Real simple question about WS wipers on old GMs.

[zubzub]

Are the valves that control them variable, i.e. can the wipers be adjusted faster or slower, or is it more of a on /off thing?

[TomCat]

The twin controls for the air powered windshield wipers on my Thomas coach, each have a button that must be lifted to start the wipers into motion.

That same button has the capability to twist clockwise/counterclockwise, and change the speed of the wiper arm movement.

If I stop the wipers operation, and need to 'Park' the arm at the bottom of the glass, I press down to the wiper control button.

And although I have heard they exist, I do not have intermittent air wiper controls.

That is as variable as my wiper controls get.

HTH

Jay
87 SaftLiner

[HighTechRedneck]

The ones on my RTS (and one I scavenged from an MC-9 being scrapped) are variable speed.  On them there is a detent at the off position.  To park them you turn slightly further, up against a stop, and they park, when you let go it returns to the detent.  To turn them on you turn it the other way and the further you turn it, the faster the wipers.

[bryanhes]

My 4905 has a knob for each wiper. If you turn the knob one way they get faster, the other way slower. The only thing that drives me nuts is that they are never in sync and when you turn them off sometimes they don't stop where they are supposed to so you have to give the knob a quick turn to place them back into park . I thought about changing to electric 

Bryan

[HighTechRedneck]

Bryan, a lot of folks do go electric and I probably will one day.  The dual knobs is the way mine is set up too.  When you turn them off, have you tried turning it a little past the "stop" you feel?  On mine, when you do that it feels like you are pushing against a spring, but it is actually air pressure and doing so parks the wiper properly.  When you ease up on it the knob returns to the stop position.

[bryanhes]

Mike,

Yes I do turn it back past the stop. It sometimes parks properly sometimes not. Anyone have an idea on cost to change to electric?

Bryan

[Lin]

I still have air wipers and would consider electric better, but unless you switch to a single motor system, the two will not be synchronized.  I believe many that go electric still have separate controls and motors.

[johns4104s]

i am sure Luke has some rebuilt ones

John

[WEC4104]

As far as I know, the air operated wipers on my 4104 are the original equipment. There is one knob for each side, and they are definitely variable speed. They are not "self parking", so getting them to stop in the right location (when I want to turn them off) usually takes me 2-3 tries. 

[bryanhes]

Mine also has two knobs. If I changed over I think I would have one motor with an arm to the other. That is part of what bugs me is the two not being in sync and the wife then wants me to turn hers on so she can see (dont know why she's not driving  ) then when they are on they are running at different speeds  . Thats a project for later I suppose.

Bryan

[TomCat]

.

[Barn Owl]

Just go to the local truck parts place and you can buy new ones for around $20-$29 if I remember correctly. I scavenged some free ones off of an old truck in a salvage yard. They are variable and have a "park" position like others have said. The location of the line inputs where different on the replacement but that was no big deal to change with a few fittings. The only thing I don't like about the air is sometimes the noise they make and not being able to have them on a time delay. Bottom line, if it is the valves, it is an easy fix.

[gus]

My original 4104 air wipers work just like High Tech Redneck said.

I really like them and hope they never wear out. The best part is they can be made to move incredibly slow.

If they don't park properly I turn the knob in the reverse direction against the spring and put them where I want. They will not make a full sweep using the park feature.

I don't really care if they are synchronized and can't imagine why this is important? I kind of like each one doing its own thing!!

If you link both together then when you have a problem both wipers are down. At least the original setup will usually leave you with at least one working.

[zubzub]

Thanks I was just wondering.....I scavenged the valves from the old prevost.  The valve doesn't feel variable  when I run air through it, but I haven't adjusted the air pressure etc...as per the book.  It is amazing though, the original air motors ar really tight and strong.  I have had tons of problems with electric motors/gear assemblies from the 60's so it was a nice surprise to get my wipers working.

[Barn Owl]

My old valves were worn out and did not have the precise control of the speed that I have now. They also didn't park and they leaked and hissed all of the time. Better, used valves made a big difference for me.

WEC4104, If your variable speed is working well then you should have park. When you bump the knob to park, the wipers should park from any position without trial and error.


In case there are those out there like I was and just didn't know (I didn't know park existed until I got good working valves): The valve is Park-Off-On and the park position is momentary against the internal spring. For example, when I turn my wipers off I turn counter clockwise to off, then a little more counter clockwise to park, then release and switch returns to off position.