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Some of you may have been following along on some recent threads I started on my first track day, where it was recommended that I change my '88 5spd transmission fluid to STA gear oil to help with some notchyness I was feeling at the track. I decided to start a new thread to document what I found when I drained my transmission case. It's not clear when the spring broke but my day at the track likely caused that piece to roll around and get chewed up.
I found that my centering spring tip had broken off and the centering spring had failed into the bottom of the transmission and took some piece of the transmission gears with it.
Here is the rear drain plug. Some metal but not too bad.
Here is the metal I pulled from the front drain plug and you will not the transmission gear tooth
Here you can see the bottom of the centering spring. You can just make out the part number and the shredding of the metal from the transmission gears.
I was able to fish out the tongue of the centering spring.
This is a huge bummer. But fortunately Colin Jensan has come to the rescue. He has a spare transmission and we are in discussions on how best to get it into my car again. Stay tuned for more details on this.
Hmm... Yes, that is disappointing, and it is ashame that this happened. I can't imagine though that it has anything do to with the type of transmission fluid you were using.
It highlights something that had not been 100% on my radar screen, and I thank you for bringing it to the table:
What is the proper thing to do, when one suddenly notices that the centering spring has broken?
Did you notice this during the track day? Or did it happen much earlier?
Did you notice this during the track day? Or did it happen much earlier?
The centering spring has no been functional since I purchased my car in 2015. Six month after I purchased my car, I had the transmission removed and had the case repaired (welded) by the local Porsche dealer. the 3rd previous owner (now diseased) had repaired the case with Permatex after something punctured the case from inside. Rennister's presumed it was the tip of the centering spring. When I had the case properly welded the dealer informed me everything looked good and there was no metal parts inside. I remember having them inspect the syncros and the the gears as well. No rebuild was required, just weld the case and refill. I wasn't knowledgeable enough to know what to ask for and what to have looked for. I now realize the head of the centering spring broke but the rest of the lever was still in there and it must have ultimately fallen to the bottom and sat there until my track day when it started rolling around and playing with the gears.
I also realize that the technician at the dealer was not knowledgable enough to understand what had happened and what was going to eventually happen with the centering spring. At the time I didnt know how to make big repairs on my car so the dealer seemed to be the best local option since we dont really have 928 shops here anymore. I now realize they didn't know and there was not factory guidance to inform them either.
After speaking with Colin Jensan, we decided it would be best if I bring my 928 to him and we can swap out the transmission. Great no problem, I'll just call AAA and have it flatbedded. Wait, what?! It's 350miles?
Hmm, time for a new plan.... Colin suggest I strap a magnet onto the tranny to hold the internal debris in place and drive it on up. Sounds like a crazy idea right? Check it out.... A little google searching helped me discover an industrial magnet supplier pretty close to my house. The helped me source a STRONG magnet that has the strength to pull through the case and it really worked! I positioned what was left of the munched spring such that it had plenty of clearance from the gears above, and per Colin's suggestion I strapped it down and filled the case with some basic 75/90 gear oil ready for the trip.
I am planning of heading up on Thursday if I can get the parts I need. Namely the top cover gasket and possibly some trans mounts.
This reminds me of a time years ago when I was hillclimbing and another driver had his valve spring break just before his last run. Solution? Just tie it up with string to be able to make the run up the hill. Necessity truly is the mother of invention..
Give serious thought to the idea that the damage was done well before your latest track day, maybe as far back as when the centering spring let go. More than a few gearboxes have had many thousands of miles added after a stray bit of steel knocked the corner of a tooth into the sump area. At this point there's no easy way to find out. One you and Colin have a look at the cleaned pieces, you'll make an educated guess on what caused the breakage. Look at the fractured face for metallurgical issues, and the gear faces for evidence of the metal spring passing through.
5-Speed owners might do well to replace the centering spring as a PM effort before the old one lets go. My feeble memory has a couple of our inventor-engineers with improved versions of the spring available.
5-Speed owners might do well to replace the centering spring as a PM effort before the old one lets go. My feeble memory has a couple of our inventor-engineers with improved versions of the spring available.
You are in good hands with Colin. Made that trip a few times from Seattle. Once you get across the border (which over there is a breeze) you are only about 10 minutes from Colin's shop.
09-30-2019, 06:53 PM
Broken 5spd
