Jump to content

IGNORED

Transmission Noise in 3rd Gear - F4W71A


Recommended Posts

I finished disassembly of the main shaft, all the individual gear needle bearings look to be in good shape. Even wear patterns on the collars that they ride on as well. From what I can tell the collars that my arrows point to for 3rd and 4th are part of the main shaft and there is no ball bearing under those collars like the one under 2nd? (I removed that small ball bearing, not pictured but it was in place). 

2021-07-31 10_58_33-Greenshot image editor.png

Link to post
Share on other sites

It looks like it is an issue with the third gear. Its you have no end play in the main shaft it is not the ball bearing in the adapter plate. The needle bearing between the input shaft and main shaft shows some wear, but it's not causing any problems.

I'm not and expert on the 71A transmissions, but most of the components are very similar to the 71B used in the 720 trucks and the later Zeds.

The next step I would take is to dismantle third gear. You will need to remove the cluster shaft front bearing and front gear, which is held on with a circlip, to be able to remove the input shaft.

Pay particular attention to damage around the circlip holding the 3rd/4th gear hub on the main shaft. I have only seen it happen once, but the circlip came off and the hub could move back and forth. That made some serious clunking sounds only in third. It was also making some much quieter noises in 1st and 2nd. That happened after a guy did a home rebuild and when it started clunking he bought it in to have checked.

I wouldn't expect this from the factory, but these cars are old and many repairs later....

The 3rd/4th hub and sleve are pos 4,5 and 6. The gear pos 16 needs to be removed from the cluster shaft pos 17 to remove the input shaft pos 2.

Screenshot_20210731-170004.jpg

Link to post
Share on other sites
16 minutes ago, AnvilZ said:

I finished disassembly of the main shaft, all the individual gear needle bearings look to be in good shape. Even wear patterns on the collars that they ride on as well. From what I can tell the collars that my arrows point to for 3rd and 4th are part of the main shaft and there is no ball bearing under those collars like the one under 2nd? (I removed that small ball bearing, not pictured but it was in place). 

2021-07-31 10_58_33-Greenshot image editor.png

The needle bearings in the gears look good. That dull colour on the shaft is slight wear, but not excessive damage. It's normal.

The are actually 3rd, 2nd and 1st. 4th is a direct drive through to the input shaft and doesn't have any reduction though the cluster shaft.

The photo looks like the 3rd gear needle (left side row) shows signs of blueing which could be a sign of excessive heat build up.

Are all the hub, sleeve and shifting inserts ok?

How was the circlip holding the 3rd/4th hub? And the end clearance to the circlip?

Link to post
Share on other sites
Posted (edited)
30 minutes ago, EuroDat said:

The are actually 3rd, 2nd and 1st. 4th is a direct drive through to the input shaft and doesn't have any reduction though the cluster shaft.

Yes, that is my mistake. The 3rd gear needle bearing is not blueing, just the lighting in the picture. No discoloration on the left side row. 

The circlip was in place and tight, no damage that I could see. The 3rd gear assembly looks ok to me as well.

The only thing I notice on the hub is some wear on the 4th gear side where the 4th gear synchro rides. I circled it in the picture but there are two dents or chips there, the 3rd gear side looks much better. I assume the wear around the inner diameter is from the circlip, is that normal?

 

3rd Assem.png

You can actually see one of the dents/chips I mentioned in the assembly picture above as well, on the right side of the hub. 

3rd Back.png

3rd Front.png

3rd Synchro side.png

4th Synchro side.png

Edited by AnvilZ
Link to post
Share on other sites
2 hours ago, AnvilZ said:

The only thing I notice on the hub is some wear on the 4th gear side where the 4th gear synchro rides.

3rd Synchro side.png

4th Synchro side.png

Those marks are only wear marks from the circlips. That is most probably why they changed the design to springs under the shifting inserts in the B version. I don't see any serious issues in the photos.

The way the syncho works is simple. This is a basic description of how they work. The shifting inserts are pushed into the outer hub by the circlip or springs. The outer hub is held in the correct position by the selector and selector detent ball/spring. The shifting inserts insert into the three tabs cut outs in the synchro ring and lock it with the hub. The synchros turn with the hub. When the sleeve moves toward a gear it pushes the shifting inserts and the synchro onto the cone of the gear. When pressure is applied the synchro will speed up or slow down the gear until its rotating at the same speed. When more pressure is applied the sleeve slips over the hump on the inserts and engages the gear. Its held in gear by the selector detent ball/spring.

Looking at your photos. The hub, circlips and gear needle bearings look ok. Makes me wonder if you were not experiencing a frequency vibration that was worse in third gear and causing a rear engine mount to tap against too long mounting bolts for example. I'm not saying that is your problem, but it could be something outside the transmission.

Link to post
Share on other sites
5 minutes ago, EuroDat said:

Looking at your photos. The hub, circlips and gear needle bearings look ok. Makes me wonder if you were not experiencing a frequency vibration that was worse in third gear and causing a rear engine mount to tap against too long mounting bolts for example. I'm not saying that is your problem, but it could be something outside the transmission.

I wondered about this as well, however I may have found one of my issues. When I pressed the larger main shaft bearing out of the adapter plate and inspected it further it does not spin smoothly. It chatters a little bit and seems like it may be going out. I am wondering if under load in 3rd gear it causes the excess vibration. You mentioned 3rd puts the most load on the main shaft correct?

Link to post
Share on other sites

iirc the forward most servo hub is directional, unlike the others. not sure but i think is possible to go in the wrong way. I dont know if this could cause the clunk issue, but i would recommend you look at it very closely and check the fsm. I think it mentions this. 

Link to post
Share on other sites

Good to know, thanks for the suggestion. I will triple check the hub orientation during reassembly. 

Link to post
Share on other sites
7 minutes ago, Dave WM said:

iirc the forward most servo hub is directional, unlike the others. not sure but i think is possible to go in the wrong way. I dont know if this could cause the clunk issue, but i would recommend you look at it very closely and check the fsm. I think it mentions this. 

I should also ask, do you know if this applies to both the A and B transmissions? I downloaded my copy of the FSM from Xenonzcar but the 72 version was the earliest available and I would assume it covers the F4W71B. Is there a 1971 FSM floating around somewhere?

Link to post
Share on other sites
On 7/28/2021 at 10:31 AM, AnvilZ said:

The frequency is definitely speed dependent though, it would increase with RPM. It does not clunk with the clutch pedal down in 3rd.

Have you checked the action  of the shift fork on the coupling sleeve, and the sleeve on the hub?  I wonder if the sleeve could get cokced on the hub as the fork pushes it over.  Like if one tine of the fork was ahead of the other.  The sleeve should lock in, or center over its final position, but maybe you're getting incomplete travel and final engagement.  You have it all torn donw now but you might find some sign on the parts.  Maybe a loose fork on the rod.  The roll pins do fail.  Ideally, you would check the action by moving the shift rods with it mostly assembled.  There are also the detent pieces in the adapter plate.  The balls, springs, and pins that set the final position of the shift rods after a gear selection.

Your description sounds like something relatively large wobbling around the shaft.  If all of the bearings and other parts seem undamaged and correct then it seems like the parts must not be correctly positioned.

Link to post
Share on other sites
13 minutes ago, AnvilZ said:

I should also ask, do you know if this applies to both the A and B transmissions? I downloaded my copy of the FSM from Xenonzcar but the 72 version was the earliest available and I would assume it covers the F4W71B. Is there a 1971 FSM floating around somewhere?

Xenonzcar doesn't have the 71A. I don't know where you can find one these days. They were available, but I never downloaddd it. You are one of the thew that wants to rebuild a F4W71A.

I'm no an 71A expert, but I think the sleeves and selector forks are interchangable and the sleeves reversable on the 71A. That is not the case with the 71B.

 

Link to post
Share on other sites

I found a pic of what I was trying to describe in my 75/76 FSM. Its fig MT-28 on page MT-8

they show two "synchronizer hubs"

front is 3rd & 4th (move the sleeve one way to lock 3rd to the main shaft, move it the other to lock the input to the output no gears.

there is also an illustration of the 1st & 2nd "synchronizer hub". If you look carefully at the see thru side view you will see how 3rd and 4th have an offset while 2nd & 3rd look to be symetrical.

  • Like 1
Link to post
Share on other sites
57 minutes ago, AnvilZ said:

Is there a 1971 FSM floating around somewhere?


CanTech Z uploaded this 1970 FSM to the site a while ago, it describes the F4W71A.  For whatever reason the 1971 FSM is oddly formatted but it has a chapter also.  The 1971 document has the same description as 1970, so it looks to be the same transmission.  The 1970 document is a clearer copy.

image.png

https://www.classiczcars.com/files/category/11-240z/

 

Link to post
Share on other sites
57 minutes ago, Zed Head said:

Have you checked the action  of the shift fork on the coupling sleeve, and the sleeve on the hub?  I wonder if the sleeve could get cokced on the hub as the fork pushes it over.  Like if one tine of the fork was ahead of the other.  The sleeve should lock in, or center over its final position, but maybe you're getting incomplete travel and final engagement.  You have it all torn donw now but you might find some sign on the parts.  Maybe a loose fork on the rod.  The roll pins do fail.  Ideally, you would check the action by moving the shift rods with it mostly assembled.  There are also the detent pieces in the adapter plate.  The balls, springs, and pins that set the final position of the shift rods after a gear selection.

Your description sounds like something relatively large wobbling around the shaft.  If all of the bearings and other parts seem undamaged and correct then it seems like the parts must not be correctly positioned.

Good suggestion, I did check all of the shifting mechanisms once I removed the transmission housing before disassembling everything. The coupling sleeves and selector forks were aligned and everything clicked into placed pretty smoothly. The forks were held onto the selector rods tightly by the pins. Seemed like the detent balls/springs were doing their job as well. 

I mentioned in post #31 that I might have found my issue, or one of them. The main shaft adapter plate bearing seemed like it was starting to fail once I removed it from the plate and inspected it further. I didn't really notice it when the shaft was still installed but checking the bearing itself once removed it is not rolling as smoothly as it should. Maybe under higher loads it causes excess vibration. I have a replacement on order and will replace both of the main shaft bearings when they come in. 

17 minutes ago, Zed Head said:


CanTech Z uploaded this 1970 FSM to the site a while ago, it describes the F4W71A.  For whatever reason the 1971 FSM is oddly formatted but it has a chapter also.  The 1971 document has the same description as 1970, so it looks to be the same transmission.  The 1970 document is a clearer copy.

image.png

https://www.classiczcars.com/files/category/11-240z/

 

Thanks, I will definitely check that out. Probably more helpful than the 72 FSM I have been using. 

Link to post
Share on other sites
9 hours ago, AnvilZ said:

Good suggestion, I did check all of the shifting mechanisms once I removed the transmission housing before disassembling everything. The coupling sleeves and selector forks were aligned and everything clicked into placed pretty smoothly. The forks were held onto the selector rods tightly by the pins. Seemed like the detent balls/springs were doing their job as well. 

I mentioned in post #31 that I might have found my issue, or one of them. The main shaft adapter plate bearing seemed like it was starting to fail once I removed it from the plate and inspected it further. I didn't really notice it when the shaft was still installed but checking the bearing itself once removed it is not rolling as smoothly as it should. Maybe under higher loads it causes excess vibration. I have a replacement on order and will replace both of the main shaft bearings when they come in. 

Thanks, I will definitely check that out. Probably more helpful than the 72 FSM I have been using. 

If the bearing in the adapterplate start failing, it generally is first noticable in 1st gear. 1st being the closest gear that puts sideways pressure on it. I would expect the sound to be most audible in 1st then 2nd then 3rd and 4th being a direct drive the least of the noise.

You can get noises when certain frequencies match, but 3rd gear clunking when a mainshaft centre bearing fails is one I havn't heard of before.

That is why I focussed on the third gear as the area that would cause a noise in third, but noticably less in 1st or 2nd.

Link to post
Share on other sites
6 hours ago, EuroDat said:

If the bearing in the adapterplate start failing, it generally is first noticable in 1st gear. 1st being the closest gear that puts sideways pressure on it. I would expect the sound to be most audible in 1st then 2nd then 3rd and 4th being a direct drive the least of the noise.

You can get noises when certain frequencies match, but 3rd gear clunking when a mainshaft centre bearing fails is one I havn't heard of before.

That is why I focussed on the third gear as the area that would cause a noise in third, but noticably less in 1st or 2nd.

Interesting, based on what we have looked at so far it seems like this is the only issue from the transmission internals correct? Anything else I should check before replacing the main bearings and reassembling? Would you recommend replacing the synchro rings as well while I have it apart or leaving them alone, I know new is not always better but definitely don't want to pull the transmission again in the near future if I can help it.

Link to post
Share on other sites

if you were not having issues with sycrhonization i would tend to let it be. there are measurements that you can take to see how much wear there is (gaps) to give you some idea about how much life you have. If you decide to replace them there is a guy on youtube that does nothing but transmissions. i cant recall him but a search should find easy. He goes into great detail about what to look for as far as the brass parts are concerned.

Link to post
Share on other sites

All the ball bearings and the needle bearing between input and main shaft should be replace

I would replace all the seals regardless of how they look.

You can check the wear on the synchros by following the procedure in one of the 71B manuals. The original nissan synchros would need to be very worn before I would go after market. 

Next is to check the shifting inserts and the circlips. If you can get new circlips, them I would definately get them.

Remember what I wrote above. The pressure the circlip applies to the shifting inserts determines how much force the sleeve can apply to the synchro ring before the sleeve rides over the shifting insert and engages the gear. A weak circlip (or on the 71B it's 3 springs) will allow the gear to grind a little when going into gear.

If you can find new detent springs for the selectors, then it would be a good time to change them.

 

 

 
 
Link to post
Share on other sites
1 hour ago, Dave WM said:

if you were not having issues with sycrhonization i would tend to let it be. 

 

40 minutes ago, EuroDat said:

You can check the wear on the synchros by following the procedure in one of the 71B manuals. The original nissan synchros would need to be very worn before I would go after market. 

 

 

 

 
 

Thanks for the tips. I am not having any issues with synchronization, so I will check them according to the manual and hopefully they are fine to continue using. I will plan to replace seals/ball bearings/detent springs/main shaft needle bearing etc. 

Maybe thinking too far ahead here but once that is done and the transmission is back in the car, assuming I am still having an issue is there a recommendation for how to isolate which part of the drivetrain it is? I had considered the idea of removing the prop shaft and running through the gears to see if there is any noise to try and narrow it down to the trans or something else. However I don't know if the same issue would occur without the load on the transmission. 

 

Link to post
Share on other sites

if its really that loud, you should try bench running it. a large drill and some rubber hose over the input shaft. I know its a long way off from actual loads and rpms, but its fun and who knows maybe something will turn up.

  • Like 2
Link to post
Share on other sites
On 8/1/2021 at 12:50 PM, Dave WM said:

if its really that loud, you should try bench running it. a large drill and some rubber hose over the input shaft. I know its a long way off from actual loads and rpms, but its fun and who knows maybe something will turn up.

I will give that a shot, thanks.

A few of the bearings will not be in until the end of the month. I will update the thread once they are in and I have tested the transmission. 

Link to post
Share on other sites
  • 2 weeks later...

@Zed Head @EuroDat @Dave WM I found another possible issue when I was digging back through all the part numbers from my engine/transmission rebuild that I was hoping someone could help clarify for me. When I started this project 2.5 years ago and had little to no knowledge of Z cars, one of the first things I ordered was this Transmission Service Kit from Z Car Source: https://zcarsource.com/transmission-service-kit-240z-260z-280z-72-78-new/ 

Mark it up to inexperience or my own stupidity at the time, but I did not look closely enough at the fact that this only works for the B type transmission. Pretty obvious based on the compatible years in the title, kind of kicking myself for that. Anyway, this kit is what is currently on the car with their clutch kit (14400103 - Clutch Kit, 260Z 280Z 280ZX 300ZX, 74- 83 Non-turbo 2+2, 81-86 Turbo - new) and flywheel (13100402 - Flywheel (Manual Transmission), 260Z 280Z 280ZX, 74-83 2+2 and Turbo - new).

From what research I have done I am a little confused on compatibility year to year but it seems like the flywheel interface is the same for all Zs 70-83. Would that mean that this flywheel will work for my 71 regardless of the description stating 74-83? Similarly for the clutch disc and pressure plate, the overall kit itself states compatibility for 72-78, while the sub kit with the disc and pressure plate says 74-83. Some other kits with a clutch disc and pressure plate say 70-74, that seems to indicate that the disc and pressure plate for a B type trans will also work for the A type? 

Hope that makes sense, just trying to determine if any or all of those components need to be replaced and if that may be contributing to my issues at all. It may be that other components in the Transmission Service Kit like the clutch fork or rubber shift boot are why it is labeled for B type only. 

 

Link to post
Share on other sites

clutches and flywheels can get complicated.

you have the 225 and 240 mm versions, the smaller IIRC had 6 bolt holes for the pressure plate, the larger (2+2 and ZX) has nine holes so you have to have a matching flywheel and pressure plate. 

Next up is the throw out bearing, there are 3 diff lengths IIRC, not sure which goes where but you want it right so the pressure plate fingers are depressed correctly when you disengage the clutch. 

I am not even sure the pressure plates are the same within the 225 and 240 sizes, that is some may be taller than others. 

Link to post
Share on other sites
Posted (edited)

The zcarsource description is wrong on the clutch kit, turbo and 2+2 are the same parts.  Can't exclude one and include the other.  Edit - actually I see that what they did is to just add irrelevant information and leave out other relevant info.  It could be turbo, 2+2, or turbo 2+2.  All 240mm.

But you might have the right parts.  The pictures match.  Looks like the 240mm clutch setup.  The parts that you said are on the car look like 240mm also.  So, odds are you'll be fine.  92mm is the critical measurement.

https://zcarsource.com/transmission-service-kit-240z-260z-280z-72-78-new/

https://zcarsource.com/clutch-kit-260z-280z-280zx-300zx-74-83-non-turbo-2-2-81-86-turbo-new/

https://zcarsource.com/flywheel-manual-transmission-260z-280z-280zx-74-83-2-2-and-turbo-new/

 

 

Edited by Zed Head
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.