• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

ZF rebuild

skifast

Full Member
Joined
Oct 26, 2005
Messages
325
Loc.
Sandhills, NC
Anyone rebuilt their ZF transmission?

In neutral it makes a terrible rattling sound. It did not do this on initial startup after the replacement. Starts fine, shifts well but, just makes a racket.

Can anyone else take a stab at what I might have going on?
 

nik

Sr. Member
Joined
Dec 3, 2007
Messages
617
Loc.
Corcoran, CA
Didn't rebuild mine, but mine makes the same racket in neutral like there's a marble bouncing around. From what I've heard this is fairly common for the ZF.
 

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
Input shaft bearing? My NV4500 started making a similar sound before I pulled it and that's what it looks like, but I have yet to tear it all down and rule everything else out.
 

siderbox

Bronco Guru
Joined
Nov 5, 2007
Messages
1,119
Neutral rattle is a fairly common noise in a manual trans.
I'll back that up with 15 plus years as a tech.
Now with that said there are possibly for repairable noises, like the ones Apogee and BB have stated.
Do you know anyone else with a ZF?
Or someone else that you value there opinion close to ya?
 

hmh800

Sr. Member
Joined
Nov 5, 2009
Messages
365
I've got one that could shift 3-4 better, and it vibrates a bit in 4th. I've been searching the web for writeups. There's a couple out there, if I can find the link I'll post it up. The rebuild kits seem to cost $350+, depending on what parts you need. Syncros seem like a weak link on high milers. I can't decide after reading what I've seen if it's something I want to tackle. I did my own R&P, and transfer case, but there's a lot more parts in a ZF. Let me look for those links...
 

broncokak

Bronco Guru
Joined
Jun 13, 2006
Messages
3,968
My ZF does the same thing and everyone said it if pretty common.
 

bigmuddy

Contributor
Bronco Guru
Joined
Dec 28, 2004
Messages
7,001
Loc.
Marthasville Missouri
They call it neutral rollover noise. Same reason that Ford did a recall and fixed it by sticking some heavy padding between the carpet and the tranny tunnel. My seems to be worse after driving all weekend in low low around the 4x4 park. Normally it's just mildly aggravating but I try to not let my bronco idle much.

Ben
 

trtlsoup22

Sr. Member
Joined
Feb 8, 2005
Messages
652
Mine sounds like it's got gravel in it while in neutral... It's been installed for about 4 years.. The ZF came from my paw-n-laws well used farm truck. All I have done to it is changed the fluid.
 

hammer

Bronco Guru
Joined
Nov 13, 2006
Messages
1,359
Yup mine makes a bunch of noise in neutral. Same thing with the one I put in my f250 as well.
 

Knifemaker

Full Member
Joined
Apr 4, 2011
Messages
174
Loc.
Youngsville, La.
I use to have a 96 250 with the ZF and it made the rattle sound when in nuetral pretty much from new till I sold it with 150,000 miles never a bit of trouble with it.
 
OP
OP
skifast

skifast

Full Member
Joined
Oct 26, 2005
Messages
325
Loc.
Sandhills, NC
When I first installed it, there was a whirring sound. New input bearing, new clutch assembly, BC ZF install kit and junkyard 89 F-250 ZF S42, just the back story.

It sat for two months while I was doing body and cage work. Started it and now all the racket it is loud like the transmission is tearing itself apart. The wife even asked if there was something wrong with the Bronco. Although still seems to shift fine.

It seems all my co-workers are a new car crowd and not alot of older F-250's running around to compare the sound of their ZF noise.

A long time ago I drove an Army buddies truck with the ZF and you could hear the transmission but, it was nothing like this. Or so I remember.

I have the Haynes manual for the year model F-250 I pulled the trans from and it said " noisy in neutral engine running" Input shaft bearing worn, damaged main drive gear bearing, worn countershaft bearings, or worn or damaged countershaft endplay shims.

I hear the folks say just run it but, I think the noise it is making is a little more than transmission noise, maybe?

In the end I am not a mechanic and have made it through all of my Bronco repairs by reading the book on the fender as I am doing it.%)

So run it or rebuild it, I guess I could just pad the heck out of the trans tunnel and wear ear plugs!
 

bigmuddy

Contributor
Bronco Guru
Joined
Dec 28, 2004
Messages
7,001
Loc.
Marthasville Missouri
I hate to admit this, but right after I installed my ZF I forgot to add fluid and let it idle like that for about 30 min in neutral. Fluid for the tranny didn't make the punch list for start up for some reason? It made one helluva a racket and sounded like rocks in the tranny. I realize that the ZF takes a synthetic tranny lube but I have been succesful in adding a pint of lucas oil to the tranny to get it to be a bit quieter. Not saying you should do it, but it worked for me.
 

KyleQ

Bronco Guru
Joined
Apr 24, 2008
Messages
5,480
It's very common for people to add a bit of extra fluid to quiet it down. Another thing to consider is that our Bronco's are like one big resonating speaker, that same transmission in a newer pickup with it's curvy steel with foam and carpet over it makes a big difference.

I would just add at least a quart of fluid to help quiet it down - the guys on OilBurners will even damn near fill it up and they are pulling heavy loads with them...
 
Top