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Cardinal Grammeter

Member Since 18 Mar 2014
Offline Last Active Jul 20 2017 11:19 PM
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Topics I've Started

Can't find my content older than July 2016

13 July 2017 - 06:41 PM

I wanted to close out an open problem thread that I just solved.


620 Silver Door Side Mirrors vs Car Mirrors: Arm Length and Angle

10 July 2017 - 12:58 PM

I have just become aware of this difference because of recent eBay auctions.  At first I thought I had a shot at RHS mirror(s), but they all appear to have a shorter arm than my LHS mirror.  (Please note, I acquired this LHS mirror and cannot vouch for its correctness.)

 

First, there are at least 2 bolt patterns:

  • Staggered:  one hole high on the flange, the other low,
  • Staggered/Centered:  The forward hole is centered at about he vertex of the arm and flange itself.
  • unknown - there may be others...

I believe the S is 620 and the S/C is 510.

 

Second, there may be 2 arm lengths.  The long arm is about 4.5" long the arm leading edge from the center of the ball joint to the longitudinal centerline of the flange mounting surface.

 

Third, there may be 2 arm angles: the short arm appears to be nearly perpendicular (90*) to the flange mounting surface plane, while the large arm is 30-40* from the mounting surface plane.

 

Regarding arm length and angle on the 620:  It appears the factory mounting position is just in front of the leading point of the bullet "fin" which is not in the higher, top concave portion of the door panel - the mounting flange will not seat properly and will rock.  It could be that the longer arm and tilt is used to position the mirror higher relative to its mounting point while also not letting the mirror stick out more like big truck mirrors.

 

 

 

 


Any Synchro Test/Check for Junkyard 620 5-spd transmission? and Parts?

02 May 2017 - 11:33 PM

Looking to purchase junkyard 5-spd for my 74 L18 620.

 

Looks like there is no inspection plate for visual inspection.

 

I think once, a long time ago, I once did a crude synchro test by spinning clutch on input shaft by hand w/trans in neutral and then jam into gear.  If the synchro was broken, it would grind.  Worn is another matter.

 

Other than that, I got nothin'

 

Also, where would you buy synchros  to freshen up?


1974 620 Power Brake Flutter - feels like ABS

29 April 2017 - 09:33 PM

This is a new symptom that's started after driving truck for about a year and 8k miles:

 

If I am going at least 15-20 mph, and I quickly stab and hold the brakes for a very slight braking effort, the pedal will pulsate like ABS while providing the expected slight braking effort.  I can clearly hear "air pumping in and out" when this happens - it is clearly audible in the cab and also vibrates everything because it is also a braking force oscillation too.  

 

This flutter can be maintained indefinitely going down a hill if the precise amount of pedal pressure is established - and increase and the flutter stops and the brakes work as expected.

 

Crazy Engineering Theory:  a kind of mechanical-servo instability (oscillation).  The culprit could be air in he lines which acts like a spring.  Since this only happens when I jab the pedal, the jab would kick the mass of the system off it's equilibrium point and you'd get an oscillation.  The PBU assist would then cycle Yes, No, Yes, No...  Slow application of pedal usually does not cause this flutter.  As far as air goes, the brakes don't pump up which indicates there isn't any air in the system.

 

Some History may help identify what is happening:

 

TRUCK SAT:  for 10-20 year.

 

POWER BRAKE UNIT STICKY CHECK VALVE:

 

The PBU (power brake unit) had a sticky check valve that resulting in the brakes not be released by the PBU - you pushed the pedal and when you released the pedal, it remained at its depressed position.  Then with some kicking, pumping, etc. I would hear a "click" and the pedal would return. 

 

At first, I thought something was hanging up in the linkage.  I had the booster out a couple of times and cycled it on the bench with an external vacuum source.  It seemed to work just fine.

 

I don't remember how at some point I figured out it was a check valve (I confirmed the existence of his check valve by studying the PBU operation).  So I removed the boot and cover from the rear of the unit and spared some dry teflon garage door lube into the booster.  That seemed to make it work OK.

 

POWER BRAKE UNIT NOT SPONGY:

 

Every PB I've driven has a spongy feel - like there is a balloon between your foot and the pedal.  This unit has a barely detectable sponge at times - it feels like a manual brake pedal.  But it definitely has power.  Again, bad memory, I seem to recall when I first started driving after fixing up, there was more sponge.

 

POWER BRAKE HOLDS VACUUM 10-15 sec AFTER ENGINE OFF:

 

Apply brake and hold with foot

Engine off

10-15 seconds later, pedal pushes foot back.


620 Heater Vent Pull Knob: I use my truck - I've busted two of them

13 March 2017 - 02:29 PM

Yeah, you throw a bunch of stuff up in the cab over the hung and... rack up another pull knob.

 

Maybe I should make one with a hinge:  when it is out, the hinge lets the rod point down against the vent.  To push in, straighten the rod and push.

 

Or make it of some unbreakable polyurethane.

 

Cool concept but not so cool in a work truck.