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tristanblue
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Joined: May 30, 2019
Posts: 346
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 Posted: Thu Aug 08, 2024 5:37 pm Post subject: What do you guys torque final drive side covers to (swing axle) |
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I have a couple bus transmissions here (swing axle 62 and 67) that I am cleaning, re seal and torque. What do you guys torque the (differential) final drive side covers to? I see Bentley says 18ft lb in one spot then 18ft lb and 22ft lb -1965 in another spot. Then I think I see 14ft lb for IRS trans.
That 22ft lbs seems a but high for such a small fastener (8mm-1.25) don't wanna pull a stud on a nice working trans.
Last edited by tristanblue on Thu Aug 08, 2024 5:44 pm; edited 1 time in total |
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Bruce
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Joined: May 16, 2003
Posts: 17632
Location: Left coast, Canada
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| Posted: Thu Aug 08, 2024 5:43 pm Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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Every VW publication I've seen is consistent at 22 ftlbs.
Which Bentley and what page say otherwise?
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mcmscott
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Joined: March 12, 2010
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Location: sanger ca
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| Posted: Fri Aug 09, 2024 7:41 am Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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I have torqued them to 20 for close to 30 years.
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chrisflstf
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Joined: February 10, 2004
Posts: 4142
Location: San Diego
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| Posted: Fri Aug 09, 2024 9:33 am Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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| Max torque on a grade 8.8 stud of 8mm is 28.8 ft lb. But what is torque limit in aluminum ? Number of threads engaged affects torque limit as well. Loctite would seem to help strengthen joint |
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tristanblue
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Joined: May 30, 2019
Posts: 346
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| Posted: Fri Aug 09, 2024 4:40 pm Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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| chrisflstf wrote: |
| Max torque on a grade 8.8 stud of 8mm is 28.8 ft lb. But what is torque limit in aluminum ? Number of threads engaged affects torque limit as well. Loctite would seem to help strengthen joint |
The strength of the aluminum or magnesium (whichever the trans case is made of) is what worried me as well. I know the steel fasteners can handle it but the threads in the trans case letting go is what I was worried about.
I had torqued everything to 18ft lbs. then went out last night and hit them again at 22ftlbs and honestly there was very little difference bewteen those two settings. It was just a couple millimeters in movement of the torque wrench at most. |
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modok
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Joined: October 30, 2009
Posts: 27724
Location: Colorado Springs
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| Posted: Fri Aug 09, 2024 10:31 pm Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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A larger diameter nut tends to require a higher torque value to achieve the same stretch.
I don't actually remember the history of what exact type and sizes of nuts and washers were used on the transmission, but I'm pretty sure following general guidelines should work well enough, and I agree these side covers do need the max of what the fasteners can stand.
What is on there? rusty 30 year old nuts? new zinc plated locknuts?
the side covers being magnesuim (high creep), it will help to use a large stout washer and/or a larger diameter nut, or a flanged nut, to spread the load out. |
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Bruce
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Joined: May 16, 2003
Posts: 17632
Location: Left coast, Canada
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| Posted: Sat Aug 10, 2024 9:02 pm Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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| tristanblue wrote: |
| chrisflstf wrote: |
| Max torque on a grade 8.8 stud of 8mm is 28.8 ft lb. But what is torque limit in aluminum ? Number of threads engaged affects torque limit as well. Loctite would seem to help strengthen joint |
The strength of the aluminum or magnesium (whichever the trans case is made of) is what worried me as well. I know the steel fasteners can handle it but the threads in the trans case letting go is what I was worried about.
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There's no need to question this. VW has tested it more than 30 million times.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17632
Location: Left coast, Canada
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| Posted: Sat Aug 10, 2024 9:04 pm Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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| mcmscott wrote: |
| I have torqued them to 20 for close to 30 years. |
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17632
Location: Left coast, Canada
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| Posted: Sat Aug 10, 2024 9:11 pm Post subject: Re: What do you guys torque final drive side covers to (swing axle) |
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| modok wrote: |
What is on there? rusty 30 year old nuts? new zinc plated locknuts? |
The stock fasteners don't usually rust. VW provided a continuous rust prevention coating system on every transmission. The nuts for the side covers are copper plated from VW.
I clean up the original fasteners and reuse them. I trust 50 year old German over new China.
I was talking to Gary Berg once and he told me he collects all the original VW hardware. Once he has a large enough collection, he send them out for cleaning, tumbling, then zinc plating. Then reuses them on his builds.
| modok wrote: |
| the side covers being magnesuim (high creep), it will help to use a large stout washer and/or a larger diameter nut, or a flanged nut, to spread the load out. |
It's interesting you should point that out, because VW provided a fairly large diameter, thick washer that is hardened for the side covers. Every rebuilt trans I've seen, those excellent washers are discarded and replaced by a thinner, smaller OD, mild steel washer.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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