What were the road wheels made of, aluminum alloy or steel?

Aluminium :

http://www.tgl-sp.com/m551-road-wheel

H.P.

Aluminum. In fact, almost the entire vehicle was made from aluminum. In March, 1979, I was at Range 42 at Grafenwohr, when a brand new M551A1 replacement came from the rebuild facility and was unloaded from the HET. While loading it up with main gun ammo, the loader tore one of the caseless rounds open, and spilled propellant all over the sub-turret floor. There was an electrical short, and the propellant ignited, setting the vehicle on fire. The crew was lucky to get out without more than minor burn or two. But the M551 burned all afternoon and into the night-- the fire was unextinguishable with foam or water, and soon the Graf FD just gave up and stood "fire watch". The next morning, the only identifiable parts were the gun and mantlet, the engine block and some individual track pads scattered about. Everything else had either burned completely, warped out of shape or melted into rivulets of aluminum leading away from the concrete pad. The thing glowed for hours after the fire burned out. We broke out a mattock and chipped away at it for souvenirs. I still have a peice somewhere in my collection of junk.
VR, Russ

Thanks to Russ and Frenchy! I see where the industrial page indicates aluminum and steel, with the reinforcement being steel.
Was the outer portion of the rim, visible from the outside, aluminum?

Trying to decide on adding an appropriate color to the rims. I know the track guide teeth would not have had contact with the outer edge of the road wheel, maybe heat discoloration from friction removing the paint from the rim?

The outer portion of the wheel has an aluminum rim, topped with rubber around the outside edge. The wear ring is just inside the lip of the inner surface of the raodwheel-- you can see the steel portion just under the rubber and atop the inside edge of the aluminum wheel in the cutaway. This is the part that moved against the track guides. You wouldn't see it from the outside. The outer facing part of the wheel itself really doesn't come in contact with anything, except maybe dirt and debris kicked up by the track, so they didn't "wear" a lot. However, occasionally you'd find a wheel or two with the outer layer of paint scraped off in a spot from rubbing against something it came in contact with. You might also find one that had a slightly different shade of paint, or a brand new one which would have looked clean without much wear. Another factor was the oil or grease filled hub. The early M551 hubs were oil filled, and there was a clear glass insert in the center of the hub, which could be checked for fluid level. These were replaced with a grease fittings on later hubs on the M551A1, or when the wheel hubs wore out and were replaced--- sometimes we had tracks with both types of fittings. They always collected a little grease around the hub which attracted dirt, discoloring the wheel a little in that area around the hub. A major streak of oil/lube would also discolor the wheel, but this was ALWAYS corrected fairly rapidly by the crew and the maintenance section by replacing the hub seals (the alternative was a set of burned out needle bearings-- not fun to replace). This "streak" of lube might discolor the wheel a little (it was primarily the way we found a leak). Another area of the wheel where paint chipped off was around the mounting bolt heads or the rivets around the rims. We kept our tracks touched up pretty well though, so you wouldn't find a lot of wear for the most part. Constant operational use during Vietnam would have been different though-- you'd expect more wear to appear. And on occasion, we'd run the vehicles for 1-2 months on exercises and gunnery and more wear would appear, and would have been more obvious.
VR, Russ

One of my favourite authors is David Drake who served as an interrogator assigned to the Black Horse Regiment in Vietnam. He saw first hand armored warfare in 'Nam including the M551. He wrote a fictional short story called "The Way We Die" about fratricide using the M551 burning abilities. If you get a chance you should read it.

Combat lost M551's Vietnam
http://68.233.228.194/~atrp34cav/Photos/1969/1312.jpg

http://68.233.228.194/~atrp34cav/Photos/1969/1319.jpg

http://68.233.228.194/~atrp34cav/Photos/1969/935.jpg

Mine damage
http://68.233.228.194/~atrp34cav/Photos/1969/551mine.jpg

http://68.233.228.194/~atrp34cav/Photos/1968/Albrigh2.jpg

Yep-- and these are mine damage WITHOUT fires. During my 30 years on active duty, I've witnessed the catastrophic burning of two armored vehicles. The first was that M551A1 I mentioned above, the second was in 1983 at Yakima Firing Range when a fully loaded M60A3 had an engine compartment fire which spread to the crew compartment and ammo storage area (I was not an Armor officer then, but knew the Brigade Commander, who'd been my Squadron Commander in Germany). My Company happened to be about a hundred yards from the tank in question while we supported the unit (2/77 Armor). That M60A3 burned for nearly 36 hours-- as the FD couldn't reach it with enough fire retardant to put it out. The hull actually glowed red for awhile into the next morning. Folks don't realize how easily these metal monsters burn, or how hard it is to extinguish fires in them. A Sheridan fire almost always resulted in total loss of the track--we had at least two others while I was in the CAV 76-80, (but I didn't witness them).
VR, Russ

We started two brush fires at YFC in 89. On happened when the parking brake on a M1025 Humvee jammed and burned out and melted the fuel cell and the other was my platoon leader thru a smoke grenade into the scrub during an August field ex that surrounded my squads 2 humvees. The first generation Humvees had the disk style parking brake mounted on the rear driveshaft in front of the rear differential. They would catch all kinds of crap and jam and so you could release the brake handle but the brake was still set. At YFC they'd get jammed up with volcanic ash and dust all the time. The brake disk would get so hot the disk would melt and stretch finally burning thru with molten metal being thrown around the under side of the rig with the fuel cell right beside it. Diesel doesn't explode like gas but it does burn. All three humvees had multi million dollar ECM/ESM systems but luckily we got the the rigs moved out of the flames. Firefighters got the fires under control fairly quick but several acres of Yakima were blackened. Goes to show you can't give a 2nd Lieutenant anything dangerous.

Jim, ARAAV -- Armored Reconnaissance Airborne Assault Vehicle. Since the Sheridan was designed and built to be air dropped (by parachute) and able to "swim," it was hard to find much on the M551 made of steel. Aluminum was the material of choice trying to save weight wherever possible. Maintenance was relatively easy with the Sheridan because components were aluminum, lighter and easier to handle. It is incorrect to refer to it as a "tank" or a "light tank." Armored Vehicle is the correct label. Just as M113s are Armored Personnel Carriers and not "tanks," so too the M551. It's armor did not hold up very well against heavy weapons or armor piercing ammunition. However, whatever its faults, the Sheridan is a very cool (armored) vehicle! One of my all time favs. I'm looking forward to building Tamiya's new release.

While I'd agree it was a "cool" "idea" for a vehicle, it was a maintenance nightmare in reality. They constantly broke down, were unreliable, and had many issues with the drive train due to gun recoil. You could literally punch a large tree limb through the aluminum outer body (we patched ours with the lids off #10 coffee cans from the mess hall). I lost all six of mine after an ARTEP due to engine failure on a road march home once-- all within 10 minutes for blown engines while negotiating a steep climb uphill on a paved road. Probably the worst thing that happened to me in my M551A1 was the bolts shearing off the commander's armor plate, tossing me in the air, tearing off the laser battery pack, and dropping into the mud after bouncing off the back deck after gun recoil. The recoil of the main gun was just to heavy for such a lightly built vehicle. Final drive bolts sheared during recoil, obturator seals jammed, and electronics failed and shorted. It was fast though, and was a fun vehicle to drive. It was really designed around the missile that we never had enough of to shoot. I once had a TC in my platoon break a throttle cable, and I thought he was out of action. Next thing I knew, he pulled up alongside, pulling on a length of WD1 commo wire, rigged to the throttle thru the back deck. The driver would tell the TC when to speed up or slow down! So the engine was easy to reach, but that's all I can say about its ease of maintenance.
VR, Russ

I was a Sheridan driver in A troop 1/11th ACR in Fulda FRG. The turret of the Sheridan was steel the hull aluminum armor. It was a sloped armored body covered in flotation foam and thin sheet metal. That's why you could punch holes in it. They were dogs by the late 70s. In the 8 months I drove one our platoon had frequent break downs. We never got paint, since they were being replaced by new M60s the Army only put the bare minimum in them to keep them going. First Squadron bolted aluminum bar stock between the front and rear TC shields to keep them from shaking loose and falling off.

Tom

The Patton Museum at Knox had one. Got to drive it just once. It was a bit of a shock when I looked up under the sponsons, directly above the tracks and it was nothing but unprotected white expanded floatation foam.

Then I noticed the sponson itself, it was, like Russ said, just thin sheet metal over the foam. A big coffee can lid would be the perfect patching material it you happened to punch a hole in it!

Thomas, I was in H company, 2/11 ACR at Bad Kissingen, but I only spent four months there when I moved to Fox Troop, where I spent more than a year as a Platoon Leader, then moved to HHT as the XO, finally ending up as the interim S4 during M60A3 transition. They were wild times. I left in May 1980.

Michael, yes, it was an interesting vehicle. But I think the one you drove had been "tampered with" somewhat. The underside of the sponsons was indeed filled with foam, but there was a thin sheet aluminum covering over it, and as Thomas has said, the sides were covered in this aluminum sheet as well. A stout fir branch could penetrate the sheet metal easily at the right angle with enough force, and I had several "round patches" on my vehicle (F36) at one time. I've told a story here on Armorama about that in another post somewhere. A rivet gun and coffee cans were one of the Sheridan crews favorite tools. The top sides of the sponsons had a rubberized cover over the wading screen. These covers were flexible, so when you stepped on them they'd give a little. Folks don't realize this when they look at Sheridan models-- but in reality, the vehicle had rather "soft" sides for an armored vehicle. The crew sat in an aluminum box inside the sponsons, rated for .50 caliber defense, that was about it. This vehicle was designed for reconnaissance, not toe-toe combat with an MBT. And the CAV mission on the inter-German border was to act as a "speed bump" for the Warsaw Pact hordes until heavier forces could get to their GDP positions. We were supposed to be light and highly maneuverable, but survival wasn't a requirement. Fun times!
VR, Russ

Russ I was a knox trained M551 crewman. Pulled from 11D training after graduation for 3 weeks of 551 school. Actually swam one in Tobaccoleaf lake in Fort Knox. I was with A Troop from 77 to 79, I missed the A3s by a few months. I didn't get to TC one until 1989 in the NG. I may wait until the Rye Sheridans come out they will be closer to the ones we had.

Tom

Thomas, we were there at the same time. But I didn't leave til May of 1980--spending 3+ years in the Regiment. I think we must have been at Knox at the same time too, but I was at Motor Officer and the Missile Transition Course at that time. I came down on orders to the Regiment, with duty at H Company (the tank company in 2nd Squadron). I only spent about 4 months on M60A1s in the Regiment, then went over to Fox Troop as a Platoon Leader. They found out I'd been to MOC and the missile course and figured I was wasted on the M60A1. But that M60 experience did pay off in the Spring of 1980 when I became the Squadron transition officer for the A3-- and why they kept me for an additional 6 months past my normal rotation--besides my Squadron CO was PO'd that I had transferred to the Chemical Corps by that time too-- which is a long story. In short I'd been doing desk work as the HHT XO, then the interim S4 for over a year, and I was ticked off they'd taken me away from my tanks (I'd have spent 30 years as a CAV platoon leader if I could have!). I had a friend who was a Chemical Officer, and he convinced me I should transfer since the Chemical Corps was so short officers with experience. But I kept going back to line units even as a ChemO, Spending time in the 9th Division, 9th Divarty, 2nd DIV, and 25th DIV. Funny thing, while assigned to Dugway Proving Ground as a Chemical Officer in 1984-87, I was working on M1 tank decontamination systems, then got pulled off to do a series of tests with the USMC on M60A1 operations in NBC environments at Camp LeJeune and at Pendelton-- I just couldn't seem to escape being around tanks!
VR, Russ

Russ I probably saw you in the PX all those years ago. I PCSed to Fort Stewart to M60A1 IR tanks. It was a big difference from the 11th. It soured me on the Army so I ETSed and went to college. I started missing those steel beasts and found a NJ Guard tank unit, M48A5s an even bigger step back. It filled the need though and I got to drive though several American towns for parades. I progressed though M60A3 TTS and finished as a PSG on M1s.

Allons

Tom