Wiper Sweep Adjustment???
#1
Melting Slicks
Thread Starter
Wiper Sweep Adjustment???
I did the 95 - 96 wiper swap on my 1986 some years ago; never drove it in rain since...
Got it inspected last week; yep, it was raining...I noticed that my driver side wiper goes past the windshield pillar but parks in the bottom of the wiper well OK...passenger side works OK; sweep is correct...
Is there some way to shorten the sweep???
This swap was detailed in the old Tech Tips -
http://web.archive.org/web/200405051...D=42&TopicID=2
Got it inspected last week; yep, it was raining...I noticed that my driver side wiper goes past the windshield pillar but parks in the bottom of the wiper well OK...passenger side works OK; sweep is correct...
Is there some way to shorten the sweep???
This swap was detailed in the old Tech Tips -
http://web.archive.org/web/200405051...D=42&TopicID=2
Last edited by Rich B.; 12-04-2011 at 06:50 PM.
#3
Melting Slicks
Thread Starter
There must be something somewhere that acts as a limiter for sweep, and reverses the wiper arm direction (or shortens it)...but where??? Is it mechanical or electronic???
I'm thinking a mechanical arm, with some kind of adjustable clamp, that adjusts the degree of rotational travel...Maybe under the windshield base???
The shop manual mentions a 'park switch assembly' (pg 8E-5) but doesn't mention any adjustment for it...
Last edited by Rich B.; 12-05-2011 at 03:31 PM.
#5
Melting Slicks
Thread Starter
BTW, it's been ~10 years since I did the swap...I can't recall if it had a key or splines...
Last edited by Rich B.; 12-05-2011 at 03:48 PM.
#6
Drifting
I'm not familiar with the older setup, but maybe they are similar. The adjustment is mechanical, under the screened air intake panel. See if this makes sense for yours:
A. Remove the right arm and blade assembly.
B. Loosen, do not remove, the transmission nuts. (these clamp the inner ends of the left and right arms to the crank on the motor)
C. Rotate the left arm assembly to a position slightly below the blade stops.
D. Tighten the transmission nuts (spec is 12 lb/in.)
E. Position the right arm and blade assembly slightly below the blade stop, and install arm assembly to transmission shaft.
F. Lift the right and left blade assemblies over the stops.
G. Check wipe pattern and park position. Distance between top of driver's blade to windshield reveal molding on outwipe should be approximately 0.8". Distance between top of passenger's blade to windshield reveal molding on outwipe should be approximately 2". When in park position, the tip of the passenger's blade should be a maximum of 2" from the center of the driver's blade. The correct outwipe and park position and outwipe dimensions are determined with the wipers operating at low speed on a wet windshield.
Thus spake the '92 FSM. Hope this helps.
A. Remove the right arm and blade assembly.
B. Loosen, do not remove, the transmission nuts. (these clamp the inner ends of the left and right arms to the crank on the motor)
C. Rotate the left arm assembly to a position slightly below the blade stops.
D. Tighten the transmission nuts (spec is 12 lb/in.)
E. Position the right arm and blade assembly slightly below the blade stop, and install arm assembly to transmission shaft.
F. Lift the right and left blade assemblies over the stops.
G. Check wipe pattern and park position. Distance between top of driver's blade to windshield reveal molding on outwipe should be approximately 0.8". Distance between top of passenger's blade to windshield reveal molding on outwipe should be approximately 2". When in park position, the tip of the passenger's blade should be a maximum of 2" from the center of the driver's blade. The correct outwipe and park position and outwipe dimensions are determined with the wipers operating at low speed on a wet windshield.
Thus spake the '92 FSM. Hope this helps.
#7
Melting Slicks
Thread Starter
#9
Drifting
Could the geometry be different between the years? If so, maybe you need to change the so-called "transmission" arms that attach to the wiper motor, or adapt the old ones somehow.
#10
Melting Slicks
Thread Starter
I tried setting the arms to the 92 FSM instructions posted below, and there is a problem with "E. Position the right arm and blade assembly slightly below the blade stop, and install arm assembly to transmission shaft"... If I do that, the blades catch on the blade stop when activated...[not good]...
Back when I had a good paying job, I ordered a bunch of spare parts from Jeff Kopp at Superior Chevrolet...The 86 wiper arm was one of them...
I suppose it could be lengthened or shortened by cutting & welding...but which one??? Longer or shorter???
Last edited by Rich B.; 12-11-2011 at 05:10 PM.
#11
Drifting
Having never done this mod, I can't advise you directly. But, if you compare the new parts with the ones you took out, and visualize what has to happen with the transmission arms to get the correct positioning, that might answer your question. If the offset on the new part from the center of the wiper arm to the pivot is shorter than the original, the wiper will travel a wider arc than originally, you would need to compensate for this, possibly at the bellcrank on the motor.
#12
Melting Slicks
Thread Starter
Having never done this mod, I can't advise you directly. But, if you compare the new parts with the ones you took out, and visualize what has to happen with the transmission arms to get the correct positioning, that might answer your question. If the offset on the new part from the center of the wiper arm to the pivot is shorter than the original, the wiper will travel a wider arc than originally, you would need to compensate for this, possibly at the bellcrank on the motor.
GM lists this part for 84 - 96 Corvettes (among others), so there is no newer part...
#13
Drifting
Rich, I just went back and reread your entire thread, and looked at the link to the replacement. It occurs to me that it seems odd that one side works correctly, and the other does not. Apparently, the motor bellcrank is correct.
Question- when the wipers are operating, on a wet windshield, is the driver's side arc correct at the inner end? In other words, does it go far enough toward the bottom of the windshield? Possibly you could look at another car to compare.
Question- when the wipers are operating, on a wet windshield, is the driver's side arc correct at the inner end? In other words, does it go far enough toward the bottom of the windshield? Possibly you could look at another car to compare.
#14
Slingshot
Here is a good how to write-up on adjusting your wipers on a C4 Corvette. When the arm swing is adjusted properly, you should be able to place your thumb at the first knuckle on the edge of the A-pillar and the blade should not touch your thumb.
Try adjusting the driver side are first and then see how the sweep is. Let us know how this initial adjustment works.
Try adjusting the driver side are first and then see how the sweep is. Let us know how this initial adjustment works.
#15
Melting Slicks
Thread Starter
OK, I had a chance to work on the wipers today...There was a comment above about moving the arms on the splines to adjust them...My 86 wiper gearboxes (and the 95 - 96 arms) are splined and keyed...The arms will only go on in one position...
I took the leaf screen off to get at & see everything...Here's the adjustment nuts for the wiper arms...
And here's the pic of my initial setup...You can see that the arms do not quite touch the stops when parked (red circle)...
So, I adjusted them per the instructions provided by the members here (Thank You!)...Both the PDF and the 92 FSM instructions (which are basically the same)...
Looking at things before adjusting anything, I see that when I initially adjusted the 95 - 96 wipers, I did not go "to a position slightly below the blade stops"...I went to the stop only...So this time I went below the stop...
Trying it out, the driver wiper blade now goes right up to the windshield molding...just kisses it...and in park position, the blade is pressing against the stop...I adjusted the passenger blade so it doesn't hit or interfere with the drivers blade...No real difference in sweep there...
It's better...Still not right, but closer...
One note: The yellow circles indicate the ramps which are supposed to lift the blades off the windshield glass when parked...They don't...There is still adjustment available, but the ramps are right up against the glass, so they can't be adjusted any more...I suppose that means the windshield was replaced, and positioned a bit too low...So the ramps don't lift the wipers...I'm thinking of cutting some plastic shims to fit under the ramps to get them to lift the blades when parked...
I still think the motor arm/bellcrank needs to be shortened a bit...Not much; maybe 1/32" or 1/16"...Since I have a spare, I may try that...
I took the leaf screen off to get at & see everything...Here's the adjustment nuts for the wiper arms...
And here's the pic of my initial setup...You can see that the arms do not quite touch the stops when parked (red circle)...
So, I adjusted them per the instructions provided by the members here (Thank You!)...Both the PDF and the 92 FSM instructions (which are basically the same)...
Looking at things before adjusting anything, I see that when I initially adjusted the 95 - 96 wipers, I did not go "to a position slightly below the blade stops"...I went to the stop only...So this time I went below the stop...
Trying it out, the driver wiper blade now goes right up to the windshield molding...just kisses it...and in park position, the blade is pressing against the stop...I adjusted the passenger blade so it doesn't hit or interfere with the drivers blade...No real difference in sweep there...
It's better...Still not right, but closer...
One note: The yellow circles indicate the ramps which are supposed to lift the blades off the windshield glass when parked...They don't...There is still adjustment available, but the ramps are right up against the glass, so they can't be adjusted any more...I suppose that means the windshield was replaced, and positioned a bit too low...So the ramps don't lift the wipers...I'm thinking of cutting some plastic shims to fit under the ramps to get them to lift the blades when parked...
I still think the motor arm/bellcrank needs to be shortened a bit...Not much; maybe 1/32" or 1/16"...Since I have a spare, I may try that...
#16
Slingshot
OK, I had a chance to work on the wipers today... I took the leaf screen off to get at & see everything. So, I adjusted them per the instructions provided by the members here (Thank You!)...Both the PDF and the 92 FSM instructions (which are basically the same)...
Looking at things before adjusting anything, I see that when I initially adjusted the 95 - 96 wipers, I did not go "to a position slightly below the blade stops"...I went to the stop only...So this time I went below the stop...
Trying it out, the driver wiper blade now goes right up to the windshield molding...just kisses it...and in park position, the blade is pressing against the stop...I adjusted the passenger blade so it doesn't hit or interfere with the drivers blade...No real difference in sweep there...
It's better...Still not right, but closer...
Looking at things before adjusting anything, I see that when I initially adjusted the 95 - 96 wipers, I did not go "to a position slightly below the blade stops"...I went to the stop only...So this time I went below the stop...
Trying it out, the driver wiper blade now goes right up to the windshield molding...just kisses it...and in park position, the blade is pressing against the stop...I adjusted the passenger blade so it doesn't hit or interfere with the drivers blade...No real difference in sweep there...
It's better...Still not right, but closer...
#17
Melting Slicks
Thread Starter
I could bend the stops back farther...They're only metal strips...That would allow the blades to go down more...But then the blades would be below/off the windshield glass...If the ramps were working properly, that wouldn't matter, because the blades would be up & off the glass already...
Last edited by Rich B.; 12-13-2011 at 06:44 PM.
#18
Drifting
What happens then is that the blade presses against the stop...quite a bit of pressure...It is all mechanical linkage...
I could bend the stops back farther...They're only metal strips...That would allow the blades to go down more...But then the blades would be below/off the windshield glass...If the ramps were working properly, that wouldn't matter, because the blades would be up & off the glass already...
I could bend the stops back farther...They're only metal strips...That would allow the blades to go down more...But then the blades would be below/off the windshield glass...If the ramps were working properly, that wouldn't matter, because the blades would be up & off the glass already...
Sorry for the iffy picture quality, the product of a dark garage, slow shutter speed, and shaky photographer.
#19
Slingshot
If you are not particularily interested in meeting NCRS or factory standards, you can make the adjustment so that the wiper blade stops just short of the window trim edge. As long as it does not hit the window molding while on the high speed setting, you will be ok. It the blade hits the molding you will eventually damage both the molding and the wiper blade.
FWIW.
P.
#20
Le Mans Master
Any success with getting this resolved?
I adjusted mine per the FSM - and at speeds of 50mph or less, approximately, the blade does not contact the molding. However, the faster I go, the farther out the blades are pushed, leading to a significant overshot of the molding. I wonder if there's something worn in the linkage, which would allow higher speeds to cause the blades to be pushed outwards.
I adjusted mine per the FSM - and at speeds of 50mph or less, approximately, the blade does not contact the molding. However, the faster I go, the farther out the blades are pushed, leading to a significant overshot of the molding. I wonder if there's something worn in the linkage, which would allow higher speeds to cause the blades to be pushed outwards.