3 to 4 shift.... drivetrain lockup???

I've been having issues with the 3/4 shift. Last year I was just botching the shift by trying to hurry and powershift. I started concentrating more on the shift and taking my time with it which works 4 out of 5 times. When I do botch it, it just won't go into 4th. Yesterday, when I shifted to 4th, it locked up the drivetrain with a huge crunch and tire squeel and sent me spinning out of the NASCAR oval into the infield. I was concentrating, breathing, taking my time and shifting slowly. Once I came to a stop, I shifted into first and took off... all the way through 4th so I didn't scrap the tranny and it shifted smoothly and sounded fine....

What happened? Is this a clue that somethings going south in the tranny or something that needs adjustment???

I'm not the only driver of the car that's having the 3/4 shift problem. A very well known driver that's driven every type of car you can imagine and has been driving for decades is occasionally having the problem as well.

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Scott
It's not what you build...
it's how you build it

<A HREF="http://www.pfmracing.com" TARGET=_blank> http://home.swbell.net/srhea66/PFMSigPic.jpg
www.pfmracing.com </A>

I seems pretty obvious to me that something is amiss witht he transmission. I woul ddefinately swap it out with another one and give the old one a teardown to see what exactly is going on. First gen trannys should be a dime a dozen I would think.



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Paul D'Angelo
73 ITS CENDIV
Indy Region
www.iridiumracing.com

3RD GEAR SYNCRO IS BAD

Quote:

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Originally posted by 7'sRracing:
3RD GEAR SYNCRO IS BAD

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Is it for sure the synchro or the shift fork. I think either would cause that.

Scott, I am not a betting man, BUT, ifen I was a betting man the end result sounds like you went into second gear presuming the shift was a 3rd to 4th. That works better than stepping on the brakes & ya get to see where ya just came from. http://Forums.ImprovedTouring.com/it/redface.gif Now ask me why I'm saying that & I'll tell ya.

Have Fun http://Forums.ImprovedTouring.com/it/wink.gif
David
CenDiv
Spec-7 # 14

Daryl, how do ya determin if it's the syncro, the levers, or ect. without taking the trans apart?

Either that or you managed to get two gears at once which is a very remote possibility. If you get two together you've effectively locked the input/output and counter shafts together. Stepping on the clutch won't even do ya any good. Might as well pull the e-brake.

Chris

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Chris Ludwig
08 ITS RX7 CenDiv

Quote:

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Originally posted by ddewhurst:
Scott, I am not a betting man, BUT, ifen I was a betting man the end result sounds like you went into second gear presuming the shift was a 3rd to 4th. That works better than stepping on the brakes & ya get to see where ya just came from. http://Forums.ImprovedTouring.com/it/redface.gif Now ask me why I'm saying that & I'll tell ya.

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Well, I wouldn't doubt it and unfortunately there's no video, but wouldn't that have zinged the motor pretty good (was shifting at 7,200 Rs). I don't recall the motor revving. Maybe the recall tach would show us something if that be the case.....

The first thing I assumed after the race was that I had hit two gears at once. The fact that myself and another driver are occasionally having problems with 3/4 led me to wonder if it was an adjustment or fixable issue.

I don't think there is much in the way of adjustment in the mechanism. Maybe a wear issue allowing some sloppiness?

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Chris Ludwig
08 ITS RX7 CenDiv

Been there, done that. Just like David. http://Forums.ImprovedTouring.com/it/wink.gif Maybe you got two at once, but man when you go to 4th and you get 2nd, it's a miracle if nobody rams you up to your axle! It is such a shock, and as you are expecting, and preparing for, acceleration, it feels as though you stuffed a wall when 2nd hits.

That said, I have had all kinds of troubles caused by a clutch at the end of it's wear limits. It would be grabbing fine, but it would feel like the synchros were trashed.
How easy does it go into reverse? If you have to wait a bit, the clutch might be the culprit.

Just some thoughts....

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

Get over on the Spec Miata page (Blasphamy I know), I've seen at least two Miata's do the same thing and they share most of the guts from an RX7 tranny. From what I've heard it is a thing with two gears engaged at once. Don't know the cure. The SM guys might know more.

Quote:

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Originally posted by lateapex911:
I have had all kinds of troubles caused by a clutch at the end of it's wear limits. It would be grabbing fine, but it would feel like the synchros were trashed.
How easy does it go into reverse? If you have to wait a bit, the clutch might be the culprit.

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Well, the clutch is only a year old Centerforce Dual Friction, but that's definitely worth checking. The cars been driven quite a bit by several different drivers this year.

I only tried to put it in reverse once and it did grind, but I was a little frustrated while doing it http://Forums.ImprovedTouring.com/it/wink.gif

I will definitely check out the SpecMiata (bleah http://Forums.ImprovedTouring.com/it/biggrin.gif) page for some info...



[This message has been edited by Speed Raycer (edited July 28, 2003).]

Scott, you do need to get the tranny rebuilt as it sounds like there may be a few things amiss in it. A Loose shift fork, or worn bearings will cause things to misalign especially in a quick shift, resulting in problems as mentioned above. A cheap tranny rebuilder will throw some syncros at it but a good rebuilder will also check for bearing wear and will more than likely change them. Or you could do what I used to do. Trannys were plentiful back in the days so I would swap one out every few races because that's about how long they would last http://Forums.ImprovedTouring.com/it/biggrin.gif Not a good plan. Trannys from a boneyard, or even the ones you get from some dude that claimed the tranny was in a car yesterday, are going to have some righteous miles on them so they should probably get a rebuild before you put it in your car. JMO.
Ray

Chris, if the shots turned out from Gingerman please send to [email protected]

Thanks http://Forums.ImprovedTouring.com/it/wink.gif
David
CenDiv Spec-7 # 14

Just gank another tranny from a first gen.. those trannies are a dime a dozen.. I had something like ten at one time.