View Full Version : Windshield Wipers-Wiper Arm Slipping

11-25-2009, 08:12 PM
Has anyone experienced stripped wiper arm splines where the arm connects to the car? One of my wipers is doing that, only problem is that the splines are so fine its hard to tell which part is stripped out. Thought about drilling a small hole where the two connect and tapping in some threads and screwing in a set screw to hold it in place. Got to be a better way. Any suggestions?

Mad Scientist
11-25-2009, 08:53 PM
deleted double post

Mad Scientist
11-25-2009, 08:54 PM
Put the good arm on the bad side. If it fits and does not slip then it is the arm that is bad.

Hopefully it is the arm that's striped, cause you really do not want to have to change the drive.

From my experience with my MG a set screw will not hold the torque. You would need to drill through both parts and pin then together. Of course you might find that they used a tough steel that does not want to be drilled. :(

11-25-2009, 10:01 PM
Well, I tried to take the other arm off, but it refuses to budge. I don't want to force it, then I'll probably wind up with two screwed up arms. But yes I was planning on drilling into the drive and tapping both the wiper arm and the drive at the same time. Im not planning on drilling all the way through, just deep enough to maybe put a 1/4 inch long set screw in and screw it tight.I'll let the set screw act as a pin.

Barry Wolk
11-25-2009, 10:14 PM
You're better off drilling all the way through the shaft and into the other side of the arm. You'll then be distributing the torque over two contact points.

You don't want to have to restring the wiper cable if you don't have to.

Is the fluted shaft straight or tapered?

11-25-2009, 10:49 PM
It is a straight shaft. How about if I drill all the way through as you suggest, and tap in a roll pin. those usually fit pretty snug. No need for making any threads.

Barry Wolk
11-25-2009, 10:56 PM
I don't know about beating on that shaft to drive a roll pin. A socket-head stainless steel cap screw is a far less violent installation. It wouldn't even show if you put it on the bottom of the parked wiper.

11-25-2009, 11:14 PM
So then were still talkin tapping in a set of threads. Sounds less painfull. Kind of worried about the size the head of the cap screw.

Barry Wolk
11-26-2009, 08:33 AM
I'm talking about the rounded head screws. They're pretty small. I would think that a 10-32 would do it.

Roger Zimmermann
11-26-2009, 11:11 AM
Is the shaft hardened steel? If yes, you will have trouble to bore it. To be sure, try with a file. If it bite, it's mild steel. If the file is sleeping on the shaft, you have to search for another solution.

Chuck Lutz
11-26-2009, 12:20 PM
This might not be a concourse fix but I'd first try some .005 brass shim stock. It's sold in small rolls in hardware stores. A small strip around the shaft then the arm tapped on to the shaft. With luck the brass will conform to the splines and take up any slop.
IMO, If I could have the parts in a drill press and a fixture... no problem but hand drilling bent over the hood with any accuracy.. I don't think so. Don't forget that a 10-32 clearance hole would be about .172. That's a lot of meat off that shaft. Again, I make the claim that the SS fasteners which are produced in 18-8 stainless steel are softer than steel. Not that they would necessarily shear off but it important to remember. The other SS alloys are stronger than steel but not the screws.

11-26-2009, 12:44 PM
Well I think the 10-32 screw with the rounded head might be the easiest solution provided that its a soft metal. Even if its a hard metal, a good quality bit should do. Probably start small and work my way up. Is their that much torque where I should worry about the screw shearing? I wonder if there is such a thing as grade 8 screws?

Roger Zimmermann
11-26-2009, 01:15 PM
Even if its a hard metal, a good quality bit should do.
I don't think so. The bit will be just as hard as the part...No good. Maybe with a bit for hardened steel can do the job, but not on the car.
Of course, you have first to determine if it's hard or soft.

Barry Wolk
11-26-2009, 02:34 PM
Due to the location and the angle I see no problem doing it on the car. I also see no problem with shear strength. The only problem I foresee is getting the drill chuck close enough to the windshield. An air drill would work well.

The key to drilling hardened metal and stainless steel is sharp bits and slow speeds with even pressure. The slower the better. Yes, starting with a smaller bit always works well. If you have a compressor it might be a good idea to blow air in the bit tip as you're drilling.

I would drill the tap side hole almost all the way through the arm, then tap to the fullest depth. This will give you the strongest connection as nothing can move if it's threaded through the stem.

I have some spare parts from my '68 Lincoln. I'll see of I can drill through the shaft.

The brass foil idea has some merit, but I'd be concerned about hammering the arm on.

I'll look closer when I get to the shop tomorrow but I believe that the arm under the stainless cover is the sacrificial part. Why not just buy a new arm?

Chuck Lutz
11-26-2009, 05:15 PM
The key to drilling hardened metal and stainless steel is sharp bits and slow speeds with even pressure. The slower the better. Yes, starting with a smaller bit always works well.

Yes.. all that and don't forget plenty of spray lube like Chemtool or at least WD40.

11-26-2009, 05:23 PM
The reason I don't buy a new arm is because its hard to tell which splines are bad. The splines are very fine to begin with so it makes it difficult to see which ones are bad. My eyes ain't the best. Hate to buy a new arm and find out its not the arm. I think will stick with the drilling. Sounds like my best bet.

Mad Scientist
11-27-2009, 09:21 PM
I would be a little concerned about using a 10-32 screw. My gut feeling is that the diameter of a 10-32 (.190) would be getting close to the diameter of the portion of the shaft that is in the splined section and that this might weaken it to much. I would use a #8 or even a 6-32 (.136) but I would definitely use grade 8 hardware. There is a lot more torque there then you might imagine.

Also I donít think I would try to tap this, just drill all the way through and put a nut on the bottom. My concern is assuming that this spline is going to be at least relatively tough steel it is not going to be easy to tap plus it will be awkward to get at and have a tendency to turn.
And the very last thing you would want to do is break a tap in it. :(

11-27-2009, 10:12 PM
Sounds like a good idea.I think I'd use a 6-32 screw. It would be easier to drill. the smaller the screw, the less noticeable.

Barry Wolk
11-28-2009, 11:51 AM
You guys are way overthinking this problem. The first picture is my Mark II but the wiper knob I experimented on is from my '68 limo.


The chrome arm is a zinc casting, very easy to drill. The knurled knob is also a zinc casting that's been pressed onto a mild steel shaft.

I used an 1/8" drill bit, initially. It walked right through the knurl and bit right into the center shaft leaving metal curls like mild steel. No lubricant was necessary. Just a sharp bit and slow speed.


I then drilled out the hole to a #29 bit for 8-32 tapping. I chucked my tap into my screw gun fairly loosely on slow speed, ran it in and out and tapped the hole in no time.


I would still use a stainless fastener. A through hole is not a bad idea as removal of a sheared threaded screw would be tough. I would start with a 6-32. If that sheared it would be absolutely no big deal to bore the hole to fit a 8-32 screw.

Mad, I don't think there's as much torque as you might think. Even a new vacuum motor is deficient compared to an electric motor. The clutch in the wire winding would slip long before shear would happen. It probably won't be used in heavy snow, so the worst condition it would face would be a dry windshield.

Mad Scientist
11-28-2009, 12:42 PM
That the wiper arm is a casting and easy to drill does not surprise me. But I am sort of surprised the splined shaft is not hardened. :confused: Your right regarding the torque I was thinking an electric motor not a vacuum one.

However there is no clutch in the cable assembly. I had my center drum out to replace a worn bushing, it is now a ball bearing:D, and the only clutching action there is if the cable locking clamp were to slip.

Unless you happen to have the dash all torn apart this is an assembly that you donít really want to have to play with.

Barry Wolk
11-28-2009, 01:08 PM
When I say clutch I mean "tensioner". As the arms of the wipers can be moved independently the slippage in the cabling would protect the fastener from shearing.

And yes, you do not want to have to restring the cable that drives the wipers. Schematics do little good as you're typically looking at the mechanism upside down.

Mad Scientist
11-28-2009, 04:44 PM
And yes, you do not want to have to restring the cable that drives the wipers. Schematics do little good as you're typically looking at the mechanism upside down.

Before disassembly I took many pictures, put masking tape flags on the cable ends to identify them. Still when you get under there everything looks upside down and backwards. :eek::):)

11-28-2009, 05:56 PM
OK. once and for all, I'm going to drill and tap all the way through for a 6-32 screw.

Barry Wolk
11-28-2009, 06:03 PM
No, he's right. Drill a clearance hole for a 6-32 and put a stainless Nyloc on the other side. The threads could seize while a clearance hole will not. Also, should the 6-32 shear it will be very difficult to get out while the slug would simply drift out of a clearance hole. I'm convinced that that's the way to do it.

11-28-2009, 07:14 PM
OK, drill a clearance hole big enough for a 6-32 screw and lock nut.

Barry Wolk
11-28-2009, 07:16 PM
Yes, If that shears you can always go bigger.

11-28-2009, 07:31 PM
consider it done!!!

Mad Scientist
11-28-2009, 11:07 PM
9/64 dia. (.140) should do it.

Keith W Colonna
11-29-2009, 10:36 PM
How many of us REALLY drive our MKII's in the rain and use the wipers regularly???. So the repair of this function is to put it into minimum service....not to withstand a downpour. If I had this problem, I would use an adhesive, or lab metal...JB weld, etc. All can be removed if needed with a butane hot air miniature torch. I would also use Rain-X on the windshield which also helps rain to roll off.

Barry Wolk
11-29-2009, 10:40 PM
I have driven my car in an absolute 3 hour downpour on the way to a show in Ohio. Believe me, they got quite a workout.

I don't know about glueing them on.:confused: