Transmission question

Wilbo · 05-24-2016, 10:41 AM

I'm thinking my first and second gear syncros are going out on my 86 911. Is it possible to replace them, or is it necessary to have the entire tranny rebuilt? And either way, does anyone have a rough estimate on the cost? Thanks

Oh Haha · 05-24-2016, 11:19 AM

What are the symptoms? It could be a simple clutch cable adjustment.

How many miles on the gearbox and when was the gear oil changed last?

The box needs to come apart for the repair if that is what's needed.

The cost will really depend on the shop, the work done and even the area you live.

I paid about $1200 back in 2004 for 2nd gear replacement. I removed the engine and gearbox and dropped it off to the shop, saving the cost of them doing it.

Wilbo · 05-24-2016, 11:53 AM

Don't know when gear box oil was changed last. Odometer is 56k. Grinding if trying to put it in 1st gear when moving slowly. Same with 2nd gear, but not as severe.

Oh Haha · 05-24-2016, 12:15 PM

I would try adjusting the clutch cable first along with inspecting the shifter bushings.

The low miles would lead me to believe the internals are probably ok.

My 1st gear would sometimes grind if I was moving just a little too fast coming to a stop but not consistent enough to worry.

My 2nd gear problem was my own fault by shifting it like a modern muscle car. You absolutely should not do that.

Oh Haha · 05-24-2016, 12:17 PM

You might consider showing your location as Pelicans are around the globe and you may have a fellow close that could help you at least diagnose the issue.

DRACO A5OG · DRACO A5OG's Garage

Depends, where are you located?

john walker's workshop · 05-24-2016, 12:49 PM

The 1&2 syncros and related items can be replaced without a complete teardown. End cover off along with the gears under it. Center housing off. Remove both roller bearings. Remove 1st gear. remove fork bolt and remove sleeve and hub and 2nd gear.

Discseven · Discseven's Garage

I'm with Wayne... mileage doesn't fit worn syncros unless shifting was chronically done incorrectly---which is possible... no offense Wilbo.

To drop and replace engine & trans is about $700. To pull gear stuff out and replace syncros, I'd estimate 3 hours in turtle mode. $100 and hour puts job around $1000. Syncros are not much. Might need dog teeth if trans has been tortured. Not sure what those cost now and there'll be a cost to remove old teeth and install new. With engine out... THERE'S ALWAYS MORE TO DO. Who does work can make big difference in price.... and quality. Suggest only dealing with Porsche specialist for this.

Agree that all externals should be confirmed OK before diving into trans.

Matt Monson · 05-24-2016, 01:10 PM

Do you have to? No. Does it make sense to do it all while you are in there? Yes.

Get a labor quote. It will be pretty much the same no matter what you do. When your labor is 4 figures another couple hundred dollars to make sure it serves you another 50-75k no makes sense. So many half arsed 915 rebuilds over the last 30 years are part of why people think it's a dog shyte gearbox.

MARISOL78sc · 05-24-2016, 02:40 PM

Just rebuilt my 915 as 1st synchro failed. Replaced everything worn as new as I was in there and wanted it done correctly. $4600 Link to thread 915 Rebuild advice

I wouldn't advise shifting into first while moving Bad for first gear synchro.

Wilbo · 05-24-2016, 04:10 PM

I've only had the car for 1 year. I've put maybe 600 miles on it. So I don't know how the po drove the car. It's not a super critical issue for me at this time, but I wanted to get as much info as I could given the fact that I'm not a mechanic.

Oh Haha · 05-24-2016, 04:31 PM

It's cool Wilbo.

One thing you'll find here on Pelican is folks willing to help. Most, if not all are DIYers and will dive into a project that might scare off someone who doesn't have the skills/tools.

We also have some of the bet Porsche mechanics that are willing to share info,knowing that they aren't making anything by doing so. John Walker is one of those fellas.

yelcab1 · 05-24-2016, 04:53 PM

This is 6 years ago now. I bought a used 915 gear box, took out what I needed, bought a few new things, rebuilt my gear box, sold the rest of the stuff and basically broke even. I am not sure that can be done today. I would just redo 1 and 2, and see if that makes you happy. If not, you can always do more.

Wilbo · 05-24-2016, 07:04 PM

Thanks for all the great info. If it bothers me to a point that I can't deal with it anymore I will search for a labor quote. I had an 86 911 about 10 years ago and I had no such problem with shifting up and down through all gears. Also my former 86 seemed to have more, or should I say extended power through the liwer gears. What I really notice is that my old one could easily reach 90 mph in 3rd gear while still well within safe red line limits. This new 86 911 (new to my ownership) seems to have difficulty reaching 60 to 70 mph in 3rd gear?? Just curious why the difference? Thanks to everyone for the feedback

pmax · pmax's Garage

Quote:

Originally Posted by john walker's workshop

The 1&2 syncros and related items can be replaced without a complete teardown. End cover off along with the gears under it. Center housing off. Remove both roller bearings. Remove 1st gear. remove fork bolt and remove sleeve and hub and 2nd gear.

Sounds like a doable project to me.

I would go for it.

Matt Monson · 05-25-2016, 10:01 AM

Quote:

Originally Posted by Wilbo

Thanks for all the great info. If it bothers me to a point that I can't deal with it anymore I will search for a labor quote. I had an 86 911 about 10 years ago and I had no such problem with shifting up and down through all gears. Also my former 86 seemed to have more, or should I say extended power through the liwer gears. What I really notice is that my old one could easily reach 90 mph in 3rd gear while still well within safe red line limits. This new 86 911 (new to my ownership) seems to have difficulty reaching 60 to 70 mph in 3rd gear?? Just curious why the difference? Thanks to everyone for the feedback

Sounds like someone may have installed a 7:31 ring and pinion into your 86 gearbox. As you indicate, 6000rpm in a stock 3.2 with 8:31 is approximately 90mph.
Put a 7:31 in there and you are looking at something more like 78mph. Add in that the car may have a smaller more low profile tire than it had stock and you get down 5-8mph more to the kind of numbers you are seeing. Your car will accelerate faster than it did when stock.

Matt Monson · 05-25-2016, 10:01 AM

Quote:

Originally Posted by pmax

Sounds like a doable project to me.

I would go for it.

Says the guy who didn't know to drop his engine and gearbox at the same time.

Wilbo · 05-25-2016, 05:57 PM

Thanks Matt. Maybe that's the culprit? What you indicate is exactly what I'm experiencing. I like the 90 mph in 3rd gear at 6k. 1st through 4th don't have the range (speed and toms) that my old 86 911 had. As stated earlier, I'm not a mechanic, but if I have the 1st and 2nd gear syncros repaired I want the 8:31 in my car. Love the feedback here on pelican. Thanks