Wiper Arm scratching Bonnet with correct Wiper Blades

[Heineken]

Since I bought my NSX in 2015, there were deep scratch marks on the underside of the bonnet:

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After an online search I came to the conclusion that the wrong type of wipers are fitted - unfortunately that seems not to be the case since the arm touches the bonnet even without a wiper attached and even the black bolt rubs against the bonnet:

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Today I disassembled the wiper mechanics and could confirm "some" play in the bushing of the affected wiper but I'm unsure if that's really the case? Are there are other more likely cases?

[Heineken]

The distance from hood to glass is ~40 mm which is quite a tight fit for the wiper arm.
Created a video that shows the amount of deflection:


https://youtu.be/QNfGXz0Oq1I

The main question: Is that excessive play?

PS: The wiper arm shaft seems to run in bronze bearings but I'm not aware of any replacements being available.

[wixer]

Mines the same but I haven't investigated why it rubs.

[britlude]

Undo the wiper arm nut, press the 'elbow' sprung hinge on the wiper arm toward the screen, it'll probably move an inch, retighten nut.

The spring in the arm stops the spline seating properly, so it leaves the arm at an angle to the mounting spindle, and will touch the bonnet.

Been there, worked that one out...... :)

Wipers make no difference as the pivot point is outboard of the bonnet anyway, you can lift the wiper blades inches off the screen and the arms still won't touch the bonnet

[Heineken]

That one I'll try out - It's already further away from the bonnet since I re-installed the wiper arm - that fits your experience!

[Heineken]

Holding the arm down while tightening creates sufficient clearance but this might be related to the fact that several mm of bonnet was already scraped away ..

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I'm tending towards explaining the issue in both wear and a wrong mounting of the wiper arm - guess I'll be off to get an new wiper assembly.

[Old guy]

This is the end of the wiper assembly that appears to be suffering from the excess play (not my car)??

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I looks like the pivot shaft of the wiper arm rides right in the frame of the Link (Honda's name for the assembly) which appears to be an aluminum alloy of some sort. Honda has conveniently provided a circlip to allow removal of the shaft. It should be relatively easy to remove the shaft and measure the ID and shaft OD to determine if you have what appears to be excessive clearance. I expect that all the wear will be in the aluminum and it might not be too difficult to have a bronze bushing fabricated and inserted into the frame of the link after it is bored out to fit.

You are fortunate in that the Link is still available from Amayama for RHD cars. The link for LHD is discontinued so this would actually be a bigger potential issue for North American and EU owners. Perhaps less of an issue for me because the wipers have probably been operated a total of 20 minutes in the last 10 years.

If you can figure out how to fix an NSX head unit I figure this should be a trivial exercise for you .

[Heineken]

Well, it's different from Electronics :D
Already had a look inside the bearing and found two bronze bushings pushed into the Aluminium. Unless the pivot is worn too much it should be sufficient to replace those - don't ask me how to get them out, acquire new ones an re-install them though ..

[Kaz-kzukNA1]

Could you take a photo of the both existing wiper blades ideally removed from the wiper arm and the rubber in the air without touching anything?

I mean the entire blade including the pantograph mechanism, wing, rubber and not just the wiper rubber.

Also, what is the rubber length?

From your signature, I believe you have JDM NSX.


Kaz

[Heineken]

It's a 1997 JDM, correct. The rubber length is 55 mm on both arms.



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Driver Side with Spoiler


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Passenger Side





Sorry for the pictures not being very professional ..

[Heineken]

Here are two more pictures (click to enlarge):




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Driver Side


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Passenger Side

[Kaz-kzukNA1]

Hi, Heineken.

Thank you for the extra photo.
That is exactly what I wanted to check and the reason why I asked to take the photo with the rubber blade in the air without touching anything.

On JDM, the blade length is 550mm long whereas the European replacement ones (driver & passenger) are 500mm even for the UK RHD spec.

With the OEM RHD 550mm wiper blade, the rubber section would stay in straight line for the driver side when placed in the air without touching anything, just like in your 1st photo above.
At the passenger side, due to the angle of the wiper blade against the curve/R of the 3D windshield, the rubber blade is on purposely curved by the two silver metal inserts, again, just like in your photo.

So, you are indeed using the OEM wiper blade set.


I looked into the issue of passenger side wiper arm scratching against the bonnet well over 10 years ago and thus, need to refresh my memory so some of the info could be dated or even wrong so please take that into consideration.





https://lh3.googleusercontent.com/pw/AM-JKLUQ0xBdO8art5jao-cDT2v_5nz0qhMBdbwFjbfeZKGzkGhQxIkr__i71E_dVKYqGTw5 Ya9Jv_NOYXZfH_YhevHIPOpjgJNV9m7ucV39myo1xEi1xv6J9y KUJdUqBbTVK4giKDG6IbnnYA-CXsBBWF1D5A=w1080-h810-no?authuser=0
Tried to find some photo but at that time, I was focusing more on the lower windshield visor (or whatever it's called) held by the multiple yellow clips so couldn't find suitable one.
Based on your video, looks like you already have good access to the wiper motor/linkage assy so hope you can understand my poor explanation below.

By the way, I was about to say not to try removing the wiper motor assy without first getting hold of the extra spare yellow clips.
Though, in your video, somehow you managed to remove the meshed plastic cowl/tray without first removing the lower metal visor unless you just placed it back.

Anyway, as Old guy mentioned in post no.7, the passenger wiper arm is operated through the linkage with a shaft passing through the wiper motor/linkage assy.
It's long and just below the black plastic sleeve #6 in the diagram.

The bottom side of this shaft is indeed held by the E-clip/circlip as Old guy mentioned.
There are also a metal washer and o-ring to prevent the moisture getting inside.

At the other side where the shaft meets the short metal link (protected by plastic cover #6) sits, there are a spring washer pressing against another metal washer with the o-ring behind.

There is a different metal material bushing (what Old guy called as bronze bushing) pressed into the aluminium alloy wiper motor/linkage assy where the shaft rotates.
If I remember correctly, just like the CL release bearing, there is a single slit inside the metal bushing to trap the grease.

Because of the spring washer, I can see you would get small vertical play along the shaft axis but should be very limited sideway movement around the shaft considering the shaft length unless the metal bushing was heavily worn.

What I found interesting at that time was the way Honda installed this whole assy.

On the right side chassis frame near right front wing/fender, there are two notches/pins sticking out horizontally (2 x blue arrow).
At one end of the wiper motor/linkage assy, there are two rubber cushion grommets (2 x #3) mounted at the blue dots.
The two pins are inserted into these two rubber cushions at the blue dots and no fixing bolts/nuts involved.


Addition to these, Honda used further three rubber cushion (3 x #4) with the metal collar inserted to each cushion (3 x #5).
They are mounted at the red and yellow dots.

At the two red dots, the washer bolt (2 x #21) was used to squash the rubber grommet down against the chassis frame.

Due to the design of the linkage, you can't access the rubber grommet hole from above at the yellow dot location.
Thus, no bolt used there and the rubber grommet + the metal collar just sits against the chassis frame.
I would say almost all NSX that I removed the meshed cowl/tray showed scratch marking there as the metal collar was touching the painted surface. Some even had rust there.

The use of rubber mounting is nothing new around the wiper motor and most of the cars are using it.

As a side note, with the engine at the back on our NSX, the thermal shock condition seemed to be in much better condition compared to other ordinary production cars with the engine under the front bonnet/hood.

Quite often on other cars with the engine at the front, you would see the white plastic holder ( the dome shaped parts, opposite to the rubber seal parts #8) at the ball joint of the linkage cracked/worn causing big play or noise.
Never seen on our NSX.

However, with the age and the heat cycle, the rubber cushion #3 and #4 hardened and took set allowing some play around two pins (2 x blue arrow) and reduced torque at two bolts (2 x #21) at the two red dots.

The ID of the metal collar #5 is much larger than the body diameter of the washer bolt #21.

Thus, over many years, the entire wiper motor/linkage assy can shift and even change its alignment against the chassis frame.

Similar to the reason why we should not use the cheap jubilee clip on OEM EPDM rubber coolant hose.
Instead, should use either the OEM hose band or invest in the high quality jubilee clip.


When you use the aftermarket wiper blade that raises the wiper arm slightly, it should not cause this 'scratch' issue because the actual pivot is behind/below where the wiper arm scratches against the back of the bonnet.

However, my observation was that the increased height of the wiper arm would increase the spring tension of both the driver and passenger wiper arm towards the motor/linkage assy.
Also, the force would change during the wiper operation.

With this increased force and because of the way the wiper motor/linkage was mounted as described above and the diameter difference between the metal collar #5 and washer bolt #21, the entire assy can tilt or even shift once the rubber cushion loses its plumpness.

I could be wrong but that was my view at that time as I only saw the scratch issue on NSX with the aftermarket wiper blade in use.
Not with the OEM one unless other factors played the role.
Some even showed immediate improvement by just replacing the wiper blade back to the OEM even without going through the heat cycle.


As stated at the beginning, your NSX is indeed using the OEM wiper blade.

However, at least the passenger side wiper arm was installed incorrectly.
This is likely to be one of the factor for the scratch issue even when you were using the OEM wiper blade.


So, there is still a chance that you may have bent wiper arm at the passenger side but since you already have good access to the wiper motor/linkage assy, I would first try replacing all of the rubber cushions (2 x #3, 3 x #4).
Don't know the latest price of the passenger wiper arm #16 but used to be not that expensive so may as well replace it any way.

In order to remove the wiper motor/linkage assy, you need to first remove the lower windshield visor held by lots of yellow clips before lifting/removing the plastic meshed cowl/tray so please get hold of the new yellow clips with extra spare as most likely, the locking tabs are dead by now and not recommended re-using them.


Kaz

[Heineken]

Thank you very much for the extensive information provided, I can confirm all mentioned aspects and will order the rubber bushings.

The yellow clips are an interesting topic. For the conversion to LHD traffic the OEM HID lights were removed, including the driver packs on the left hand side of the cowl area. This task was performed by the import company and obviously they disconnected all the yellow clips without replacing or even re-installing them properly - that's the reason why the cowl cover could be removed so easily ..

Some rubbers are on backorder and might take three months to be delivered but since it's almost winter it isn't that much of an issue.

[Heineken]

After as significant delay I was able to install the new rubber grommets and a new wiper arm. The old rubber parts were in OK condition and unfortunately, the situation is nearly unchanged.
Since this would rule out the rubber mounting points and the wiper arm being bent I'm back at excessive play at the passenger wiper arm bushing.
Looks like I'll need to order a new wiper assembly ..

[Heineken]

Since Japan Post has suspended air shipment and the part is too big for surface shipment I'll try my luck with a used part that showed up.

[Heineken]

The used item turned out to be a brand new part (note the more-or-less undisturbed grease at the end of the linkage arm):

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All that's required are the three motor mounting bolts and the piece that connects the motor drive shaft to the first linkage arm - all could be transferred from the old setup:

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Didn't have time to install everything yet but it should allow for a good analysis of the initial root cause :)

[Heineken]

Spent the evening in the garage to install the new wiper linkage and hoping this would resolve the issue but I was wrong and I'm out of ideas

The new linkage has less play than the old one (that's good) but not by a large margin (not so good).
The clearance (on an unscratched bonnet) I could create is just barely one or two milimeters which I don't consider sufficient (the arm was installed while being pushed to the glass):

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Another observation I made is the very small clearance between the wiper arm mounting shaft and the bonnet:

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When installing the arm and the domed nut, the clearance it's nearly zero. When slightly pushing the bonnet with one finger, it hits the domed nut:

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The only way I was able to obtain sufficient clearance at both the arm and the domed nut was to install the wiper arm linkage without the three metal sleeve rubber mounts and move the assembly as far away from the glass as possible.
Since this can't be the original intention from Honda I'm asking for advice how to continue .. does the bonnet settle over time?

[Heineken]

Checking with Andrew from NSX Prime: The clearance between the bonnet and the glass (is 40 mm but should be 45-50 mm) is too small and correspondingly affects the clearance between the domed nut and the bonnet (is 1 mm should be 5 mm).
Could someone in the forum check the clearance of the domed nut on their car?

Maybe my bonnet is simply too "flat" and does not leave enough space for the wiper linkage and arm. This could be due to manufacturing tolerances, the bonnet "sagging" over time or it's simply bent.
I checked if it's possible to bend the hood upwards (by hand) but it's way too sturdy.

Currently I'm wondering if it would be better trying to lower the linkage by modifying the mounting rubbers or getting the hood to a body shop .. what would be your suggestions?

[NSXGB]

I'd check mine for you but I have an aftermarket bonnet, so no good.
Is there any adjustment available in the height of the bonnet, without causing panel gap issues?

[Heineken]

According to the manual the hood height near the glass is controlled via shims at the bonnet hinge - but the hinge bolts are untouched. All the gaps and heights are flush.
Further down towards the front there are rubber stops and finally the hood lock. There seems to be no way to adjust the height without lifting everything up - but I'm having zero experience with such things.

[britlude]

here's a couple of pics of mine, tho the car is in the sun so made it tricky.... bonnet centre is about 45mm from screen (perpendicular)

looks like about 5mm from nut to bonnet
https://live.staticflickr.com/65535/52039586911_144ec226b9_c.jpg (https://flic.kr/p/2nhyua6)Nsx wiper clearance (https://flic.kr/p/2nhyua6) by NSX Jon (https://www.flickr.com/photos/152809076@N06/), on Flickr

and the arm clears the bonnet... you can see the gouge from previous owners not putting the arm on squarely....
https://live.staticflickr.com/65535/52039586896_42284d2dab_c.jpg (https://flic.kr/p/2nhyu9Q)Nsx wiper clearance (https://flic.kr/p/2nhyu9Q) by NSX Jon (https://www.flickr.com/photos/152809076@N06/), on Flickr

i can take some more pix at dusk, when i can see what i'm looking at, if need be

hope that helps

[Heineken]

Thanks Jonathan for the images - they are illustrating the point nicely!
This looks like exactly the 5 mm clearance I'm missing on my NSX - either my hood sits too low or the wiper linkage assembly too high ..

[Heineken]

Some more replies via e-mail and message services came in. All owners without the issue reported a distance from glass to centre of the bonnet of 50 mm. The reported clearance between the domed nut and the bonnet was 5 mm.
One driver from the Netherlands reported very similar issues with the domed nut hitting the bonnet and measured just 45 mm (glass to bonnet) - same as mine.

Interestingly the BWW 7 suffers from similar issues - both with worn bearings as well as *drum roll* a sagged/bent bonnet .. the official fix from the factory (performed at the dealer) is to bend the bonnet back into shape: https://www-7--forum-com.translate.goog/forum/showpost.html?p=906112&postcount=2&_x_tr_sch=http&_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp

[Heineken]

Since the issue with the scratching wiper arm and colliding domed nut more and more sounds like an issue with the bonnet, some more detailed measurements were made.
With the bonnet closed, the distance from the glass (at the edge of the visor) to the bottom of the bonnet is 40 mm:

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.. from the glass to the top of the bonnet: 45 mm:

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The values should be 45 and 50 mm, respectively, which gives a sufficient clearance of about 5 mm between the domed nut and the underside of the bonnet (like stated previously).

Now, contact to my local and experienced body shop was made. They stated that it's possible to bend the bonnet into shape but it's high effort and risk - they would only consider it as a very last resort.
While talking and explaining the situation, it was observed that the required clearance can be obtained without permanently bending the bonnet - hence the idea to support the bonnet from underneath in such a way that it's kept in a proper shape while being closed. For testing purposes, two improvised rubber mounts where put on the sheet metal holding the weather strip:

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(the rubber domes should probably be more close together)


After closing the hood, this resulted in a clearance of 43 and 48 mm - almost according to spec :)
The tricky part is how to combine this with the cowl cover and the weather strip - ideas are welcome.

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(not like this obviously)

[Heineken]

Update from the scratching wiper issue and a trip to the DIY store. Came back with this 25 mm rubber door stop:

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Can be installed on top of the weather strip, at the centre hole. The weather sealing strip easily moves around since it's no longer mounted to that position.

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A separate nut and bolt will be required to mount it, though.

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Obviously this interferes with the weather strip functionality as it opens a gap at the centre but this can be resolved by using a soft foam seal at the underside of the bonnet (if required).

I feel a little ashamed for opting for such a low tech solution but it creates a nice clearance of 45 and 50 mm - well according to spec - and the sides of the bonnet rose only very slightly. Maybe a rubber stop with less than 25 mm is sufficient as well, I'll give that a try during the next days, then the sides would rise even less :)

[NSXGB]

Thinking out loud, could it be that your foam seal has deteriorated and therefore sits lower?

[britlude]

i was going to suggest some stand offs to see if it helped :)

[Kaz-kzukNA1]

https://lh3.googleusercontent.com/pw/AM-JKLVKF6QqXW1_H0br7JTuldBtiwmjWpWSjy9TI6cXulXEj5BfB v7eT4CKOba83Gzb-oS7LP8SD8nREcmaHLclA7Pgj3Yjl2AKBKSpqpFlqSaysxMm9eO _-QnlC5zFHJukbnjmFF_8lil4W5Fj3M0byqVJJA=w1080-h810-no?authuser=0
Very interesting and thank you for sharing the findings.

In case someone experiences the same thing in the future, I'm going to post all the photos and the comments forwarded to Heineken.



My NSX is 94 JDM and I'm the only owner so I know all the history apart from when it was on the slow boat on the way to UK.

5mm centre punch on top of the fixing nut.
Can slide it left to right or back and forth so should be at least 5mm gap there as mentioned by others.





https://lh3.googleusercontent.com/pw/AM-JKLWzdWp1LNnvYVcmOv5M4N5r3F4FQI_PNEWfS_ZCrYNQmJ_6K qPGXBSIhXjkj8wBsC4l7iMkvTAaI3O52kztYAHA3tuNr_o2DUL D_LYrkizDSdFRqX2dvezPdE-D1WIX2xVQkdRHCiH_SQQ13LUuG2P_kw=w726-h1080-no?authuser=0
When placed the ruler at the centre of the windshield and right at the edge of the rubber piece of the lower visor,
the distance to the back of the bonnet/hood is about 45mm.

The bonnet itself is about 6mm thickness at this edge.



Discussed about the hinge fatigue, spacer and the alignment.

While there could be some shims behind the bonnet hinge, never heard of fatigue issue there.

However, I didn't inspect in detail so will check later.


I didn't pay much attention on the number of shims behind the hinge but don't think I have ever seen many of them sandwiched there for the alignment purpose.

On my NSX, there is none at both sides.





https://lh3.googleusercontent.com/pw/AM-JKLU5qLsEJEuE7vBKVXOrhUZ2WTuxEkPTMMcib67EeClT4M8XX jTQ6jBWqm77oc7xqwV6q_ZB1JPgXPU116AiqpzF5RaeMeNRhpQ jSuM58Yz4_7hKdRskNopmQDxyln700jjrMzWvcGMI_IhnwpXdx HccWA=w1080-h810-no?authuser=0

https://lh3.googleusercontent.com/pw/AM-JKLXXKi6REQqhYi0OZL6wmOKyjQ-LxYDTB_R93ti-tJFWZuho41cMkU1ERZZCf5WBInzPgOYagVQYpIUefwxkzx-oYGvjobpfrngxGVayrkB4ujosvxVdXic7R8fs5LoyNSb8TVYT0 mcIAT0xE4nDu9aLTg=w1080-h810-no?authuser=0
For the forward/aft alignment, Couldn't draw smooth line but the edge of the bonnet top should lead to the wing panel smoothly like in blue line.

By the way, my passenger side JDM spec wiper blade sits here.





https://lh3.googleusercontent.com/pw/AM-JKLWwoOxnzFPIs-kdtuOkRwBjYuZtTU4edw6rHFz5qC7eeujWkEtqKfiaN9RlDKWU Yi3Un6LI77OMxucNG_9-MXETqUoP0p77B63Ot4SkbpWyJe-7Sr6Z52_g3WgvYP2tdJOsi-KBaPqj5KdboCJmpqGq8A=w1080-h810-no?authuser=0
On the other hand, I'm aware that many owners experienced alignment issue of the boot lid panel.

It is caused by the fatigue and wear of the hinge bracket/assy.

If the cause is the same, it can be fixed by replacing it although the new one comes in just base coat grey paint so you will need to have it sprayed with matching body colour.


On my NSX, years ago, I started to notice that the right side forward section of the boot lid always sticks out higher just a bit compared to the right rear wing when closed.

Seems to be tiny play/wear around the hinge shaft/hole and due to pressure of the gas strut, it just pushes up.

Not sure you can see it in this photo but it's not flush to the wing panel.

I used to open/close the boot regularly when I was doing the grocery shopping every few days or week for months every year.

So, most likely the reason for the wear.


There is no gas strut at the front and I opened/closed the bonnet/hood so many times since new yet I never noticed panel alignment issue at the front, unlike the boot lid.

Will take a close look at the hinge later.


In the meantime, interesting that your solution can increase the gap fairly easily.

As we really don't have the specific reference point for the measurement, don't know where exactly causing your issue.


Still, learnt something new and made me wonder what was happening while I was applying enough force to remove the coating/polish from the bonnet panel.....


Kaz

[Heineken]

As promised, here's the update on the scratching wiper issue. Used the available time last Saturday to reinstall everything. The area under the cowl cover was cleaned and the new wiper arm linkage installed. During installing it was taken care that the unit's final position was as far away from the front window as possible, resulting in the lowest possible installation position and maximizing the distance to the hood.

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The cowl cover was attached with small washers since the company who removed the HID headlights broke all of the mounting tabs in the process.

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The visor was re-installed including new clips - even though they don't feel perfectly attached it's not worse than before and therefore considered sufficient.

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Both wiper arms were installed pushed down and the resulting clearance was according to spec (45 and 50 mm). Unfortunately, the hood was a little too high around the headlights. After shortening the rubber stopper from 25 to 20 mm this was no longer observed (or so minimal that it couldn't be recognized). The clearance reduced to 49 mm but still sufficient.

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So after about six months of tinkering, checking, discussing and spending close to 500 Euro in parts (new wiper arm, new linkage), the fix was a 1.15 Euro door stop, cut down from 25 to 20 mm .. ;)