In this article I am going to go over rear axle seals. Why? Because I see them put in wrong a lot and if you put them in wrong not only can they leak, but you can cause rear axle bearing problems or drum problems. So just follow along and see if you’re doing it correctly. If you are great, and if you haven’t been, then maybe you should redo yours.
Now most of this applies to swing axle cars. Bus IRS seals are sold as each so you can’t go wrong there and the inner seal on those is the same as the outer seal, so I won’t cover those. I think the main problem I see is when you buy an axle seal kit, it comes with more things than what you need. The only time you would use all of what they give you is if you have an early small axle reduction box set up.
Let’s go through what comes in the kit. Two gaskets, one large o-ring, one small o-ring, lip seal, and a shim. Here is what you’re going to use on the different types of cars.
Type 1 or KG, crash box transmission, you will use the large o-ring, small o-ring, shim and seal. No gaskets. The stack goes as follows: Place backing plate on axle tube. Stretch the large o-ring around the bearing into the backing plate. Shim against bearing. Small o-ring against the shim. Seal should be installed in the cap with the open side towards the bearing. Place the large bearing spacer into the seal with the inner bevel towards the bearing. Bolt the bearing cap to the axle tube. Tighten the bolts to 43ft lbs.
Type 1,3 or KG, syncro swing axle transmission, you will use the large o-ring, small o-ring, shim, seal and one of the two gaskets. The stack goes as follows: Place backing plate on axle tube. Put the gasket against the backing plate. Stretch the large o-ring around the bearing. Shim against bearing. Small o-ring against the shim. Seal should be installed in the cap with the open side towards the bearing. Place the large bearing spacer into the seal with the inner bevel towards the bearing. Bolt the bearing cap to the axle tube. Tighten the bolts to 43ft lbs.
Type 1,3,KG or Thing, IRS transmission, you will use the large o-ring, and the seal. Now, the inner seal is the same as the outer seal. Install it with the open side towards the inner bearing. The stack up goes as follows. Starting with the stub axle. Place the small spacer on the axle with the inner bevel towards the CV flange. Place the axle through the inner bearing. Long pipe looking spacer over the axle once the axle through the inner bearing. Install outer roller bearing into the arm with its inner race. Put the backing plate on. Stretch large o-ring around outer bearing. Seal should be installed in cap with the open side towards the bearing. Place large spacer into the seal with the outer bevel towards the bearing. Bolt the bearing cap to the arm and tighten the bolts to 43ft lbs.
Type 2 small nut reduction boxes, you use the large o-ring, small o-ring, shim, seal and the two gaskets. The stack up goes as follows. Place one gasket against the reduction box. Then install the backing plate. Then the other gasket against the backing plate. Stretch the large o-ring around the bearing. Shim against bearing. Small o-ring against the shim. Seal should be installed in the cap with the open side towards the bearing. Place the large bearing spacer into the seal with the inner bevel towards the bearing. Bolt the bearing cap to the reduction box. Tighten the bolts to 43ft lbs.
Type 2 large nut reduction boxes, you use the large o-ring, small o-ring, seal and the two gaskets. The stack up goes as follows. Place one gasket against the reduction box. Then install the backing plate. Then the other gasket against the backing plate. Stretch the large o-ring around the bearing. Stretch small o-ring against the bearing. Seal should be installed in the cap with the open side towards the bearing. Place the large bearing spacer into the seal with the inner bevel towards the bearing. Bolt the bearing cap to the reduction box. Tighten the bolts to 43ft lbs.
So that’s the correct way to set up the seals and gaskets. Here are some of the problems I see. It is not uncommon that a person puts his axle and tubes off his crash box trans onto a syncro trans. So how would I know what stack up to use? Crash box axle tubes usually have a straight lower shock mount. Not a twisted mount. Also and more important the lip on the casting will not stick through the backing plate. It only sticks through the plate half way. Also the bearing cap has a lip on it and not a bevel like the later model caps. On the later style syncro swing axle transmission there are two different caps. One that is deep where the bearing sits and one that is shallow. To make sure you have the correct one, measure how much the bearing is sticking out and then measure the depth in the cap where the bearing sits. On all caps that do not have a lip sticking up I sand the cap to make sure it’s flat. Next The large o-ring stretches around the outside of the bearing. It does NOT go into the bearing cap.
Last notes here. Do not fill your swing axle trans until the drums are on and tight. If you do it will leak out the axles. Make damn sure you tighten the drums to 217 at least- I go 250ft lbs. Once you have oil in the trans, drive the car around the block and retighten the nuts. If the nut moved, drive around the block again and retighten. Keep doing that until the nut quits moving. If you don’t do this step there’s a good chance you will be buying a new drum soon. Once the nut quits moving you can put the cotter pin in. If the hole doesn’t line up tighten it to the next hole. Never loosen the nut to get the pin in.