Another FS5W71B 56mm bearing victim

[giantcone]

¡Hola Gang!

 

   So I fell victim to the front counter-shaft bearing blowout issue.  Had that gravel sounding issue right around the time I replaced the clutch and thought I had screwed up the throw-out bearing install. Nope, I did clutch correctly, only to have that 56 mm front counter-shaft bearing finally grind the races to a nice silver paint and put a crack in that front cast aluminum housing part.

 

Given that the front plate is cracked, and that getting a front plate sized for the 62 mm counter-shaft front bearing would likely be easier, I'm thinking about getting a rebuild kit for the later model FS5W71B transmissions to get the larger bearing and also get a new front plate to accommodate it.  The only issue would be getting the bell housing hole for that front counter-shaft bearing bored out to the larger size.  I'm going to take the housing and that front plate to a machine shop to get an estimate for going the larger size, or just welding up that front plate up.

 

Any advice on this would be greatly appreciated as usual.

[datzenmike]

'85 to '86.5 720 and S12 (200sx) 71Bs had the larger 62mm bearing and cover plate. '86.5 and on the 71C was used and they all were 62mm. Any 71C cover plate will work if you machine out to 62mm for the counter bearing.

 

Check the gear oil every year and replace every 30K

[bottomwatcher]

Went through 4 Bs, slapped in a used C about 14 years ago.Still going strong.

[giantcone]

Thanks Mike & BW,

 

I'm still kicking rocks around about what to do with this 71B.  My father and a friend say to get a bearing kit and replace all of them and rebuild. I talked to a local machine shop about boring out the front counter-shaft bearing hole in the bell housing from 56mm to 62mm; that'll be $100 to $150.

**I'm assuming here that when Nissan did that mod on the 71B (or 71C?) that they kept the distance between the main and counter-shafts the same.** 

 

If I play the naive replace route, I'd just slap another 56mm front counter-shaft bearing in it, leave the bell housing alone, and I guess apply JB Weld to thee: crack on that front bearing cover and hope for the best.

 

I have been scouring the Ratsun 720 forums about this issue and have good background info.  I'm seeing some rebuilt FS5W71C transmissions at 

https://www.midwesttrans.com/FS5W71_Manual_Transmission.html going for just under $1000, but I need to ask if they have ones with the extended ass end.

(Interesting that the FS571C was used on the 2000-2004 Frontier...)

[datzenmike]

Yes. The mains and counter shaft distances are the same. In fact it should be 71mm center to center and why it's called a 71B.

[giantcone]

Thanks Mike,

 

That's reassuring. I was a bit concerned as the minimum thickness of aluminum in the bell housing between the two bearing holes is 7.5 mm. The machinist didn't mention any concern about that point, so I suppose I should not worry myself over it either. 

 

I guess I got one from the bad batch of the 1985 720s. The driver door plate states it was manufactured AUG 1984. So it got slapped with one of the older FS5W71Bs with the smaller front counter-shaft bearing. 

 

Looking at my maintenance logs going back to when I got the truck back in late 2007 with only 28,154 on the odometer, the times I've changed the transmission fluid:

 

2010-NOV-07:  42,612: Sta Lube GL-4 80W-90

2015-SEP-14: 110,914: Red Line MT-90 GL-4 75W-90

2018-DEC-15: 163,885: Sta Lube GL-4 80W-90  (also replaced the clutch, PP, and TO bearing w/Luk clutch kit.  Old clutch was wafer thin)

 

2019-APR:  167,763: current state of affairs 

 

Definitely, too long of a gap between changes in terms of both mileage and time...

[datzenmike]

'85 720 diesel

 

Earlier 56mm spacing...

 

B and C cover plates...

[bottomwatcher]

The C series is plentiful and cheap. Mine has a ka sitting in front of it now and probably over 200k on it. Mike says they are 2x stronger and I went  to the syncromesh on his recommendation and all has been good. Mine came from a 1988 harbody with a z24. I have a back up I picked up from a u-pull for $100, I still have trans nervous issues from the B series. You will need to have the driveshaft lengthened and cut a new hole for the stick and make a small adapter plate for the trans mount. If you plan on keeping truck go for the c.

[giantcone]

Well that does give me more rocks to kick around... thanks B.Dub! 😛

 

I guess I could go the FS5W71C route, if the transmission rebuilders are willing to take the 71B as a core.  It would save me time that I don't have to repair a transmission that I suppose is deemed questionable by the Ratsun Regents.  Was there really no long extended 71C like was done with the 71B?

 

The main issue I have would be getting the tweaking work done for fitting the 71C on the truck. I could get the longer driveshaft done in Albuquerque, and as for the transmission cross member support, I suppose that would need to be modified to be positioned closer to the front of the truck.  It's little things like this that end up taking a simple job and making drawn out... at least for me anyways.

 

Also what are the key differences between the FS5W71B and the FS5W71C besides the larger front counter-shaft front bearing?

 

___________________________________________

Question about details for the FS5W71C:

 

I'm a bit confused from another thread where [Mike discusses the FS5W71C]:

 

 

in the context 240SX. Seems to be several different mentions of ratios for the FS5W71C in the above linked thread, quoting:

 

"The FS5W71C 240sx transmission is           1st 3.321, 2nd 1.902, 3rd 1.308, 4th 1.0, 5th 0.765" [from StupidFast]

"Genuine 5-speed (FS5W71C ) 3.3214 1.9023 1.3084 1.0000   .8378"  [from bmoses]

 

I take it from a picture Mike put up in that thread, the 2nd of the above is the proper FS5W71C used for the latter D21 successor to the 720 series?  Info out on the web seems sketchy about this transmission.  Did they use the same transmission, for cars but changed the input drive ratio?

 

Putting link to another useful thread here related to this topic:

 

Thanks for all the info!

[wayno]

Your front lower bearing lasted over 10 years, just buy a good quality 56mm Japanese made bearing and replace the front cover and shim if destroyed, do not use your busted cover.

I have a couple aluminum 62mm front covers if you have yours bored out, $100.00 to $150.00 to bore out your case is not that bad, I paid over $200.00 to have it done to my diesel case, but I had to find someone to do it first, not all shops have what is needed to bore a hole that deep into a transmission case.

 

PM me if your interested in the 62mm front cover.

 

[giantcone]

So I made up my mind and will rebuild the transmission I have, but get the bell housing hole for the front counter-shaft bearing bored out to accommodate a 62mm bearing.  I'll buy the 62mm front cover from wayno to get the job done.  I'll clean up the transmission guts with mineral spirits and lube with light oil this Saturday to check if the remaining bearings are okay.  I'm not seeing or feeling any bearing binding or roughness in the transmission as I rotate the input shaft.  I'm really not keen on tearing this all apart to replace the other 5 roller bearings (I believe I have that count correct), although my father and another friend seem bent on persuading me to do so.  If anyone else wants to comment on that matter, I'll heed your advice.

[Stoffregen Motorsports]

Have you ever rebuilt a manual trans? There are some things to look out for.

 

First is the tools. I made some special transmission sockets to be able to use an impact gun on the tailshaft nut. If you decide to make and use this tool, be careful to check the gear endplay upon reassembly. Worn thrust washers and/or bearing spacers may cause binding and actually weld the gear hubs together. But don'e be scared, just pay attention.

 

 

 

Second is disassembly. Use two 2x4's placed on the ground. Stand the trans up on the bellhousing end on those 2x4's (one on each side of the input shaft). Remove the tailhousing first (with some wiggling of the shift striker), then pull the front cover and snap ring. Then get the entire gear assembly out of the bellhousing. Next, you pull the plugs that hold the detent balls in the mid plate. Use a pencil magnet to get the balls out of their bores and do not loose them. Remove the tailshaft nut and the rear gears/bearings, then tap the shafts forward (with a deadblow hammer) to get them out of the mid-plate. Watch out for the detent ball inside the thrust washer as it will undoubtedly fall out and roll across the shop floor. Make neat stacks of gears/hubs/bearings and remember where they came from and from what direction. Most are self evident, but some parts can only be assembled in one direction. One prime example of this is the thrust washer on the main shaft just in front of the mid plate bearing. If it has grooves worn in it, reversing it may cause binding upon reassembly (as I described above). Leave the shift collars on their hubs, but if you insist on disassembling them, be careful to pay attention to how the springs and pawls are situated. Did I mention not to loose track of any of these small pieces? One very important thing to watch out for is gear damage when removing the bearing from the cluster gear. If you are using a standard bearing puller, it can contact the edge of the gear and actually break chunks off the tips of the gear. If this happens, depending on the size of the chip, it's not the end of the world. You can (to some degree) spin the gear on a belt sander to smooth out the rough edges. Like I said, lots to look out for!

 

Inspect the shift rails for wear. Check for bent or broken roll pins in the shift fork assembly. Check that thrust washer for wear. Spin each bearing and feel for wear. Check the synchros against their respective gears (they should sit flush with the edge of the gear. If they go past the cone on the gear, they are worn and should be replaced).

 

Reassembly is basically the reverse of disassembly. You will want to use some type of grease of vaseline to hold the detent ball inside the thrust washer. Then apply a good bead of "The Right Stuff" RTV on the front case, drop the gear assembly into the front case, followed by another bead of RTV on the tailhousing, then you can start wiggling the shift striker into place to bring the tailhousing home. When reinstalling the front cover, use RTV instead of a gasket. This helps shorten the shift stops making for a tighter shifting feel. Oh, and make sure you use RTV on the front cover bolt threads (if they go through the case, which I am pretty sure they do), and also make sure you get the short bolt into the hole nearest the cluster gear, or else it will contact the gear and stop the shaft from spinning).

 

Got it? Easy, right?

[datzenmike]

FS5W71B and FS5W71C

Most noticeable thing is the shifter. (see picture)

Internal gears are the same diameter so to make them stronger they were made slightly wider.

Synchros were much improved.

Shift forks stronger.

First/second shift rod 16mm rather than 14mm although some late Bs may have this improvement.

While most Bs are 31.5" long some 720 Bs are 26". Cs are either 34-35 inches for cars and around 30 inches for trucks, sorry I don't have hard numbers for this.

 

S13 top and D-21 (Hardbody) bottom

[giantcone]

Found the following post @ Datsun1200. Linking it here for posterity's sake as it has a good compilation of info about the 71 series transmissions:

 

http://datsun1200.com/modules/mediawiki/index.php?title=71-series_Transmission

 

Seems that the 71C also comes in the long-tail versions as well (?).  Must have if used in the D21 trucks, right? Or perhaps they just were made with one overall length? Longer than the 71B "stumpies" but shorter that the 71B long-tails?

 

I think I'll stick with my plan for now for fixing the 71B and getting the truck on the road again.  I can take the time to do my proper research and upgrade to a 71C in the future when life become less hectic.

 

Thanks for the info gang!

 

[giantcone]

Another possible complication:

 

I checked out the Nachi bearing catalog and couldn't find a bearing that had a 22 mm inner diameter with a 62 mm diameter outer race.

 

I recognize the "63/22" bearing model number from the outer race of my 56 mm front counter-shaft bearing. The 62 mm outer diameter bearings only seem to come in a 25 mm inner diameter race (the model # 6305).  I did a cursory check for NTN and SKF bearings and came up with the same results... Would anyone confirm if the change in the counter-shaft front bearing size also meant an increase of the diameter of the counter-shaft itself?  If so, then I'm going to have to go with just replacing with the 56 mm bearing... or pursue the 71C transplant as @bottomwatcher suggested.

 

I'll keep looking, but I obviously need to pay attention to all the details when it comes to replacing bearings.

[datzenmike]

Both 56mm and 62mm counter bearings will interchange on the B or the C transmissions. Counter shafts are the same size.

 

Have you tried the Nissan dealer? The 62mm were used up until at least 2000 and may be being used today. The Nachi 56mm was about $12 CDN, so expect the dealer to want close to double that. You don't have to go to 62mm, a new 56mm will last as long as you have the transmission because you are more likely to keep the oil level topped up and changed than all the previous owners.

[wayno]

I tried finding 62mm bearings a few years back and failed, I did find/buy four 56mm bearings, but I didn't try the Nissan dealer.

The 56mm bearings I bought were NTN brand, don't know where they were made, and I saved all my good used 62mm bearings out of transmissions I removed the napZ front case and replaced it with an L case(56mm), I can hold the bearings in my hand and spin them up with air gun till they are spinning so fast they act like gyros, the bearing just wants to stay in the position it is in in my hand, there is resistance when I turn/twist my hand, I set one of the bearings on the work bench spun up it kinda danced a hula.

[bottomwatcher]

When I was replacing mine before the internet was what it is I would go to a "bearing house". It was a long trip but most cities had shops that specialize in bearings. I bought a used trans and trying to prevent another blow out replaced the front countershaft bearing. I just took them what I had and they got me a fag (German company in brazil) bearing. Lasted 30k something miles. My problem is a 4x4, lift and big tires plus the aerodynamics of a brick really puts a strain on the fifth gear. That is why it is not recommended to tow in fifth but the load driving a modified truck is the almost the same as towing a load in 5th. The hardbody frontier crowd has counter bearing issues with the c but they are heavier more powerful trucks.

[datzenmike]

2 hours ago, wayno said:

I tried finding 62mm bearings a few years back and failed, I did find/buy four 56mm bearings, but I didn't try the Nissan dealer.

The 56mm bearings I bought were NTN brand, don't know where they were made, and I saved all my good used 62mm bearings out of transmissions I removed the napZ front case and replaced it with an L case(56mm), I can hold the bearings in my hand and spin them up with air gun till they are spinning so fast they act like gyros, the bearing just wants to stay in the position it is in in my hand, there is resistance when I turn/twist my hand, I set one of the bearings on the work bench spun up it kinda danced a hula.

 

I've done this wayno on a wheel bearing I rinsed and was air drying when it exploded!!! A piece tore my shirt and left a red welt. Some of the balls went through the ceiling. Extremely dangerous. 

[wayno]

All is well, no explosions here, I was just blowing the dust out of them when one spun up, I will not do it anymore.

[datzenmike]

It was spinning on my index finger and all that was left was the inner race. Felt like someone grabbed my finger and gave it a good twist. Lord knows how high it revved up.

[Stoffregen Motorsports]

I have heard of that but never been witness. So it does really happen? Scary.

 

Yeah, try the Nissan dealer, or even Napa. All Transmission Parts in Portland may have them too.

[wayno]

I was holding the outside of it in my palm, kind of cupped in my hand, and blowing oil onto my hand thru the bearing after spraying it, and it was spinning really fast, it took a long time for it to stop spinning in my hand, like how long a top spun on a really good spin back in the olden days when I was a kid, back when we made skate boards out of metal strap on roller skates.

[Stoffregen Motorsports]

Oh, I meant the blowing up shrapnel thing. I've never seen that, but always think about it when I'm spin cleaning a bearing.

[datzenmike]

It was my bosses snowmobile trailer that he wanted 'winterized'. So I was cleaning and backing the bearings. 120 PSI from an air gun nozzle. Made a rising zing sound that rose above hearing range mixed with the sssss for the air. I was holding it on an angle and blowing air across the outer race. Found only a few pieces. I don't recommend doing this .........