theYBLEGAL

Heyyy everybody.

Forums have been slow lately. So I thought I'd throw this one out there.

Last year, I rebuilt my transmission with the full carbon lined rebuild kit sold by Sychrotech. I replaced all the bearings, seals, etc.

It shifted fine up until about 2 weeks ago. About 6 weeks ago I was at WMHM racing it. But otherwise, it's a daily driver.

Transmission: Y21 factory lsd

Problem: 3rd gear grind (any rpm). It feels like I get no resistance upon entering gear, other than the grind, and then it enters gear fairly fast and easy. Feels like maybe the synchro spring is broken/gone. However, it does not pop out of gear on acceleration. It started 2 weeks ago by only grinding going into 3rd when it was cold. RPMs were always under 4000 during those times. After it warmed up, it shifted fine. But the last 3 days, not fine. Now it grinds when warm too.

Edit: All other gears work fine. After changing to AC Delco FM, it was easier to get into reverse. After I fix this, I'm using AC Delco / GM FM Synchromesh again.

Things I've done: Replaced Honda MTF with AC Delco / GM 10-4014 Friction Modified Synchromesh. If anything, later that day it seemed "worse" as in grinding when warm and not just when cold. Only extremely fine particles were found on the magnetic transmission drain plug (grain of salt, just mentioning).

Anyone want to take a stab as to what the problem is?

I'm thinking broken synchro spring, or I cracked the synchro, which would be bad for Synchrotech. I hope that would be warranty-able.

I'll be pissed if the synchro ate my cone. Tolerances were all well above service limits when I checked it last year. I drive fairly easy, seriously doubt it's my fault in any way.

I'm about to drop this sucker and take it apart.... But lets see if anyone can guess! lol

theYBLEGAL

There's a lot of room between 1st and 2nd gear. Idk what's up with that yet. 2nd gear synchro spring looks beat on.

3rd gear looks fine. No pics yet sorry, but face of synchro is still carbon coated and looks fine, and cone looks smooth. Haven't put a feeler gauge on it yet but seems like there's life left in the gear still.

Sorry pics suck, used phone.

Was hoping the problem would be easy to spot. Crap. So any suggestions?

theYBLEGAL

1st/2nd had play because I missed the distance washer at the start of assembly on the countershaft. I referenced the s4c diagrams, which has no distance washer, compared to my Y21. Good thing I saved all old/extra parts. Thats fixed.

So going to check gap on 3rd gear synchro, and if ok, reassemble...Gear oil will be delivered tomorrow. Hondabond will cure overnight. No tests today unfortunately.

Slop on the countershaft cause a 3rd gear grind but no popping out of gear?? Is this possible experts?

theYBLEGAL

So, I'm going to surmise that it wasn't leaving 2nd gear very well. All the slop between 1st and 2nd gear probably made leaving 2nd more difficult. Therefore, when going for 3rd, I had 2nd gear dragging the synchro putting more resistance on 3rd gear. The sound may have actually been coming from 2nd gear and not 3rd, as second gear's hub made contact with the synchro or 2nd gear teeth while leaving.

But gear oil is out for delivery today still. It's all bolted up and ready for fluid and a test.

PSI GUY

iTrader: (2)

Clearance looks good on the synchro for third, hard to see but was there any burrs on the sleeve at all, even a couple little burrs will cause poor engagement and possibly a grind. The spring was definitely worn down, I would have looked closely at the sleeve and hub for signs of wear or binding. Other than that, check the linkage and SCH assembly for wear or damage.

theYBLEGAL

Fixed. Bet 1/2nd hub was hittin reverse idler pulley, if what I said earlier was wrong.

But it's smooth as butter now, and no grinds cold or hot.

aera

Hey mate, did you find the issue to what caused the third gear grind? Just installed the same kit in my ep3 and had this issue with 3rd gear the second day driving it (today). The guy that put the trans together thinks it may be the 3rd gear synchro spring being broken like you said. What was the fix to this issue? Cheers