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  #1  
Old 04-23-2013, 01:17 PM
davidmij davidmij is offline
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Default Manual shift trans is grinding.

The other day I was driving my car, it has a 4 speed toploader. While sitting almost still I was trying to get it into gear and it seemed as though the linkage was binding - it wouldn't shift into any gear. I stopped completely and put some arm into it, double clutched and it seemed to unbind. It was shifting normally again.

I drove down the street through all 4 gears, when I started to slow down I tried to down shift into 3rd but all it would do is grind. I'd double clutch, and slow down, but it would still grind. I could downshift into 2nd OK and then even 1st. Up shifting is no problem, it goes right through all the gears as normal. But whenever I try to downshift from 4th to 3rd it grinds.

Anyone have any idea whats going on? Did the binding shifting cause a problem with the syncro?

thx, Dave J
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  #2  
Old 04-23-2013, 01:34 PM
KULTULZ
 
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1) Clutch Dragging (Adjust) Or Worn

2) Shift Linkage Out of Adjustment And/Or Linkage Bushings

3) Bad Blocking Rings

Is it a fingered or diaphragm pressure plate?
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  #3  
Old 04-23-2013, 01:40 PM
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simplyconnected simplyconnected is offline
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Your shifter linkage bushings are either too sloppy or they aren't set correctly.

Shifter forks in the trans are detented. If you shift very slowly, the fork may not return to neutral before the shift lever engages the next fork. This creates a 'binding' situation, especially if the fork is still in 2nd but the shifter already let go of that fork and is trying to move another fork.

Because the gears are detented, shifting a little faster will seem to make the situation go away.

Pull the shifter linkage rods off your rock crusher and see where they naturally 'fall' with the shifter in neutral. I used to pin my Hurst shifter in neutral with all the 'tabs' centered. Adjust the rods so they easily slip over the trans studs when they are in neutral as well.

If the shifter still leaves a gear before it is returned to neutral, rebush the shifter linkage. - Dave
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  #4  
Old 04-23-2013, 08:38 PM
davidmij davidmij is offline
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Gary and Dave, I know next to nothing about transmissions so I don't know if it's a "fingered or diaphragm pressure plate. It's a 1969 1 3/8 input and output close ratio trans - tag number RUG-AJ. I bought a basic (refurbished) flywheel, clutch, pressure plate and throwout bearing all from the same place - they are supposed to be for correct for a 1969, and I'm pretty sure they are because they went in no problem and have worked well for about 200 miles.

The shifter is a refurbished Hurst super shifter I got on e-bay - it looked brand new. All the bushings etc. looked brand new as they should with a rebuild.

I bought the linkage brand new from Hurst, I called them and they helped me get the correct stuff - fit like a charm. That was pricey stuff!

I adjusted the linkage before installing the trans. I used the Hurst instructions with the plastic pin to align the shifter in neutral. I then adjusted the lengths of the rods to go on to the shift studs as easily as possible. I then set the stop bolts according to the instructions.
Next I taped all the linkage rods together so they wouldn't turn or move any when I removed the shifter from the trans before stabbing the trans.

I just got back from a ride and it seems to be a little better. It now will down shift from 4th to 3rd but it makes a bit of a "crunch" instead of just grinding. Just to reiterate, it does fine up shifting and down shifting except for down shifting from 4th to 3rd.

I'm guessing I should start by undoing the 3/4 gear rod and readjusting it to make sure it's positioned correctly.

Dave, what's a "rock crusher".
Gary, what are "blocking rings".
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  #5  
Old 04-24-2013, 06:45 AM
KULTULZ
 
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Quote:
Originally Posted by davidmij View Post

I'm guessing I should start by undoing the 3/4 gear rod and readjusting it to make sure it's positioned correctly.

Dave, what's a "rock crusher".
Gary, what are "blocking rings".
Correct, ascertain correct linkage adjustment and clutch adjustment. A hanging clutch will cause drag inside the trans.

Blocking rings are at the synchronizers and slow the gear(s) to mesh correctly. If you were "double-clutching" and the shifts were better, you have a drag or bad blocking rings/synchros.
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  #6  
Old 04-24-2013, 10:33 AM
davidmij davidmij is offline
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Thx Gary,
yeah, double clutching, triple clutching and clutching over and over again makes no difference. Even revving the rpm's to match the speed of the wheels turning doesn't help.

I adjusted my clutch linkage per my 1959 T-bird shop manual. I'm not sure that is the way to go being that I have a 1969 trans and a Lakewood bellhousing. I also had to fabricate my Zbar and linkage because I couldn't find exact parts. It all worked great for a while and I believe it is OK. Although my clutch push rod between the Zbar and the clutch fork angles downward - I'm not sure if it is supposed to be like that or if it should go more straight in. I would think it should be straight as possible.

I'll try adjusting the 3/4 linkage this weekend and see if I get any better results.

thx!
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  #7  
Old 04-24-2013, 05:16 PM
KULTULZ
 
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Check all of the clutch linkage also to make sure something hasn't failed.

Get back to us...
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  #8  
Old 04-28-2013, 02:22 PM
davidmij davidmij is offline
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I pulled all 3 shifter linkages and readjusted them. Reverse needed one turn and so did 3rd/4th, but they were very close to where they should be so naturally it didn't help any.

The clutch linkage looks like it always has so I don't think that is a problem. If it was the clutch linkage I would expect it to grind when I down shift to 2nd and/or 1st also, but it only does it on a downshift to third from 4th.

I read a couple of things on line about using synthetic oil instead of gear oil. They said that can loosen things up sometimes. Others said that it can also cause problems such as the tranny jumping out of gear on its own. Any thoughts on this gents?

thx, Dave J
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  #9  
Old 04-29-2013, 04:35 AM
KULTULZ
 
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If you are FULLY SATISFIED THE LINKAGE IS ADJUSTED CORRECTLY and there is no clutch disc drag and the problem is only with 3rd - 4th, I am going with a 3-4 synchronizer and or blocking ring.

-DAVID KEE TRANSMISSION LUBRICANT INFO-

ADDENDUM From HURST-

What is the proper way to adjust my Hurst four speed shifter?

There is a 1/4 inch hole at the bottom of the Hurst mechanism that runs through all three levers. This is called the neutral alignment hole. To ensure proper adjustment, run the shifter from first into second and then back to neutral. Insert the neutral alignment pin (or a 1/4 inch drill bit) into the neutral alignment hole. If the 1-2 lever interferes with the smooth insertion of the alignment pin, remove the 1-2 linkage rod from the shifter and thread the adjuster button either in or out to eliminate the interference. Repeat this procedure with the 3-4 lever and reverse. To adjust the stop bolts, back the bolts out of the shifter frame until only a few threads remain. Push the stick firmly into third gear and hold. Screw in the stop bolt until contact is made. Release the stick and back the stop bolt out one turn and tighten the jamnut. Push the stick into fourth gear and repeat the procedure.


Rule of Thumb-

Cast iron cases take gear oil, aluminum cases take ATF. A synthetic may cause hard shifting.

Last edited by KULTULZ : 04-29-2013 at 04:56 AM. Reason: AD INFO
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  #10  
Old 04-29-2013, 10:54 AM
davidmij davidmij is offline
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Thx Gary, I used the instructions Hurst sent with the shifter linkage, they are basically the same as you sent, and I am certain the shifting is adjusted correctly.

The info from David Kee's site is good to know, thanks for that.

Being that it is only a problem when down shifting to 3rd I'm guessing that what you said about the "3-4 synchronizer and or blocking ring" is most likely the problem. According to the link I sent below clutch drag could ruin my syncros.

Also, I'm not too sure about my clutch. Being that my Z-bar, and Z-bar engine side mounting bracket are custom made pieces I'm not sure if the pedal throw is optimal. I looked up "clutch drag" and found this short article; http://www.jackstransmissions.com/pa...kills-synchros
I have been driving it fairly aggressively, (that's kind of why I built this car). My clutch fork push rod does not go into the clutch fork perpendicularly, it points more downward. If I were to make the Z-bar lever about an 1 1/4 inches longer it would be close to perpendicular. Does that make sense? That would give me more pedal throw too.

I'll take some pictures after work today and try to post them, but it's hard to get in there with the camera. I might draw it up and post a scan of that instead.

I also get a bit of stutter or shimmy when I let out the clutch at lower rpm's in first gear. If I have the choke engaged it runs at a higher RPM and does a lot better. Could that be telling me anything? My idle is set at about 750 RPM.

thx again, Dave J
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