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Topic: Stupid brakes!
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The620Kid
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bullet Topic: Stupid brakes!
    Posted: 03 April 2005 at 6:38pm

So I was driving my truck today and I went to come to a stop and I kept rolling. So as Bleach knows going down my hill with out brakes is a BAD thing. I had to put the truck into the side of the mountain to stop. Not to mention I bent my bumper and fender DAMMIT! I mean the truck isn't the nicest in the world but thats not the point. So now I have to figure out what went wrong with the brakes. Well I'll keep you all posted on the adventure of my brake searching.

TheKid

NOS is like a hot chic with an STD, you wanna hit it but you know the consequences
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Hainz
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bullet Posted: 03 April 2005 at 7:38pm
Ck the brake master?
Ck the wheel drum so if leaky wet?

As I always say get new master cylinder if yours look old! Fuid seems to dissapaear means something

Sorry to hear about the truck
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VilleBill
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bullet Posted: 03 April 2005 at 9:29pm
bummer..... but ya know there is that parking/EMERGENCY brake handle thingy down by yer right knee...... just under th dash?.... completely mechanical?... no fluid required?.... adjustable even?.... just for like .... when the pedal sez its on vacation?

good thing to keep in working order... just in case. Its there. Only does the backs... didja know that if yer on a curve and use just enough pull on that handle to break rear traction that you can steer through turns broadsie on?

hee! its fun to do and a bit of experience about how to deal when things go wrong.... well.
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mklotz70
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bullet Posted: 03 April 2005 at 10:17pm
Since your screen name is 620kid.....I'm guessing you were driving a 620? Didn't they all come with dual m/c's? If so, how did you end up with no brakes at all? If you were driving a 521 with the single circuit m/c, now would be a really good time to upgrade to a dual circuit m/c!! Rebuilt m/c for the 620 is only about $27...I just put one in my '72 wgn.
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Hainz
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bullet Posted: 03 April 2005 at 11:24pm
mklotz,
If he has a 521 w single res, he would have to find a new splitter distribution block correct. That would be hard to find know woulndnt it?

I highly reccommend getting new masters if you think its old. I chaned mine weither it needed it or not.
Bought 2 new ones from Beck Arney(NAPA) 50$ Made in Taiwan but seem ok so far
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datsunaholic
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bullet Posted: 03 April 2005 at 11:54pm
The distribution block isn't the issue- there is a 3-way block that splits the MC pressure to the front/rear circuits (on the firewall). Either you replace the lines fron the next connections downstream or you put 2 straight-through blocks in place of the 3-way.

BUT- the later dual circuits really need a proportioning valve. If you run them straight the rears love to lock up. The prop valves need to be mounted to the frame at a particular angle.
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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mklotz70
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bullet Posted: 04 April 2005 at 8:37am
Hainz,
Not quite sure what you mean. I was only saying that if he's in a 521 with the original single res m/c(which is also a single circuit m/c) and it went bad, now would be the best time to modify/upgrade the brake system by putting in a dual res/dual circuit m/c.

As for the block, You can use the stock distribution block if you disconnect the line to the rear and plug that hole in the block. Then use a butt connector to hook a new line from the rear line to the new m/c. You'll most likely need to run a new line from the m/c to the distribution block because the new m/c will connect to the line on the bottom side. It's probably easier to make a new one, then to try to bend the old one into position.

The other thing to keep in mind is that the 521 is SAE and any new dual res m/c will be metric. Since my calipers are metric, I ran all new lines to the front. Originally, I used blocks from a 620 so they would match up to the metric lines. I put a metric line nut on the line from the rear so that I could connect it to the metric block from the 620. But!!! As Datsunaholic stated, the rears locked up bad!!

So....I put a proportioning valve (from an S10) in the system where the blocks were. Huge improvement. No more locking rear brakes.





This is actually a combonation valve, which means that it also has a metering valve in it as well as the proportioning valve.

The prop vavles that are mounted to the frame in the rear have a rod that connects to the rear end....something like that anyway....the proportioning is regulated by the angle of the vehicle. If it has a heavy load, it will get more rear braking...if it's light, it gets less. That's probably the best way of doing it, but also the hardest.

If you don't run a prop valve, you might be able to back the rear shoes away from the drums so that they won't engage as fast as the fronts. I wouldn't recommend it, but it would be a way to get a dual circuit m/c in .....then go back and put in the prop valve later.

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Hainz
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bullet Posted: 04 April 2005 at 8:54am
You the man.
I knew the 521 was different . Even the back brake bleeds are like 11mm instead of like the 10mm of the 510.
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Bleach
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bullet Posted: 04 April 2005 at 11:39am

Yes, your hill is suicide! You can't just drive a beater with old brakes. Not to tell you what to do, but really you should stop looking for new projects and put some money into one Datsun! Buy all brand new brakes. I think i've said this a few times before, but fix your brakes first! That's basically the very first thing I go through when I get a new Datsun that I plan to drive. Bleed the brakes and check/replace the rotors and pads. Replace or rebuild the master if at all possible. Maybe you planned to do this later, but now you know.

4-wheel drums are flaky as it is and you could seriously die if you get stuck in the straightaway while the brakes go out.

sorry to hear about the wreck. Did you drive the truck home or leave it in the ditch?

And on top of that, make sure your parking brake works good and you have it adjusted properly. I'm not perfect here either. My rear parking brake works, but its a little past due for an adjustment on the shoes. But all my brake hardware is new including the master cylinder.

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The620Kid
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bullet Posted: 04 April 2005 at 7:29pm

I'm driving a 521 and I only have one project which is my 521. The truck needs the unstoppable oil leak fixed(oil pan gasket) and body workother then that runs great. As for my 210 it's my daily commuter. I never thought to check the e-brake so when I pulled it I got a WHOLE lot of nothing. There was a ALOT of slack in the cable even when it was pulled. So far on the brake issue I have replaced the M/C, both rear wheel cylinders, and shoes all around, I gonna replace the front wheel cylinders soon aswell. Now I am able to stop again it's still a lil sketchy though. I'm really thinking about the Dual M/C idea. What year of s10 did you get the block thing from. Thanks TheKid 

NOS is like a hot chic with an STD, you wanna hit it but you know the consequences
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mklotz70
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bullet Posted: 05 April 2005 at 7:22am
The one that I have in now is from a '91 S10 which had rear ABS. I want to change it out to one from an '84-86 S10 which did not have ABS. I may mount it horizontal next time too, but that would mean changing lines again...so I probably won't. I've seen the same style blocks mounted horiz and vertical....so I don't think it matters much.

If I remember right, the drum/drum 620's had prop vavles on the firewall. That would probably work fine if you put in a dual m/c and keep the drums up front.

Maybe with this new job, I'll have time to finish the design on the disc mod. If I manage to do what I really want, then it will be pretty much a bolt on for hardbody hubs/rotors/calipers. Just need to get the time and a couple of bucks for the machine work.
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datsunaholic
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bullet Posted: 05 April 2005 at 12:10pm
All 620s had the prop valve on the frame, under the passenger side of the cab, irregardless of the front brake type. They're surge type so orientation is critical. 280Zs had the prop. valve on the firewall.
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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mklotz70
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bullet Posted: 05 April 2005 at 7:27pm
Ya...you're right! I looked at so many rigs and pulled several prop valves....having trouble remembering just what I tried. I am sure about the S10 valves, since I wrote the info down. I think I have a prop vavle from a 280 and an Isuzu.
I'm pretty sure the springs in the prop vavles are different, so you'll want to get one out of a small pickup so the proportioning will be close.
A wilwood adjustable should work too.....that's been recommended a lot. I got the s/y ones for $5ea...instead of $50.
Datsunaholic....thanks for keeping things straight! I don't like to give out bad info, but it still seems to slip out every now and then!
Don't have to be too bright to be me!
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The620Kid
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bullet Posted: 09 April 2005 at 2:07pm

Well it happened again I have like almost no brakes one of my new rear wheel cylinders started leaking. I finnally got the 2 front ones replaced and the truck was stopping fairly well. Then all of the sudden I have like almost no brakes again. Could a leaky cylinder cause this or do I have another brake issue some where togo along with the leaky rear cylinder.

Work done to the brakes so far: M/c, cylinders all around, shoes all around, new hard line across the axel, had them adjusted by mechanic, etc.

Am I missing anythign I havent thought about?

Thanks TheKid

NOS is like a hot chic with an STD, you wanna hit it but you know the consequences
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Bleach
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bullet Posted: 09 April 2005 at 10:52pm

How did you replace them? Bought complete brand new, or did you buy new seals (rebuild kit) or did you replace yours with used cylinders?

If it is a slow leak, you can refill your brake fluid each day or two. If the brake fluid gets to the bottom of the resivour it sucks air and then you lose brake pressure. Get thick boots. Stick your foot out the door!

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datsunaholic
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bullet Posted: 09 April 2005 at 11:31pm
Hoses? You did flush all the old garbage fluid out before installing new cyls, right? Where is the cyl leaking from? It could have the flare fitting all screwed up. But you did say the lines were replaced, hopefully done right (a bad flare will leak)

Or just get a big, thick tubular bumper for those "hit the hill" stops.

I have an extra boat anchor you could tie to the rear and throw out if need be...
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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The620Kid
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bullet Posted: 10 April 2005 at 4:45am

No I replaced my wheel cylinders with brand new ones took a week to get here had to order them from Oregon  I flushed the lines aswell. The wheel cylinder is leaking fron the two little push rods that exspand when the brake fluid is pressed into the wheel cylinder. Not form and of the flares on the brake lines. Thanks for the help/info

TheKid

NOS is like a hot chic with an STD, you wanna hit it but you know the consequences
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Bleach
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bullet Posted: 10 April 2005 at 3:08pm
Sounds like they are bad. Take 'em back and get new ones or get your money back!
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