3rd Gear Grinds?

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Nov 11, 2009 | 12:07 PM

#16

Alvin in AZ

Postmaster

Joined: Aug 2005

Posts: 2,760

Likes: 8

From: Gadsden Purchase

Quote:

Originally Posted by Praesul Presul

Consumer Info

Bottom of that page mentions something about sticky/dirty input shaft etc! :)

Here's the reply and the guy sounds like he knows what he's talking about...

Quote:

Reply:
Two very important items that I have come across over the years that can
cause the symptoms you are describing. First and by far the most common
cause is improper cleaning and lubing of the input shaft splines. Use a small
wire brush to clean all the accumulated gunk off the splines of the input
shaft, put a FINE coating of temp resistant grease on the splines and check
the splines of the new clutch disc to make sure there isn't a coating of
corrosion inhibitor on them. There should be no burrs, nicks, heavy coating
of any kind. Install the disc onto the input shaft and make sure it travels
smoothly. Even without the proper prep you could test the disc on the input
splines and all will feel fine. For this reason some may not feel the prep is
necessary. Warning: Even though the disc may already slip easily on the
splines, DO NOT SKIP THE STEP OF PROPERLY PREPPING THE INPUT SHAFT
SPLINES! I have seen techs get bit from this one too many times. For the
grease we use Amzoil synthetic.

The second problem could be the pilot bearing and input shaft tip condition.
Again, they should be in excellent condition so that the tip of the input shaft
cannot be grabbed by the bearing or bushing, which ever may be the case.
A little bit of grease here also. The first cause above that I described is a
surprisingly common problem. Be very careful in the prep of the input shaft
splines.

Also check the shifter seats. Some models of transmissions use plastic seats
at the pivot point of the shifter shaft that disintegrate from old age and can
cause various shifting complaints. It's just a matter of putting new seats in.
Total transmission disassembly is not required.

My ZF was having a problem with 3rd gear too and the salesman said...
"just give it a little time and it works fine, the guys get in a hurry and
grind third gear :)"

I found three things so far...
1) It had gear oil in it instead of ATF. :/
2) Slave cylinder was loose, bolts used were too short and had stripped
~1/4" of threads out of the bell housing (I installed 8mm studs;).
3) The pilot bearing is a crap design! :/ (going to use a 6003 ball bearing)
Maybe I should spring for the $50 Zoom Kevlar pilot bearing?

And now four since reading your link...
4) All the holes were wide open in the bell housing and the input shaft
etc were covered with thick+gooey grease, dirt and clutch disc dust.

A few different transmission guys I called said...
"call Loren, he really knows his stuff on ZF manuals :)"
...but can't get 'im to call me back. LOL :)
I'll post what I learn about it, might take a few days.

Thanks for the link, Presul! :)

Hmmm...
If I were you guys, I'd try spraying the splines with "brake cleaner" while
a helper worked the clutch pedal. Try not to get run over in the process,
it might hurt like hell. ;) I picture doing that at night using a flash light.
What do you think?
Worth a try?

Alvin in AZ
ps- Made a stand/tool that holds the ZF bell-up,
...from a 5 lug VW Bug wheel! Works great. LOL :)
pps- The 8mm studs are from aircooled VW heads.
ppps- Splitting the ZF case is a pie of cake. :)
pppps- All I have for a ZF rebuild manual is the '91 Ford Truck Shop Manual.

Nov 11, 2009 | 12:33 PM

#17

phillips91

Postmaster

Joined: Apr 2008

Posts: 4,724

Likes: 4

From: Rogersville, TN

Quote:

Originally Posted by propstrike

I know this, because i paid $2300 on a rebuild on my M50D2, and it didn't make much difference.

Just curious, but why was it that expensive??? A brand new tremec tko 600 is only about $1600. I had a t5 completely rebuilt(including new synchros) about 6 years ago and it was $250. My zf-5 grinds in 1st, 2nd and 3rd and they quoted me $750 to rebuild it and replace all the synchros. I can get the zf rebuilt for $500 if I take it out and put it back in myself.

Nov 11, 2009 | 08:23 PM

#18

bill11012

Modular motor junkie

Joined: May 2009

Posts: 6,190

Likes: 8

From: Texas

Quote:

Originally Posted by Praesul Presul

My first post obviously. Amazing how many Ford truck sites there are

.

My 02 F-150 4.6L/5speed 4x4, was bought new and has been a good truck. A couple years ago I noticed on a long drive at interstate speeds that when I downshifted or upshifted into 3rd that it would refuse to go in gear without letting RPM's come down. It has progessed to the point that yesterday was hot and grinded every time I hit 3rd. Pull over let it cool off no problem. Cold outside no problem. Drive for an extended period at speed (20+ minutes) or hot outside - grinds. No other gears do it, and as a Mustang owner too, I know 3rd is the one you tear up in those too - usually a bent shift fork. But once bent it is always bent, not like this which is obviously heat related.

Anyone seen this before? 3rd gear shift fork or syncho?

Also I have changed the fluid twice (syn) with no avail. Some told me heavier oil - no sure about that one. Right now its IV Mercon ATF is memory serves.

You should double clutch it, that will stop the damage from grinding it.

Nov 15, 2009 | 04:24 PM

#19

Kijutsu

Senior User

Joined: Jan 2004

Posts: 427

Likes: 0

From: allen park

Quote:

Originally Posted by Praesul Presul

My first post obviously. Amazing how many Ford truck sites there are

I've no experience with a manual in an F150, but my ranger does the same thing, and at one point the ranger and f150s used the same manual transmission, with the difference laying in either the alloys used in the gearing, or the gears themselves were heavier duty. nevertheless, I've been told lots of times that the synchros are going out and the trans needs a rebuild (180K on the trans). Try double clutching for shifting into 3rd, it may help, it has on my ranger. It got a lot better than I flushed it out and put ATF in it. When I bought the ranger is had heavy weight gear oil in it, and it refused to shift into gear at all when below freezing.

Nov 15, 2009 | 06:01 PM

#20

whimsey

Senior User

Joined: Feb 2004

Posts: 303

Likes: 0

From: "Garden State"

Quote:

Originally Posted by Praesul Presul

Well I don't see what they are talking about or my truck isn't leaking in this area. Needed to report I tried the Royal Purple Syncomeshmax fluid and things are the same.

I have had some other recommendations - tell me what you think:
1. Change to 75w-90 gear oil
2. Overfill the transmission

Once again as long at the fluid/transmission is cool, no grinding, so it is without a doubt a temperature issue.

Don't use gear oil, it could harm the "yellow" metal in the tranny. Use a Manual Tranny fluid such as Amsoil's. They offer a manual tranny fluid that is basically a 75W-90 fluid that is safe for trannies. I also believe Red Line offers a similar manual tranny fluid. Don't go with too thick a fluid. From what I understand it could cause lubrication problems.

The Royal Purple Synchro Mesh fluid only stopped my grinding going into 3rd 95% of the time, still will do it in the summer if I try to shift quickly. The tranny still shifts like *****. It's like trying to move a broom handle through a bucket filled with golf *****. It's real notchy, never smoth unless it's real cold outside. But once the tranny warms up it's back to notchy. Yet my 1989 F-150 with the same tranny was as smooth as butter with the ATF all the time