My gearbox revision thread

[ozon02]

as I understand you write two issues:
1.
"makes some noise at idle with the clutch pedal up"
2.
"the 5th gear was making some kind of the sound of marbles at 1500 rpm cruising around."

1.
may be ball bearing in flywell issue?
2.
I would go in the direction of Kaaz mentioned

and I am doing all the measurements according to the instructions (needle bearing surface etc.)

[darock]

Thanks for documenting all this!

This will help me a lot when doing my gearbox. I have some whiny gearbox noises in fifth gear and also a little gearbox leaver movement when getting on and off throttle in fifth. The housing of my gearbox looks to be replaced at one point. I assume it was a snap ring issue. I think the one who did the install messed up the clearance of at least one gearbox shaft.

I was hugely lucky right before Christmas. Found a near complete set of gearbox rebuild parts about 4 streets away from my house for about 2/3 the current price including parts that are NLA. I didn't even know there was another NSX nearby. Christmas gift to myself

Bernhard

[goldnsx]

I have some whiny gearbox noises in fifth gear and also a little gearbox leaver movement when getting on and off throttle in fifth.

If it does this I'd check the snap ring immediately by opening the big screw (1/2 driver) and see if it looks broken like the one of asylum recently. You don't want to have to replace more parts than needed.

Good luck!

[goldnsx]

I went on with the clutch job today. I was surprised to see that the discs still had 7.9 and 7.3 mm, not bad for 130k km on them. The red circle points to the roughness but the pic doesn't represent it so good related to the flash light.



Not so nice was the mid plate:

[goldnsx]

... and the flywheel:



For the future, I think I've left my 'wild years' behind me. Whenever I think about 0-100 times or other silly things I'll have these pics in mind.

The release bearing was good but not perfect, some little noise. I've taken a video of it. The flywheel bearing was ok too.

As a new clutch is ready to be installed I'll replace it even though the old one would have been good to go for many, many miles but out is out.

Pride: Good point, yes, I'll change the clutch fork too. It was worn quite a lot and I think that this added to the suspicious 'knocking noise' I have observed. The noise went immediately away when I lightly pressed the clutch pedal. Too much play between the shift fork and the release bearing I guess.

[goldnsx]

Happy New Year!

Additions to the broken 2nd synchro. I've tried to replicate why the dual cone synchro was misaligned when mounting it. When you place it in the sleeve the inner ring tends to hang on the bearing and is pushed upwards out of the synchro set. If you mount it you have to push on the inner synchro ring to make sure that doesn't happen.

So, how not to mount it:



Another question about the mainshaft clearance adjustment. In the initial step I've measured 1.20 mm. When I move on to the final clearance inspection how much has to be corrected? +-0.10 or +-0.20 or even more? I'm going to order the shims in 0.05 steps in the required range (before I spend too much money on ordering all possible shims ).

Thanks again!

[Kaz-kzukNA1]

Hi, goldnsx.
If you are doing CL service, you may find this info useful.
These are the parts that will be replaced during my CL service although I know you don't like replacing the parts that amy be re-used for some time.

OEM CL set
Flywheel bolt x 8
Release bearing: probably too late but HUK is the cheapest, about GBP42 at the time of writing
Release bearing guide: this is a MUST unless there is no markings or rust
Release fork: this is a MUST
Release fork hunger
Hunger spring
Hunger bolt x 2

Please invest in good quality grease. Honda OEM Urea grease is expensive but very good especially for CL task.

When removing the flywheel, I normally replace the crank end seal at the triangle cover plate if not done for years.

For the mainshaft clearance, you already have 2 x shim from the previous service so just temporarily install the thinner one (I think you have 0.65mm) and carry out the final inspection method for 0.14 – 0.21mm clearance target.
Then, calculate the total shim thickness required aiming around 0.17mm. That's what I normally do unless freshly building the gbox from new parts.


By the way, I don't know how old your friction disc is but the torsion spring looked rusty but not too bad at all for the mileage covered.
Quite often, they are much more rusty and even broken off resulting in not being able to disengage the CL.
On the other hand, the mating surface at the pressure plate, mid plate and flywheel looked to be partially contaminated by oil/grease and also some blue markings…


When you removed the gbox off the engine, did you find any oxidation on the fixing bolts?
If the gbox was removed in the past and care was not taken on re-assembly, some of the mating thread on the eng side could be damaged and you won’t be able to apply enough torque when re-installing the gbox this time.
You may want going through all of the mating thread on the eng side by tightening the bolt with just the finger to see any changes in friction before re-assembly.
I normally apply dash of silicone spray to prevent future oxidation.

Also, having 2 x much longer fixing bolt with bolt head cut off and tapered can be useful as they can be used as the gbox case alignment guide when re-installing the gbox especially if you are doing this task on the floor….


Kaz

[goldnsx]

"the 5th gear was making some kind of the sound of marbles at 1500 rpm cruising around."

1.
may be ball bearing in flywell issue?

Haven't checked that so far but will do for sure. Anyway, a complete new clutch will be installed.

I think that the 'sound of marbles' in 5th was more due to the play between the worn synchro sleeve teeth of that gear (see pic above) and maybe the sleeve/hub (I didn't see yet). In 4th at 1500 rpm the noise was not there but would have been too if it was a bearing. I first thought about the countershaft bearing with the snap-ring in as it's the nearest to the 5th gear and is prone to go bad but it was really like new (surprised). I think Kaz is spot-on with his explanation even though I rarely shift from 4th at WOT in 5th (speed limit here 120 km/h) but I do drive in 5th >80% of time (fuel saving, haha). Also, I'm CTSCed. So it could be just wear and the popping out on the German Autobahn back in 2008. More over this, the 5th gear needed a little bit more force to engage when the gearbox was cold but was ok when warmed up.
In my friends tranny the synchro sleeve teeth were worn also BUT not like mine. The teeth looked like rounded off you normally see when a gear grinds while shifting.

[Kaz-kzukNA1]

The later design 5th shift fork is interchangeable without other parts involved. Just the craw/fork strengthened by new shape. Just remember to replace the spring washer.

You already found the answer for the sleeve and hub orientation. The tiny groove on the sleeve and the channel or the diameter of the collar of the hub show the orientation.

Despite the usage of the straight edge, I never felt confidence in selecting the shim using that A+B or A-C measuring method.
I just use it as an initial guidance and move on to the final inspection target of 0.14 – 0.21mm.
You don’t need the SST.
After tapping the mainshaft gently, just use the dial gauge and pull up/out the mainshaft using whatever the method you have and then decide the thickness of the shim.

I think now you are aware that there is no problem using the 2 x shim.

Are you servicing the DF?
If not, just replace all of the oil seals and leave these outer race for the tapered bearings on both side of the DF.
Otherwise, you will be forced to replace not just the outer race but also the tapered bearing at the same time.
If you have to, CL case one with oil guide ring is not too bad as you can punch it out from behind.
For the trans case one, normally people will tell you to heat up the case using the heater gun or very hot but not boiling water but I never had any luck using this method.
It just doesn’t want to come out or even move a tiny bit.
For this, I use the commercially available race removal tool that hooks the race edge from inside while heating up the case with the heater gun.
If the race is not on the gbox, you could use the welding trick but too scared for this area.

Kaz

[goldnsx]

Thanks for all your replys, esp. to Kaz.

Today I've replaced the bearing in the clutch case and the bearing races of the diff. As the diff bearing come complete as a set I'll replace the ones on the diff too.

The bearing in the clutch case was tricky to press out. There's a special tool (adjustable bearing puller) from Honda I didn't have. So we (with some helping hands) have used the tools available. As you can see we had to improvise a little bit to pull it out as straight as possible. Heating up the case helped too. For the new bearing a press was used. Note that the two little holes in the bearing are facing upwards.


Both diff bearing races were pretty simple to get out. Just had to work out in what order. For the 90 mm one you hammer on the oil guide plate first. As soon it's free it leans against the race. So you hammer (with great care of course) until both are out. You have to install the oil guide plate first. Then you press in the race. There were some small marks in the races.



Next week I'll change the bearings on the diff and then will do the adjustment procedure of the shim at the 75 mm bearing. Till now, a 2.09 shim was used.

I'll set my diff to NSX-R. There a great video on youtube about how to install the additional spring and new plate.