ZF S-42 issues

[Optikalillushun]

When cold (temp) my truck doesnt like to go into 2nd gear (dont normally need to get out of 2nd around town). it feels like its VERY hard to pull into gear...sometimes i think it is in but when i let the clutch out i get the "zizzzzzz" and have to try again.

also, when im runnin hard and trying to get into third it does the same thing or goes in and almost feels like it pops out. when i drive slow it doesnt do it, but when im trying to merge or get up to speed is when it occurs (not everytime).

also, it seemed hard going into reverse sometimes. after i come to a complete stop and shift into R, it'll sometimes not enguage and i get the "zizzzzz"

any other situation it shifts smooth and easy. it doesnt seem like the syncros but maybe something in the shifter itself. i read there are plastic bushings inside that can often go bad and cause all kind of fun stuff.

i do plan on changing the fluid with some nice syn (as well as the diffs and t-case) in the next few days so while im doing that i can check out anything anyone points out here.

 

[BigRigTech]

My ZF does the same thing in 2nd when it's cold. It's a real ***** the first time I go for 2nd when I leave the house every morning...I don't have any grinding in reverse but I do feel the synchro's meshing when I put it into 3rd. I was going to try some new blocks in the shifter too but honestly I think my tranny needs a kit, it has 277,000KM on it and so does my spare ZF. Kits are $200 on fleabay with new bearings included.

 

[tonkadoctor]

Are you running gear lube or ATF. ZF5 tranny needs ATF.

If running ATF it sounds like the syncros are going OR possibly the clutch slave may be getting weak and not completely disengaging the clutch.

 

[Optikalillushun]

AFAIK it is ATF assuming it like everything else is stock, im putting in syn ATF shortly. the clutch slave is new (within a year, PO installed it). he doesnt half ass anything so its done right.

BUT clutch its a firm feel and no squishy. but ya that first time going into 2nd can be a real nightmare! . the truck has 137,000 miles and was very well cared for and never abused. it was used to pull a light welding trailor and the PO's parents small camper a few miles.

 

[BigRigTech]

I have 50W synthetic in my ZF....Same stuff we use in the rig transmissions at work.

 

[Exekiel69]

I have dextron something ATF o mine,change every six months to a year and always feel it hard to get in 2nd the first few times, specially when cold. It's done it since I have the truck for years and all I do is just start in 2nd the first few miles if I'm not pulling the trailer.

 

[BigRigTech]

The 50W Syn really quites them down, especially noticable in reverse....Helps a lot with the heat issues these tranny's are known for.

 

[Optikalillushun]

just drove it some more today to try to get a feel for exactly what it is doing. when i shift it feels like when im pulling it into 2nd or 3rd i can feel a somewhat resistance and then it goes in.

 

[BigRigTech]

That's probably the synchro's ******* in.

 

[Cheaper Jeeper]

FWIW, I use Mobil 1 syntheic 15W50 in mine. I get the benefits of the thinner 15W when its cold and the thicker 50W when it warms up. Seems to work fine both cold and hot.

Just curious, do these trannys even HAVE syncros on the 2nd gear? If so, mine must be bad - 'cause I can't shift down into 2nd unless I've coasted almost to a stop - like under 5 mph. If I try to downshift from 3rd to 2nd when moving any faster than that it grinds...

 

[82F100SWB]

The ZF5 is full syncro, maybe even reverse too(I know the 6 speed is) but, 2nd gear seems to be the most common failure. Any one I've driven that had bad syncros, it was 2nd that was done in.

 

[Optikalillushun]

great, why didnt u tell me that on AIM . now im begining to worry bout teh tranny...better take it easy.

also gunna check out for any signs of firewall flex/cracking.

 

[Exekiel69]

Mine has the same problem downshifting from 3rd to 2nd for years and nothing changed. I don't know about 50w synthetic, maybe for very high mileage but I rather use regular syn atf, like the amsoil.

 

[BigRigTech]

I changed the nylon blocks on my shifter today, $9 at the dealer....I'll see if it makes any difference tommorow when I go to work in the monring.

 

[Optikalillushun]

let us know!