'72 620 brakes

[Shaggy620]

Hey everyone! I'm new to the page and the Datsun world. A couple weeks ago I purchased my first Datsun, my dream car/truck :)

 

Anyway. Today I was driving her for the first time in the rain, and when I brake slightly the truck yanks itself to the left. It scared the crap out of me. This is my first car without ABS so I'm not used to this. I'm assuming it only does this in the rain because when they're dry they work perfectly fine other than they take a little longer to brake.. I'm wondering if there's any advice of if its my alignment? I'm not familiar. Also i know there's front disc brake conversions I don't know what's the good stuff. Thanks :)

[datzenmike]

Two things...

 

1/ The left (driver's) side brakes are working but the right front or rear, or both are no or to a lesser extent.Truck wants to slow down on one side and rotate, cartwheel around the working side brakes. The 620 has four wheel drum brakes that need adjusting so that they brake evenly. The 620 brakes are very good but they need to be constantly adjusted a couple of times a year.

 

2/ My 620 did this also, but only in the rain. The front alignment was way out. Toed in. Both front tires severely worn smooth on the insides of the tread. On dry road the two tires just fight and cancel  out, But in the rain one has more traction and suddenly there isn't any on the other and over into the other lane you go. I pointed my truck out the driveway and walked across the street. Standing in my neighbor's ditch and looking at the wheels I could see that they were both aimed right at me. Just do the same or have a friend turn and adjust the steering wheel so that if you sight down the side walls of the front tire you can line it up with the rear behind it. Takes a few tries but get the front lined up with the rear.

 

Now go over to the other side and look down the sidewalls. Can tou see rear tire tread? This may indicate toe out. If you can't see the rear tire you may have toe in. 

[G-Duax]

Wow, culture shock.......

Going from modern ABS system, to something that is on the level of my 1935 Dodge.

 

First, make sure all the wheel cylinders are actually working (they tend to freeze up after 40 years).

If not, do a complete brake job (wheel cylinders, master cylinder, shoes, lines, adjusters, and have the drums turned.

This will put you back at 100% 1935 capable brakes. (arg!)

 

Then check the aliegnment, as Mike says, and corner weights.

If it's perfectly aligned, and one spring in the rear, or one torsion bar a little off than the other, then one front wheel will carry more of the braking, and will wear it's shoes quicker, making them grab later than the other side.

 

Then, stay on top of the adjustments.

 

With the above service work, less the corner weight check, I'm adjusting the damn things about once a month to keep it braking almost in a strait line.

Can't wait until I do a disk conversion (if I live that long).