02 P5 3rd Gear Grinding
 

Hello,

Have a 2002 P5 with about 50K miles on it.

Recently ive noticed that third gear kind of makes a grinding sound right when you shift up to it.

anyone know what could be the cause?

try to run some thicker weight fluid in the tranny it should help

i actually changed to synthetic gear oil about 4 months ago, keeping the same viscosity, ..could that have something to do with it?

does it pop out of third on occasion? if it does, your shift fork is going south for the spring.

This is what i was thinking

no, it has never poped out of gear. Only a grinding, difficult to shift sorta thing. and it doesn't happen all the time. and the temperature of the engine has nothing to do with it, it even happenes sometimes when ive driven well over 2 hours. it probably happens about 30% of the time.

If those synchro rings are brass, like in the old Muncie 4speeds (yeah I'm old), then a little lighter oil might give it better grip on its collar to match speed during the shift. I'd try going back to the original oil. The synthetic stuff might be too slick for the synchro ring.

If the shifter fork was sloppy, wouldn't it grind in 4th, and also during downshifting too?

see, it did this even while i had the regular gear oil (non-synthetic). and i had way more clutch chatter before i switched to synthetic.

I'm at a loss too, because i don't know what the hell is going on. and i don't want to ignore that if its going to damage the tranny.

o.k, so ive read alot about this problem elsewhere. and the synchros supposively should be changed to carbon.
now here is the question.

how hard is it to change the synchro, ive only replaced a clutch once in another FWD car, so i'm pretty familiar with the removing of the manual tranny, but, how much complicated in the synchro?

also, does anyone have an idea on how much it would cost to get the synchro replaced.?

The trans has to be out, on the table and disassembled. Remove the gears from the mainshaft and put it back together with new synchronizers. The hard part is putting it all back together using grease to hold all the needle bearings and thrust washers in the case. You kind of have to get it all in place and slap it together before it falls apart again.
If a shop does it, the labor, once it's on the table is probably an hour or two.

Thanks Rusty. Will attempt to get it fixed by the dealer first. (under warranty)