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Discussion Starter · #1 ·
Are any of you having problems with synchronizing gears? I have been told, and have had a sneaky suspesion, that maybe the high torque of the motor is too much for quick shifting on the crappy brass rings.

I have broken 2 and I am about to get really pissed. I am going to have them fixed, and put in another clutch, (Centerforce II), but I would like to replace them with a beter than stock part. Anyone have any ideas?

I've snapped 2nd and 3rd gear now. The 2nd gear ring had hardly any wear on it at all, it just snapped in two. All of my linkage and moving parts are in good order, I've already had them all checked out. I just keep running accross a weak link, the synchros. I had 2nd gear fixed, and everytime I go to shift into 2nd, I have to wait a split second, before I actually go into 2nd. It's like there is a wall, and then it just slips right in. I can shift just as effeciently without the clutch as I can with the clutch. I broke the synchros, both times while using the clutch, but have never broken one while speed shifting witout it.

Any help would be greatly appreciated. I have been dealing with this gremlin for over a year now, and he keeps showing his ugly, and VERY expensive head.


Chris Behney
Redline Autosports
 

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RE: Chris, it is the way you drive....

Chris,
As you know I have the 3.1 as well, about the same hp as you too. I initially toasted my syncros in my first 5 speed, but that was b/c I had the wrong shifter,(gotta have the 78 shifter to use the 5 speed in a Z). anyways, you say you broke the syncros while using the clutch, but you have posted here about that when you race, you do speed shift, and therin lies your answer. the zx box just cannot take speed shifting. period. it has nothing to do with the power of our motor, although that does accelerate it, you speed shift it, it tears up the brass syncros. if you are sick of paying the high price, call nissan motorsport and see if they still sell their comptetion box that has steel syncros. it is listed as
FS5C71B w/ the close ratio part number as 32010-N3130 and the wide ratio being listed as 32010-N3030. Remember these boxes only have a .864 overdrive vice the ~.75 we have. It states that the FS5C71B and the F5C71B,(1:1 5th gear), as both utilizing the servo-type (steel) ,synchro mechanisim. The number to them is 1-310-538-1462 They have an 800 number but i can't find it, and they only want orders on that line, tech support you gotta pay for.
Bottom line, powershifting will kill your tranny, especially if you are just slamming it in and not even using the clutch. no ifs and or buts. i did it a couple of times trying to post a base line for my z at the drags,(got one w/out powershifting, open 3.54, cheap-o tires, late ZX 5 speed, 13.8 at 99). I I expect to be in the low 13's, maybe 12's if when I get the 4.11 or 4.38 LSD and sticky race tires,(autocross ones, but much better than my $40 specials).
anyways, i hope that gives you something to go off of. Good luck, and you can get the times w/o breaking the tranny.
-Bob Hanvey
 

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Discussion Starter · #3 ·
RE: Anyone with a 3.1 please read and help me ou

You better start practising your shifting because trannies mentioned by Bob are no longer available. However, they may still have some service parts left for comp. trannies.
FYI. They don't have 800 number.
 

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RE: Speedshifting is THE gremlin....

...Those 5 speeds are not designed to be speed shifted. As the other posters said, the brass rings can't take it. It isn't so much the matterial as it is the thickness of the Syncro. They aren't designed to be abused like that and if you don't think so then just keep speed shifting, but start collection 5 speeds because you are gonna need them.... And remember, when thpse parts break they can easily take out other gears and completely lock the trans, which can transmitt the load right back to the motor..... Bad news......
Your options are two: Fix what you have and quit speed shifting or Get real good at swapping trans...

Check with Richmond gear, they may have steel syncros in your size.....But I would quit speed shifting.

Good Luck ....
Mike
 

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RE: Speedshifting is THE gremlin....

If it's that bad..and you absolutely must (I know the feeling but resist) then why don't you look into having them made at a machine shop. There are tons of general machine shops that will carve anything you want out of anything you want it carved out of..it's just metal to them. If you know a draftsman/engineer get him to draw up a sheet on it and set it in front of a good machinist. Once you get the syncros stronger you can then move on the the next weak link, where ever that happens to pop up, because it will. Speed shifting is death to a tranny! I have seen quite a few and heard of more T-10s and rock crushers that were smashed to bits by big blocks on drag strips, that's just a fact of drag racing. You will just have to get use to it. A friend of mine put it "them clutches just keep ya reachin in that back pocket fo mo!" That's why all the Chevy and Mopar boys have worked over autos at the strip with high stall converters and trans brakes.

Ken
 
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