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931 bellhousings - differences and part numbers?

 
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taymar  



Joined: 08 Feb 2017
Posts: 5
Location: FL

PostPosted: Wed Feb 08, 2017 9:02 am    Post subject: 931 bellhousings - differences and part numbers? Reply with quote

Hello all,

I believe I need to source a 'late/series 2 924 turbo bellhousing' for my project.

I've done some research and searching but have found some confusing results regarding series 1/series 2 bellhousings, conflicting part numbers and so on.

It's my understanding that a series 2/late bellhousing will have a reference sensor mounting location, though I am unsure exactly how to identify this on signt.

The part numbers in the PET for an <85 turbo bellhousing don't seem to match any of the casting marks I'm seeing on real-world parts.

PET lists: 931 116 043 02 but I haven't seen any with this cast or stamped on them.

I have found pictures of several with 9311164012R on them, and have found a fairly rough one for sale with this stamping. I'm not sure if it's the correct item though.

If anyone could give me a shove in the right direction, either to help identify the correct item or to source a nice one, I would very much appreciate it. Also, what is a fair price for one of these? The salvage yard I was talking to is now ignoring my emails and has just put it up on ebay after I got off the phone with them.
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11353
Location: PacNW

PostPosted: Wed Feb 08, 2017 12:47 pm    Post subject: Reply with quote

I don't think the 931 bellhousing changed. Don't be fooled by the numbers on the part, they are casting numbers and don't always match the Porsche catalog number.
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Shurick  



Joined: 15 May 2005
Posts: 481
Location: Russia, Moscow.

PostPosted: Wed Feb 08, 2017 9:34 pm    Post subject: Reply with quote

The only difference that I found was the hole for a crank position sensor in series 2.
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taymar  



Joined: 08 Feb 2017
Posts: 5
Location: FL

PostPosted: Thu Feb 09, 2017 12:08 am    Post subject: Reply with quote

Ah, thank you guys. The casting number is probably what's throwing me off.

Shurick - is there any chance you could tell or show me where the sensor hole is please? I've been sent a few pics by junk yards and it would be great to know where I'm looking for that hole.

thank you again, much appreciated!
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taymar  



Joined: 08 Feb 2017
Posts: 5
Location: FL

PostPosted: Thu Feb 09, 2017 10:21 am    Post subject: Reply with quote

Does this look like the correct one for a late 931, including reference sensor please? I'm told it's off a 1980 924 turbo.



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ideola  



Joined: 01 Oct 2004
Posts: 15493
Location: Woodstock IL

PostPosted: Thu Feb 09, 2017 1:24 pm    Post subject: Reply with quote

That is a series 1 bell housing, it does not have the hole for the crank reference sensor.

Why do you need the crank reference hole???

For reference, the sensor hole is directly adjacent to the "window" used to see the TDC mark on the flywheel.

Here is a photo:


Where the bellhousing meets the block, directly underneath the WUR, you can see the S2 sensor hole.
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taymar  



Joined: 08 Feb 2017
Posts: 5
Location: FL

PostPosted: Thu Feb 09, 2017 3:29 pm    Post subject: Reply with quote

Thank you! This picture explains the difference perfectly.

My thinking was that having the crank reference hole would give me another option to mount the crank trigger if needed. (This bellhousing will be mounted to an Audi 5-cylinder engine).

Several forum posts have indicated that I need to find a 'later 924 turbo bellhousing' for the swap, but have not really gone into much detail as to why.

So a 924 turbo bellhousing WITH the reference hole does exist? (assuming that's what is pictured in your photo).

Thank you so much for shedding some light on this for me, the pieces of this puzzle are slowly coming together. The one I posted a photo of was reportedly from a 1980 car. If I find one from say an '82 should I be virtually guaranteed it'll be series 2?
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ideola  



Joined: 01 Oct 2004
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Location: Woodstock IL

PostPosted: Thu Feb 09, 2017 11:55 pm    Post subject: Reply with quote

The photo I posted is from a Euro-spec 1981 S2 931.

ALL 1981-onward 931 will have the S2 bell housing with the hole for the crank reference sensor.

However, I think you are misguided by assuming you need that version of the bell housing. If I were going to install a crank reference, it would not be there where it is virtually impossible to get to with the engine in situ. You don't need to be constrained by that design. Just put a trigger wheel on the front crank pulley assembly and fab a little bracket up there. If you are doing an Audi 5cyl project, surely you possess the nominal fab skills required for that!
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taymar  



Joined: 08 Feb 2017
Posts: 5
Location: FL

PostPosted: Fri Feb 10, 2017 12:39 am    Post subject: Reply with quote

Thank you very much Ideola, this is an enormous help.

Great call on the trigger wheel. This certainly sounds like it'll be easier to source a bellhousing now.
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Shurick  



Joined: 15 May 2005
Posts: 481
Location: Russia, Moscow.

PostPosted: Fri Feb 10, 2017 7:56 pm    Post subject: Reply with quote

Just like Dan said. It's much easier to put crank sensor to the front of the crankshaft.
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'86 924S -- R.I.P.
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morghen  



Joined: 21 Jan 2005
Posts: 7825
Location: Romania

PostPosted: Fri Feb 10, 2017 9:00 pm    Post subject: Reply with quote

much easier but manufactures put the sensors over there to respect "runs after initial frontal impact" requirement.
If you have a fender bender (or hit a deer) and the sensor is up front, big chances are you're stuck in the middle of the road.

I would too consider the factory location for a crank sensor.
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ideola  



Joined: 01 Oct 2004
Posts: 15493
Location: Woodstock IL

PostPosted: Fri Feb 10, 2017 10:51 pm    Post subject: Reply with quote

morghen wrote:
much easier but manufactures put the sensors over there to respect "runs after initial frontal impact" requirement.
If you have a fender bender (or hit a deer) and the sensor is up front, big chances are you're stuck in the middle of the road.

I would too consider the factory location for a crank sensor.


With all due respect, if you're using my trigger wheel (that sandwiches between crank pulley and Gilmer pulley), and you have a frontal impact that would reach the pickup sensor, you won't be driving anywhere. And you'll probably have a bent crank.
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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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morghen  



Joined: 21 Jan 2005
Posts: 7825
Location: Romania

PostPosted: Sat Feb 11, 2017 3:53 am    Post subject: Reply with quote

ideola wrote:
morghen wrote:
much easier but manufactures put the sensors over there to respect "runs after initial frontal impact" requirement.
If you have a fender bender (or hit a deer) and the sensor is up front, big chances are you're stuck in the middle of the road.

I would too consider the factory location for a crank sensor.


With all due respect, if you're using my trigger wheel (that sandwiches between crank pulley and Gilmer pulley), and you have a frontal impact that would reach the pickup sensor, you won't be driving anywhere. And you'll probably have a bent crank.


Fair point, I was not referring to the setup you developed and sell, I was referring to DIY setups I have seen around the web. Sorry for not being clear from the beginning.
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Shurick  



Joined: 15 May 2005
Posts: 481
Location: Russia, Moscow.

PostPosted: Sun Feb 12, 2017 10:13 pm    Post subject: Reply with quote

Mostly when you install a trigger wheel located at flywheel you have bigger teeth and gaps between them. It helps to detect angle at high revs. But for our relatively low revving engines it's not a concern.
I've made a flywheel trigger wheel on mine 931 and it's a PITA to adjust sensor gap and even to get there.








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'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
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