Found metal at the bottom of my 5-speed. What next?

[EuroDat]

3 hours ago, Captain Obvious said:

Haha! There is much disdain in machinist circles for those who use their drill press as an arbor press.

Similar to the amount reserved for the people who use their calipers as adjustable wrenches. 

Yer, Thats on my list with electricians using pliers as spanners.

[Captain Obvious]

Sounds like I've brought out the inner Bubba in a bunch of you guys?  

I'm just going to cover my ears and pretend I don't hear any of this!

[Zed Head]

No harm, no foul!  If the tool is the same, undamaged, after its unintended usage, you've added value.

Vise-Grips probably started as a pair of pliers with a C-clamp on the handles.  Bubba doing R&D.

 

[KDMatt]

Hey gang, sorry to leave you all hanging on my progress.

I managed to use the gear puller and "improvise" a way to get that shaft bearing off... which involved some metal pieces with pre-drilled holes (thanks to the hardware store) ... which extended it out the needed 12/13" to pull the bearing loose. I used a 1" wrench to go between the puller and the bearing so I wouldn't harm it. 

After that, I was able to get everything else off (keeping it all in order of course) so I could whack the main-shaft out of its bearing. The countershaft fell out early in the process (because of the broken countershaft bearing) which meant I had to use a screwdriver and a punch to pound out the outer bearing ring, and my vice and some heat to get the inner ring off of the countershaft itself. 

With those things both free, I got the new bearing into its home (6503 with C3 tolerance, came in the mail yesterday!) and used a punch to make sure it was seated completely around the edges. After that it was a matter of gently pushing both shafts back into their respective bearings and pounding them in all the way. I had a brief hiccup with the main-shaft, since there's a shim or washer of some kind that has to slip over a little ball-bearing lock, so I had to back out and re-align it, but once that was where it needed to be, I was home free.

I didn't really molest or disassemble the front parts of the main-shaft nor countershaft in any way, so it should be good to go. I've attached some pics of everything meshing up. Do I look okay here? 

Only hiccup is that I forgot to slide a shim over the backside of the countershaft as I slid it in... so now I have to remove the reverse idler (which I was trying to avoid) to slip it on there. D'oh!

Is there anything else I should be looking at or keeping an eye out for as this thing goes back together? Thanks again for your help so far everyone.

[KDMatt]

Alright, I've got all the gears and shafts put back together. The clutch forks are back in, and once I get some silicone sealant, I'm ready to put it back in the housing.

No extra parts - nothing missing! So far so good.

Also, random question... How the heck do I calculate the gear ratio? I counted all the teeth (except reverse) and when I start dividing I end up with some SUPER weird numbers.

Here's what I got, when counting the teeth, from front to back

Main: 21, Counter: 32

Main: 26, Counter: 28

Main: 28, Counter: 19

Main: 33, Counter: 14

Rev: (Didn't count)

Main: 22, Counter: 38 (Overdrive??)

 

Thanks for your help everyone!

[EuroDat]

Those ratios are from a 820, but the input shaft is from the 720 truck. I think its the combination that came omn a limited number of the 720 trucks. Normally you would have a 22/31 input ratio, but you seem to have the truck version which gives you the low first gear and an odd final 5th ratio. Aarh btw I'm no expert on trucks so I'm going on approximate knowledge here if you know what I mean.

One thing I can give you is a calculator for your ratios. Its an Excel file you can play with. (Had to zip it to upload). I guesstimated the reverse for the form. If you change the input to 22/31 you get the Datsun 810 (from June 78). These transmissions are getting old and if you like to play with them, you can make some wierd combinations. It is possible someone changed the input shaft or it could be original Datsun (Not from a Zed).

 

BTW. Looking good. Not parts left over when you are finished is a good sign.

 

Calculate ratios (Excel97-2003).zip

Edited May 14, 2016 by EuroDat
Screenshot

[KDMatt]

Oooh, so you think it might be an oddball 720 transmission? This was originally a car from the southern US, not sure how that particular owner would have come across an 820 transmission here in the states... I don't think they were particularly common here, but that was before my time so I'm not of liberty to say.

... and yes indeed, I think my re-assembly has gone well so far. Only problem I had was one of the metal pins attaching to/securing one of the forks didn't want to get punched in all the way, no matter how many times I tried to redo it. It came through enough on the other side that I doubt very much it's in any real danger of shearing off. I should grab a picture of it though. Maybe I can find a replacement. I have no idea how much force they're really designed to cope with. 

Thank you for the spreadsheet btw. SUPER USEFUL!

Edited May 14, 2016 by KDMatt

[KDMatt]

Looking at this spreadsheet (http://www.gracieland.org/cars/techtalk/gearing2.html), it looks like a the gear ratios (at least gears 1 through 4) are identical to the 240/260 transmission ( F4W71B)

The same ratios were also in the 620 it looks like (as a 5-speed) though again, I can't find anything like the ratio for my 5th gear, as you mentioned, so I suppose it's possible something got swapped around at some point. Who knows.

[EuroDat]

Thats was my conclusion as well. The problem with the 620 transmission is it has a short rear extension. Well that is what I have read about them.

The F4W71B was build for a 3.364 diff. That can explain why it uses the lower gearing. The 5 speed in the 280 wss for the 3.54 diff.

The 5th ratio just doesn't make sense in you tranny. Something must have been changed somewhere in its life.

[KDMatt]

7 hours ago, EuroDat said:

Thats was my conclusion as well. The problem with the 620 transmission is it has a short rear extension. Well that is what I have read about them.

The F4W71B was build for a 3.364 diff. That can explain why it uses the lower gearing. The 5 speed in the 280 wss for the 3.54 diff.

The 5th ratio just doesn't make sense in you tranny. Something must have been changed somewhere in its life.

I suppose since I'm suffering from "while I'm at it" syndrome, I could try to pull the diff out and see if I can figure out what the rear-end ratio is. 

[Zed Head]

No need to pull the diff.  You can mark the tires and the input flange and turn the wheels.  Turn both wheels one revolution and count how many times the input flange turns. If you lay under the diff you can reach both tires at the same time while looking up at the flange.  As long as they both end up where they started the math will be right.

[EuroDat]

You don't need to pull the diff out to check the ratio.

You probably have the standard 3.54. The 280Z and 300ZX had 3.7 and later 3.9 in the R200. Its easy to check by turning the wheels like in the video. I like his method turning ten wheel revolution. You know the number will be a little under 34, a little over 35, 37 or 39 etc.