How to fix hard upshift to 5 gear? Any good shop in NY or NJ ? Or should I try ?

My gearbox in 91NSX has a VERY hard up shift to 5 gear. It has only 32k miles, but with CTCS short gears and final drive. All work was done by Comptech.
Unfortunately Larry is booked for couple of months so I have to find another shop or try it myself. I can do simple jobs like LMA, clutch, timing belt, but I didn't have the guts to open a gear box yet.
If I jump the fence, what should I replace for sure and what is a good idea to do when it's all open. Only problem is the 5 gear.

Thanks

Jerry

You can double clutch to 5th? I have a habit of double clutching from 4th to 5th, only those gears though because I rarely go to 5th as is except highway cruise.

What oil is in the gearbox?
Did you check the shift cable adjustment?
Are you sure that the clutch fully disengages?

5th is a little bit harder to select in any NSX as there are more parts involved inside but only by a small amount.

If I came to the US and started working on NSXs would my shop be booked for months too? No, I won't come, sorry guys. I was in the position like yours before the winter. If you are brave enough to open the gearbox the first time here you go: http://www.nsxcb.co.uk/showthread.php?14344-My-gearbox-revision-thread

You could try Joe @ Poughkeepsie or GT Japanese Automotive in Edison. I took my car to GT and was very happy with Bill's work. He showed me pictures of the repair being completed (on his totally old school digicam). Not sure if he does gearbox work though. He used to own an NSX so he knows the innards pretty well.

goldNSX said:

What oil is in the gearbox?
Did you check the shift cable adjustment?
Are you sure that the clutch fully disengages?

5th is a little bit harder to select in any NSX as there are more parts involved inside but only by a small amount.

If I came to the US and started working on NSXs would my shop be booked for months too? No, I won't come, sorry guys. I was in the position like yours before the winter. If you are brave enough to open the gearbox the first time here you go: http://www.nsxcb.co.uk/showthread.php?14344-My-gearbox-revision-thread

Click to expand...

Thank you for that link. Exactly what I'm looking for. A lot of info and pictures. Great.
I think that the clutch is disengaging. There isn't a problem with any other gear.
I just bought the car so I'm not 100% sure what oil is there, but was replaced by a dealer 2 years ago.
I'll check cable adjustment tomorrow. Good point.
Double clutching doesn't help. Only brutal force works.

New oil won't change 5th gear if all others are fine. By needing a little bit more force to shift in 5th I mean about 20% (compared to 1st-4th). I'd change the oil to see if there are broken parts in there. Don't forget the filter. If you're going to use brutal force you are liked to open the gearbox soon. :wink: I hate to say but if you can't find anything else wrong you're going to have to open it to find the reason. I like this to be a winter not a summer project because it needs some months just waiting for parts alone. If you avoided 5th would the car work for you in all the other gears til next fall?
You can unhook the shift cables at the gearbox and shift by hand. There's a schema in my link (#41).

goldNSX said:

New oil won't change 5th gear if all others are fine. By needing a little bit more force to shift in 5th I mean about 20% (compared to 1st-4th). I'd change the oil to see if there are broken parts in there. Don't forget the filter. If you're going to use brutal force you are liked to open the gearbox soon. :wink: I hate to say but if you can't find anything else wrong you're going to have to open it to find the reason. I like this to be a winter not a summer project because it needs some months just waiting for parts alone. If you avoided 5th would the car work for you in all the other gears til next fall?
You can unhook the shift cables at the gearbox and shift by hand. There's a schema in my link (#41).

Click to expand...

I decided to take short ride before I pull the transmission out. I can shift to 5 gear very slowly if I let the RPM drop. Double clutching made it next to impossible. Also fast shift from 2 to 3 was notchy. Cable adjustment was good.
After seeing some metal parts in oil I removed the transmission. Didn't have a chance to open it yet, but 5 gear synchro is most likely gone. One stupid question: If it has short gears, are the synchos 2/3 different ?
The 5 gear should be the same. Also where can I see picture of a new 5 gear fork? If I have the old one I would change it. To bad that I can work on my toys only over the weekend.

Happy wrenching and reading: http://www.nsxcb.co.uk/showthread.php?14344-My-gearbox-revision-thread

Synchros are all the same.

acuhon said:

I decided to take short ride before I pull the transmission out. I can shift to 5 gear very slowly if I let the RPM drop. Double clutching made it next to impossible. Also fast shift from 2 to 3 was notchy. Cable adjustment was good.
After seeing some metal parts in oil I removed the transmission. Didn't have a chance to open it yet, but 5 gear synchro is most likely gone. One stupid question: If it has short gears, are the synchos 2/3 different ?
The 5 gear should be the same. Also where can I see picture of a new 5 gear fork? If I have the old one I would change it. To bad that I can work on my toys only over the weekend.

Click to expand...

Synchros are the same between the JDM and the US/EUDM because sleeve/hubs are the same sizes. 1st and 5th gears are the same. 2-3-4 gears (that are on the mainshaft) are different and the countershaft is different to match these different 2-3-4 gears.

This is a 5th gear fork : http://www.ebay.co.uk/itm/HONDA-NSX...746276?hash=item2efd64efe4:g:lgkAAOSwB-1Yo8kC

Thanks goldNSX for your gearbox revision thread. That gave me the last push to finally open my gear box.
On the left is 4 gear and right picture is 3 gear. I'm not sure if I should change them also. Everything 5 gear related has to be replaced.
Any input is greatly appreciated.
UOTE=goldNSX;1933722]Happy wrenching and reading: http://www.nsxcb.co.uk/showthread.php?14344-My-gearbox-revision-thread

Synchros are all the same.[/QUOTE]

I can't really tell from the angle in the pictures. But if the gear teeths near the synchro are not rounded off but still look like sharp triangles, there's no need to replace them. While driving the car did you hear if one gear was louder than the other? If no you should be fine. Did you measure the distance between the synchro ring and the gear? AND did you also check if the synchro grabs on the gear? I'd change 3rd gear synchro for sure because it will be the first one to let go.

Ok, you have only 32k miles on the gearbox if that no. is correct. Formerly track car?

Pic of the 5th gear? What was wrong with it? What caused the karate-like shifting?

How do the main bearings sound like? I've put the mainshaft and countershaft on a large piece of wood and turned them by hand. The wood acts like an amplifier (like a piano). I write this because the main bearing next to the 5th gear ruined my 5th gear due to a complete idiot who pretensioned the mainshaft by 0.7 mm instead of setting a play of 0.14-0.21 mm.

View attachment 142916View attachment 142917View attachment 142918View attachment 142919This is 5th gear 5th synchro 3rd synchro and clutch. I need 5th gear and synchro, 3rd synchro for sure.The 4th gear has some marks, but I think that will pass. Main bearing doesn't sound bad, but I'll replace it with the one close tho 5th gear. I had 0 play. Didn't measure how much pretension was there. I guess first I have to order all what I need and than to measure for trust shim?
I drove this car only 6 miles and didn't notice any transmission noises. It has comtech intake,headers and exhaust so it's hard to hear anything:biggrin:. Love CTSC pull. I didn't measure synchro clearances because they gone be replaced. Anybody knows what kind of clutch is this?

No pics can be seen.

You can't measure the play of the mainshaft with the countershaft and reverse gear installed. I've replaced about the same parts as you and ended up within 0.05 mm of the old clearance. If you measure your old shim which should result in 0.14-0.21 mm play of the mainshaft if installed correctly by the former installer you will end up within +-0.10 with the new parts. So you need two shims above and two shims below I guess. No need to buy 20 shims.

5th gear and hub/sleeve are discontinued in the US. I had to buy them in Japan directly where they were even cheaper. 5th fork too.

I was working with the SM. There are several pitfalls. Putting it together is obviously more complicated than taking it apart.

Hope that these pictures will work. 5th gear, 5th synchro, 3rd synchro, clutch. I know that this will be quite learning experience. What landmines should I avoid while assembly?

acuhon said:

What landmines should I avoid while assembly?

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Many. Let me know when you got the new parts ready for assembly. :wink:

The condition of the parts in the pics look like someone was not used to drive MT or thought it was a semi-automatic gearbox. Not to make a joke over someone but it reminds me of the glorious threads of people asking HOW DO I DRIVE A MT. Back to technics: is the clutch fully disengaging? Is the clutch hydraulics ok?

I actually can't see much of the clutch in the pic. But one thing is sure: there is not much grease in the groove of the release bearing. As you went that far maybe it's a good idea to have a look at the friction discs for wear and oil contamination while you're waiting for parts.

Did you also measure the clearance between the shift forks and the hub/sleeve or the thickness of the shift fork fingers per the SM? If someone manages to ruin a gearbox within 32k miles he's qualified to ruin other parts as well like resting his hand on the shift lever while driving around. It looks cool but it's poison for the gearbox internals.

How does 1st/2nd hub/sleeve on the countershaft look like?

What is the condition of the countershaft bearing and the snap-ring. Weak point, better replace them as well.

BTW do you have CT FD 4.55? There have been some of them going bad.

EDIT: just wondering how the 3rd itself looks like if the teeths of the hub/sleeve are worn.

View attachment 142967View attachment 142968View attachment 142969View attachment 142970The owner wasn't gentle with the gear box. Pictures of clutch, 1st gr,2nd gr,3gr. I measured clearances between shift forks and sleeves and they all checked out.Forks look straight. I didn't check the free play on the clutch pedal. Now is to late, but I gone replace master and slave CL cylinder. There are some marks on the clutch like it was hitting something. I bought with the car all stock parts and there was beaten starter. Makes me think what clutch is this? I don't know what kind of DF is there but it was installed by comptech and has 68 teeth. Anybody has a part # for short 3rd and 4th gear? I think that I gone change everything .

Only one pic can be seen. Without dismounting the clutch you can't actually judge its condition. Looking at the internals I'd expect everything from the clutch too.

Also: the oil seals behind the flywheel is 26 years old.

Part no. of the short gears can be found in the NSX wiki or FAQ. You'll only be able to source them in Japan. https://www.nsxprime.com/FAQ/Performance/gears.htm

1,2,3rd gear. I think that I'll change them all. Thanks for the link to JDM parts.

They look pretty good, not rounded off, still a triangle (well, from what can be seen in the pics). As the short gears have been installed later it's a possible explanation that the synchro/hub show much more wear than the gears themself if the 'how do I destroy me gearbox'-period was mainly with the long gears.

Did you check the synchros for grabbing on the gear?

You're wanting a closer ratio gearset?

I have spent about 250 hours during the last few months researching and compiling everything pertaining to Honda V6 manual transmissions.

See that tiny reverse idler gear synchro? 43or 44mm. Yeah, 1980 Civic Hatchback 3rd gear synchro.

Bense said:

You're wanting a closer ratio gearset?

I have spent about 250 hours during the last few months researching and compiling everything pertaining to Honda V6 manual transmissions.

See that tiny reverse idler gear synchro? 43or 44mm. Yeah, 1980 Civic Hatchback 3rd gear synchro.

Click to expand...

Do I recall your name from HT back in the day? Fantastic work compiling all the data. Please treat yourself to a vacation once finished to allow your brain to heal.

JohnWayne said:

Do I recall your name from HT back in the day? Fantastic work compiling all the data. Please treat yourself to a vacation once finished to allow your brain to heal.

Click to expand...

The idea of there being another Bense 'tranny guy' is a scary thought.

the brass blocker rings in your pictures are shot,some are bottomed on the gears ,losing their locking ability . some people call them synchos ,they are not ,they are a part of the synchronizer assy.Their purpose is to allow two different rpm events to couple without a clash. They work as a brake on one component and as the same time to speed up another component to allow mesh ,they are designed to be the wear part. I would suggest you look at articles on how a constant mesh synchronized tranny works . Take your time but you must have access to a manual , certain tools and a press{depending how deep you get into this} . You will also be replacing many bearings

I can rebuild your transmission for a very fair price.

I am not certain as to how the rules work on this forum, So I'm going to play it safe and send you a PM.