it costs for new master cyl & DOT 5 AND/OR whatever ELSE is needed to make your brakes work like new, that cost will be NOTHING when compared to the costs of a rear-end collision, school cross-walk accident, no brakes on a downhill grade... (not to mention lawsuits, attorney'$ fee$, hospital/medical costs, insurance increases...)

 

[kassim503]

... Pretty sure I stopped so hard, my back end lifted off the ground (just guessing cause it was loud when it came back down)....

LOL ! I swear I have wheelstanded my 1009 too! Try emergency stopping before a speedbump, that is one haaard stop

 

[jimmy-90]

I hate to be the bearer of bad news, but master cylinders seems to be one of those parts that you may buy new, but it may not be worth a ****. We're getting so much chinese junk passed off as parts and shelved in inventory of parts stores that it's a wonder we can fix anything anymore. I've read threads of guys going through a few before they finally install one that is works.

Keep in mind, that's not calling it a quality part. Only that it worked.

I hope your luck is better.

Been working on my brakes over the past couple of weeks and I almost have them working right. Unfortunately like Timber said I had to try more than one master cylinder. The first one I got from Napa was made in China and you guessed it. I couldn't even get it to work as good as the one that I was replaceing. I went to the GM dealer and they said that the master cylinder that I needed for my truck was no longer in production. They were able to give me a part# though. I went to a local non chain auto parts store and they ran the # that the GM dealer gave me and ordered me a Wagner master cylinder that says made in USA on the box. I put it on the truck and bled everything. Now I have really good front brakes but the back ones wont really catch and the pedal is still kinda soft. While I was bleeding the back brakes this last time I noticed some yellow fluid come out with the purple. I suspect that is why my petal still doesn't feel right and the back brakes don't lock up. Probly still air in there too. When I get some more money to buy another quart of D.O.T. 5 I'll bleed the back brakes again and see what that does. Also that Wagner part that is made in the USA cost a little bit more than $35.00 but when dealing with my brakes it's probly better to just pay triple the price of the Chinese part and play it safe.

 

[WARWAG]

Do you still happen to have that part #? Sounds like the Wagner is the way to go.

 

[WARWAG]

Found it.

Wagner: MC108145

 

[jimmy-90]

Found it.

Wagner: MC108145

Yep I can confirm that. I just ran out in the garage and looked at the box. MC108145 is the number on the box.

 

[scootertrs]

That Dot 5 brake fluid is a wonderful thing, but requires great patience grasshopper... I read where you used the mightyvac, but if during the install or changeover you did a full travel pedal to the metal push, your master just traveled into lands not previously known and more than likely damaged the seals. No big deal, just understand that bleeding silicone is never a one pass thing. I usually start with a gravity bleed, then let it sit overnight, do it again, let it sit overnight, do the vac drain thing... etc. What happens is that silicone has this "special" ability to form these small bubbles that form bigger bubbles overnight... it is a job, but well worth it if you splash some on your paint while topping off!

 

[als804]

You fixed it? Mine is similar to yours. My brake works but there is no resistance until reaching to 3/4 travel of The pedal. And there is no any fluid leak in car and master cylinder reservoir still has full of fluids. But No brake pedal pressure but i can feel pressure at almost maximum travel. And i tested the brake that i was putting both brake pedal and gas pedal together then car didn’t go. I noticed there is still brake power .

 

[scootertrs]

You fixed it? Mine is similar to yours. My brake works but there is no resistance until reaching to 3/4 travel of The pedal. And there is no any fluid leak in car and master cylinder reservoir still has full of fluids. But No brake pedal pressure but i can feel pressure at almost maximum travel. And i tested the brake that i was putting both brake pedal and gas pedal together then car didn’t go. I noticed there is still brake power .

Yes, but a pita anyway. Finally almost out of the mv hobby/maintenance/love affair-When I replaced booster-after several years. it fell into dis-use and even having a remote monitoring/fill cap it heeds replacing again. I am done. If you look in the classifieds, you will see the fire truck for sale (I am including a new brake/booster pump-I just cannot drag myself under this truck to do the repairs I used to.

I turned 70 this year, and finding a good reliable, knowledgeable, and affordable wrench in South Florida has proven to be a real challenge. Musi also be FLEXIBLE enough to do the jobs...

 

[Dave Kay]

FWIW, I see this thread is old, and I'm no brake expert, but here's what I learned:

When I first got my M1008 it had approx 65,000 miles on it and weak-ish braking and a not very solid feeling. Not at all like my two civvy WT square bodies (1977 C20 and 1986 GMC 3500) with the same type brakes. Both those trucks would stop on a dime! I had completely rebuilt both of their brakes with all new brake hardware, over a period of time. Yeah, that cost a me a bunch, but considering the liability of bad brakes and an accident with my CUCV, it's damned well worth it!

Fix for my M1008; After doing parts search, I discovered there are two different part numbers for the CUCV brake boosters; one for M1009 and another for M1008. Pulled my 1008's booster and discovered it had PN for an M1009. A lot of eBay sellers claim the boosters are interchangeable. Anyone, please feel free to correct me if I'm wrong, but this may not be true.

RESULT: so I searched and found a surplus GM NOS booster w/PN for the M1008 and replaced it with my drums and rotors too. Also Installed steel braided brake lines up front and new stock lines in the back. Bled the system w/MightyVac, filled w/new DOT 5, now, an emergency stop in Old War Horse will put you through the windshield!

Another point I think should be made is IF the condition of your vehicle's drums and rotors are too far beyond tolerance to be turned, throw 'em away! Get new ones! THAT may be giving you the low-pedal feeling described earlier, especially w/worn-out rear drums. Mine were at their life's end so I bought new.

Sorry I don't have the M1008/M1009 booster part numbers anymore; this was like 10 years ago. Hope this may help somebody tho...

 

[Keith_J]

The parts technical manual 9-2320-289-34P has the GM part numbers. 1 ton use 2770209. M1009 use 2770317.

The acronym UOC in the parts TM is Useable On Code, each CUCV model has its own UOC. The M1009 is UOC 209. This is all detailed in the preface of the TM, Section 1 page 4. M1008 is 208, M1010 is 210, M1031 is 231. But the M1028 with all its variants loses innate reference.

If the part has no UOC, it is for all models.

 

[cucvrus]

I may be wrong but the only difference between the 2 hydro boost assemblies is the flanged bracket that mounts them on the firewall. The military NOS came completely assembled in a box/foil wrapped. I looked them up and they were the same part number without the mounting flange. I used them on whatever I needed them to fit just by changing the flange to the correct vehicle. I bought a few and changed them over the years after the NOS supply dried up. Good Luck and Have a Great Day.

 

[Keith_J]

The M1009 uses different high pressure accumulator, pedal rod and that bracket. The one ton brake system has larger wheel cylinders and needs more force as the master cylinder is correspondingly larger.

Use of a M1009 on a one ton will reduce braking power.

In proper functional state, CUCV brakes are some of the best feeling brakes from 1980s Detroit.

 

[chevymike]

I know my M1010 stops way better than my Dodge Ram 2500 (past '97 and current '00)

 

[cucvrus]

I researched this and this is what I found.
Duralast Remanufactured Brake Power Booster 52-7248 (autozone.com) This is listed for the K5

Duralast Brake Power Booster 52-7307 (autozone.com)This is listed for the K30
So I guess they are different and when I ordered parts I just ordered them for the correct model. But a visual of the item shows no difference. It must be internal. I stand corrected on assuming the only difference was the mounting flange. Good Luck. Don't mess with brakes. Do it right the first time.