Drive shaft overhaul. Part 2


(AndyBlakey) #1

All three old U-Joints showed some signs of brinelling on the bearing surfaces. Though probably not enough to cause any problems yet.

The yoke that holds the rear bearing in place is splined onto the drive shaft section and held in place with a bolt. Metric here too, I needed a 17mm socket to fit the bolt head. There is a bend up lock tab on the bolt head, and a thick U shaped spacer. Make a note of which way the U shaped spacer goes so that it can be replaced in exactly the same position.

Make sure you have suitable marking in place on the driveshaft and yoke too - the splines aren’t keyed.

Once the tab was bent flat I tried the bolt. I couldn’t move it by hand, made more difficult too by no way to hold the driveshaft and stop it rotating while trying to turn the bolt with suitable wrench. Do not be tempted to put anything through the opposite yoke ears to hold the driveshaft. I resorted to using a ½” drive battery impact driver which made easy work of it.

The splines were assembled dry and would not pull apart by hand. I had to use the puller again. Then you have to pull the bearing off. I replaced the bolt and used it to give something for the puller to push against.

Finally ready to pull the bearing. First thing to do is cut the rubber around the bearing so that the outer frame comes away. I tried the puller on the remaining bearing housing, but much of it is rubber and it soon tore away from the actual bearing race which is moulded into the centre. With the puller readjusted the bearing finally came off the drive shaft.

On reassembly I pushed the new bearing onto the shaft as far as it would go by hand, which will only be part way onto its seat. Then greased the splines and used the yoke and its retaining bolt to push the bearing into place. Use hand tools for this so you have some feel for progress. It doesn’t take much force.

For final tightening I gave the bolt a quick blast of impact driver again before bending up another ear of the lock tab to ensure it stays in place. (I’m sure the bolt has a torque value, but with no easy way to hold the driveshaft I couldn’t use a torque wrench anyway. If you have a strong workbench and vise then so much the better – use a torque wrench.)

The thread cut into the new bearing frame did not fit the original 5/16” UNF bolts. It seems that new bearings are being manufactured with metric M8 threads. This is quite common - other folks have commented on it in the archives. As far as I can tell the same bearing is used in the XJ40 and X300’s so it doesn’t surprise me that parts manufacturers updated to metric specs.

All parts were given a thorough clean, some rust patches were treated, and a cursory spray of paint.

The new U-Joints were fitted using a giant C-clamp style press kit.

Clean out the yoke ears and especially make sure the grooves for the retaining clips are perfectly clean. Scotchbright is OK. A very light sanding with fine abrasive paper to remove any rust spots is also OK but keep it gentle. You don’t want to remove material. The U-Joint bearing cups rely on a friction fit into the ears.


On the same point, the U-Joint manufacturer’s fitting instructions recommend against using any lubricant when pressing the new bearing cups in. The friction fit is important and you don’t want anything that could assist a cup to move or rotate in use. In practice, I found that trying to press a bearing cup in place with no lube took a worrying amount of force. The last thing I wanted was a bent yoke ear . Against perhaps better advice I succumbed to a smear of bearing grease inside the ear and around the outside of the bearing cups. This helped a lot.

The bearing cups should press in smoothly. If you feel one locking up its most likely because you are pressing off centre so it won’t slide in straight. STOP. Press the cup out a little and start again.

When fitting the new joints always take care to match each bearing cup with the same trunnion that it came off. With sealed joints the manufacturer adds a precise quantity of grease at the factory. If you mix up the bearing cups you risk transferring grease from one bearing to another. This leaves one bearing with a surplus of grease and another with a deficit which could promote early failure.

The joints I bought also have a thrust washer in the bottom of each bearing cup. Take care to ensure these stay in place. This may vary from one manufacturer to another though.

Despite what some may think a U-Joint should have some end float. If they are installed too tightly they will wear and fail prematurely. 0.001”-0.002” is about right. I did find that the original snap rings were thinner than the three sets of snap rings, of varying thickness, that Spicer supplied with each joint kit. Leaving no option but to reuse the originals. There was then very little end float left anyway.

Make sure the retaining clips are seated perfectly. If a clip works free and falls out then the bearing cup could work loose too with potentially disastrous results. Check the clips again after a few hundred miles or so.
I know folks will question my use of factory sealed U-Joints instead of serviceable joints with grease points. As I view it, the original factory joints had no grease fittings. Once in the car two of the joints are virtually inaccessible anyway. These new joints are top quality and OE on many modern vehicles - where they are almost always the sealed type. I’m more concerned about fitting them correctly. There should then be no problem with them lasting a very long time.

Gently pull apart the splined joint. I cleaned all the old grease off. The rubber boot should probably be replaced, but mine was still in good condition - soft and flexible, with no signs of perishing. I reused it. The larger clamp was just a soft aluminium ring, dented in at one point to tighten it. This was easily prised up to release the rubber boot.

The splines were lubed with molybdenum disulphide grease, the kind used for certain types of CV joint, which is good for high pressure metal sliding against metal applications.

I’m not sure about the smaller end of the boot. Mine had no clamp or ring of any kind on it, but the parts manual does show some sort of retaining ring.

I noticed that the original retaining clamp was not that tight. It’s not the same requirement as say a radiator hose clamp. You could use a new CV boot clamp to replace it, but I used nylon cable ties. They are very light and shouldn’t add any significant imbalance weight to the drive shaft – which the worm screw mechanism of a hose clamp could.

Use a straight edge to ensure that the registration marks left by the manufacturer line up. Here again the splines aren’t keyed so you can reassemble out of line.

Finally ready to refit in the car.
I had two aluminium spacers between the centre bearing frame and support. These were reused.
I took some time to position the support exactly as it was before. Vibration wasn’t problem before I started so I don’t want to change the angles of the joints now.


So the results.

The bearing rumble has gone and that was the original problem. From 0 to 70mph the car is smooth and quiet with no noticeable vibration from the drive shaft. Next time I’m out in Germany and have an opportunity to make a higher speed sprint we’ll see what happens. The tarmac on continental roads is often smoother than found in the UK and that will also help to separate drive train noises and vibration from other sources. So far so good.

I’ve rechecked the U-Joint retaining clips after this road testing, they are all still in place.


(Jochen Glöckner) #2

Thanks, Andy,

good to have that kind of info in the archives! Good work and obviously rewarded appropriately

Best

Jochen

75 XJ6L 4.2 auto (UK spec)


(Robin O'Connor) #3

I can attest to the fact that if a circlip is not installed correctly then you have a problem, I did this on my ‘66 ‘S’ about 28 years ago and going down a hill the car suddenly developed a huge shudder, yep a circlip had freed itself and a cap had moved.
I tend to give the yokes a VERY light hone with a brake hone just to clean up the internal area, this gives a more consistent polish.
I will reiterate it is a very light touch.
Just a note,I had to correct the auto correct twice when it decided that I meant circling instead of circlip!


((Paul)) #4

Thank you very much for taking time to post these.
Nice refresher and very helpful when the time comes.

…and just a friendly reminder to everyone to always put safety first and be careful under these cars with jack stands!
ALWAYS have a backup (stability) support in place.

Even experienced, long time enthusiasts (on this forum) have died as a result of a moment’s lapse in judgement.

Kind regards


(tony) #5

Interesting…when I did my rear drive shafts, the new Spicer Snap rings were also too thick

At least one of my old snap rings was damaged from removal, and a new one too from rage

I rang Spicer Tech about this.

He stated it was “common in the field, and chamfering the new snap rings was acceptable”

not happy!..so unhappy I did not change out the Inners, which are relatively easy to get at,
(unlike the outers which need the outer half-shaft removed from the hub), as they were in good condition, and I was waiting for the special metal nuts that hold the brake disc

I chamfered them with a quick wizz with angle grinder blade,they have not fallen out anyway


(Aristides Balanos) #6

Very nicely done, and a great post Andy!
I’m about to tackle that job in the near future, so this is extremely helpful.

Best regards,
Aristides


(Paul M. Novak) #7

Andy,
Brilliant work!

Thank you for the post, pictures, and detailed write ups.

I have replaced a couple of the center bearings but no U-joints yet. Your post will come in handy when I do.

Paul