Morris Minor - propshaft repair

Symptoms of problem : Vibration + rumbling at about 50mph.  Universal Joints move slightly when propshaft gripped tightly and waggled.

Vehicle : 1957 Morris Minor 1000 Pick-up (LCV) - a CKD MM built in Petone, New Zealand. (part Series II, part Minor 1000 I think!)

Time : 2-4 hours   Difficulty : 4/10   Parts required : 2 x Universal Joints (Ref. K5-LGB80R or UJ431 )  Cost : approx. 20 (2005 prices)

Special tools required :  Set of circlip pliers (the type that work like pliers i.e. to compress an internal circlip), correct size half-inch drive socket to use as a drift = 5/8" AF (any socket whose body is a mm or so less diameter than the cap of the Universal Joints will do),  short (50-60mm) 10mm diameter steel rod to use as a drift, AF open-ended spanners, 2lb hammer, 2 x axle stands or suitable wood blocks.

Step 1    Removing the propshaft from the vehicle

The Morris Minor propshaft (drive-shaft) is 4' long and weighs approx 6kg - it has two Universal Joints (UJs) - one at the rear which is adjacent to a flange with 4 holes for attachment to a similar flange on the rear differential and another UJ at the front, which connects to a splined sleeve which slides over a splined shaft at the rear of the gearbox.  Each UJ has a hollow 'body' with 4 cylindrical ends, over which slides a needle-roller bearing housed in a 'cap' - the rollers are held in place inside the cap by a rubber seal. A grease nipple on the side of the body distributes grease to each of the 4 ends via holes inside the body. (These UJs are sometimes called 'Hardy-Spicer' joints, the name of a long-term manufacturer of this type of joint)

Park the car on a level surface, use a trolley jack (they are so cheap nowadays you should have one!) to raise the whole rear of the vehicle - use axle stands to support the differential on both sides. Add wooded blocks under each rear chassis member for safety.  Put the handbrake on firmly and chock the front wheels for safety. Place an old newspaper with an old basin on top just below where the propshaft enters the gearbox, to collect any oil spillage when the propshaft is slid out of the gearbox. (No oil at all came out of my gearbox)

CAUTION : Using Tipp-ex or white paint, carefully mark each end of the propshaft - make reference marks on every surface that can be moved relative to another surface, so that the 3 separate parts of the propshaft and the differential flange can be reassembled in the same relative position as before, once the new UJs have been fitted. Reassembling with the propshaft ends in the same relative positions (relative to the gearbox drive and rear flange) should hopefully avoid any propshaft balance problems (assuming there were none in the first place)

Using a 1/2" AF open-ended spanner (there is no space for a socket or even a thin ring-spanner), remove the 4 (nylock) nuts and bolts connecting the two flanges at the rear of the prop-shaft. Rotate the propshaft if necessary to get at the 4th bolt (this was not necessary on the LCV because removing the rear deck gives excellent access to these 4 bolts)  Leave one bolt in position until the other 3 are completely removed, to take the weight of the propshaft (which is not that heavy)  You will need to use a large screwdriver or crow-bar to stop the propshaft from turning when undoing these bolts - they may be a bit corroded (but are usually OK because of slight oil leakage from the differential) - you will need a second spanner or adjustable spanner to hold the bolt head as you undo the nuts. (Usually tapping the end of the spanner with a 2lb hammer will crack any 'seal' that has built up on these nuts over the years)

     Rear universal joint      Rear UJ                                   

                                                                              front universal joint   Front UJ

The rear end of the propshaft should now drop freely away from the flange, but will not reach the ground - there is a hole in the chassis member just behind the gearbox which catches the front end of the propshaft and stops it from falling all the way down.  Move nearer the middle of the propshaft, grip it firmly and pull it gently towards the back of the car (about 15cm total movement) to slide the front end off the gearbox splines.  Lift the propshaft out from under the car onto the floor or workbench. Some oil might leak out from the back of the gearbox into the old basin.

Work on one end of the propshaft at a time - remove the old UJ then fit the new one, then do the same at the other end.

CAUTION : the propshaft will probably be rusty - give it a clean-up with a wire brush or wire wool, but do not paint it. Painting is supposed to cause propshaft balance problems - I find it hard to believe that a thin, even, layer of paint could unbalance a propshaft any more than an uneven layer of rust would, but I don't want to take the risk!

Step 2    Removing the old Universal Joints from the propshaft

Removal of the old UJs should be fairly easy - you don't need to be as careful as when you install the new UJs, but don't damage the yokes. Examine the old UJs - they may or may not be corroded, but they should be greasy. Using the circlip pliers, remove all 8 circlips which hold the 8 caps of the old UJs in position. Depending on their condition, some of the stainless-steel caps may already move in the yokes once these circlips are removed. The original Haynes manual says that you can push the old UJs out with your fingers - ha ha - I had to hammer them strongly to get them to move at all. 

The method is to remove the 4 caps one at a time by driving them out of the opposite side of the yoke about 6mm, just far enough to grip them securely with Mole grips. Once these caps are removed, the main body of the UJ is small enough to slip out from inside the yoke.  Place one end of the propshaft on a wooden block and, using the socket as a drift, tap the cap on one side until it moves down far enough to push the cap on the other side out about 6mm - you may find that these caps move easily for a few mm, but need several hard hits with the hammer to move them further. Note : unscrew the old grease-nipple (if one is fitted) which will allow the UJ to move a little further in one direction. Grip the sticking-out cap firmly with the Mole grips (see photo below), give it a spray of WD40, then waggle it until it comes out of the yoke completely. The cap will probably be quite tight inside the yoke and need a bit of persuasion to come out. (note - the caps move more easily inwards than outwards) You will notice that some of the old needle rollers from inside the cap may fall out separately or may be mangled by the waggling - this is not a problem. Reverse the UJ, then use the 10mm steel rod to drive the opposite cap out of the yoke - you may find that it has actually come free inside the yoke, but you have to realign it and drive it out in the same way as the first cap. Use plenty of WD40 inside and out to make removing the caps easier. Once two opposite caps are removed, you can now slide the old UJ out from that yoke which now makes these two parts of the propshaft separate. Repeat this procedure for the remaining two caps, then remove the body of the old UJ completely, leaving two empty yokes ready for the new UJ to be fitted.

cap removal  removing a cap from front UJ

Look carefully at the holes in the yokes - if they are oval then you need to go to the scrapyard for a replacement, but this is not common.

CAUTION : Check that all the handling of the propshaft has not rubbed off your Tipp-ex or paint reference marks.

Step 3    Fitting the new Universal Joints to the propshaft

CAUTION : the new UJs must be fitted the correct way round - if fitted the wrong way round there is no space to put a grease-gun on the grease-nipple, so the new UJs cannot be greased at regular intervals and will wear out quickly. The new front UJ must be fitted with the grease-nipple facing towards the front of the propshaft, and similarly the new rear UJ must be fitted with the grease-nipple facing towards the front of the propshaft. (older UJs overcame this problem by using long grease nipples)  Study the available spaces to understand what this means before starting any reassembly with the new UJs.

new universal joint   New UJs, with cap and circlip

The method used is the reverse of removal - the 4 caps are inserted one at a time, and the 4 ends of the body of the new UJ are inserted in the caps one at a time. However, there is so little clearance inside the yokes, that the caps are just inserted into the yokes and no more (maybe 2mm in), then the body of the new UJ is inserted - if you tap the caps in too far, the body cannot be inserted, and you'll have to tap the cap back out again !

CAUTION : depending on the wear on the inside of the holes in the yokes, you may need to hit the new caps quite hard and often to get them positioned correctly, so there are two things to watch out for - firstly that the grease-nipple does not press against the yoke - they are easy to damage or shear off if you do not notice that they are pressing against the yoke when hammering the opposite cap.  Secondly, that the heavy hammering does not dislodge any of the new needle rollers inside the new cap - the grease which the manufacturers use should hold them in position, but be very careful that they don't come loose during assembly. Adding extra grease into the rollers will help keep them in position.

Clean the insides of the holes in the yokes with a rag. Clean the circlip slot inside each hole with a small screwdriver blade and rag. Insert one cap just a mm or two into one of the 4 empty holes in the yoke. Check that you have the UJ the correct way round (for future access to the grease-nipple) then insert one leg of the UJ into this cap and the whole body of the new UJ into position inside the yoke. Pressing the yoke onto two pieces of wood with a gap between them, tap this first cap down into the yoke, so that the circlip slot can be seen. Insert the new circlip (there should be 4 new ones supplied with each new UJ)  Checking that the body is still pushed into the cap, use the 10mm steel rod (now inside the circlip) to push the cap further down into the yoke. This is done to help ensure that the needle rollers on the other side of the UJ do not get dislodged when the cap on that side is tapped into place. Fit the second new cap to this side of the yoke, then use the socket drift to tap it gently but firmly into position, checking that none of the needle-rollers are being mangled as the cap moves down. Keep tapping until the circlip slot is visible on this side of the yoke, then insert the second circlip - the new UJ is half-installed !

Check that your alignment marks are correct, then repeat the above procedure with the other part of the propshaft that you have dismantled. Check that the grease-nipple is undamaged and that a grease-gun can be attached to it. Note : I found that the bearing I used had very poor grease nipples which the grease-gun could not grip once the UJ was installed - if you have the same problem unscrew these grease nipples and replace them with new ones (which will usually be slightly longer) - the usual size is a 6mm thread. The newly fitted UJ may be surprisingly stiff to turn. This completes the installation of 1 of the 2 new UJs.

Repeat the removal and installation sequence as above with the other end of the propshaft.

Step 4    Refitting the propshaft to the vehicle

You will need a helper - lie below the vehicle and lift the front of the propshaft - check that the reference marks line up at the rear, then push it forwards onto the splines at the rear of the gearbox, then have your helper lift the rear of the propshaft and push it towards the front of the vehicle while you waggle the front end - the propshaft will eventually slide fully onto the splines. The helper should then put one bolt through the flanges at the rear to hold the propshaft until you can fit all 4 flange bolts. Tighten the 4 flange bolts as much as possible without damaging the heads or shearing them. Check the gearbox oil level (filler plug accessed through hole under grommet in LHS of transmission tunnel) - check full to level with bottom of the threads - fill with new engine oil if needed.

Test-drive the vehicle - the vibration should have gone and it should drive more smoothly.

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