How is manual 4th gear supposed to work on Ranger (M5R1)?

[scprotz]

I've swapped transmissions in the past with no difficulty. I have a 1994 Ranger that is sickly - I bought the truck from an acquaintance and he said he was having to top off the fluid (ATF) about once a week and putting 300 miles/week on it and that 4th had stopped working.

I pulled the transmission out of the truck - the first thing I noticed was the inputshaft bearings (or in this case, lack of). The bearing casing was disentegrated. The bearing cylinders were still in there, but this was 'why' it was whining and wasting fluid. I figure new bearings and new seals should take care of that (with a thorough cleaning).

The other issue though is that 4th gear didn't work and doesn't seem to work while I've got it down and working on it. I pulled the cover and tested each of the gears and all work and engage properly except 4. When I put it in 4th gear it shifts (or I can shift the shift bearing by hand when the cover is off) but it won't engage.

Looking into the body of the transmission, there don't appear to be any destroyed teeth and the synchronizers look fine. I just don't understand HOW it is supposed to work to know what is broken.

Can anyone explain how 4th gear engages and why it might not work on my transmission?

(For TL;DR - looks good inside transmission housing, but 4th gear doesn't engage even though it shifts into the 4th gear position - what should i look for?)

Thanks so much
-scprotz

(I'll post pictures if needed - just let me know what you want to see - i also got a schematic from southwestgear.com for the M5R1, so feel free to use that numbering and I can check out any part)

 

[Rick]

Maybe something in this thread will help:

http://www.explorerforum.com/forums/showthread.php?t=248249

Welcome to our forums

 

[scprotz]

Input Shaft gear?

Thanks for the response. I reviewed the rebuild guide and I was looking at the input shaft on this image:

http://i567.photobucket.com/albums/ss116/tobydog42/IMG_4698.jpg?t=1246331132

It appears my 4th 'gear' on the input shaft spins free of the shaft it is on (that is the gear with the diamond-like shape). Is it supposed to do that or should it only spin as part of the input shaft?

 

[PopRichie77]

I would say, It should be fast, you need a new input shaft.

 

[KPT]

It appears my 4th 'gear' on the input shaft spins free of the shaft it is on

That shaft is one piece. Nothing should spin independent of the shaft.

 

[scprotz]

Thanks for the feedback. I've ordered the new input shaft, bearing and front seals to replace it. Crossing my fingers that is the only real issue and should solve the whine (bad bearing) and missing 4th gear (bad input shaft).

I'll post if we have success on my first transmission repair

 

[scprotz]

Success - Kinda - a quick question

So the rebuild went relatively smoothly (thanks so much for the rebuild in pictures). I think the rebuild link above must be for a slightly different transmission because the tail piece doesn't look the same as the one off my 94 ranger.

One thing I found was that my 5th gear won't engage or stay engaged. I think when I assembled it I missed putting a spring on the ball in the shift fork.

Would that sound like the reason for the problem? I'm pretty sure I missed part number on this diagram: part 77 http://www.southwestgear.com/swg/components/com_virtuemart/shop_image/product/M5R1_Case_4cf17baa57492.jpg

And is there an easy way to install it? (I realize I'll have to take the tail piece off again - this was a step not shown in the step-by-step link earlier in the thread)

Thanks so much,

 

[Rick]

I don't have an answer for your, but here's a bump so hopefully someone else will see it.

 

[scprotz]

Thanks for the bump.

I pulled the tailpiece down again and put the spring back in the 5th/reverse shift fork. Now it clicks properly into 5th/reverse, but still won't stay in 5th. Works fine in 1-4 and Reverse.

Any ideas on what can cause this? Before I tore it down, 1235R worked and no 4. Now I have 1234R working and no 5th.

Is it possible to have 5th gear installed backwards or the synchronizers backwards and cause this problem?

Thanks for replies

 

[scprotz]

How to tell fifth and reverse synchronizers apart?

Hi all,

Is there any way to tell them apart? I have the tail torn down (and yes...as far as I can tell, I put the 5th gear slider on backwards). I just don't know how to tell which synchronizer goes where. I'm just going to try them both ways..maybe I'll get lucky and they only fit one way each.

Any ideas on differentiating the two?

Thanks,

 

[scprotz]

Finished

So the fifth synchronizer and reverse synchronizer have different inner hole size. If you get the slider and hub positioned correctly (dot of hub facing back of vehicle and inner slider so that it actually fits on countershaft with the 2 semicircle clips), everything falls into place. So my only note would be MAKE SURE YOU GET THE DOT FACING THE REAR OF VEHICLE

With that, the M5R1 Tranny rebuild is complete. Only had to buy $104 in parts (not counting 3 quarts of Fluid) and spend some time learning to build them.