I had the gear oil changed about a month ago. Mechanic said a small metal part was in fluid and he showed me the part. Looks like it had broken off, about 1/4 inch long, round.

He couldn't remember what it could be and said he's seen it happen before and sometimes there's no problem and then again he's had to re-do synchros for another client that had a similar part come out with old fluid.

Well, long story short, yesterday (less than 80 miles since gear oil change) went to down shift from 3rd to 2nd and grinding started, so I stopped. Tried it again, grinding again.

Sounds like synchros from searches I've done.

I wonder if I left the orignal fluid in if this would not have happened or if it's a coincedence. Pretty bummed. This may get expensive.....

 

Cesar,

Obviously parts falling out the drain plug are a pretty safe indicator that something has failed. Gearbox parts that would produce fragments that size are either from the synchros or gear teeth, both are pretty easy to identify. Parts failure not withstanding, proper gear oil is everything to synchro function. Synchronizers are nothing more that a clutch, a cone clutch specifically. Too much lubrication and they won't produce enough friction to quickly match up gear speeds. Too thick, the longer the oil film takes to get squeezed out of the way, both cause poor shifting. One issue that compounds oil choices is that we have a ring and pinion to lubricate as well. I won't get into oils because everyone has their favorite. Just make sure the ones being used have specific friction modifiers for synchronized transmissions. It also has to take into account the R&P and Limited Slip Diff if one is fitted.

If you want a synchro trans to shift quick ATF is one of the best fluids, just enough lubricative qualities to stop the gearbox from seizing, thin to get out of the way. Just won't work in our transaxles.
Rick

 

Cesar,

From my recollection - a synchro doesn't have "round bits"

They look like rings with square teeth on one side - IIRC - and 3 or 4 bourbons in...

I would change oil again to see if it is the oil - in the end its CHEAP insurance against an un necessary rebuild.

Simon.

 

One of the proactive maintenance items I did right after purchasing my 993 Turbo was a gear oil change. I used Mobil Delvac 75W90. Car shifted butter smooth before the change and still does after the fluid change. I just wanted to play it safe, and zero out the maintenance. Mileage was 33,000. Now have almost 49,000.

I did a Blackstone used oil analysis on the old fluid, and the report was very good.

 

I agree with the suggestion of doing the Mobil 1 Delvac change before pulling the transmission. Maybe the grind is really bad, but $100 gear oil change is a cheap way to find out if it is a simple fix.

 

The receipt says they used Mobil 1 Synthetic Gear Oil 75/90 DR.

Not sure if that's the Delvac you guys mention or not.

I'll have to ask them.

 

Change the oil one more time and hope for the best
Delvac
or
Red Line No Shock

http://www.redlineoil.com/product.aspx?pid=42&pcid=8

are probably the best two choices.

i was disappointed with Mobil 1 75 / 90, when installed i noticed "notchy" 2 - 3 shifts.

good luck

Craig

 

Cesar, this is a good read for you:

https://rennlist.com/forums/993-turb...il-change.html

 

Confirmed, they used Delvac.

So what would make synchros go bad? I don't tend to "always" blip the throttle when downshifting and I rarely downshift just to go faster, it's usually when slowing down the car.

Granted I purchased the car with 35k miles, but up until the gear oil change last month all was great with shifting for the 10k miles I put on the car since 11/2005.

Again, thanks for all the info!

 

cesar,

Don't assume its the synchros until you have more information. BTW, "blipping" the throttle on downshifts helps to not upset the car's balance, and saves a tiny bit of clutch wear. To save the synchros, you have to learn to "double clutch" your downshifts... probably overkill for our modern gearboxes, but I habit I can't seem t break from my early days.