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Thread: Wiper Blades

  1. #1
    DSC Off Gammaman's Avatar
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    Wiper Blades

    The stock wiper blades are 20.5 inches long. Anyone know if the 21" Bosch Icons will work, or do you have to go down to 20"? Thanks.

  2. #2
    I'd say get the longer ones, better half an inch spare than too short. Let us know how they fit, and if they are good upgrade.
    Andrew Macpherson

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  3. #3
    DSC Off Gammaman's Avatar
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    Will do. The clean lines of the Icon should look good, and even if they don't have as much downforce as the stock blades, for all the driving in the rain I do (only when I get caught) it should be a moot point.

  4. #4
    DSC Off Gammaman's Avatar
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    Here are the Icons. The extra 1/4 inch on each end doesn't seem to be a problem. The Bosch part # is 421A driver side, and 421B passenger side. Amazon had the best price, with free shipping.
     

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    It is normal for wiper blades to measure 1/2" shorter than their specified length, so if your blades measure 20.5" you should order 21" blades.

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    If that is so, then why doesn't Bosch list the 21" blade as being the correct fitment? They don't list any as being available for the Z8. I haven't actually measured the length of the Icons, but I'm not doubting you Grease Monkey, as you never seem to be wrong

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    DSC Off Gammaman's Avatar
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    I measured, and the actual length of the 21" Icons is 21".

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    Perhaps it's not a hard and fast rule, however, every wiper blade I've ever measured was roughly 1/2" shorter than a whole number dimension. Furthermore, in my experience, if you order a 21" wiper blade, it will measure 20.5". I have never seen an SAE or DIN standard for wiper blade length so it is certainly possible that your Icons measure 21" but can you confirm that you are measuring the contact surface and not the supporting frame? In any case, they should work just fine on your Z8. By the way, if you want to really have some fun, check this out:

    One of my favorite things about the Z8 is looking out over that voluptuous hood and watching the passing world dance in its curved surface (did the same thing in my 427 Cobra). Unfortunately, the stock wiper blades, with their bulky air foils, come to rest high up on the windshield and block a significant portion of that view (I'm 6'). So I decided to modify them.

    The process is relatively straight forward but you must be comfortable working with tools. The wiper arms are held on with nuts which are hidden beneath plastic caps. Pry off the caps, remove the nuts, then carefully pry up the wiper arm at its mounting point. It is a press fit so it will be stubborn (there are special "pullers" you can buy for this). You will notice that the wiper arm and the shaft it's mounted on are splined. If you reinstall the arm using a lower position on the splines, you will change the rest position of the wiper blades. The problem is, the wiper blades will now be at cockeyed angles to each other and their ends will hit the cowling. The solution is to change the existing curvature of the wiper arms. This is a trial and error process but what you are shooting for is to have the wiper blades sit closer to the bottom of the windshield when at rest and be parallel to each other. If you wrap the wiper arm in a cloth, you can gently bend the thin upper part in a vise until you achieve the correct geometry, without leaving any marks.

    At the same time, I replaced the bulky wiper blades with ones that are much thinner. I used the PIAA blades which are impregnated with silicone and leave a thin film on the windshield during wiping. This makes water bead up and stream off so the blades don't have to do as much work (sort of like using Rain-X). This is important since by eliminating the air-foils used on the stock wiper blades, you may get less downforce from your wiper blades at very high speeds. I have used the PIAAs in the rain, at high speeds, and they worked great. If you are uncomfortable undertaking the wiper arm mod, you can at least replace the wiper blades with less bulky ones which will improve your view.

    You should be aware that there are a few drawbacks to the wiper arm mod. Because the wipers sit much closer to the edge of the hood when at rest, you must not attempt to raise them with the hood shut or they will hit the edge and possibly chip the paint. This is particularly important if someone at a service station is cleaning your windshield. If you raise the hood, the wipers can be raised with no problem. The other thing is, because of the change in geometry, the blades will not wipe the outside edge of the windshield like they used to. The new wipe arc will start lower on the windshield and not go quite as far to the side. The change is relatively minor and you may not even notice it. The end result is a much cleaner look to the windshield and a substantially improved view out over that lovely hood.

  9. #9
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    OK, I measured exactly: 21 3/8" including the plastic end caps which are 3/8" each, thus the true length of the rubber is 20 5/8". GM, could you post a picture of your mod? Are you saying that when modified the wiper arms won't flip out with the hood down even when they are out at 90 degrees?

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    Unfortunately, my Z8 is at Dinan's getting more upgrades so I can't post a picture of the blade set-up. If you look at the pictures in the article Andrew did on my car for Roundel, you can get a pretty good idea of what I'm talking about. You'll notice that the wiper blades are essentially hidden. The only clearance issue occurs when the hood is closed and the wipers are in their resting position. If you try to lift them up to wipe the windshield, they can contact the upper edge of the hood. You can lift them enough to wipe the windshield, you just can't raise them into their cocked position. If you really want to raise them all the way, you can turn them on and shut off the key when they are at the top of their arc. Also, if you raise the hood, you can lift them all the way up. No big deal for the owner; just a worry in case someone who doesn't know about them tries to lift them aggressively with the hood down. For me, the improved view is more than worth the minor inconvenience and the lack of clutter on the windshield makes the car look swoopier. Coincidentally, the unmodified wipers on my X5 4.6is have the same problem: the passenger side wiper cannot be raised into its cocked position because it hits the upper edge of the hood when it is closed. So even the factory considers this limitation acceptable.

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    Even the standard wiper blades can't be fully lifted for cleaning the windshield when they are in the parked position; according to BMW you are supposed to activate the wipers and then turn off the key when they are at the top of the arc as you say. I, too, have the same problem in my X5 4.8is; fortunately if you forget to lower the wipers before you start up the car in their full sweep position they will remain there until you hit the wiper switch again, assuming you just hit the switch for a single sweep before turning off the key.

  12. #12
    GM, what are the upgrades that you're doing this time round?
    Andrew Macpherson

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    In order to remain competitive in the racing world, Dinan must continually find more power and reliability from his S62 motors. As a result, Steve asked me to return my Z8 so he could upgrade the motor to take advantage of what he has learned over the past year. One of those upgrades is to reconfigure the header tubes to allow an alternative gathering order. Another is a revised cam shaft profile. He is also considering switching to titanium intake valves which are considerably lighter than the previous version. I did provide him with a set of underdrive pulleys to free up a few ponies from parasitic drag and reduce the rpm requirements imposed on some of the auxiliary drive units, which he agreed to try. Steve said there are a few other tweaks he'd like to try but I can't reveal the details. At the same time, he is installing Michelin PS2s (265/35-19 and 285/35-19) combined with his newly discovered alignment settings which greatly improve their stability at high speeds. Of course, he is also working on an alternative strut tower brace for the Z8 and playing with a faster ratio steering rack. Suspension upgrades have been discussed but he may not have enough time to pursue them this time. I hope to pick her up soon so I will have more to report then. I have set up my X5 4.6is for towing and purchased a car hauling trailer which I plan to take to California to pick up my Z8. While I am there, Steve is going to install his supercharger kit on my X5 (451 HP and 439 lb/ft of torque) and has invited me to participate in the final tuning of the package. What fun! Once my baby is back home, I have 2 custom built, lightweight seats ready to install along with a 4 point harness. This Fall, Stop Tech's new carbon ceramic rotors will be available and I am in line to receive one of the first sets. These will eliminate another 10 lbs. of unsprung weight from each corner. They have also developed a 6 piston front caliper which I would like to install and Dave Zeckhausen is trying to convince them to engineer the necessary brackets. I have also discovered a new product which replaces the fixed spring perches on a coil-over set-up with hydraulic damped pivoting perches which eliminate the "stiction" problem associated with coil-overs on street cars. As a result, I may pursue a completely new suspension set-up for my Z8. Are we having fun yet?

  14. #14
    Wow, sounds simply superb, I can't wait to hear how it all evolves. I'm very interested to see the Dinan strut tower solution, and the e46 steering rack mod, I have a hunch that might be a total revelation. Please do keep us posted.

    I know it would be something everyone would enjoy if you started a thread for your car, and detailed the whole story, cataloging the changes and results of this wonderful project. I'd suggest putting it in the Z8 History part of the site, as this car is so unique, and it is also so well known. I have to make on more trip up to Monterey to set everything in stone for our August trip, so maybe I could swing by Dinan to photograph some of the new changes too.
    Andrew Macpherson

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  15. #15
    Z8 Ate My Homework! Norcal's Avatar
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    Please let me know when you come out to pick up your car. I'd love to meet you at Dinan, and check out the new upgrades.

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    Back on the wiper topic: I've been putting some miles on my recently purchased Z8, which has the stock wiper set-up, and was amazed at how much wind noise there was with the top up. Then I remembered that my other Z8 has the modified wiper set-up described above and is much quieter at speed, so I moved the wiper mod to the top of my list and after completing it, most of the noise is gone. I modified my other Z8 so long ago that I guess I'd forgotten about this benefit.

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    GM, do I understand you correctly that modifying the wipers has reduced the wind roar that we hear with the soft top up? This is the first Ive heard about this. Sounds like an excellent reason to do your mod. Is there any chance you can provide before and after sound level measurements near the driver's head at 55 MPH?

    Oops, I just noticed that the new car is already changed. Well, never mind.

    harvey2

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    Yes, I believe the wiper mod does reduce audible wind noise with soft top up or the hard top on. I also believe you would reduce audible wind noise on a Z8 just by changing to a wiper blade that doesn't have the air foil as part of its design. Whether the wiper mod is worth the effort depends on how much you are bothered by the noise and whether you are willing to live with a somewhat reduced wiper blade coverage area. My suggestion would be to replace the stock blades with PIAA blades and see if you notice the difference. If you want to go further, then just finish up with the arm mod. One more thing to consider if you decide to proceed: when you relocate the driver's side wiper arm to a lower position, it may contact the plastic cowling in the engine compartment. If so, you can just heat up the area with a heat gun or hair dryer and use gloved fingers or a rounded screw driver handle to create a small indentation in the area to provide sufficient clearance. It won't be visible when you're done. I'll try to post a picture of the modified wipers so you can see the difference it makes.