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twt
Joined: 19 Dec 2002 Posts: 20 Location: Singapore
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Posted: Thu Mar 01, 2007 3:49 pm Post subject: G31 1st gear synchro |
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Hi,
I noticed that the PET states that the G31.03 transmission used in the 924CGT uses a different synchro ring for the first gear (915-302-301-06) which happens to be cheaper and instock than the one for the G31.01 used in the 924 Turbo (931-302-301-02). Given that the 924CGT is newer and more powerful, I'm incline to think that the synchro ring would be better as a replacement, assuming it will fit. Are there any differences btw the 2 transmissions?
Does anyone have any thoughts on this? |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11724 Location: PacNW
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Posted: Fri Mar 02, 2007 2:29 am Post subject: |
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That is a fascinating question. Here is what PET says for 1st Gear Synchronizer Ring:
- In 1985 PET, it is pictured as Part 47
- For Turbo tranny (G31.01, G31.02), part number is 931 302 301 02
- For GT tranny (G31.03), part number is 915 302 301 06
- There is NO similar part split for free or stationary 1st gears, nor any split for 1st/Reverse guide sleeve, nor for ANY OTHER gearset component
Taken together, this seems to indicate that the 915 part should fit. It is listed in stock through PCNA Atlanta at $84.89.
This is worth investigating further! Great post, twt. _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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emoore924
Joined: 13 Apr 2004 Posts: 2815
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Posted: Fri Mar 02, 2007 3:24 am Post subject: |
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For porsche part #'s, that trailing 2-digit number usually indicates a version, generation or supercession number on the same part. Since they both share 915 302 301, the 06 is the same part number as the 02, just 4 versions further "improved" by Porsche. Talk to a good Porsche parts person and he/she can tell you for sure wether this was true in this case. Based on the same part number being used, my guess would be yes. |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11724 Location: PacNW
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Posted: Fri Mar 02, 2007 3:29 am Post subject: |
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emoore924 wrote: | Since they both share 915 302 301. . . |
They don't, the Turbo lists a 931 part number. _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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-nick
Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA
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Posted: Fri Mar 02, 2007 7:51 am Post subject: |
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I'd talk to powerhausII. When I talked to them a few years ago they had just gone through a CGT trans and mentioned that it was interestingly different than the stock 931 unit.
I believe that Partwerks of Chicago was selling/doing some kind of conversion to use the 915 1st gear syncro in the stock 931 box. Last I heard, their reputation was soured by lots of bad deals. I have no idea if they're even still in business.
I highly doubt that the 915 will fit right in. If that was the case, then the folks at powerhausII would have known it when I called them up for trans parts. They've seen lots of 915's and have done a great job for me of chasing 931 trans parts. _________________ 1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11724 Location: PacNW
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Posted: Fri Mar 02, 2007 8:01 am Post subject: |
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Check out the PET, man. The bearings, forks, case, final drive might be different, but the gearsets look the same except for that one part. . .
Not to argue, BTW, I just think its flippin interesting. _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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emoore924
Joined: 13 Apr 2004 Posts: 2815
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Posted: Sat Mar 03, 2007 3:33 am Post subject: |
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Quote: | They don't, the Turbo lists a 931 part number |
Uh, yup, never mind, my syslexdia musta be kickin in. |
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938GTNick
Joined: 16 Nov 2006 Posts: 10 Location: UK
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Posted: Sat Mar 03, 2007 10:12 am Post subject: |
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The 924 CGT used the 911 synchro for better shifts from cold.
3rd, 4th and 5th gears plus the pinion head are shot blasted (if anyone can explain why this improves the wear pattern I would be interested to know) and have different part nos to the Turbo:
Gear Set/ G31.01/ G31.03
3rd/ 477 302 903/ 477 302 903A
4th/ 477 302 904/ 477 302 904A
5th/ 477 302 905A/ 477 302 905B
Ring/Pinion/ 931 302 911 01/ 931 302 911 33
Everything else- case, ratios, forks are the same.
Except one spring...... _________________ 924 Carrera GT
No. 434
(& No. 322) |
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endwrench
Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana
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Posted: Sat Mar 03, 2007 4:00 pm Post subject: |
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938GTNick wrote: |
3rd, 4th and 5th gears plus the pinion head are shot blasted (if anyone can explain why this improves the wear pattern I would be interested to know) .. |
Shot blasting "peens" over any imperfections, hairline surface cracks and sharp edges. It also creates microscopic "dimples" that help hold lubricant. This is the theory I was taught.
Todd _________________ '79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!.... |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Tue Oct 07, 2008 2:00 am Post subject: |
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This topic is worth resurrecting. Anybody find out any more info on this? _________________ erstwhile owner of just about every 924 variant ever made |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Wed Nov 19, 2008 5:25 am Post subject: |
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nobody ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Tue Jan 13, 2009 4:59 am Post subject: |
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Has anybody tried this ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Tue May 05, 2009 2:37 am Post subject: |
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Time for the periodic bump...
Anybody??? _________________ erstwhile owner of just about every 924 variant ever made |
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Power Tryp
Joined: 16 Apr 2009 Posts: 434 Location: Calgary, Alberta
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Posted: Wed May 06, 2009 2:53 am Post subject: |
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Any one know if that part is still in stock? If it is then I'll see if I can pick one up from my local guy. Just so you know though I'm not dropping my transmission till winter rolls around so it'll be a while till you hear results.
Tryp _________________ Melanie - 1980 931
NoName - 1980 931 (seeking rebuild)
Green tartan interior, you don't see that on a Civic. |
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v8carreragts
Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ
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Posted: Fri May 08, 2009 12:18 pm Post subject: |
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I'm sure it will fit. If you look in the factory turbo manual and the factory early 911 manual (w/915) the dimensions are the same and the turbo manual states that it is "same as 915." The Carrera GT transaxle is identical to the G31/01 (ROW) except for the first gear synchro ring and shot peened gear sets.
The GTS/GTR has some parts that are very different. |
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