Manual shift trans is grinding.

[davidmij]

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

[KULTULZ]

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?

[simplyconnected]

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

[davidmij]

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".

[KULTULZ]

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.

[davidmij]

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!

[KULTULZ]

Check all of the clutch linkage also to make sure something hasn't failed.

Get back to us...

[davidmij]

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

[KULTULZ]

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.

[davidmij]

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

[KULTULZ]

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/pages/clutch-drag-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

I would re-check the linkage, especially if fabricated. If you have a three finger pressure plate and the fingers are not depressed equally, it could warp the plate and/or the disc.

That sounds like the main problem. The fingers have to be depressed equally or the spring pressure is going to warp something.

Maybe consider going to cable actuated?

It takes a really hard man to break a F/4/S...

[DKheld]

Getting hotter (summer) so maybe your oil viscosity needs to be changed? Makes a big difference in the small 4 speed gearboxes I am more familiar with (although the top loader would probably take up the whole engine compartment on my "other" car - an MGA)

There is always a lot of discussion on oil types causing shift problems on the MG forum. Those cars use engine oil for lubrication (20W50). One fellow (who has owned his car for 50+ years) tries different types of oils and lubricants and gives his impression of the product.

For example this was his review of a synthetic product: "Several years ago I tried Redline MTL in my MGA gearbox for a 12,000 mile test. Immediately I didn't like the way it shifted, having to ham fist it to avoid grinding. The racer types might like that effect. I was very happy the day I drained it and returned to using 20W50 oil in the gearbox returning to finger tip shifting."

I was suprised to see that David Kee site recommends gear oil for the top loader - would have thought they had the same style gears as the MG (only bigger) and used engine oil - oh well - live and learn - now I know.

Hope you don't have to pull the tranny and install a new syncro.

Good luck,
Eric

http://www.davidkeetoploaders.com/specifications.htm

[davidmij]

Thx Eric and Gary.
I just realized I could give you this link and it will show you my Z-bar, bracket, and fork. If you look at pictures 54 through about 58 you can see that the pressure from the push rod to the clutch fork is tilted downward. However it seems to me that the throw out bearing would still be even on the 3 clutch fingers because the throw out bearing is held straight by the tranny shaft.

Hm, actually I guess the throw out bearing isn't a super tight fit to the trans shaft though. And even the slightest uneven pressure on all 3 fingers would cause a problem just as you say Gary. Although the fork only hits 2 places on the throw out bearing so once again it should be even pressure.
Thinking about that, and then what the article I posted said about the syncros getting torn up very easily - I wouldn't doubt that this was the cause and the effect from my off angle push rod and clutch fork connection.

Eric, I read a few things that suggest the same thing you are saying, and the past 2 weeks the temperature here has gone up from the 40's to the 70's. Night time lows were still freezing until the last week. With that, changing the viscosity is a quick easy try so I'll do that this weekend and see. I'm using straight 90 weight right now, maybe changing to 75-90, or trying the 20-50 oil.

Let me know what you think from these pictures Gary if you don't mind, and thx again.

https://picasaweb.google.com/101492851059660555641/StreetRatProject?authuser=0&authkey=Gv1sRgCJSKjNbR6eunsgE&feat=directlink

[DKheld]

That's a cool build. Thanks for letting us come by your shop - even if it was "electronically"

I love that home-brewed slide hammer

Yeah - the other guys may know more about the linkages. The linkages on my MG's are enclosed and of course stock so no need for the mods like you are having to deal with.

On the oil thing - the main reason we don't use hypoid gear oil in the MG transmissions (which look similar only smaller) is that the EP (extreme pressure) additive sulfur stuff in the hypoid gear oil eats away at our brass synchro's and gear selector forks. Kind of looks like a brass syncro in your tranny (uh-o) but the expert dude recommends hypoid so just not sure on that.

Eric

[KULTULZ]

It is difficult to tell whether the clutch linkage is binding/deflecting by the photo(s). You have a one piece blow shield? One cannot look @ clutch operation with one (no inspection cover).

I hate to say it but you may have to pull the trans to check for any irregular clutch component wear and check the synchros/blocking rings while down.

The brass toothed rings in your photo are the blocking rings and the steel is the actual synchro.



ALMOST FORGOT-

Go with the lube recommendations of the David Kee site. Usually, in this hemisphere, heavier engine oil usage is usually restricted to heavy truck transmissions. The F/4/S is meant for gear oil and the multi-grades are much better than the older straight weights (75W until the rear reaches operating temp and it becomes 90).

I have overhaul tech articles if you need. That dragging clutch tech article you found was great.