CV Joint Bolts Came Loose!!

[RichardF]

I fitted new CV joints to the front inner and all four outer drive shafts last September, 4,000 Km ago.

This is the second time I have removed and reassembled the joints since I bought the beast in 1999. The first time was in October 2000, 114,000 km ago, when I fitted one new joint, cleaned and relubed the others and fitted new gaiters. All the bolts were still (very) tight when I removed them in September.

We just made a trip to S Spain and back. On reaching N Spain again, after 2000km, we noticed a knocking sound from the rear end.

I found the RH outer CV joint completely off the hub drive flange, clattering against the inside of the trailing link. I hung up the loose end with a rope and drove a couple of km (thanks to 4WD!) to where I could work on it. There I also found the left outer just about to fall off, and all 6 bolts loose on both inner joints. BUT both front inner joints were still perfectly tight.

I retightened all the bolts and drove a further 200 km back home. Here the bolts are still tight.

I had the Bentley Manual when I fitted the new joints, and torqued them all to 45Nm (33lbft), according to the figure for the rear joints. I have since noticed that Bentley gives a figure of 35Nm (26 lbft) for the front joints, even though they are the same, but as I did the rears first I think I used the higher figure for the fronts also.

The new UJs were bought via eBay, and came with new bolts and gaiters, but no lock washers or locking plates.

The metal flanges on the new gaiters had slightly larger raised areas between the bolts than the previous ones, so I had to grind a small amount off the inside of the locking plates so that they would lie flat.

As the new bolts had 12 point socket heads, I used the original VW ones, with 6 point sockets, as I thought they were less likely to strip out next time I removed them, with old lock washers and locking plates. This could be a factor, but doesn’t explain why the front bolts didn’t come loose.

The new joints also came with gaskets to fit between the joint and the flange, which I also fitted. There were no gaskets when I first removed the joints in 2000, and none came with the new joint which I bought then. I also added thin paper gaskets between the gaiter flange and the joint to try to stop oil loss from the grease by this route.

I now intend removing, cleaning, regreasing and refitting the four rear joints with the new bolts I have, with new lock washers and the old locking plates. I can't see any function for the locking plates, except to spread the load of the bolts, as they don’t seem to lock anything. I am also considering drilling and wire locking the heads of the bolts. Belt and braces approach, as used on aircraft I used to work on.

Does anyone have any experience of UJ bolts coming loose, or any ideas to contribute, please?

Dick

[syncrosimon]

I think the 4 star bolts are less likely to strip than the old allen bolts. I had a rear drive-shaft come off exiting the peage at Nice. I think that just doing the bolts up evenly and as tight as you can is the way to go. New bolts really help.

[syncropaddy]

I think the 4 star bolts are less likely to strip than the old allen bolts. I had a rear drive-shaft come off exiting the peage at Nice. I think that just doing the bolts up evenly and as tight as you can is the way to go. New bolts really help.

Grease free and a wee bit of stud lock or something

[RichardF]

Just talked to the guy who sold me the joints. He is very kindly sending me 8 tubes of grease FOC.

He reckons the cause of bolts loosening is worn threads on the mounting flanges, and possibly vibration from slightly bent shaft(s). There has always been some vibration at the back at about 80Km/Hr, not cured by wheel balancing, but the bolts never came loose before.

He reckons cleaning the threads and putting Loctite on them should solve the problem.

I have 24 new Schnorr lock washers on the way, will use the new 12 point star head bolts I didn't fit before, and Loctite for further insurance. If that doesn't work, I'll drill the heads and wire-lock them.

If I can find someone with a long enough lathe I'll check the shafts for runout while they are off.

[mot falia]

just stripped my hub to fit new bearing today. And guess what, bolts all loose only the 2 now bent ones holding the shaft on

[Simon Baxter]

They often are loose, normal to see some missing, it's nothing unusual.
Clean the grease from the threads and swing on them when they go back, don't fanny about with torque wrenches, you just know when they are right.

[paul1275s]

They often are loose, normal to see some missing, it's nothing unusual.
Clean the grease from the threads and swing on them when they go back, don't fanny about with torque wrenches, you just know when they are right.

Tighten to shear then back half a turn...
Anyone ever thought of wire locking these bolts?

[Syncro G]

Mine developed an expencive sounding 'clunk' noise when I changed gear, then not long after I though that sounds expencive but before I thought to poke the rear driveshafts it fell off shagging the bolts in the process (at least a syncro has a spare axle to drive home on). Luckally it didn't damage the threads so new bolts sorted it - the expencive sounding clonk disapeared If I hear it again I know what needs doing, within 500mi if I don't want to replace bent bolts again.

[RichardF]

I'm wondering if new Schnorr washers every time might be the answer. Plenty available on eBay.

I reused the old ones the previous time, and they were still tight after 9 years and 114,000km. Maybe this time they were just too old.....

[Syncro G]

Well this time I replaced the washers and so far so good (none of the others have worked loose on the old washers eather though). I only tightened them to the book figures too. I used to have a Daihatsu F50 and if you overtightened the bolts on the free wheeling hubs (which is easy as again they don't take alot) they were likely to sheer off in use - its better to just check they are torqued up when you service it.

[RichardF]

I replaced the bolts with star head 13.9 bolts and new Schnorr washers. Checked them after 1000km and found I could get an easy 1/8 turn or so on about a third of them.

I removed them one by one and replaced with original type allen head 10.9 bolts and new, hardened Schnorr washers. Torqued to 33 lb-ft as per Bentley.

Whereas the washers definitely cut into the 10.9 bolt heads, the 13.9 bolts I removed were completely unmarked by the washers. I found a couple of websites which said Schnorr washers should never be used with 13.9 bolts for this reason.

Also, with the recommended torque, I don't think the 13.9 bolts are stretched enough to hold well. I did not want to apply any more torque and risk damaging the flange threads.

Only 600km since then, checked twice and still OK. Fingers crossed.

[HarryMann]

Tighten to shear then back half a turn...

Ha Ha!

Anyone ever thought of wire locking these bolts?

Thought, but how'd you do that without a hex head then?

===================================================

The most critical thing when clamping any joint up, is:

1) to ensure the faces of the joint are flat, true and clean;

2) to pull up the bolts evenly in several stages to an accurate and adequate torque.

Burrs and thread hole pullouts must be removed so the faces can sit truly flush, then the torqueing can develop full clamping force (so important to check, and keep back of your wheels flat and clean)

I like to use the 12-point bolts, 30~32 lb-ft torque max and so far, touch wood , haven't had any (of mine) loosen yet, with or without shnorr washers. Have seen it happen many times, on 4WD and 2WD T25s...

Loctite is fine if you have a recurring problem, but I wouldn't really want to use it as getting a shaft off quickly without wrecking the bolt heads can be important on a Syncro when out and about. If one hex or 12-point keyway is rounded off you are in drift it/molegrip/heat it up territory.

PS. If you have to flat the faces of drive-flange or joint, make damn sure the carborundum grit doesn't get into the joint or grease (disassemble the joint if necessary). Deburring cut sheet edges or holes properly seems to be a fast fading art.

Finding flatness and trueing surfaces

PS2. Don't forget the front inners require 2mm longer bolts

[Aidan]

new washers are 6p each, well worth replacing every time

those cv joints with the paper gasket are like what Matt fitted last summer in the field, the one that lasted 9 miles

[RichardF]

new washers are 6p each, well worth replacing every time

those cv joints with the paper gasket are like what Matt fitted last summer in the field, the one that lasted 9 miles

Mine came via eBay, one is already making clicking noises and has play after about 3000km. Lesson learned, next time I'll get the more expensive ones from JK etc.

HarryMann: Re wire locking the bolts - I think with a suitable clamp, a 1mm or so cobalt drill (or a few) and a lot of patience one could drill the heads on 13.9 bolts. I'm just putting off this chore until I feel it's the only solution.

[Titus A Duxass]

HarryMann: Re wire locking the bolts - I think with a suitable clamp, a 1mm or so cobalt drill (or a few) and a lot of patience one could drill the heads on 13.9 bolts. I'm just putting off this chore until I feel it's the only solution.

Having done a fair bit of wirelocking, I would build a drilling jig from a piece of plate to assist you with this ball ache of a task.