Busted 3rd Gear in the Turbo Cab!
11-15-2005, 06:27 AM
#19
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Originally Posted by Luis de Prat
About a month ago I went out driving with some other Porsches. On the highway at over 130 mph I put quite a bit of stress on the gears, downshifting to third and flooring it to get maximum acceleration. The 951 is geared so long that even though 3rd seems short, it actually was not.
Drove back home about 60 miles without a problem. Parked the car and the following day I went to get some new rear tires and as I was driving through town slowly I suddenly heard a pop from the back of the car and a constant clicking sound.
At first I thought it might be a CV joint but then I narrowed it down to 3rd gear. My guess was confirmed when I eventually I saw the wreckage...
The car is repaired now, and 3rd gear is as good as it ever was with a new synchro ring and needle bearings, but I wonder what may have caused this. The gears didn't grind when I downshifted. I just put a lot of pressure on the car to accelerate, but would that cause a pinion to break three teeth like mine did?
Drove back home about 60 miles without a problem. Parked the car and the following day I went to get some new rear tires and as I was driving through town slowly I suddenly heard a pop from the back of the car and a constant clicking sound.
At first I thought it might be a CV joint but then I narrowed it down to 3rd gear. My guess was confirmed when I eventually I saw the wreckage...
The car is repaired now, and 3rd gear is as good as it ever was with a new synchro ring and needle bearings, but I wonder what may have caused this. The gears didn't grind when I downshifted. I just put a lot of pressure on the car to accelerate, but would that cause a pinion to break three teeth like mine did?
My vote is for fatigue. As stated previously, magnafluxing that (if you are interested) will show what's really going on there. The only other alternative is that some sort of debris got in there and caused the damage, which is unlikely, unless there was damage to something else in there.
Metal fatigue would have cracked/ split the entire gear, not just a few teeth- imho.
11-15-2005, 08:56 AM
#21
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Originally Posted by GOBOGIE
Chris, I'm hurt you took my quote out of your signature ;-)
11-15-2005, 10:56 AM
#23
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Originally Posted by bearone
lucky indeed. fools and children.
87951
87951
Luis is one of the more vocal opponents of street racing so i dont think it happened doing something childish.
Glad you got your baby back Luis. sorry it cost 1290. OUCH!!!! maybe you shoulda thrown a clutch and a..... while you were in there.
11-15-2005, 03:37 PM
#24
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Hi fellas, sorry I couldn't respond sooner. Long day at work today.
Indeed, this incident happened in Spain. As for the downshifting, I meant to say that I downshifted repeatedly uphill from a speed of around 80 or 90 mph to get up to a cruising speed of 130+ mph.
As for the repair, actually the most costly items were the parts. The rebuild was relatively inexpensive at 648 Euros, considering it was an 18 hour job altogether. The pinion prices are outrageous. The broken one on the left cost 136.34 Euros but the matching one cost a whopping 252.92 Euros.
Looking at the damaged area itself, I noticed two things. One, there's a yellowish residue around the damaged part of the broken pinion and another yellowish spot on the matching pinion. The other thing I noticed is that the broken teeth have ridges on the part that was originally solid metal. Perhaps it was a defective pinion to start out with? Car has a brand new stock clutch in it btw, which may have had added to the stress factor. If you think this repair was expensive, stock clutch parts prices are beyond belief...
One thing I didn't know is that there's a magnet in the tranny and it picked up the broken bits before they did any damage to the rest of the gears. That's quite a smart design and it probably saved me from having to buy a few more gears or scrap the tranny altogether.
So, I chose to go ahead with the repair because the damage was relatively minor and another LSD tranny like the one on this car was going to cost me at least double what it cost to repair mine assuming I could find a used one. Oh well, you play, you pay!
Indeed, this incident happened in Spain. As for the downshifting, I meant to say that I downshifted repeatedly uphill from a speed of around 80 or 90 mph to get up to a cruising speed of 130+ mph.
As for the repair, actually the most costly items were the parts. The rebuild was relatively inexpensive at 648 Euros, considering it was an 18 hour job altogether. The pinion prices are outrageous. The broken one on the left cost 136.34 Euros but the matching one cost a whopping 252.92 Euros.
Looking at the damaged area itself, I noticed two things. One, there's a yellowish residue around the damaged part of the broken pinion and another yellowish spot on the matching pinion. The other thing I noticed is that the broken teeth have ridges on the part that was originally solid metal. Perhaps it was a defective pinion to start out with? Car has a brand new stock clutch in it btw, which may have had added to the stress factor. If you think this repair was expensive, stock clutch parts prices are beyond belief...
One thing I didn't know is that there's a magnet in the tranny and it picked up the broken bits before they did any damage to the rest of the gears. That's quite a smart design and it probably saved me from having to buy a few more gears or scrap the tranny altogether.
So, I chose to go ahead with the repair because the damage was relatively minor and another LSD tranny like the one on this car was going to cost me at least double what it cost to repair mine assuming I could find a used one. Oh well, you play, you pay!
11-15-2005, 08:38 PM
#25
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Originally Posted by Luis de Prat
Oh well, you play, you pay!
Keep us posted on the repair and return to the road Luis! You have a gem there!!!
Cory
11-15-2005, 09:32 PM
#28
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Originally Posted by vette4lyfe
Your CAB is still the best lookin 951 ive ever seen
11-15-2005, 11:00 PM
#29
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the magnetic drain plug used to be in place of an oil filter on older cars. they are on all manual transmissions exactly for the reason you stated.
i bought one for the GTO motor, even though it is mostly aluminum. since i dont know if i will keep the car at the end of the lease, i got it for forensics. if it is clean every oil change i will contemplate buying it. if there are excessive fragments it goes back to gmac.
i bought one for the GTO motor, even though it is mostly aluminum. since i dont know if i will keep the car at the end of the lease, i got it for forensics. if it is clean every oil change i will contemplate buying it. if there are excessive fragments it goes back to gmac.