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Discussion Starter · #1 ·
A rainy and unusually cold May weekend provided an opportunity for me to work on one of those low-priority projects that I've been wanting to do for a long time. Namely, to figure out a way to use YJ windshield wipers on my CJ. Which I did and will now describe, with apologies that it is so wordy, but there are various fiddly bits that fit together in odd ways and I want to be as clear as possible about what I did and how. That said, this hack turned out to be pretty straightforward once I got my head around it.


First, a little terminology. I don't know the proper names for some of these parts, so here's what I'm calling them:



The wiper arm is the whole assembly, consisting of the upper arm, which is composed of a flattened solid bar attached to a sheet metal shell, and a base which looks like an aluminum casting. The upper arm and base hinge together around a pivot pin which fits through a (brass?) bushing which in turn rests in a hole through the base. A tensioning spring attaches to the upper arm and base. There is a permanently-attached tab where the spring attaches to the upper arm; the spring attaches to the base by means of what I'll call the J-clip. The wiper blade attaches to the end of the upper arm, and the base fits over the (rotating) pivot post sticking out of the Jeep's hood/cowl area.


As everybody knows, but which I will summarize anyway, YJ wiper blades will not fit on CJ wiper arms. Neither will YJ wiper arms fit on the CJ pivot post, because the YJ pivot posts are larger. That leaves several options ranging from modifying CJ wiper arms to accept YJ blades to swapping out the mechanicals so YJ posts and wiper arms can be used.


I didn't want to get into welding or digging into the linkages, so I decided to find a way to build a workable and not-too-ugly Frankenstein wiper arm by fitting a YJ base onto a CJ upper arm. I had an old pair of CJ arms, so I pulled a couple of YJ arms off a dead Wrangler at the local boneyard and disassembled them for comparison. They are virtually identical in design with the YJ version being a scaled-up version the CJ one. As usual, nothing fits. The main problem with grafting them together is that the YJ upper arm is wider where it meets the base; likewise the CJ base is smaller (thinner) than the YJ one. The pivot pins are also of different diameter, with the YJ being thicker.


It was a simple matter to make the lower end of the YJ upper arm narrower by squeezing the upper arm shell in a vise until it approximated the width of the CJ base. I had thought to re-use the original pivot pins, but because I had to grind them down to remove them there was not enough material left to re-swage them. I had thought there would be, but it turned out that the ends of the pivot pins (both versions) are of smaller diameter than the main part of the shaft, so that wouldn't work.


I thought about using some solid aluminum bars or tubes to make new pins, but needed something with a snug fit to eliminate side-to-side play between the upper arm and the base. I searched the local hardware stores and hobby shops (model railroading shops have a ton of useful stuff for fabricating) but it was Goldilocks.


I decided I'd just try a bolt and nut, and went back to Lowe's to see what I could find. I decided that I wanted a socket cap machine screw with a fine thread, preferably stainless.



8-32 was too thin, but 10-32 was just a hair too thick. It would be simple to enlarge the pivot pin holes in the YJ arm shell, and I figured I could find a way to open up the bushing since it was brass and should be fairly easy to work.

I was back in my shop messing around with all this when I realized I had a tap-and-die set sitting in a drawer somewhere, and I could just cut 10-32 threads through the bushing. That would solve several issues, such as centering the improvised pivot post within the YJ arm shell and tightening it properly, and by threading the screw into the bushing the concern of wear to the bushing by the screw's threads is eliminated.


To sum up, it worked perfectly.



I enlarged the pivot pin holes in the YJ shell using a simple reamer.


Cutting the threads through the bushing was very easy because of the soft material. (Note: it was very important to make sure those threads were really clean so the screw would thread all the way through with very little resistance. If the screw were to bind up during assembly, it would be very difficult to keep the bushing from turning with the screw.)


I used a few #8 washers here and there as spacers, then threaded on the nut and tightened it up until snug. Because the bushing is slightly longer than the base is wide, the upper arm still moves freely on the base.


Finally, and this was probably the hardest part, is attaching the tensioning spring. One end of the spring fits through a tab attached to the upper arm almost at the end of the bar, but the other end is the tricky bit. I don't know why automotive engineers always find a way to make things unnecessarily complicated and hard to work on, but the other end of the spring attaches to a flat J-clip which in turn attaches to the pivot pin. That spring is not very big, but factor in the constrained space, the lack of leverage and the fact that you're using a pointy hooked tool to stretch the spring by main force, and it is hard to do. (Thankfully the J-clip has two holes in it, one for the spring and one for your tool.) Be sure you keep your free hand well out of the way so you don't tear it open with whatever you're using to get purchase on the J-clip.

After that it was simply a matter of fitting the new hybrid wiper arm to the Jeep, which went on exactly like the originals.

Problem solved, total work time a couple of hours, including thinking, pondering and fiddling, but not counting trips to find workable parts.


Pictures to follow...
 

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Discussion Starter · #2 ·
I tried to take pictures of what I did, but some of it was really hard to photograph because my hands were both occupied or I was figuring it out as I went along and didn't realize I should have taken a picture.

The difference in appearance is pretty dramatic.

Speaking of appearance, I'll test this for awhile and modify if necessary.
Once I'm comfortable that it works, I'm going to replace the nylon locking nuts with acorn nuts, and of course, sand and paint the shells.
 

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Discussion Starter · #5 ·
I had to use what I could find, and this was kind of a process of figuring out how to do it. Call it prototyping, to use a fancy word for trial-and-error. :laugh2:



Now that I know it works, I'll probably go pull another pair of YJ wipers and do it again, taking more care about appearance.


That's when I'll go to Fastenal or the local Bolt & Screw and get some nice-looking hardware. I'd even thought about using pop-rivets but couldn't find any with enough reach.
 

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I purchased a quality set of Trico wiper blades and have been quit happy with how they work. Do the YJ blades do anything the CJ blades do not other than being easier to find? You can order almost anything from Amazon now days.
 

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Discussion Starter · #11 ·
I purchased a quality set of Trico wiper blades and have been quit happy with how they work. Do the YJ blades do anything the CJ blades do not other than being easier to find? You can order almost anything from Amazon now days.
Well they are wipers; it's not like they'll bring in the evening paper, make you a Martini or massage your feet...

But the YJ wiper is more robust (more rubber means the blade won't tear away from the wiper body as easily), mounts more securely on the wiper arm, is both wider and longer (up to 13"), is available from more brands in different versions, and has a stronger tension spring so the wiper bears down harder and won't blow away from the windshield.

But that's about it.

.
 

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I like the write-up. Nothing wrong with improving something like wipers. Would be nice to find a good fix for the CJ pivot posts. I like the idea of having more tension on the blade and a better selection of blades to choose from.
Shawn
 

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The arms/blades on my CJ-7 get blown around on the freeway. One is different than the other, and falls apart easily. This is definitely something I’ll be looking into. Thanks for posting your little experiment.
 
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