Syncro Front Half Shaft axle nut Question

[warmblood58]

So, in the middle of installing the GoWesty remaned front half shafts on my new to me Syncro and noticed that they include both a 12 point nut and also a large nylon lock style nut - any preference in the community on which one to use? I would think that the nylon lock nut might be preferred so that it cannot back off easy? I understand that I will still use the spacer that came off with old nut and I believe that I torque this nut to 276lbs? Thanks!

[warmblood58]

Ooops, looks like large spindle nut on the outer end of the half shaft is torqued to 236 ft lbs vs. 276

[insyncro]

Great way to wreck the sealed bearing.

[warmblood58]

[warmblood58]

Anyone know the Bentley procedure on this? My manual is 40 miles away otherwise . . . .

[djkeev]

After Dinner I'll pull out my Bentley and look for you.

Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[djkeev]

It's dark, you need to tip your head but here ya go!!

258 ft lbs

Dave
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Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[warmblood58]

[warmblood58]

Big thanks to djkeev and insyncro, the job is complete, and as always learned a few new things. What I imagined to be the most difficult part of this work, i.e, removing front half shafts wasn't - they come out quite easily if you remove transaxle side cv bolts first, upper ball joints and brake line connection. Removing large spindle nut is easy with a large breaker and wheels on the ground, a light tap on the splined axle shaft with nut in place to protect the threads freed up the shaft easily and by rotating the spindle and moving transaxle side of axle shaft towards the rear, the half shaft should slip away - no need to disturb front diff mounts/alignment! Upper ball joints also easy to remove but do thread 10mm mount bolts by hand to avoid cross threading - I had to use a air impact to tighten large ball joint nut. Outer tie rod bushings were easy as well, do count threads/take a pic or take measurements so that you can install at the same settings before removing old tie rod bushings. The unanticipated hard parts . . . . . power steering boots will try your patience! I used a heat gun and stretched boots over a 2 inch pvc pipe, heated a little more and with boot still warm on pipe, crawled under van, slipped off and quickly attempted to mount - this took four passes! Lower drop arm bushings were also a challenge (see my other post), per insyncro, hang everything by a few threads and gradually tighten everything up - getting the last lower drop link bushing nut on required a compression strap and a floor jack. I have the links tightened at about 90% of spec, Ill let things settle in for a few miles and then torque to spec on level ground. Front end feels great and I can breath easier with new sealed axles/cv joints as the old joints had torn boots. Nice to clean up things as I work on this new to me syncro - lots of cv grease flung here and there from torn boots . . .

[IdahoDoug]

Nice feeling, eh? Be sure to leave suspension joints loose until it is lowered to the ground and the suspension is compressed to normal ride height. That ensures that a rubber encased joint doesn't get rotated too far and tears away from the steel. It has an amount of suspension movement it was designed to handle up and down.

DougM
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[warmblood58]

[insyncro]

Glad to have helped.

Here is a great thread full of Syncro assembly:

http://www.thesamba.com/vw/forum/viewtopic.php?t=525134&highlight=corter

[zackalope]

So, I'm doing this job right now, and the new axle nut that came with my axle is about half the depth of the one I pulled off. I'll torque it to spec, but it being so much smaller makes me nervous. Should I not worry, can this little thing really take 258 ft-lbs?

[smurfpike]

I also am about to redo this job and my bearing just died with 5,000 miles on it. I am not sure what happened with it since I did everything by the book, oh well.

I would check with your local VW dealer for the axle nuts, I just bought some from my dealer and I think they came out of California.

I know that the nylock nuts being sold are from a Jetta(so I was told, not sure what year) and I'm sure they will work but I like the original oval lock nut and how beefy they are. There are some out there and I think they are NLA so when these are gone who knows.
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[pbrown]

[hardway]

When I worked at The Rabbit Hutch in Tualatin OR. we worked on lots VW track cars. The racing crowd had a lot of premature front drive wheel bearing failures. The shop owners were engineers. First they tried special greases. After that didn't solve the issue the stub axle torque was increased.

As i said they were engineers. They tested the stub axles by increasing the torque until they got failures and elastic deformation (stretching). They determined that the torque could easily be doubled with no ill effect on the stub axle and nut.

So they increased the torque. Bearing life was increased. The failures were caused the inner bearing races moving under higher loads than the vehicles were designed for. The two inner races bear against each other, that is what the clamping force of the torqued axle fastener is pushing against. If the clamping force is increased and the inner races and hub do not compress or deform under the force then no harm will be done.

Think about the rear stub axles. The axle nut torque is a minimum figure and then it is increased by turning to the next slot. The inner races and spacer resist the clamping force.

I acquired my 1980 Dasher diesel wagon because the front crank sprocket was loose and had damaged the crank. I replaced the crank and sprocket to repair the engine. I torqued every fastener to spec. The crank sprocket got loose again. It was a design flaw. My theory is that sprocket could not handle the extra load of the AC compressor. After that the sprocket got locktite and a new bolt installed to a higher torque, significantly higher. I drove it for another 150,000 miles until it ran away one day when I had the speedometer pegged on the highway.

I replaced the 1.5 diesel with a 1.6. The 1.6 crank has a much beefier snout and a bigger bolt. I bet I was not the only one who saw that failure.

Torque specs are not magic. They are determined by experimentation and measurements. It is important to understand that nothing is truly solid. All solids have plasticity. Steel stretches, cast iron bends. Some torque specs are very important and others not so much.

So what I am saying here is that understanding the factors involved in torque specs is important. Syncro bus front wheel bearings need the inner races and hub clamped together securely. The stub axle and the proper nut are up to the task. So I would want to err on the side of more torque rather than less.

I have a lot of torque wrenches. I used to be cavalier about just tightening fasteners. Just like most people and definitely most mechanics. I have those new electronic torque wrenches now. The feedback from these tools has taught me a lot. I now know that that with beam and click type wrenches that I was consistently over-torquing fasteners by 10 to 15 %.
It is a good thing that it wasn't that critical.

[4Gears4Tires]

That's really great information hardway. Thanks.

[Sodo]

Yeah good info Hardway.

Insyncro helped in his way by not adding more condescending non-info.
Which I think was influenced by the poster clevrly saying “thanks for nothing”

Heres a pic appropriate to this technical thread.
Useful to print the image and add it to your Bentley.

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