Front wheel cylinders D24

[Conn47D24]

Question,  are both WCs supposed to move simultaneously,  even motion ? Mine are not. One moves, other sluggish at best. 

 

Recently inspected front driver side wheel cylinders after a lock up.   Both needed rebuilding.   Heat was intense.   Passenger side were clean.

I have bled the system and still tweaking the adjustments.   Other than more bleeding, what am I missing?

Thanks all.

 

 

 

[Doug&Deb]

Try bleeding first. I believe both cylinders operate simultaneously. If you rebuild do all 4.

[Dan Hiebert]

Yes, both front wheel cylinders are supposed to move in unison.  If one is sluggish, there may be a bit of crud or some fallout from the rebuild restricting fluid movement to/from that one cylinder.  It doesn't take much.  Would hold true for being slow to return as well, which is what could be causing the overheating - that one shoe dragging.  I don't know if there is a technical term for it, but is it the second, lower cylinder in the system that is sluggish?  That one can be affected by issues with the first one and is supposed to be bled first, I always switch back and forth an extra time or two when bleeding the front cylinders.  I usually get a bubble or two that's snuck past the first bleed.  I'd echo Doug&Deb, assuming from you writing they "needed rebuild" that you've rebuilt them, a thorough bleed may do the trick. 

[Conn47D24]

I'm going to check the cross over tubes next.  Thoght I blew them out bon install years ago but worth checking.  I'll keep at it and check back.

[kencombs]

The timing of their motion is totally dependent on the force needed to move shoe.  The pressure in both will be the same, laws of hydraulics.   And that pressure is determined by resistance to movement.  Just a little drag from rubbing on the backing plate, difference in springs etc, will change the timing.  But as soon as one touches the drum, the other will move.   IMO, it would be highly unlikely to see both move beginning at the same time and continue at the same rate.  Just to many variables in the parts.   I'd just make sure the piston and bore is in good condition and assemble the brakes.

[Sniper]

To add to Ken's thoughts, if you have the drums off to observe the wheel cylinder action you might want to put a strap around the shoes so that the system can build pressure.

[Conn47D24]

Thank you guys I had a suspicion that maybe with the drums on pressure transfers more accurately if that makes sense. 

I'll test it with a cargo strap so I get the visual reassurance then I'll get the drums back on.

 

Thank you !

 

[squirebill]

Hydraulic systems take the path of least resistance. In a multiple  cylinder system the cylinder with the lightest load will actuate first.  That being said, are your return springs the same?  If they are different sizes or one is stretched and they don't have equal tension they will not act in unison. 

[Conn47D24]

Bill, All my springs are the same, and new.  I was concerned that they were too strong, more " coils" than the parts book indicated.  However its the same spring and coils sold by every dealer I see.  Waiting on help with bleeding and then I'll take a look at how they are operating.

[kencombs]

1 hour ago, Conn47D24 said:

Bill, All my springs are the same, and new.  I was concerned that they were too strong, more " coils" than the parts book indicated.  However its the same spring and coils sold by every dealer I see.  Waiting on help with bleeding and then I'll take a look at how they are operating.

Mass produced springs are probably not very consistent in force needed to extend.  And it only takes very little to cause the 'problem' you've observed.

[Conn47D24]

This was the cause of multiple issues !

 

I was using new style ( short ) pins with the deeper wheel cylinder pistons.  Couldn't get a good feeling pedal.

 

Also, the WC's were leaking, seems they piston was trying to push out too far due to the pin.

 

Rebuilt all WC, used my original pins  ( thank God I horde stuff )  Brakes are feeling and working fine now.

 

 

[Conn47D24]

I have also completed the new Wilwood MC as others here have done.   BIG help with photos and info here on the forum.

 

Wish I had done this from the start.  Feel much safer.   So I'm 99 % stock, it's OK.