Stub axle bushes and front brakes.

September 25th, 2011

More minor progress. Bit by bit you clean and restore things. And eventually you get to reassemble everything with nice, clean parts. I figured out I didn’t get the wrong rear brake cables. I forgot that the rear cables aren’t ball and cup but have forked cables over the lever and a clevis pin.

I finished cleaning up the brake components. The adjusters and the cam unit. I do have new cams and bushes to install but I will need the bushes reamed. I don’t think the old ones are that worn to be honest but since I don’t know for certain I prefer to start with all new parts and know there is zero wear. These are the brakes we’re talking about so best to be sure!

IMG_0796_1 Brake parts.

I will need to find a new cam body from somewhere. One of mine had a loose stud. When I tried to tighten it is broke a chunk off the body! I swapped it over with one of the rear ones for now since that will be rebuilt later.

I also worked out that with the semi Girling brakes with the later, wider shoes there are actually two different kinds. Those with studs for the springs and those with holes. According to the red book you can drill out the studs and fit the later springs. Since I have the later springs now this is what I did. Brake springs are another part that look OK but people recommend not using them so I prefer to replace with new ones.

To remove the studs I first ground the back of the stud flat. Then I centre popped them and drilled them through with a 1/4 drill bit. This is slightly smaller than the size of the stud pin but it makes the pin weak enough that a good belt with a hammer and punch will knock them out. I also ground the back of the brake lining rivets and punched them out in the same way. Since they are soft metal there is no need to drill them. Interestingly with the linings off I could see how someone had previously sawn the rivets off it seems! Again the original linings looked OK. They weren’t worn much. But you never know what’s been done to them so I feel better replacing with new.

IMG_0787_1 IMG_0788_1 Removing studs.

You can see above how I ground the stud backs flat so I could drill them in the left hand picture. In the right hand one you can see one stud removed and the other drilled ready to punch out.

IMG_0790_1 IMG_0792_1 New springs.

You can see the new springs above. They are smaller and have little loops to help attach them. You can also see how the new springs are much tighter. Not sure if this will be an issue or not. Might be buggers to get on!

Next I cleaned up the drag link. This is the rod that links the steering box arm to the steering arm on the right hand stub axle. At each end is a ball joint with spring loaded cups. I bought a kit to replace all of these as play in the steering could be at best annoying and at it’s worst downright dangerous. The drag link has caps on the end held by a bolt. You remove the bolt and the ends can pop off. This reveals one half of the cup and a spring. The other end of the cup is inside the drag link. Mine were of course stuck in there. To get them out I carefully sawed a slot in the end of the cup then holding the tube in a vice I tapped it out using a chisel resting in the slot I cut. That got one end out. To remove the other I just poked a long length of steel bar down the tube and pushed the other cup out from behind.

IMG_0785_1 Removing drag link cups.

I also replaced the bushes in the track rod arms. The track rod is the bar that goes across the car and links the two stub axles. When the right hand axle moves the track rod makes the left hand one follow. The rod has arms each end with bushes and a pin that link the arms to the rod. The ends are screwed on (and clamped with a bolt) so that you can adjust the toe in of the wheels. Toe is the amount that the wheels aren’t parallel to each other. Toe in means the wheels are closer together at the front of the car. Toe out means they are wider apart at the front. On a rear wheel drive car like the MGB you have the wheels toed in slightly. The amount is small. About 1/16 of an inch at the wheel rim. On a front wheel drive car they are often toe out. On the Austin 7 I have no idea (slight tow in I imagine). Better find out!

To replace the bushes in the arms I first pushed them out using a vice and a couple of sockets. Then I just pushed in the new bushes with the vice. You must make sure the hole in the bush lines up the grease nipple point on the front of the arm of course. Another thing that needs to be reamed.

IMG_0781_1 IMG_0783_1 Track rod arm bushes.

I also replaced the bushes in the stub axles. I put them in the freezer for a few hours to cool and shrink them and also made sure there was no paint inside the hoes they fit into. To push them in I used my extractor tool with suitable washers and spacers. I use a dome nut on one end so I can hold it in the vice easily. Again you must ensure the slot in the top bush lines up with the nipple hole. It took me a while to work out how the grease gets to the bottom bush. The king pin is hollow. And the ends of the stub axle need to be sealed with core plugs (mine had none when I got it hence my confusion). You pump grease into the top bush, it goes down inside the king pin and out a small hole into the base to lubricate the bottom bush.

IMG_0773_1 Bottom bush.

IMG_0775_1 IMG_0780_1 Top bush.

Finally I gave the track rod and drag link a light coat of paint. Everything was originally covered in a very thick layer of primer and paint. I clean everything off and give it a light coating of epoxy just so it doesn’t rust. If the A7 is anything like the MGB it will leak more than enough oil to stop everything rusting in use!

IMG_0794_1 Painting.

The brake shoes I gave a shot of zinc primer to stop them rusting. I still need to rivet the new linings to them. This time I didn’t hang my string line in the doorway!

2 Responses to “Stub axle bushes and front brakes.”

  1. Howard Wright Says:

    Hi
    Great blog! I too have started a 7 special. The basis was a very very rusty 1935 Ruby. So far I have stripped down all the usable bits and am now acquiring chassis bits via ebay and very helpful specialists here in the UK. So far I have a 1938 chassis that has been boxed, 4 really good wire wheels and a solid rear axle case and torque tube. Check out the Oxford dreamers web site http://www.spitfires.talktalk.net/A7_Specials/Austin7_Special/Austin7_Special.html for inspiration! Cheers Howard

  2. admin Says:

    Thanks for that link. Most interesting. I am really just learning as I go along but there are loads of helpful people in the A7 world so lots of tips and advice around.

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