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5th gear impending warning signs

Started by Jay Lutz , 12-03-2012 03:45 PM

gearbox

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6 replies to this topic

#1
Jay Lutz

Posted 12-03-2012 03:45 PM

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Location:Indianapolis/St. Louis
Region:St. Louis
Car Year:1994
Car Number:33

My friend called me from Road Atlanta last Friday with news of his 140k mile SM gearbox stuck in 5th gear. No complaints but are there any cockpit warning signs of this problem? I wasn't in the car.

Thanks, Jay

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#2
Bench Racer

Posted 12-03-2012 06:22 PM

Different strokes for different folks : )

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5,508 posts

Location:Wauwatosa, WI
Region:Milwaukee
Car Year:1990
Car Number:14

Understand you said stuck in 5th. The same shift fork does reverse and 5th. For a quick check, try this.

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#3
SaulSpeedwell

Posted 12-03-2012 07:18 PM

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792 posts

Location:NEOhio

The interlock mechanisms make it impossible for the box to be in more than one gear at once ... thus, a "stuck" box is almost always a result of the shifter "escaping" the shift selectors due to wear.

The solution:

http://youtu.be/UX4eNxaNztc

I love "The King" and his videos! But understand his "fix" is simply putting the box into neutral so that the shifter can be returned to its proper home in the 3-4-Neutral gate ... the true fix is to put in new shift selectors to keep the shifter from "escaping" in the first place.

For faster reply than PM: miataboxes>>>AT<<<gmail>>DOT<<<com

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#4
davew

Posted 12-03-2012 09:34 PM

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2,297 posts

Location:Beloit, Wi
Region:Chicago
Car Year:1999
Car Number:72

It is very common with 1.6 boxes, especially early ones, to get stuck in either 5th or reverse. Reverse being the more common.

First, determine exactly what happened. If it is truely stuck in gear, which gear. Easily let the pedal out and see which direction the car wants to move.

Does the shifter move. Can you also engage 1st or 2nd? If so, put in 1st or second and slowly release the clutch. Car should not move as it will be in 2 gears at the same time.

If it is stuck in 5th/rev. You can remove the back up light switch and using a stubby screwdriver, pop the linkage back into neutral. This will allow the car to be shifted normally. But I recomend rebuild.

There have been numerous updates over the years to cure this exact problem. That is why I have a complete list of the most recent part#s on my website.

If this does not describe your problem, the box will need to be disassembled. You probably have broken the 5th gear hub clutch and possibly twisted the bak section of the cluster shaft.

Assuming a 1.8 diff: By the way, did he have a bad vibration just before the failure. If so, he probably broke the vibration damper on the pinion snout. This will damage 5th gear everytime if it is not addressed right away. This exact issue is what dropped Tom Brown from 7th to 12th at the Runoffs. I have written a letter to CRB requesting to allow this to be removed

Dave

Dave Wheeler
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