915 gearbox question worn guide sleeve
09-27-2015, 05:04 AM
#1
5th Gear
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915 gearbox question worn guide sleeve
Hi there question for any gearbox experts out there.
I have a 1980 911sc with 325000 km on it.
15 years and 50000km ago the gearbox was rebuilt.
The gearbox has never crunched in any gear.
i have the receipt from that rebuild and the work documented was
-replace differential bearings
-1 2 3 4 gear syncromesh
-3rd gear selector sleeve
parts listed are
1st / 2nd gear syncro
3rd / 4th gear syncro
5th gear syncro
gearbox gasket set
3rd gear dog ring
Recently I took my car into my local shop as i was unable to get the car into third gear this was whether the engine was on or off. all other gears were fine.
the diagnosis was that i had a worn guide sleeve which was causing the problem and that i needed a rebuild
http://www.pelicanparts.com/catalog/...TRANSM_pg6.htm
they had managed to get the car to go back into 3rd gear though but they thought this problem would come back.
However if the problem did reoccur then the car would be safe to drive i just would not have 3rd gear no further damage would occur.
my thoughts are get them to check the bushings and linkage just in case that helps and then start budgeting for this work in the future.
can anyone explain what a worn guide sleeve does and why it might cause this problem?
thanks
jon
I have a 1980 911sc with 325000 km on it.
15 years and 50000km ago the gearbox was rebuilt.
The gearbox has never crunched in any gear.
i have the receipt from that rebuild and the work documented was
-replace differential bearings
-1 2 3 4 gear syncromesh
-3rd gear selector sleeve
parts listed are
1st / 2nd gear syncro
3rd / 4th gear syncro
5th gear syncro
gearbox gasket set
3rd gear dog ring
Recently I took my car into my local shop as i was unable to get the car into third gear this was whether the engine was on or off. all other gears were fine.
the diagnosis was that i had a worn guide sleeve which was causing the problem and that i needed a rebuild
http://www.pelicanparts.com/catalog/...TRANSM_pg6.htm
they had managed to get the car to go back into 3rd gear though but they thought this problem would come back.
However if the problem did reoccur then the car would be safe to drive i just would not have 3rd gear no further damage would occur.
my thoughts are get them to check the bushings and linkage just in case that helps and then start budgeting for this work in the future.
can anyone explain what a worn guide sleeve does and why it might cause this problem?
thanks
jon
Last edited by hittoday; 09-27-2015 at 07:43 AM.
09-27-2015, 01:37 PM
#2
RL Technical Advisor
First, I would check the clutch cable adjustments just make sure its disengaging properly. 
If the only gear that's difficult to engage is third, I would be disassembling the transmission to inspect the operating sleeve, guide sleeve, anchor block, stop block, brake band, and hub engagement teeth on the gears.
If the only gear that's difficult to engage is third, I would be disassembling the transmission to inspect the operating sleeve, guide sleeve, anchor block, stop block, brake band, and hub engagement teeth on the gears.
09-27-2015, 04:10 PM
#3
Nordschleife Master
In the gearbox business we talking about rebuilding gearboxes and remanufacturing them. Rebuilding usually gets synchro rings and a couple of engagement teeth.
A remanufacture gets the sliders and hubs replaced. You did not get this done the first time around. Usually these gearboxes can be rebuilt once and then they need to be taken further. Sounds to me like your is due. You will want to do the synchros again while you are in there and quite likely a few of the shaft bearings will be showing significant wear. You didn't do them last time.
A remanufacture gets the sliders and hubs replaced. You did not get this done the first time around. Usually these gearboxes can be rebuilt once and then they need to be taken further. Sounds to me like your is due. You will want to do the synchros again while you are in there and quite likely a few of the shaft bearings will be showing significant wear. You didn't do them last time.