View Full Version : 4th Gear Syncro Gone?


Rotary Mike
03-14-2009, 02:51 PM
Hey guys, I think me 4th gear syncro is shot, or close to it.

I get a minor gear grind everytime I go from 3rd gear to 4th above 4500rpm roughly. It sucks :(

Greg or Al. Is this fixable on it's own, or does it require a new tranny? What is the general neighborhood repair cost?

01Racing
03-14-2009, 04:00 PM
You can always fix a worn syncro if thats what it is. Probably $300 - $500 range. Once your in you might a well replace them all. You have to realize these transmissions were NEVER designed for big power or drag race style shifting. We have blown up 4 stock RX-7 transmissions in the race car, and that is granny shifting it. Most of the failed RX-8 trannies I see (and I see a lot of them) are cause by not rev matching on forced downshifts or yanking the stick between gears.

Rotary Mike
03-14-2009, 05:21 PM
So if one is 300-500, how much are all 6?

I'll bring it in soon

rx8thunder
03-14-2009, 08:34 PM
Check out Syncro savers (http://www.rx8club.com/showthread.php?t=168857)

AJ's Shinka
03-15-2009, 07:02 AM
I have this same problem I think I gonna have to take her in under warranty.

01Racing
03-15-2009, 07:55 AM
Hurst call them "positive stop shifters" all there aftermarket one have adjustable nut and bolt on either end so you can overshift as well. Overshifting is only a part of the problem on most import trannies. Hydraulic clutches are another culprit.

ZmFnZm
03-15-2009, 08:56 AM
in other words, don't rest your foot on the clutch AT ALL.... use the dead pedal. I got into that habit in the first week with my 8, just in case...

shazy
03-15-2009, 01:35 PM
My problem is getting into 6th, since I've never driven a manual with a 6speed gearbox, I always go into reverse by accident... the shifter just goes down and hits reverse, it's really annoying.

I'm pretty sure that it won't be much more than 500$ because most of that money is labour that goes to when the mechanic opens the transmission.

qtwre
03-15-2009, 07:05 PM
If you shifted from 5th to reverse wouldn't you damn near kill yourself? In order to shift into reverse you have to be pressing down on the shifter, so stop doing that. Also, reverse is another gate to the right so don't apply pressure to the right when going from 5th to 6th. Just go down.

Thumper3322
03-15-2009, 07:13 PM
Check out Syncro savers (http://www.rx8club.com/showthread.php?t=168857)

Did you get this thunder? I have been looking at it.

rx8thunder
03-15-2009, 07:25 PM
^ yeah, supposed to receive in another week or two

rotarygreg
03-15-2009, 07:30 PM
the synchro saver will not mean you can slam it into gear without any ill effects. it simply prevents over shifting. you are still beating the livign hell out of the syncrhos by asking them to handle a power shift at 9000rpm, and thats where the wear comes from.

fast shifting, not over shifting. over shifting will more than likeyl damage a fork, but shifting really quickly with a syncro saver is still gonna tear up the syncros pretty bad. like al said, these transmission are made of paper. they are delicate little boxes, especially concidering all the hell they go through shifting at 9000rpm.

I always granny shift, even when im givin it really good. for the split second it gains you to slam it in the next gear, its not worth the hastle for me to have to rebuild/replace my tansmission.

Thumper3322
03-15-2009, 07:41 PM
^ yeah, supposed to receive in another week or two

Another toy lol!!

the synchro saver will not mean you can slam it into gear without any ill effects. it simply prevents over shifting. you are still beating the livign hell out of the syncrhos by asking them to handle a power shift at 9000rpm, and thats where the wear comes from.

fast shifting, not over shifting. over shifting will more than likeyl damage a fork, but shifting really quickly with a syncro saver is still gonna tear up the syncros pretty bad. like al said, these transmission are made of paper. they are delicate little boxes, especially concidering all the hell they go through shifting at 9000rpm.

I always granny shift, even when im givin it really good. for the split second it gains you to slam it in the next gear, its not worth the hastle for me to have to rebuild/replace my tansmission.

Agreed Greg, I don't shift as hard or as fast as my other car, let it go in naturally over slamming it in, so don't know if the synchro saver will be worth it or not. If I was harder and less conscious of what I was doing, then it might be worth it...i don't know...to many things to think about blah...lol.

Footman
03-15-2009, 09:11 PM
BTW.... I always want to know, how do you granny shift from 4th to 5th? The ratios are further apart from 4th to 5th than from 5th to 6th, but from 5th to 6th it's one simply motion you just go down so it could be done faster than the shift from 4th to 5th.

if you granny shift 4th to 5th, wouldn't you always ends below RPM point in 5th when you release the clutch?

Can someone give some insight on this?

Rotary Mike
03-15-2009, 09:27 PM
I granny shift the majority of time. I think the previous owner did not.

rotarygreg
03-15-2009, 09:36 PM
BTW.... I always want to know, how do you granny shift from 4th to 5th? The ratios are further apart from 4th to 5th than from 5th to 6th, but from 5th to 6th it's one simply motion you just go down so it could be done faster than the shift from 4th to 5th.

if you granny shift 4th to 5th, wouldn't you always ends below RPM point in 5th when you release the clutch?

Can someone give some insight on this?


just blip the throttle before you release the clutch to bring the revs near where they should be and make it much smoother.

shazy
03-15-2009, 10:04 PM
Oh and I sometimes skip a gear, meaning that I go from 4th to 6th and I accidently do that, it rarely happens, but everytime I hear it, it's like my body cringes or something.

Just wondering on a side note, can we swap our rx-8 transmission for an rx-7 tranny?

rotarygreg
03-15-2009, 10:12 PM
Oh and I sometimes skip a gear, meaning that I go from 4th to 6th and I accidently do that, it rarely happens, but everytime I hear it, it's like my body cringes or something.

Just wondering on a side note, can we swap our rx-8 transmission for an rx-7 tranny?

just remember, if you are skipping gears, the syncro has to do more work than normal so shift slower. if you were to shift from 4th to 5th to 6th, at a given speed, say the revs would drop 1000rpm between 5 and 6. but the shift from 4th right to 6th would result in a much bigger drop in revs than from 5 to 6, so you should really be granny shifting and waiting for the revs to come down at least a bit before you make the syncro do the rest.

as far as i've heard an rx7 tranny wont just drop in. i would think at the very least you would need a custom tranny mount and driveshaft and really probably not worth the small gain in reliability you'd get for the cost of the swap.

Smokin_LaLa
03-16-2009, 08:49 AM
how about if your in gear, lets say third gear and you just shift to neutral without clutching is that ok?

Footman
03-16-2009, 08:51 AM
Smoking'.... dimsum this Sunday?

TheWulf
03-16-2009, 09:42 AM
as far as i've heard an rx7 tranny wont just drop in. i would think at the very least you would need a custom tranny mount and driveshaft and really probably not worth the small gain in reliability you'd get for the cost of the swap.

I thought the FD trannys were a direct swap?

R.P.M.
03-16-2009, 06:38 PM
Not at all, I've already had an FD trans side by side with our RX-8 6spd.

Rotary Mike
03-17-2009, 10:38 AM
The car is at the doctor's office now. We'll see what the damage is after it is fixed :(

Thumper3322
03-17-2009, 10:55 AM
Hopefully it's not to bad. Spoke to soon eh about not having any problems with your 8 :( go figure, that's the way it always happens.

Rotary Mike
03-17-2009, 11:26 AM
Well, Al and his team is taking care of things as always.

Great work guys!

Smokin_LaLa
03-18-2009, 11:48 AM
Smoking'.... dimsum this Sunday?

What time dude and where?

Footman
03-18-2009, 12:13 PM
11am, Kennedy/Steeles, at the back of Market Village. The restaurant name is "Ga Yan Gong" (in Chinese)...Rev-Illusions has been to that one before, so he knows too.

Bring your asian friends too...

Oh yeah, any other non-asians are welcome too because I love you all... honestly I do :)

Smokin_LaLa
03-20-2009, 12:12 PM
Hey man I should be good for Sun

Footman
03-20-2009, 01:44 PM
Okay, I'll start a new thread.