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Old Jan 6, 2011 | 01:50 PM
  #1  
f350rebel7788's Avatar
f350rebel7788
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Grinding gears...

my 94 standard grinds almost everytime i shift into reverse. i've tried experementing, and putting it in gear before i start it, and when i do that it usually works fine (no grinding) but if i start it, then shift, it grinds every time and i have to play with it to get it into gear. it almost seems like the shifter is going too far to the right and passing the gear. anyone have experience with that kind of problem??? also, when i downshift from 3rd to 2nd it grinds as well. any help you guys can give is greatly appreciated!!
 
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Old Jan 6, 2011 | 01:58 PM
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Syncros going bad?

If you downshift from 3rd to 2nd without using the clutch does it still grind?
 
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Old Jan 6, 2011 | 02:02 PM
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yup, using the clutch, not using the clutch same thing...
 
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Old Jan 6, 2011 | 02:36 PM
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its a stretch especially in more serious situations like your but you could try draining the fluid and replace with some top quality synthetic. sometimes it will bring back the synchros some.

-cutts-
 
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Old Jan 6, 2011 | 03:38 PM
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I was going to say that your bushings in your pedal assembly was going out and not fully disengaging your clutch, but if you are still getting the grinding while shifting without your clutch pedal then I would agree that your syncros are going bad. You can also swap out fluids and add a tranny additive to get a little extra time out of it before it fully goes out on ya.
I would also say there is no way for the shifter to go past the spot it needs to go because of the design of the tranny. Our trannys use shift forks and I just don't see that happening.
Also try shifting from third to second below 20mph, if it doesn't grind then i would lean towards syncros going out.
 
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Old Jan 6, 2011 | 04:01 PM
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what exactly is a syncros???
 
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Old Jan 6, 2011 | 05:00 PM
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this explains it better than i can and with pictures... skip to paragraph 4

How a Transmission Works

-cutts-
 
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Old Jan 6, 2011 | 06:44 PM
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Originally Posted by rn360908
I was going to say that your bushings in your pedal assembly was going out and not fully disengaging your clutch, but if you are still getting the grinding while shifting without your clutch pedal then I would agree that your syncros are going bad. You can also swap out fluids and add a tranny additive to get a little extra time out of it before it fully goes out on ya.
I would also say there is no way for the shifter to go past the spot it needs to go because of the design of the tranny. Our trannys use shift forks and I just don't see that happening.
Also try shifting from third to second below 20mph, if it doesn't grind then i would lean towards syncros going out.

That's my vote.
 
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Old Jan 6, 2011 | 09:59 PM
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Syncros are just friction breaks inside the tranny that slow down the gears on the main cluster gear shaft and allow the gears to mesh easier to the gears for the output. The syncros are made of a wear material that is softer than the steel that makes up the main cluster gear shaft; this material is normally either a brass alloy or a composite material bounded to a steel ring. The main cluster gear set has several syncros installed on it, for our tranny it would have 6 syncros, five forward and one for reverse. You can now probably see that syncros are designed to wear out first to prevent having to buy new gears when your tranny needs to be rebuilt.
 
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Old Jan 6, 2011 | 10:10 PM
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This explains it best

YouTube - Turbulator
 
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Old Jan 6, 2011 | 10:34 PM
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Originally Posted by Gagew90
This explains it best

YouTube - Turbulator
OMG That's so funny, but the problem is that I bet there are people out there that would believe that guy, and I have no idea how he was able to keep a straight face
 
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Old Jan 6, 2011 | 10:42 PM
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Originally Posted by fishmanndotcom
its a stretch especially in more serious situations like your but you could try draining the fluid and replace with some top quality synthetic. sometimes it will bring back the synchros some.

-cutts-
It should already have synthetic in it. If it doesn't, that may indeed explain the behavior. For that matter, if there's dino ATF in it, it should be replaced as a matter of course, grinding or no grinding, since dino is not to be used in the ZF5.
 
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