Rich B.

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

HlhnEast

Not sure about an internal adjustment but the wiper arm and pivot are splined so you can bump it a few splines til you get what you want.

Rich B.

Then I'd have to bump the passenger wiper also, which has a correct sweep & parks correctly...the driver wiper also parks correctly, it just goes too far past the pillar...

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...

sailorsteve

If the newer assembly is similar to the '92, I can quote the procedure for adjustment from the '92 FSM.

Rich B.

Steve, the crank & motor is still the older 86 parts; it's the arm & blade that is the 95 - 96 parts...and I don't see any other adjustable parts...Maybe I'm looking in the wrong place???

HlhnEast, are you sure about splines??? The Tech Tip says "The wiper arms are 'keyed' so they only go on one way. If the wiper arm position isn't satisfactory, you must adjust the linkage at the wiper motor." I think it's that linkage adjustment that I need...

BTW, it's been ~10 years since I did the swap...I can't recall if it had a key or splines...

sailorsteve

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.

Rich B.

Thanks Steve! That sounds right...I can see the clamps for the ball on the crank...

I'll give that a try...When it stops raining...

VetteMed

I swapped the 96 arms on to my 91, and have the same issue. I followed the adjustment procedure in the FSM and it didn't seem to help. I'm curious to hear your results.

sailorsteve

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.

Rich B.

I pulled the mesh screen off, and checked/adjusted my linkage...It was already set to the limit...

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???

sailorsteve

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.

Rich B.

Steve - The part I linked above 2215 5286 ARM, WSW M is the bellcrank...The slotted hole bolts to the motor shaft, the ball on the other end is where the wiper linkage fastens & adjustment is done...

GM lists this part for 84 - 96 Corvettes (among others), so there is no newer part...

sailorsteve

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.

pmihaltian

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.

Rich B.

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...

pmihaltian

If your driver's side blade is kissing to windshield molding, it is going too far. The blade should stop approximately 1" from the molding. You should re-adjust by loosening the adjustment nuts and moving the blade farther below the stop holder. This will allow the blade to stop well short of the window molding. You will have to fiddle with it to get it right.

Rich B.

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...

sailorsteve

FWIW, here is a photo of my wipers in park position. The sweep is correct, and notice that the left wiper does not even reach the metal stop. At this point, I don't have an answer for you.

Sorry for the iffy picture quality, the product of a dark garage, slow shutter speed, and shaky photographer.

pmihaltian

This IS the answer. While it seems like more pressure than you would normally like to have, this is what IS required to get the driver side wiper blade to stop approximately 3/4" - 1" from the windshield's outer trim edge.

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.

VetteMed

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.