1965 c10 - hard brake pedal?

[Woogeroo]

1965 C10 - long wheel base

v8

1969 - dual pot master cylinder for all wheel drums

vacuum drum brake booster



O.K. folks, here is the deal.

I'm riding along in big blue truck and when I hit the brake pedal, I have to really put the foot into it. The pedal is not soft, it doesn't sink down, but the front end of the truck does not seem to *dive* when I hit the brakes.

This makes me think there is an issue with the master cylinder.

Which, was last changed in March, 2010 by my professional mechanic.

What do ya'll think?

Thanks for any suggestions or things to check.

your fellow truck addict,

-W

[ChiefRocka]

Hmmm, sounds like the push-rod might need to be adjusted (??)

Then again, its been cool since March.

Brakes dragging ??

[protrash64]

Booster is shot. My SB '64 has manual brakes; sounds just like it. You have to stand on it but it stops.

[Woogeroo]

Originally Posted by protrash64

Booster is shot. My SB '64 has manual brakes; sounds just like it. You have to stand on it but it stops.

Yeah, that is how it feels, it stops, but you got to LEAN into it.

Hmn...

-W

[markeb01]

If it's just a very hard pedal I'd also suggest it's the booster. I'd also check the fluid level in the master cylinder to make sure you don't have a leak in a wheel cylinder (new or not). The front brakes do most of the work and if there's a leak in that half it's going to take a lot more effort to stop the truck.

[nachodog2]

I agree with it being your booster.
Posted via Mobile Device

[jocko]

Woogeroo,
I'd have to agree, sounds like the booster. But I'm also a considering the "likelihood" that your booster would go bad when you swapped to the dual master cylinder.

Important question, I wasn't sure when I read your thread - Did your mechanic install the booster and the master cylinder onto your truck at the same time? If so - then I'd say definitely the booster.

Or, was he just replacing the dual master cylinder and you had the booster already on the truck? If that is the case, then it would be suspect that the booster would just magically go bad if it was previously good. In that case, it might not be a correctly matched master cylinder - i.e. might be worth comparing the bore sizes for the piston.

I seriously doubt it's the latter, and it's likely the booster, but just something additional to consider.
jocko

[Woogeroo]

Howdy again folks.

Thanks for all of the replies, I really appreciate it.

I found this interesting link last night, good trouble shooting tips:

How To Fix Common Brake Problems

The hard break pedal check is something I'm going to try out.


markeb01 - yep, the first thing I checked was the MC fluid level, it was the same and where I keep it filled to in each pot. I have looked around to check for fluid leaks, but have not found any yet.


jocko - nope, the MC was installed on the old booster as it had 'pedal sinking to the floor pedal after you stopped' action occurring.


Some more background: this booster and dual pot MC set up was on my truck when I bought it in April, 2003. When the first MC went south, I had a little adventure trying to figure out what year truck it was for. According to NAPA, it is for a 1969 gmc half ton dual pot master cylinder.

This shot is from 2003, the first year I owned this truck, it shows the mc/booster setup.

So, the booster is the same one as I haven't changed it out and I don't recall my mechanic saying anything about it being bad(plus I keep all my work orders). I think I'm on my 2nd or 3rd MC now. My professional mechanic doesn't have high opinions of the quality of rebuilt parts these days. He would know, I suppose.

but, I digress.

I'm leaning towards the booster too.

Now, I wonder... what year booster it will be?

Hmnn. It's always an adventure with this truck, trying to figure out what year Chevrolet something is.

Thanks again everyone!

It is always nice to have someone to check your thinking with.

-W

[Woogeroo]

Well, I was trying to inspect the check valve on the brake booster and I broke it.

ooops.

I was checking it out tho', and it had that fresh broken black plastic look, with the light gray color, but only part way around. I'm thinking it might have been cracked a bit to start with.

Anyway, I found another one and swapped it in...

So, now I need to go for a test ride I suppose.

I will report back later.

-W

[Woogeroo]

Well, I took it for a ride and it doesn't seem to be any better, so it wasn't something simple I guess.

-W

[62gmc910]

if you run the engine, shut it off then pull the checkvalve out you should have vaccum , if not run the engine with it out or pull it out with the engine running ,to see if you are getting manifold vacuum, slim chance but maybe the line is plugged. also make sure the pivot points are free, the signal to boost gets lost with too tight of pivot points in the linkage (pedal to booster)

[turbostar]

Wood,a common overlooked problem that results in a hard pedal is when one or more of the wheel cylinders do not move when the brake is applied. For example if the rubber flex line that goes to the rear brakes becomes plugged,then neither rear wheel cylinder will move. This causes a big reduction in the mechanical advantage given in the hydralic system,and thus a hard pedal. One thing I would do is elevate all four wheels off the ground and try to turn each wheel by hand while someone pushes on the brakes. If one or more of the wheels is easy to turn with the brakes applied,you will have found your problem.

[Woogeroo]

I've been trying to acquire a new brake booster.

My MC is for a 1969, dual pot deal.

So, at the NAPA store we looked up a 1969 - it was much bigger in diameter, rod out the back is longer and does not fit.

My local NAPA said they are on factory back order.

Next up I go to the local O'Reillys... they order one up, it shows up. I guess it is the '60-'63 style with the vertical bars on the back mounts, because it was all wrong as well.

*sigh*

So, the O'Reillys lady ordered another booster, in case they put the wrong one in the box and a loaded(with MC) 1965 c10 booster coming in from Nashville. She said there was only a 10 dollar difference for the loaded one with the MC... so... hey if it works, I'll be a happy camper.

Anyways... I hope that is all it is.

I will let ya'll know.

-W

[Woogeroo]

my loaded(with single pot MC) 1965 brake booster came in and I went to work on it today.

I took the single pot MC off and proceeded to line everything back up.

I replaced the vacuum line to the booster while I was at it.

So, new booster, came with new check valve and a new vaccuum line as well.

I put it all back together and it stops much better now!

Yay!

I'm glad that is all that it was.

Thanks a bunch for all of the replies, tips and suggestions of things to check folks.

They all came in handy.

What an epic quest for one part... yeesh.

I'm back on the road...

yippeee!!

-W

[Woogeroo]

I wrote out this little adventure for an old truck pal of mine, who I knew could relate.

It is just one of those 'old trucks are fun.' especially when you are trying to find parts, type stories.

Nuthin' fancy.

Read on if you like parts searching stories...

If not, stop reading now.

Old trucks are fun!


-W



--- story begins here ----


So... big blue '65 chevy truck was having this issue with the brakes where I would have to LEAN HARD on the pedal to make. it. STOP.

It would stop, but I had to MASHONIT!

HMNNNN.

So, big blue has a 1969 gmc dual pot MC(according to NAPA)... with vacuum booster assist with 4 wheel drum brakes.

Now, I start checking the brake fluid... it's good.

No leaks any where that I can see.

Pedal is good, doesn't sink, isn't soft, doesn't change...

Hmnn.

So I ask around some old truck buddies, cuz I'm thinking it's the old brake booster which was on there when I bought olde truck in April 2003.

I'm not sure tho', cuz I've never had this particular issue on a vehicle before.

I do some more hunting around and I found some interesting tech articles on things to check regarding brakes issues and how to do it.

To be simple, I swapped in a new brake booster check valve on the vacuum line. No change.

I decide booster must be slap worn out as my daddy would say.

Now! Here begins my parts quest.

Early this week, I go off to see the wizard, at the wonderful world of NAPA.

I'm thinking, it's a 1969 MC, it *might* but might not be a 1969 brake booster.

Well, local NAPA doesn't have one... but, the local North Georgia monster warehouse(which also has a store) that supplies the NAPA's is only another 7-9 miles away. So, I buzz over there...

I talk to the counter man and tell him my troubles. He brings up a 1969 c10 brake booster.

It is WAY bigger in diameter ( mine is 9 inches, this one is 11 inches)... and the rod linkage out the back is much longer as well.

Hmnnnnn.

I'm thinking it will not jive, but I buy it anyway when they tell me that the 1965 brake booster is on factory back order! AAAAAAAAAAHHHH

Well, I get home and it takes all of 30 secs to realize.... 'no, this is not going to work, at all.'

Next day I buzz back out, get a refund, etc..

I come back to my side of town and I ease by the O'Reilly store... lady says she can get a '65 c10 booster, 9 inch diameter that afternoon. Yay I says, here's da money....

That afternoon comes and I go to get it.

I go home and it looks... almost right.

But... not... quite.

I have the '60-'63 style in my hand, which I now know has vertical brackets/linkages as opposed to the '64-'66 which has horizontal brackets.

I'm in school and learning fast now!

Back to the O'Reillys and I show the counter lady my problems. She is like... 'hmnnn... yeah, that doesn't work'.

Back to the super computer!

She clicks and clacks and tells me that she can't find 'just the brake booster' anywhere nearby... so she looks for a loaded one, which in parts speak means, with a master brake cylinder attached. I don't need that single pot deal, as I have the later model MC with the dual pots... she say: it's only a 10 dollar difference and I can have it here tomorrow afternoon by 3:30.

I say: well, alrighty then, let's get it going then.

Then I go and pick up the part... of course it's misty/cold/foggy raining... and ta da, it looks like it'll work. I took my brackets with me this time.

I get home and eyeball it and it looks all happy.

OK... so, today, rain is passed, kidna chilly, but no biggie, at least it isn't raining no more. I get really *****y when I have to get wet working on cars, I must be part cat or something... but I digress...

where was I?

Oh yes... epic adventure trying to figure out which parts to put back together first in the interest of my sanity.

I only had to take one thing back apart to regroup.

Then I had to wiggle, pry and nurse everything back into happy alignment.

After all of this....

one new 1965 c10 brake booster, which came with a new check valve... and I replaced the vacuum line while I was at it.

Put it all back together, snugged everything up, put vacuum lines on... grabbed tools out of the way and took it for a ride.

It stops good now, I blip it too fast and it'll throw stuff out of the seat.

*smirk*

YAY.

I'm so happy.

I'm back on the road in my old jalopy...

VROOOOOOOM

I'm a happy boy.


-W

--- story ends ----

my old truck pal had this to write back :

So, $50 in parts and $300 in gas to finally get the right part?
Sounds about right.

[protrash64]

Nice!! Thats what it sounded like to me......and it's cool you can still get old parts at the chains.

[Woogeroo]

protrash64,

there are still a lot of mechanical/electrical parts in the system of the big chains.

brake stuff: hard ware, pads/shoes, springs, flexible lines

engine and trans stuff... rebuild kits for carbs. and other things like that.

You might have to wait a day or two, but you don't have to pay shipping. The return policy is the same as other modern parts.

For instance, no returns on electrical bits.

-W

update: a lot of big parts stores are also 'dealers' and 'distributors' for big aftermarket companies that have been around awhile. So... be sure to check that out as well.

[skysoldier173rd]

same exact scenario on my 60 GMC with updated dual cylinder. Found out what the problem was one day when i hit that hard pedal too hard and blew out a rear line. Suddenly, NO BRAKES even though i had the dual cylinder, that's just not supposed to happen. The fronts apparently were not working at all. When I got to looking, the fronts were adjusted all the way in, don't know why, maybe adjusted in when an emergency occurred just to get the person home. There was a spring broken, anyway adjusted them out to the standard position and replaced the little retainer spring and now i have both front and back brakes
that work reasonably well. That's my story, but it sounds just like what you're experiencing. I mean that pedal was rock hard, but very little stopping power.

[protrash64]

Good point Woog, the shipping really kills many orders. Just saw on CNBC that UPS will raise rates 4-5% next year.

[Woogeroo]

protrash64 - they(big brown) raise the rates every January.

Most people don't notice it, because they usually announce it the week after new years when everyone is still hung over.

--

If you can get the mechanical pieces and they work on your truck at your local store, it is all good in my opinion.

Some mechanical things tho', you will have to go the vendor and/or used parts route as it may be something very specific to our model trucks.

It is something to keep in mind, it is an option.

A lot of mechanical/electrical parts were used across multiple years and platforms... so they keep a few in the big warehouses. Depending on where you are and how close you are to the warehouse determines how quick they can get it. A lot of the big makers of various high falutin' parts have been around a long time. If you check their dealer/distributor network, you will find a lot of big name parts stores listed. With a lot of companies having their parts online now, you can find a lot of stuff in their system yourself, jot down the part number and stop by their store.

Now, if you are doing a full blown Vintage Chevrolet Club of America, graded numbers matching restoration, then it is another story entirely and you are playing with a different bank account.

-W

[protrash64]

In case people are following this; just picked up some upper balljoints at Autozone for the '66. 16 bucks a piece. The suspension places would have you believe that they are like finding the Holy Grail... Thanks Woog.