wide ratio FS5W71B slipping out of 3rd & 4th

[Jeff Berk 56]

I started this question in another thread but instead of taking over that thread, I thought it best to start a separate one.

I have a '74 260z with an engine and drivetrain from a 280z or 280zx. The transmission is a wide ratio FS5W71B. 

The transmission would slip out of 3rd and sometimes 4th gear when I let up on the gas. I replaced the transmission fluid with Red-Line MT-90 and replaced the 3 ball bearings and springs (detent springs 32831N). There does not seem to be anything interfering with the shifter and the transmission seems to go fully into gear.

I test drove the car today and the problem seems to persist. According to the service manual, after eliminating the springs as the problem, the next thing to look at are the Shift Fork and the Gears. 

My question is, whether I could tackle this level of rebuild or is this something best left to a professional? I'm also not sure how available the gears and shift fork are for this old unit.

Note that the ball bearings for the springs came in packs of 10 so I have 7 extra if someone needs any along with an extra spring since I ordered an extra expecting to loose one.

Thanks

Jeff

[siteunseen 3,428 5 Vehicles]

I had a problem with mine popping out of 5th and reverse after going to a 5sp. It was the shift rod hitting and not letting it go fully into gear. I ground some off where the nicks were and it's okay now. 

 

Edited November 12, 2020 by siteunseen

[Zed Head 2,203]

Here's your other posts, using the bipod thing.

 

[Zed Head 2,203]

Ownallday just did his.  It takes some specialized tools and some knowledge about mechanical stuff.  You might not have to go that far.  The clutch forks are easy to get to once the front case is removed.  But if you find a bearing like Ownallday's it gets more complicated.

 

[siteunseen 3,428 5 Vehicles]

7 minutes ago, Zed Head said:

Here's your other posts, using the bipod thing.

Are my bipod thing copy and paste not showing up right? I'm using my phone and it looks good on my end. Just curious, you've mentioned that a couple of times to my replies.

[Zed Head 2,203]

Yours are working.  I meant Jeff Berk's other posts when I pasted his bipod link.  He had tagged on to pogden's thread.

[Jeff Berk 56]

I don't think its the Shift Lever hitting anything. I checked from under the car while my son shifted back and forth between 3rd and 4th and it looks like nothing was binding or hitting. 

Moving to the shift fork as the next potential cause, it looks like the part potentially causing the problem would be #27 (31805) or #28 (32809N).  Unfortunately, those parts are NLA. If worn out at contact points, can these parts be repaired, redressed, or built up with welding? Or are they available as replacements through other channels? I'm just wondering if rebuilding is even an option.

Edited November 13, 2020 by Jeff Berk

[Zed Head 2,203]

The roll pin holding the fork has been known to loosen up or fall out.  The fork from a 4 speed would work.  Somebody will have a used fork on the forum or eBay.  Hard to imagine that you won't be able to find one.  You can figure out a lot without tearing it down very far.  Once you get the front case off you can manipulate the shift rods and forks and gears and see what's happening.  Then you'll know how deep to go.  Plus it might save on having a pro fix it if it's half torn down already.

You can always do what a typical Z owner does and just buy a whole transmission, fix the other one anyway, and feel good knowing that you have a spare.  Then buy another shell to put all your spare parts in.

[Jeff Berk 56]

After putting in a new clutch, I sold my transmission jack figuring I'd never do that again. Wrong as usual. I did a quick check and found a rebuilt 5 speed close ratio nearby but at >$1,000 I'll see what I can do with my transmission. Anyways, I don't want a spare transmission since I'm limited on space and with winter knocking at our door, I need to get all three cars in my 2-car garage.

At least this will give me a winter project.

I'll jump back on this thread once I get around to pulling the transmission.

Thanks!

Jeff

[Jeff Berk 56]

I'm getting around to disassembling by 5-speed to search for the cause of the slipping out of 3rd and 4th and I'm already stuck. I removed the stopper guide pin, return spring plunger, return spring plug, and plunger. I need to remove the tail end of the transmission and removed the six bolts that pass through the adapter plate and now I'm stuck. Do I need to remove the dust cover sleeve (No. 11) and seal (No. 10) to pull the tail section off? If so, is the dust cover sleeve screwed on? After their removal, just hammer and twist left to pull the tail end, right?

 

[Zed Head 2,203]

Did it come part way off then get stuck or has it not even broken the mating surface yet?  Pretty common to have to do some wiggling and shaking to get it completely off. 

Also, are you sure it's not a close ratio with the reverse lockout mechanism?

[Jeff Berk 56]

Zed...

The dust shield has a small gap between it and the body of the transmission tail piece. I've tried prying with a screw driver and twisting with a pipe wrench. Before I get too aggressive, I just wanted to make sure I wasn't missing anything. I'll try and wiggle it with a dead blow hammer and prying.

I'm assuming that the dust sleeve and seal need to be removed to pull off the tail end of the transmission.

I'm sure it's a wide ratio based on it having two bolt tabs at its tail end and I don't see what looks like a reverse lockout mechanism.

Jeff

Edited January 3 by Jeff Berk

[Zed Head 2,203]

14 minutes ago, Jeff Berk said:

I'm assuming that the dust sleeve and seal need to be removed to pull off the tail end of the transmission.

The dust shield comes right off with the tail shaft housing.  The output shaft is hanging free inside, no need to mess around back there. 

If you don't have even a tiny gap at the mating area with the adapter plate (the solid metal plate between the front and back) then it's probably just glued together with sealant.  Give it some side to side love taps to break that seal.  The FSM procedure is pretty thorough.

Dust shield still attached.

Edited January 3 by Zed Head

[Patcon 1,928]

Also, I believe it needs to be in neutral

[Jeff Berk 56]

Thanks all, got it off. I'll take a stab at the front half of the transmission case tomorrow.

[Jeff Berk 56]

OK, I pulled off the front transmission case. Keep in mind that that I have not done this before so I'm not 100% sure what I'm looking for. 

What seems to jump right out is that the baulking rings seem to have some teeth chipped off. My problem, however, was that I'm slipping out of 3rd and 4th gear.

 

[Zed Head 2,203]

Yes, your synchros (baulk rings) look terrible. Looks like one has been completely destroyed.

From what I've seen, just over the few years I've been browsing Z car internet stuff, I'll bet that one of the bearings in the adapter plate is falling apart. Grab the shafts and wiggle them around while you try to see down at the bearing area.

Check this recent thread out.  It shows the aftermath.  But the gears themselves seem very durable.  Several people have just replaced bearings and synchros despite the damage and been back to like-new condition.

https://www.classiczcars.com/forums/topic/64776-280zx-5-speed-wont-reverse/?do=findComment&comment=613709

 

[Jeff Berk 56]

If you look at MT-16-2 below, there is a little play in the main shaft at the point where it's shown as being separated from the rest of the shaft. I'm assuming that's normal. I can see the bearings in the adaptor plate and it appears to be in good condition with no play in the shaft as I try and wiggle the shaft.

Could the worn synchros be causing the slipping out of gear? I thought it would just be a problem getting into gear.

It looks like I might be able to do the rebuild myself as long as I don't need a press. If it gets too rough, I have a local mechanic that has worked on these transmissions I can fall back on.

[Zed Head 2,203]

Once you get chunks of metal floating around in there things can get jammed up.

zKars had a whole writeup on a transmission rebuild.  Others have also.  EuroDat comes to mind.  Tools can be fabricated.  There are basically two things that hold a gear in place once it's chosen, the balls in the adapter plate, and the inserts under the coupler sleeve.  It's late and I might have picked the wrong words but overall it's simple.  Making it all work right can be complex.  Definitely doable, but challenging.

[Zed Head 2,203]

I haven't looked but I seem to recall Dave WM, and maybe others, not finding the destroyed adapter plate bearings until they took things apart.  Some people rebuilt their transmission's for synchros and found the bad bearings by accident.  Most people are surprised at how well the transmissions work even with all of the damage.

If you didn't find any metal it might be that somebody already cleaned the drain plug.  Anyway, I think you need to tear it down all the way.  zKars, Dave WM, EuroDat, others I'm not remembering have all written some good stuff about it.  I'll post links as I find them.

 

[Zed Head 2,203]

 

 

Here's a shift fork problem, check those.

 

Edited January 6 by Zed Head

[mayolives 0]

Blue's collection of tech tips   I used this link when rebuilding my 5 spped a few monts ago. Lot's of good advice that, along with the FSM, walked me through it.

[Jeff Berk 56]

Thank you Mayolives! There are many tips in there that will help. I'm on hold waiting for a bearing puller/splitter to arrive. I'm also mounting three dowel rods on my work bench to sting components on in order so that I can put everything back in the proper sequence and direction. It was suggested that I engrave an F on components on the side facing the front. I might do that as well.

I'm assuming roll pins should be replaced with new ones but snap rings are fine to reuse. Correct?

[mayolives 0]

I reused mine with no problems. Be sure to use snap ring pliars when removing and reinstalling them. Best not to "dig" them out with a screw driver or other tools because you could bend and deform them. 

Edited January 9 by mayolives

[Jeff Berk 56]

Can anyone suggest a source for main and counter shaft staked nuts, with RIGHT HAND threading? I must have one of the earlier FS5W71B's. If they are NLA, can I substitute something else?