Subject
Front wheel bearings in British cars.
Working as a line mechanic from 1960 to the early 70s mainly on British cars, I noticed a lack of front wheel bearing repair work on the MGs. Jacksonville FL was a "Port of Entry" for many of the British cars brought into the US. and MG was the most numerous of any British car. This would normally make the most of any repair be on the MGs.
At first I thought maybe they have a better bearing. They do have a hefty bearing for the weight of the car as compared to domestic cars of that era. However, I am now convinced that it is the design, more than any other factor that made them live so long. For example, a 60s/70s rear wheel drive domestic car uses a "push" fit inner race bearing as the inside and outside bearing. In time and under the adverse strains applied to a wheel bearing the inner race moves and rotates to the point that it wares a grove in the spindle (axle). Replacing the bearings does not correct the problem. Now the new bearing is loose on the axle and the hammering effect of the loose play will shortly destroy the new bearings. The factory recommendation is to replace the spindles. No small cost on some cars.
Now lets look at the MG design. Outer race presses into the wheel hub just like any other car. The inner race is a push fit on the spindle. Nothing different there. But now we find an extra piece and some shims. Even though the inner races are a push fit on the spindle they are separated by a distance spacer or sleeve. The spacer is just a tad too short so if you tighten the axle nut it will lock up the bearings so they won't turn. This is where the shims come in. They are added on the end of the spacer to adjust the length of the spacer so the axle nut can be pulled down tight. Adding or removing shims will adjust the "pre load" on the bearing with the nut tight. This in effect locks the inner races to the spindle which prevents the inner races from spinning and keeps them square to each other and square to the spindle. This does NOT mean you don't have to repack your wheel bearings at prescribed times. It does mean you probably will not have to replace the bearings every time you pack them. I found the best method for me was to add enough shims to make the bearings have some free play. This can be felt by grabbing the tire at the top and with some force push and pull on the top of the tire. You should either remove the brake pads or at least pry the pads away from the brake disk. The reason for this is you want to hand spin the wheel so as to note how easy it spins with the bearings notably loose. From this point you shake the top of the tire, hand spin the wheel then remove shims and tighten the nut. Repeat these four steps until you can not feel any free play at the top of the wheel but the wheel will still coast the same amount when hand spun with the nut tight. If the wheel doesn't rotate very free due to a tight oil seal or you can't get the pads away enough and you are worried about getting it too tight. Add the thinnest shim you have until you can detect a slight play at the top of the tire then remove one at a time until you take out the play. Be sure to put a new cotter pin in the nut after you finish. Note that on the wire wheeled cars there is a spring plate inside the splined hub that covers a hole to access the cotter pin. The grease on the spline will make the access hole invisible. If you have replaced the bearings you should do one extra step. When you put it together leave the shims out and tighten the axle nut enough to note tightness in the wheel then install shims and proceed as stated above. Sometimes an outer race will not seat all the way in and this will help seat it. Also any time you replace wheel bearings you should check free play after a week or so driving. Most of problems that show up are from improperly seated outer races, not prepacking the bearings properly or by someone installing new bearings who didn't know how to set the "Preload" (adjustment).
I can't recommend that you do what I do. However for your information, I made sleeves for my daughter's TR-7 and for my XJ-6 Jag which cured an ongoing front wheel bearing problem with both cars. However, if you are not having a problem, why bother. The old saying applies here. "If it ain't broke, Don't Fix It!"
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Tech Tip
MG valve adjustment. A, B, C, Midget, Morris, A-H, 1100, etc., etc.
This works on all the Austin engines 4 cyl. and 6 cyl. in any car with a standard trans. First look in your manual and see what the valve clearance is. then remove the spark plugs and valve cover. Put the car on level hard ground or pavement. Trans. in 4th. gear and the hand brake off. At this point there are two methods that can be used. You can either set the intake and the exhaust valve of each cylinder while at TDC (Top Dead center) after the compression stroke. Or, you can set the opposite valve that is wide open. I use the opposite valve method on 4 cyl. engines and TDC method on 6 cyl. engines. I like the opposite valve method but it is too easy to lose your place on a 6 cyl. if you are interrupted during the process.
Opposite valve method
Think of the head on an MG as having a mirror half way down the head. If the first valve on the head were open all the way (spring fully compressed) then the opposite valve could be adjusted meaning it's mirror image which would be the last valve on the head. So we can say that when # 1 valve spring is fully compressed we can adjust # 8 valve. When # 8 valve spring is fully compressed we can set # 1. Thus we can continue down the head the same way. when # 2 is compressed we can set # 7, when # 3 is compressed we can set # 6 and when # 4 is compressed we set # 5. However, you will notice that two valves are compressed at one time so you can adjust two valves at one time. when # 1 & # 3 are compressed at the same time you can set # 8 & 6. when 8 & 6 are compressed you can set 1 & 3. When # 2 is compressed so is # 5 so the mirror image of those two are 7 & 4. Most of the Austin engines set the intake valves the same as the exhaust valves so you don't even have to worry which are intakes and which are exhausts. However, if you don't know they are arranged; ex, in, in, ex, ex, in, in, ex on the 4 cyl. engines. Putting the car in high gear gives you the best leverage to turn the engine buy moving the car. It doesn't mater if you push the car forward or backward. It only requires about 3 or 4 feet of movement to go through all the valves. I find it easiest to just push the car backwards using a leg as a lever against the front bumper. The main objective was to get the job done correctly. The secondary objective was to get the job done quickly as I was paid on a commission basses. Meaning the factory determined how long the job should take and the dealership charged the customer X amount per hour. So if the factory said a job should take 30 min. and I finished in 15 min I still was paid for 30 min. However, if it took me an hour then I still only got paid 30 min. The MG 1100 Sedan was a front wheel drive straight stick car with the engine mounted sideways so it was very easy to get to the plugs and adjust the valves and my opposite valve method was fast. You would be surprised how angry you can make a customer who is charged 30 min. when you are finished in less then 10 min.
TDC Method
I have used both methods on A-H and MGCs and I find that the TDC method keeps me out of trouble. That statement implies that I have got in trouble using the other method on 6 cyl. cars and that would be a correct assumption. Usually just readjusting valves I've already done. Or, removing a valve cover to readjust one I missed. A Healey 3000 would let you know when you didn't do it right. I tried marking the edge of the head next to each valve I did with a crayon, this helped. The big Healey was not an easy car to move in gear with your leg so I used the remote starter solenoid to rotate the engine. Being in the habit of putting the car in 4 th. gear before I would get out netted me a few scares when I hit the remote starter button. Believe me, a Healey 3000 with the plugs out and in 4 th. gear will bark the rear tires on concrete when the remote starter is pushed. Also, if the solenoid sticks the Healey will crush a steel work bench and do a lot of body damage. All 60s in-line 6 cyl. engines have the same firing order; 153624. The crank is configured so each of three groups of two pistons move together and are 120 degrees apart. # 1 and 6 move together, # 5 and 2 move together and 3 and 4 move together. Even though two pistons move together they are on different strokes. When # 1 is at TDC after the compression stroke # 6 is at TDC after it's exhaust stroke. At TDC after the compression stroke both valves are closed but at TDC after the exhaust stroke both valves are slightly open. with the valve cover off you can see this as you watch the valve action when you rotate the engine slowly. As you rotate the engine clockwise as you face the front of the engine, you will note the exhaust valve will be compressed then as it comes back up the intake valve next to it will start to compress. Just at the point when both valves are at the same height (both compressed slightly) you are at TDC of that cylinder and it's corresponding cyl. If that was # 6 cyl. then # 1 is at TDC and can have both the intake and the exhaust valves adjusted. Having both valves open at TDC is called "in overlap". To remember which cyl. is it's opposing cyl. just use the mirror in the center of the head. When # 1 cyl. is in overlap set # 6 and vise versa. when # 2 is in overlap set 5 , when 3 is in overlap set 4 and vise versa. also it does not matter whether you call the flywheel end # 1 or # 6. It works either way.
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