ZF issue?
Lead Driver
Joined: Feb 2002
Posts: 7,966
Likes: 595
From: Greater Austin, Texas
Mine has the opposite problem - I get a quick little "grunch!" sound when upshifting to 2nd or 4th about half the time. I also switched to Mobil Synthetic ATF and it didn't help, but it doesn't seem to have made it worse. Mine is for sure a synchro going, if I shift to neutral, pause, then go to 4th, it doesn't do it. But it's been a couple of months now and it hasn't gotten any worse, so for now I am just ignoriing it.
Elder User
Joined: Mar 2006
Posts: 627
Likes: 0
There are sliders on the mainshaft that are composed of a sliding sleeve, synchro body and synchro. When the slider moves toward the gear when you shift, the synchro, through friction, equalizes the speed of the gear and the mainshaft so the gears don't grind. The synchro you're looking for should be on the back side of 2nd gear on the mainshaft and you may be able to see it from the PTO port. Look at #s 52-61 in the diagram:
Last edited by gustang818; May 4, 2007 at 10:45 AM.
Thread Starter
|
Posting Guru
Joined: Nov 2005
Posts: 2,442
Likes: 1
From: La Grande, OR
how hard would that be to change out a synchro? would that be something that someone with average to good mechanical knowledge be able to tackle? or are we talking transmission shop?
Elder User
Joined: Mar 2006
Posts: 627
Likes: 0
Nighthawk:
You know what you are doing and I'm sure you could replace a synchro. I don't necessarily think this is something that has to be done by a shop. You just had the trans rebuilt so the bearings seals, etc. should be in good shape. Years ago I put new synchros in a 4 speed Muncie M-21 and it was a 2 hour job. In the Ford shop manual the ZF looks a little different and more involved. You remove the bolts holding the rear case on the transmission and lift the front case straight up. You then have the "gear pack" -mainshaft, countershaft, and shift rails sitting in the rear case. Ford has a special tool called "gear pack holding fixture" and nylon sling that are placed around the gear pack and the assembly is then removed from the rear case. Once it is removed, you could take the mainshaft out and replace the synchros. I could scan the ZF transmission disassembly/assembly instructions and email them to you if you decide that's what you want to do. Send me a pm or email with your address. I've learned if it's got t!ts or tires it will give you trouble.
What about the place that rebuilt the trans? Will they fix it?
You know what you are doing and I'm sure you could replace a synchro. I don't necessarily think this is something that has to be done by a shop. You just had the trans rebuilt so the bearings seals, etc. should be in good shape. Years ago I put new synchros in a 4 speed Muncie M-21 and it was a 2 hour job. In the Ford shop manual the ZF looks a little different and more involved. You remove the bolts holding the rear case on the transmission and lift the front case straight up. You then have the "gear pack" -mainshaft, countershaft, and shift rails sitting in the rear case. Ford has a special tool called "gear pack holding fixture" and nylon sling that are placed around the gear pack and the assembly is then removed from the rear case. Once it is removed, you could take the mainshaft out and replace the synchros. I could scan the ZF transmission disassembly/assembly instructions and email them to you if you decide that's what you want to do. Send me a pm or email with your address. I've learned if it's got t!ts or tires it will give you trouble.
What about the place that rebuilt the trans? Will they fix it?
Thread Starter
|
Posting Guru
Joined: Nov 2005
Posts: 2,442
Likes: 1
From: La Grande, OR
that place will probably fix it, only problem is, I'm here in LaGrande at college, and the place I had rebuild it is 300 miles back home... If you could do that with the instructions, that'd be great, I can do this this summer when I have some downtime.....This probably can't be done in-frame can it?
Did you get that image out of the shop manual?? As I was looking at it, there at the bottom, it said that the taper was too smooth after a few thousand miles, and to try some hard shifts at high RPMs and see if that fixes it... I tried it, went up to 4200RPM (cringe) in first, shifted to second, went to 4200 again (cringe more), and then up to third. Did that a few times, and for now, I can downshift again normally, so it might be fixed for now, but that's probably an indication of them being going and it'll need to be done soon.
Did you get that image out of the shop manual?? As I was looking at it, there at the bottom, it said that the taper was too smooth after a few thousand miles, and to try some hard shifts at high RPMs and see if that fixes it... I tried it, went up to 4200RPM (cringe) in first, shifted to second, went to 4200 again (cringe more), and then up to third. Did that a few times, and for now, I can downshift again normally, so it might be fixed for now, but that's probably an indication of them being going and it'll need to be done soon.
Elder User
Joined: Mar 2006
Posts: 627
Likes: 0
I don't think it's possible to replace the synchros without removing the trans. I can get you a copy of the instructions in PDF format. It will take a while to scan so I won't have it together tonight or maybe even this weekend. Let me know where you want me to send it. Yes, that info came out of the shop manual and that corrective action looked like the most fun way to try to fix a problem that I ever saw in a shop manual.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Postmaster
Joined: Oct 2006
Posts: 4,816
Likes: 1
From: Davis & Newcastle, CA
Hey nighthawk I asked my brother about your problem. He's got a 97 F250 Powerstroke with ZF and he said you problem is pretty common amongst ZF owners. He frequents a forum on ford-trucks.com under the avatar PSDFreak. Anywho, he said a lot of ZF's have problems shifting down into 2nd and most guys just avoid doing it all together. My brothers ZF, though, usually has no problem shifting into 2nd, but he still says he doesn't do it since 3rd rides him down far enough. He says that most say the ZF should take ATF (like you put in) but he uses Redline MTL and his transmission loves it. So he recommended that you change your fluid to MTL and fill it through the boot in the cab, as opposed to the fill plug on the tranny; this way you can get a full 4 quarts in, instead of 3 1/2. A gallon of MTL should cost you $20-$25. I trust my brothers opinion, hes quite the wizz when it comes to the 7.3L and the ZF, although not ALWAYS right 
. I figured this would be worth a try before you dump money into replacing the synchros. Keep us posted on what you find out.
-Chris
. I figured this would be worth a try before you dump money into replacing the synchros. Keep us posted on what you find out.-Chris
Last edited by Skandocious; May 5, 2007 at 04:25 AM.
Postmaster
Joined: Oct 2006
Posts: 4,816
Likes: 1
From: Davis & Newcastle, CA
You can use their dealer search on the site to find the dealer nearest you:
http://www.redlineoil.com/dealers.asp
Hope that helps.
-Chris
http://www.redlineoil.com/dealers.asp
Hope that helps.
-Chris
Postmaster
Joined: Oct 2006
Posts: 4,816
Likes: 1
From: Davis & Newcastle, CA
MTL is actually not a Redline exclusive product, stands for Manual Transmission Lubricant (duh), I'm sure there are other brands that are easier to come by if you search around. Redline can be a b*tch to find sometimes, but my brother loves their lubricants, high quality stuff.
-Chris
-Chris
Elder User
Joined: Oct 2004
Posts: 782
Likes: 1
From: Olympia, WA
I had similar troubles when I tried synthetic gear oil in my Toyota Tacoma 5 speed. Started to have 4-3 downshift grinding. Switched back to dino oil and seemed to fix the problem. I've read that some synthetics and additives can be too slick and synchros have a harder time getting speeds matched.
Thread
Thread Starter
Forum
Replies
Last Post
Viper2F350dually
1999 - 2003 7.3L Power Stroke Diesel
12
Nov 24, 2010 02:01 PM
sigtauenus
Clutch, Transmission, Differential, Axle & Transfer Case
4
Apr 26, 2007 05:59 PM
