ZF-5 shenanigans

[Hobbywelder]

Good evening folks, looking for a little insight

- Mercon V is the fluid recommended trans fluid correct?
ive been told to run 75w gear oil in its place, either a useable idea or an absolute disaster waiting to happen. What is safe to run thats perhaps a bit heavier in weight or better for the trans?

i think it was this stuff: https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil

1st and reverse are being real buggers to get into, especially when hot. Occasionally getting to where I shut the truck off and start it in the gear I need.
2nd is getting gummy, 3rd has always been weird but that gear was rebuilt about 100k ago. When I tear into it, im expecting shift forks and syncro’s, possibly more. Any ideas on what else I might expect?

 

[IDIBRONCO]

Since ATF is recommended, I wouldn't run anything else in mine.

 

[Hobbywelder]

Is the amsoil syncromesh still the go to or is it just the normal run off the mill synthetic ATF fluid?

https://www.amsoil.com/p/manual-synchromesh-transmission-fluid-5w-30-mtf/?code=MTFQT-EA

 

[IDIBRONCO]

I don't have any recommendations there. Honestly. I've been running dino ATF in mine, but I'm going to switch that out for Valvoline synthetic here soon.

 

[Kizer]

Mercon V is the fluid recommended trans fluid

FYI: There was a TSB regarding the use of synthetic Mercon ... the site wanted $20 to look at TSBs ... so I didn't. (Mitchell1.com or some such).

Edit: Here's the site: Mitchell1.com

 

[TNBrett]

Royal Purple synchromax is what I’m running and have been happy with it. I’ve always thought it made the shifts a little smoother than ATF, and maybe a little quieter.

Difficult shifts into first and reverse is a lot of times a clutch issue. Are you sure the clutch is releasing fully. Perhaps try bleeding the clutch hydraulics.
Is it difficult shifting from 2 to 1 while moving?

 

[Hobbywelder]

Royal Purple synchromax is what I’m running and have been happy with it. I’ve always thought it made the shifts a little smoother than ATF, and maybe a little quieter.

Difficult shifts into first and reverse is a lot of times a clutch issue. Are you sure the clutch is releasing fully. Perhaps try bleeding the clutch hydraulics.
Is it difficult shifting from 2 to 1 while moving?

I certainly could try that. Hadn’t thought about it but couldn’t hurt.

Now that you mention it, is there any adjustments that can be made from the clutch pedal on? ‘93 m/y

 

[Hobbywelder]

Royal Purple synchromax is what I’m running and have been happy with it. I’ve always thought it made the shifts a little smoother than ATF, and maybe a little quieter.

Difficult shifts into first and reverse is a lot of times a clutch issue. Are you sure the clutch is releasing fully. Perhaps try bleeding the clutch hydraulics.
Is it difficult shifting from 2 to 1 while moving?

Not usually, just slow. By that I mean it takes more time from 1-2 than any other gear

 

[The_Josh_Bear]

I really like what the Redline MTL has done for my ZF5. My syncrhos were worn out 14 years ago when I got my pickup and they are still the same ones after 13 years with the MTL. They are getting bad enough now in the winter that I need to find a core to rebuild or buy one, but that's fantastic life if I say so myself.

I've heard great things about any fully synthetic MTL. I just happened to use Redline since I could get it.

 

[TNBrett]

I certainly could try that. Hadn’t thought about it but couldn’t hurt.

Now that you mention it, is there any adjustments that can be made from the clutch pedal on? ‘93 m/y

Not really any adjustments so to say, it’s more like the total effect of all the worn out parts. The clutch pedal rod bushing wears out, and then the pin that it fits on wears down. Then the bushing for the clutch pedal shaft can be loose as well. Then there can be wear in the clutch release fork pivot. And then there’s the possibility of air in the hydraulic system, or even a bad clutch master or slave cylinder. It all adds up to when you push on the pedal, the throw out bearing doesn’t travel enough to fully release the clutch.
The “sometimes I have to shut the truck off to shift into first or reverse” is what screams “clutch issue” to me.

 

[Hobbywelder]

I really like what the Redline MTL has done for my ZF5. My syncrhos were worn out 14 years ago when I got my pickup and they are still the same ones after 13 years with the MTL. They are getting bad enough now in the winter that I need to find a core to rebuild or buy one, but that's fantastic life if I say so myself.

I've heard great things about any fully synthetic MTL. I just happened to use Redline since I could get it.

Do you remember which MTL weight you went with?

 

[franklin2]

If you are going to shift from 1st to 2nd frequently, I have found you need to make sure you rev it up pretty good in 1st. There is a large ratio change from 1st to 2nd, so the tranny synchros need all the help they can get. If you get the road speed up as high as you can in 1st, it's easier for it to get into 2nd. I used 1st gear all the time when I was running 35 inch tires.

I also experimented with different oils. mainly trying to get rid of roll-over noise. Nothing shifted better than the original ATF. I never tried a synthetic ATF but if you can afford it, it might be the best for shifting.

 

[The_Josh_Bear]

Do you remember which MTL weight you went with?

The lightest version, 75w-80.