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pjmacua
Samba Member
Joined: May 22, 2003
Posts: 199
Location: Cantal, France
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 Posted: Mon Jul 30, 2007 1:24 pm Post subject: |
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| Bruce wrote: |
| Where does your info come from then? |
http://www.181spirit.com/menu/clubsVW/scan_revue1/page15.jpg
from a VW technical book (in french)
Chapter H 1.3
Page 1-2
supplément 2.75
Modèle 181- Boîte mécanique / Caractéristiques générales
| Quote: |
| There is a list that has been copied and posted dozens of times over the years that is full of errors. |
I agree with you. Everything on internet is not true. But it is not a reason to make hurried comments or deductions 
| Pierre181 wrote: |
| Pierre-J Macua is well known in the french (european)world of VW things, he runs his own website and is asked for informations by hundreds of thing owners. You can't think he's just copying a bad internet list. Of course he has his own sources of info... |
Thank you Pierre.
Regards
Pierre-J MACUA |
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aztec08
Samba Member
Joined: November 28, 2009
Posts: 1
Location: Belgium
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| Posted: Tue May 02, 2023 11:14 pm Post subject: Re: limited slip differential |
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A question regarding this old topic:
Does anyone know which % LSD those VW 181 gearboxes have?
Thanks! |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17285
Location: Left coast, Canada
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| Posted: Thu May 04, 2023 9:32 pm Post subject: Re: limited slip differential |
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Swing axle or IRS?
If Swing axle, bi-metalic or sintered iron discs?
If IRS, steel discs or sintered iron discs?
I have never seen VW specify what the lockup % is. And I have never seen a definition of what the % actually means. If you have a reference, let me know.
However, I have heard of one knowledgeable trans expert call an IRS ZF = 40%.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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SilverThing 
Samba Member
Joined: July 19, 2004
Posts: 810
Location: Everett
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| Posted: Sat May 06, 2023 9:33 pm Post subject: Re: limited slip differential |
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I'll second Bruce; I have never seen VW say a lockup percentage. When I have tried researching what the percentage means, I have never found an answer that is satisfying. I have seen people claim that the percentage is based on the torque of the engine the differential was paired with. I have also seen it claimed that the percentage is how much one wheel will slip relative to the other or how much torque will get applied to the slipping wheel. None of them make much sense when you think about how it works.
It would seem to me that the pertinent information for plate type limited slip differentials would be the preload torque (breakaway torque), the torque turning just one axle with the other stationary (once it has broken away), and the ramp angles (45/45 for the original ZFs).
I have seen 6 different versions of the swing axle limited slip listed in the post-1968 factory repair manuals: 4 versions with 211 part numbers with 3 pairs of discs per side, an early 181 differential also with 3 pairs of discs per side, and a late 181 differential with 1 pair of discs per side introduced January of 1972. The manual only mentions one version of the type 1 IRS differential, but every copy of the pages for that differential I have seen is dated in 1969. The manuals do not mention the friction material of the discs like Bruce alluded to, which I have always thought is odd. It was common practice for the newest versions of parts to be used in repair kits so maybe that also applied to the friction discs of the differentials - just speculation on my part, though.
All that to say, the manuals don't give any good indication what the difference might be between the swing axle differentials in terms of performance. There is a test torque in the manuals for a repaired differential, but the numbers seem extraordinarily low to me.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17285
Location: Left coast, Canada
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| Posted: Sun May 07, 2023 4:03 am Post subject: Re: limited slip differential |
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| SilverThing wrote: |
I have seen 6 different versions of the swing axle limited slip listed in the post-1968 factory repair manuals: 4 versions with 211 part numbers with 3 pairs of discs per side, an early 181 differential also with 3 pairs of discs per side, and a late 181 differential with 1 pair of discs per side introduced January of 1972. The manual only mentions one version of the type 1 IRS differential, but every copy of the pages for that differential I have seen is dated in 1969. The manuals do not mention the friction material of the discs like Bruce alluded to, which I have always thought is odd. It was common practice for the newest versions of parts to be used in repair kits so maybe that also applied to the friction discs of the differentials - just speculation on my part, though. |
For swing axle, I have seen:
6 bolt ring gear and 8 bolt.
With and without the extra dowel pins to locate the outer keyed discs
Early bi-metalic and late sintered iron discs.
The bi-metalic discs are steel with bronze applied on one side. Then there's some kind of teflon-like coating on top of the bronze. These discs are always the "3 pairs per side" configuration.
The sintered iron discs are the 1 pair per side from Jan 72.
There are two versions of IRS diff.
The early one used all steel discs. When the lubrication failed, the discs would grind themselves together. The later one used the same type sintered iron for the inner splined discs as the late swing axle. Since sintered iron is so porous, lubrication failure is rare.
Here's the early diff:
And the late diff:
You might think they look the same, but look in the large hole in the side. On the early diff you can see the shafts for the spider gears. On the late diff, the shafts are rotated out of view between the large holes.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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