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Registered
Join Date: Jan 2005
Location: Gamlingay (Cambs) in UK
Posts: 139
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915 gearbox woes
The 915 gearbox in my '73 has always felt smooth and easy. Has 85k on it since new and a friend who has over 30 years of fettling 911s reckoned it was one of the best he'd driven. I've put 5k on it and it always felt just right. Got the car out the other morning and it seemed to be crunching / grinding when going into 4th both on the up change from third and the down change from 5th. Thought maybe it's just a bit cold and I'm not fully awake yet but it only improved ever-so slightly when warm. the previous night I'd been on a 250 mile run mostly motorway / freeway with some twisty roads using the box a lot in between. It felt fine. I never rush the box or try to force the lever in prefering to do double de clutching changes up and down the box to ease the loads on the syncros. I thought I might be able to adjust it out so I loosed the clamp off but I just seem to have made it worse as it now crunches a bit going into third. Thing is it feels like a syncro problem but in my experience these tend to go gradually rather than all at once. Unless I have a selector fork problem. Any ideas........
 I'm thinking that I could be facing a rebuild here 
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carreraplanes |
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11-03-2006, 03:09 AM
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Registered
Join Date: Oct 2003
Location: Michigan
Posts: 14,093
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Take the shift fork cover off and see what's going on in there. Check the nuts for tight and look for abnormal wear on the fork.
My 5th gear just stopped working one day on a fun run. Never had any problems with it. The problem turned out to be unusual but Ihad no warning, either. Change the fluid if it hasn't been done in the last few years. Try adjusting your coupler again using the factory method. While these boxes will last a long time, how the PO drove it could be a cause of concern even if you have driven it nicely.
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1981 911SC ROW SOLD - JULY 2015 Pacific Blue Wayne |
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11-03-2006, 04:09 AM
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Registered
Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,498
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check the shift coupler bushings first, under the tunnel cover in front of the rear seats. there are a couple more bushings up at the shifter too. these can be evaluated somewhat by holding the coupler still, and moving the shift handle around a bit to see if you have direct movement at the coupler, or if there is a lot of slop before the coupler moves.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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11-03-2006, 09:19 AM
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