rear wiper blade - not fully engaged

[dsdunbar]

Probably a silly topic but thought I'd ask.

My rear wiper blade does not make 100% contact with the window. The wiper is 16" long as I recall, and 4" at the "bottom" of the wiper touches the window and 2 to 3" at the top touch the window, but the middle section is arced away from the glass.

I replaced the wiper blade to see if it was the issue, and it wasn't. So I am guessing maybe the tension spring has elongated over the years to not supply enough "retracting" force to make the wiper lay flat.

I'm guessing my options are:
New wiper arm (Gowesty?)
Bend existing wiper arm
Modify spring (looked at the spring, think modification would be difficult for the benefit)
replace spring (not sure where a replacement exists)

Anyone else have a similar issue and what did you do?

Thanks in advance.
_________________
'89 2WD Westy "Grey Goose" - Manual 4spd
Crozet VA
Vanaru EJ25, Peloquin

[chase4food]

I am risking being called Captain Obvious.

Wiper blades is one of those things that pay more does not guarantee you get a better product. A lot of hypes, and some blades may not work well for our meek meek Vanagon of gentler design of yesteryears. I used to be very conservative when it comes to blade replacement. I would go to the dealer to buy the replacement inserts. That way I keep the original factory arms. Sometimes they came with the German stainless steel spines, and sometimes didn't. My experience was I get better wiper rubber consistently. Today, I am not sure.

Do avoid the retail blades that has plastic spines. The plastic spines do not slide well in the fingers of the blade holder and can cause what you see. Even with SS splines do check how well they slide on the arm fingers. I have seen smart shade tree mechanic decides the fingers are too sloppy and fixed them by crimped them tight with a pair of noodle nose pliers.

Today, I find the bottom end refills from the brandname generally not too bad. Walmart generally has adequate selections.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[bluebus86]

[chase4food]

I took some measurements using a digital fish scale at the pivot point of the wiper blade and you may find helpful. My 89 is in excellent shape and so are the wipers. I measured the spring force in oz perpendicular to the windshield. I took care to zero out the scale, as well as only lifting it a tiny amount.

2005 Mini Cooper:
front 18" blade = 27 oz
rear 11.5" blade = 18 oz

Vanagon:
front right blade 18" = 25.1 oz
front left blade 18" = 25.6 oz
rear blade 16" = 14.8 oz

you can see the rear arm on the Vanagon has less spring force even taking into account the shorter blades. I think is is normal as it fight less of aerodynamic lift. I should note that the Mini rear wiper is all plastic so is poorer in compliance to the contour of the glass curvature. Probably why it has pretty strong force compared to the Vanagon's rear.

Bending the arm don't necessary give you more spring force , without studying the over-center action of the design.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[chase4food]

I should add that compared to the much newer Mini's front wipers, the Vanagon's front is very comparable taking into account the difference in blade length. Hence it supports my inference that the spring force is likely not weaken much compared to when it is spanking new 26 years ago.

My experience and observation is import cars tend to have much lower spring force than American counterparts.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[bluebus86]

[chase4food]

Right! No need to work your brain too hard is definitely a word of wisdom.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[bluebus86]

[DwarfVader]

[chase4food]

I have no idea how much attention the OP paid to the wiper blade designs. Most European auto utilize the traditional blade design similar to that in the illustration here:

I am the first to admit when I first encounter wiper blade problem, it took a bit of careful study to realize how it all work. On this design only one end of the blade is held fixed - the side that has a locking barb (left hand side end). The rest of the blade floats in the remaining five fingers of the metal frame. There are two SS spines (only one shown here) that supports the rubber squeegee blade. It help support the span of the squeegee between the fingers to spread the force evenly. In some cheap blade a plastic stripe is used that eliminates the two SS spines altogether. These are shit blades to avoid.

Even with the typical ones you can buy like in the illustration above, some are worst than others. I always prefer to keep the factory frame unless they are worn or damaged.

While you can bend the arm to gain a bit of spring force, you have to bend it a lot to make a material difference, and it will be very unsightly. The right solution is to get to the bottom true cause(s) of the problem.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[kamzcab86]

Even Sir Bentley tells you to bend the arms if you're having contact issues.

For the record, here's my '90's rear wiper arm and it makes 100% blade contact:

_________________
~Kamz
1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子

[syncrodoka]

[dsdunbar]

Thanks all for the insight. I am appreciative of the very technical and the more "try this" approach. My concern with bending the wiper arm is not knowing how brittle the material might be.

I didn't even consider to check the Bentley.

Thanks.
_________________
'89 2WD Westy "Grey Goose" - Manual 4spd
Crozet VA
Vanaru EJ25, Peloquin

[chase4food]

Sir Bentley is always right, at least when it comes to direction wise. Bending the arm will increase the spring force F = xC where x is displacement, and C is spring constant. What is C is the key.

Risking prematurely wearing out my binary brain, I went and make some measurements. The scale wanting to do peak hold makes it more challenging, but I succeeded.

Lifting the blade just a bit but make sure no point of the blade make contact with the glass = 25 oz

Lifting the blade an inch higher = 26 oz

A whopping 4% increase if you willing to bend that much.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[bluebus86]

[kamzcab86]

[bluebus86]

[chase4food]

The posted excerpt from the Bentley is correcting the till (or perpendicularity) of the blade squeegee, not to increase the downward force and mentioned numerous times in this thread. The perpendicularity is very important.
_________________
- Vince 飲食玩睡

what Isolde wants Isolde doesn't always get, 4 I know what is best for her - Liebe macht frei

[bluebus86]

[chase4food]