 gear question, trying to figure out if a gear I have is 3rd or 4th |
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| brant |
 Sep 25 2017, 04:17 PM
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#1
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914 Wizard  Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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Hello everyone,
I have an "M" gear ratio in my stock I'm going to need to build a really short ratio box in the future and have decided that there are 2 different set of ratio's I could go with to obtain what I'm looking for.... so how do I tell if the M ratio I have is a 3rd or 4th position M? I'm guessing that it has to do with the direction of the gar angle, and which side the slider faces... can someone spell it out for me so I can decide which path to take and what ratio's to start searching for... I expect to start a separate WTB thread in the classifieds after I decide my path thanks in advance brant |
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Replies(1 - 5)
| oldie914 |
Sep 26 2017, 12:56 AM
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#2
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Member Group: Members Posts: 102 Joined: 2-May 10 From: Germany Member No.: 11,680 Region Association: None |
You have to consider a couple of things:
Porsche marked gears with the Roman numeral I if it was made to be installed on the mainshaft and II if it was to be installed on the pinion shaft. For the third gear position in the transmission, the mainshaft gear (marked I) is fixed with internal splines while the pinion shaft gear (marked II) rotates on the needle bearing. For the 4th gear position, things are reversed. The gear marked I rotates on the needle bearing and the gear marked II is fixed with splines. Conclusion: If you have an M gear pair and the gear marked I has internal splines, it was made as a 3rd gear. If the gear marked I has a needle bearing race, it was made as a 4th gear. |
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| brant |
Sep 26 2017, 07:20 AM
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#3
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914 Wizard Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains
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QUOTE(oldie914 @ Sep 26 2017, 12:56 AM)  You have to consider a couple of things: Porsche marked gears with the Roman numeral I if it was made to be installed on the mainshaft and II if it was to be installed on the pinion shaft. For the third gear position in the transmission, the mainshaft gear (marked I) is fixed with internal splines while the pinion shaft gear (marked II) rotates on the needle bearing. For the 4th gear position, things are reversed. The gear marked I rotates on the needle bearing and the gear marked II is fixed with splines. Conclusion: If you have an M gear pair and the gear marked I has internal splines, it was made as a 3rd gear. If the gear marked I has a needle bearing race, it was made as a 4th gear. Thank you! |
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| Montreal914 |
Sep 26 2017, 07:33 AM
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#4
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Senior Member Group: Members Posts: 1,560 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California
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| brant |
Sep 26 2017, 09:59 AM
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#5
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914 Wizard Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains
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QUOTE(Montreal914 @ Sep 26 2017, 07:33 AM) yes and thank you.... unfortunately my M ratio is 3rd, and I need it to be a 4th position gear oh well.... needing to define my shopping list find an I ratio, and possibly an H, or M ratio too brant |
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| Dr Evil |
Oct 6 2017, 08:58 AM
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#6
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Send me your transmission! Group: Members Posts: 22,999 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region
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Brant, is this for the box at my shop? We can talk, I have parts, and you can flip the M and it will not be an issue if you want to save some $$.
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