I have a junkyard sourced ZF that I'm on the fence about installing in my truck without a shop checking it out. I took the side panels, shifter tower, and plugs out of it today and took pictures of the syncros and gears inside. Anyone have thoughts about what I've got here? The outside of it is VERY dirty.

It shifts fine through the gears. Today I tested each gear. I had it apart, bellhousing end facing down (on a board with a hole in the end for the input shaft). I put it in first, and turned the ZF's output shaft to watch the gears inside. Everything was smooth and no grinding or anything weird. I did this in each gear with the same results. Reverse made the output shaft very difficult to turn, but it would turn if I turned the gear inside the side panel.

Outside


Through the drain plug


Side panel


Side panel


Side panel (synchros)


More synchros










Side panel


Close up of the gears just inside the side panel.


Tail shaft


Drain plug


Shifter


Shifter again


Metal shavings (very very fine)


Old ATF and some water came out when I opened it. I think the water is from when I attempted to pressure wash it several days ago to clean it. This didn't help at all.

 

About the only thing your going to be able to check out without splitting the case is the input shaft bearing wear. Grab the input shaft and see if it moves around at all. It is does, the tapered roller bearings are worn. You are not going to be able to judge the quality of the syncronizers without either tearing the trans down to measure the gap on all the syncronizers or installing and it just testing it. Spinning it by hand will not give you any idea on the condition (other than telling you its not completely locked up). Read the manual below for more information on rebuilding.

http://api.viglink.com/api/click?for...13768534185968

In other news, you've got a pretty desirable transmission there. You have the S5-47 model which only came in 96-97 trucks and has updated syncronizers and an updated shift tower. I would advise to tear it down and replace the syncronizers and bearings. Follow this guide for some tips.

ZF5 (S5-47) Rebuild - FSB Forums

 

Ah, I don't think it's the 47 model, at least according to the tag. It has a build date of '94.



Thanks for the feedback though.

 

That tag is wrong. Likely someone had that model rebuilt and they retagged it. The easiest way to tell a 47 model from the 42 model is by the extra ribbing on the case. The 47 has more. See pictures below.

S5-42 model


S5-47 model


You will also notice the 47 model has an extra rib around bellhousing mounting flange than the 42 model. This is especially apparent around the bellhousing locating dowels.

 

Wow, that's interesting. I was leaning towards putting it as is, and since you think the tag is wrong and has perhaps been rebuilt already, it's furthering that argument.

It also doesn't help that I have no idea who to take the trans to for a rebuild. I don't trust any of the local shops to do it right. And I don't have the tools (or knowledge) to do the rebuild myself. I've read those threads before but I don't have the confidence.

 

The 1307050118 part number is listed as '94-1/2 and is the very last of the S5-42 models. I would think it is possible that ZF/Ford could have implemented the improved case before the change to S5-47. There is not a lot different between the two. Not that the upped torque capacity makes a lot of difference behind a 351, but I wouldn't automatically assume it's a -47 or that it has been rebuilt based only on the case design.

 

Well, the case redesign along with the slightly updated syncronizer detent sliders and springs are likely what account for the increased torque input capacity (420 ft-lb vs. 470 ft-lb).

If you don't believe (or don't trust) pictorial evidence, I suppose the best way to determine what you have is to tear it down. If your syncronizer sliding collars have only a spring and pressure piece and no ball under the spring, then you'll know you have an S5-47. Also the shift forks should be labeled with part numbers starting 1317. All 1317 part numbers correspond to S5-47 parts, although many are interchangeable into an S5-42 model.