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4th Gear Syncro Gone?

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Old Mar 14, 2009 | 01:51 PM
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4th Gear Syncro Gone?

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?
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Old Mar 14, 2009 | 03:00 PM
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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.
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Old Mar 14, 2009 | 04:21 PM
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So if one is 300-500, how much are all 6?

I'll bring it in soon
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Old Mar 14, 2009 | 07:34 PM
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Check out Syncro savers
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Old Mar 15, 2009 | 06:02 AM
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I have this same problem I think I gonna have to take her in under warranty.
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Old Mar 15, 2009 | 06:55 AM
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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.
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Old Mar 15, 2009 | 07:56 AM
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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...
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Old Mar 15, 2009 | 12:35 PM
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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.
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Old Mar 15, 2009 | 06:05 PM
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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.
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Old Mar 15, 2009 | 06:13 PM
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Originally Posted by rx8thunder
Check out Syncro savers
Did you get this thunder? I have been looking at it.
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Old Mar 15, 2009 | 06:25 PM
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^ yeah, supposed to receive in another week or two
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Old Mar 15, 2009 | 06:30 PM
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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.
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Old Mar 15, 2009 | 06:41 PM
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Originally Posted by rx8thunder
^ yeah, supposed to receive in another week or two
Another toy lol!!

Originally Posted by rotarygreg
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.
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Old Mar 15, 2009 | 08:11 PM
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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?
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Old Mar 15, 2009 | 08:27 PM
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I granny shift the majority of time. I think the previous owner did not.
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Old Mar 15, 2009 | 08:36 PM
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Originally Posted by Footman
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.
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Old Mar 15, 2009 | 09:04 PM
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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?
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Old Mar 15, 2009 | 09:12 PM
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Originally Posted by shazy
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.
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Old Mar 16, 2009 | 07:49 AM
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how about if your in gear, lets say third gear and you just shift to neutral without clutching is that ok?
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Old Mar 16, 2009 | 07:51 AM
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Old Mar 16, 2009 | 08:42 AM
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Originally Posted by rotarygreg
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?
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Old Mar 16, 2009 | 05:38 PM
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Not at all, I've already had an FD trans side by side with our RX-8 6spd.
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Old Mar 17, 2009 | 09:38 AM
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The car is at the doctor's office now. We'll see what the damage is after it is fixed
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Old Mar 17, 2009 | 09:55 AM
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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.
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Old Mar 17, 2009 | 10:26 AM
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Well, Al and his team is taking care of things as always.

Great work guys!
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