Wheels

From Bondline

Introduction

The Cleveland wheels and brakes on the Grummans are divided into 2 groups with 2 different part numbers.

The early planes from 69-74 have the brake caliper with the smaller piston (30-55B) and a 40-86A Main wheel.

The later planes from 75 on have the brake caliper with the larger piston (30-56B) and a 40-88C Main wheel.

All the single engine Grummans use the part number nose wheel (40-77A).

A common problem on the 30+ year old wheels is CORROSION. The 70's production planes came with wheels that were painted silver on the outside, and had no paint or corrosion protection on the inside. Its not uncommon to take a wheel apart and find that under the excess grease slung into the inside is corrosion so severe as to render the part unusable.

Perhaps like THIS:

This wheel is unserviceable and had to be replaced at a cost of several hundred dollars

This happens from a lack of proper maintenance in 2 ways.

1. Too much grease is left on the wheel bearings when they are installed, and the excess is extruded into the hollow center of the wheel.
2. The wrong grease is used and the components of the grease, that cause the lubricant to gel, absorb moisture and when held against the bare metal inner surface of the wheel, cause corrosion to rapidly occur.

As a preventative measure, the wheels should be visually inspected at each annual for condition of the wheel and its data plate, the condition and proper torque of the hardware, and by looking through the axle hole with the bearing removed, the condition of the inside of the wheel. A strong light and some rags to wipe away any grease in the "corners" of the cast stiffeners will help identify areas of concern.

Wheel Bearings, Dust Seals, and Proper Installation

Greg Amy writes:

There are two different sizes of washers on the main wheels of all the single engine Grummans. The two larger ones (153-0400) are used on the inside bearing, while a single smaller one (153-0300) is used on the outer. I had paid close attention to how it was all installed, and it just didn't look right. Even after reading the Cleveland parts book I was still confused. After talking it over with Bob Steward I got it worked out.

A photo of a wheel to better describe the location, inside the outer wheel half.

I've had an ongoing discussion with my IA on some apparently-increasing damage on my wheels. There's a small lip on the inside of the outer wheel half, just above where the outer bearing race is; it's on this lip that the "C"-shaped felt seal retainer rides. Over the last couple of annuals we have been finding on my Tiger that this lip has been wearing significantly. Upon inspecting the order of installation of the parts it appeared that the outer washer/dust seal was wearing on that area. We inspected the washer and could not see how this wear could be avoided.

The affected area, about halfway down to the bearing race, below where the retaining ring seats. Notice the "cut ridge" where the too-large washer "threaded" itself into the magnesium. It's possible that this wheel can be reused, as the C-channel seal retainer should seat properly.

This year I decided to get to the bottom of this. Per the Cleveland parts book, there are two different sizes of washers; each wheel gets two of the larger ones on the inner side, and one smaller washer per wheel, which goes on the outside.

Apparently, however, these washers have been installed incorrectly on my Tiger. Some time back someone had installed one of the larger washers on the outside bearing and we've been dutifully putting them back in that order since (hey it's how they came out!) Unfortunately, this causes two problems: first, the large washer, when placed on the outside, causes the OD of it to ride on the lip in the mag wheel where the seal should ride. Since the washer does not turn this causes significant wear on that lip, and thus the damage to the wheels. Second, using the smaller washer on the inside causes it to get pinched between the axle shaft and the inner bearing; I found wear evidence on the axle shaft on that radius where the bearing is supposed to seat, plus wear marks on the washer itself. Finally, using the larger washer (with a larger ID) on the outside bearing causes the wheel nut to not get a full contact when tightened, and the ID of then is slightly bent (and the bearing is not adequately tightened because of the drag on the washer-to-wheel contact). The larger washers are also further damaged by being "cupped" due to getting forced down to the bearing by the nut. It's really a screwed-up situation all around.

Another view of the ridge cut by the too-large washer.

Here's a situation where the top of the ridge was simply worn down to even with the top of the inner bearing race. In this case the C-channel seal retainer will sit too far in. This wheel half will probably need to be replaced.

I've used the current shop as long as I've owned my airplane (1995), and they assure me they pay close attention to the order of removal and installation, but they never questioned if it was correct; thus it appears that this situation has been this way since before I owned it.

I also suggest this is a common problem: Fletchair sent to me two good used wheels and all four outer wheel halves show evidence of the same problem.

The risk of this being installed incorrectly is not particularly dire; in addition to ruining perfectly good parts, the worst that that could happen is damaged bearings and/or a slightly loose wheel nut if the washer(s) were to frag themselves. It's probably not a safety-of-flight issue (a safety-of-taxiing issue?) but I believe it's something that needs to be brought to the attention of all folks working on these airplanes; most of the techs I talked to about it have indicated they were not even aware there were different size washers on these Cleveland brakes! Hey, if you don't pay attention and just pick up a washer at random from the pile, you've got roughly a 1/3 chance of getting the first one wrong, then a 50/50 chance of getting the second one wrong if you get the first one right! Those are not particularly good odds, which explains why there's probably a lot of incorrect airplanes out there.

So remember: the two larger washers go on the inside and the smaller one goes out. I'd be very interested to hear if others find theirs to be incorrect.