Anyone know NSX gearboxes well? Advice appreciated

[Hagasan]

Hi all,

I've just had a 6-speed gearbox fitted into my 96 car......small problem!!!

I had the box rebuilt with the twin-splin shaft to use the ealier clutch, had the NSX-R final drive and a lightweight Jun flywheel for good measure also. New bearings & seals all fitted to the box as well.....

The gearbox was re-built by a reputable shop over here in the UK who also work on the NSX racecar some have you may have seen on here with the paddle-shift sequential gearbox...Was advised all the selector forks, synchros & gears were in good condition with no concerns requiring replacement.....

So anyway the point, gearbox fitted, all forward gears fine but reverse has a problem. The gearbox goes into reverse ok and if I slip the clutch I can reverse but once the clutch pedal if let fully out the box jumps out of reverse abruptly. Basically any load in reverse and boom, reverse is gone.....

The gearbox itself was fitted by an NSX dealership. They mentioned it popped out of gear once but put it down to their driving....Just to cover the bases the car was put back on the ramp to check the cables. It was found that the cables were correctly adjusted and the gear box selector could travel no further even if the cable length was shortened a little.

THe reverse lockout solenoid has not been wired up yet but my understanding anyway is the default with no power to the solenoid is to allow reverse to be engaged with the box does anyway, it just jumps out on load....

It's all a bit of a bummer as it looks like the box will have to come of the car and be opened up again which means all the time so far is effectively wasted :-(

My question really to any of those who know the gearboxes well is, ahead of it being removed, do you have any suggestions as to what would cause this situation?

Also just to confirm for those every considering this mod, my 96 car with the earlier power steering does not flag up the EPS fail with the 4.23 final drive as I think it does from 97 onwards....

Thanks,

Gary

 

[docjohn]

not sure if any of this might help as you seem to be knowledgable about your problem but check out the link in post #10...http://www.nsxprime.com/forums/showthread.php?t=97678&highlight=6+speed+transmission+lockout

 

[liftnot]

Nick KNOWS NSX gearboxes

Hagasan,

contact Nick Eustance 760-401-0253 or
[email protected]

he has mad skills especially when it comes to NSX gearbox. He has many years of building/modifying gearboxes for FX, Dali, and many others.

He does not post much at all but he is a reliable source for NSX.
He is in San Diego Ca. and well worth your time.

Tim

 

[Hagasan]

Thanks to the two posters above....

I'm in the UK so calling California for advice from a business may seem a bit cheeky.....

Regarding the solenoid....my point is that it is not needed to put the car into reverse. It is designed to stop you going into reverse and is energised to do this, either by the brake method or vss signal.

By default then when not connected, it is spring loaded and allows reverse to be selected which I can do. It is also possible to select 5th & 6th if you are careful but that's not the issue.

My issue is that I can select reverse and move the car with a feather clutch on a flat surface but any greater load on the gearbox causes it to jump abruptly out of gear....I am trying to understand what inside the box would fail to do this or what may have not been done correctly on the rebuild....

Thanks,

Gary

 

[stuntman]

Re: Nick KNOWS NSX gearboxes

Hagasan,

contact Nick Eustance 760-401-0253 or
[email protected]

he has mad skills especially when it comes to NSX gearbox. He has many years of building/modifying gearboxes for FX, Dali, and many others.

He does not post much at all but he is a reliable source for NSX.
He is in San Diego Ca. and well worth your time.

Tim

+1

Nick is the MAN

 

[docjohn]

PM Larry B......he is a trannie meister...in a good way...not like Hugh

 

[goldNSX]

I'm no expert on the gearbox internals altough I've worked on it. If the cables are perfectly adjusted the shift fork of the reverse gear or it's play is the culprit, well normally. If so the gearbox has to come out again and your shop has to fix it for free.

One question: did you upgrade YOUR 5-speed to 6-speed? Mileage?

Gearbox revisions in Europa are a pain in the a** as you only see the internals after opening Pandora's box and see what has to be changed and then wait for 4+ weeks for the parts.

 

[Hagasan]

I'm no expert on the gearbox internals altough I've worked on it. If the cables are perfectly adjusted the shift fork of the reverse gear or it's play is the culprit, well normally. If so the gearbox has to come out again and your shop has to fix it for free.

One question: did you upgrade YOUR 5-speed to 6-speed? Mileage?

Gearbox revisions in Europa are a pain in the a** as you only see the internals after opening Pandora's box and see what has to be changed and then wait for 4+ weeks for the parts.

Hi, yes it was a 5 to 6 speed upgrade....You sent me the pictures a few months ago as originally I was going to do it myself!!

The 6 speeder was about 28k miles. All the internals were checked I was told. I supplied the replacement bearings, seals, i/p shaft and 4.23 final drive. The shop just fitted and rebuilt everything. It is frustrating as I know it will have to come out again regardless of who is responsible....It was quite nice to drive it with the new box and flywheel so far......

 

[goldNSX]

All the internals were checked I was told. I supplied the replacement bearings, seals, i/p shaft and 4.23 final drive.

I'm sorry to hear your misfortune. Now, I recall, I've sent you some pics.

Well, I would not trust them saying that everything was ok. Did they really measure the clearances specified by the service manual? Only they'll know for sure.

Did you also supply them with the needle bearings for the reverse gear?

The one thing I recall of our gearbox job back in 2008 was the difficulty getting the transmission case on the transmission housing. You need four hands for his job, two holding the case, two aligning/guiding three shaft in the housing. It's a job a hammer is useless. If they've rebuilt NSX gearboxes before they should know.

Well, I'm not a good advisor in this case. I hope someone more experienced chimes in and maybe there's a solution or test without pulling the gearbox.

Good luck!

 

[Hagasan]

I'm sorry to hear your misfortune. Now, I recall, I've sent you some pics.

Well, I would not trust them saying that everything was ok. Did they really measure the clearances specified by the service manual? Only they'll know for sure.

Did you also supply them with the needle bearings for the reverse gear?

The one thing I recall of our gearbox job back in 2008 was the difficulty getting the transmission case on the transmission housing. You need four hands for his job, two holding the case, two aligning/guiding three shaft in the housing. It's a job a hammer is useless. If they've rebuilt NSX gearboxes before they should know.


Well, I'm not a good advisor in this case. I hope someone more experienced chimes in and maybe there's a solution or test without pulling the gearbox.

Good luck!

They have done NSX boxes previously....THey said they measured the selector forks, etc and checked the synchros.against the book specifications...All thes parts would have been removed from the old shafts. THe reverse gear shaft assemblyhowever would not need to be dismantled, just removed to allow work on the other two...Maybe they let this go?

I didn't supply any reverse gear bearings, just the main & countershaft ones.

I am thinking something may be out of alignment or is it even possible a gear could be upside down on a shaft...I guess not as the are not straight cut gears....What's weird is it goes in gear ok?

I will be speaking tomorrow and pushing for a quick solution as I want the car to use after the time and payment waiting to get to this!!

THanks for your comments and thoughts.

 

[goldNSX]

They're right about just removing the reverse shaft if no revision is planned. At 28k miles on the gearbox I can't see any parts being out of specs unless the car was raced intensively.

There are no straight cut gears in the gearbox. The service manual mentions a 5th/reverse shift piece and fork and spring pins.

While mounting the gearbox housing the shift lever is a critical thing. But as you can shift I guess it's ok.

 

[whrdnsx]

Could it be something like a detent not fitted or stuck.

I've had it happen on other gearboxes, not 100% sure with the Nsx 6 speed.
although it sounds similar.

Had this exact same problem on a GTR & it was a stuck ball detent.

 

[Larry Bastanza]

If you hold it in reverse is it OK?

Regards,
LarryB

 

[Hagasan]

If you hold it in reverse is it OK?

Regards,
LarryB

Hi,

holding it in reverse was one of the things I tried early on....forgot to mention that. Even holding the shift lever in the car does not stop the box from jumping out of reverse. I tired this to keep some "tension" in the selector on the box but it's still no good.

The shop that did the rebuild seem to have this idea it could have been installed during installation! There nothing really to be done wrong, fit it on the ramps and reverse off. It then jumps out of gear!! The dealer is an NSX dealer and the guys in there do know this sort of stuff ok....

Any thoughts, my feeling is it's a duff tranny build? I don't recall them ever mentioning to me shimming the two new shafts, main & counter, as the manula describes. I wonder if this could have a bearing on my problems...

Thanks,

Gary

 

[Larry Bastanza]

I hate to say it, but I really think the transmission will need to come out. The only other thing it can be is something with the cable adjustment, but it is a long shot.

What I would do is remove the shift cables and by hand get the trans in reverse, then release the clutch. If it jumps out of gear, the issue is definately inside the trans. If not, the cable is not right. I have not had to adjust the cables on any 5-6 speed swap.

With that said, the reverse gear assembly can be tricky to reinstall. You need to have the mainshaft and countershaft assemblies in the right spot to slip the reverse gears in place. I use some shims to set the shafts then install the reverse gear assembly. The NSX transmission does have a reverse syncro, so something maybe is not right with the syncro, or the syncro spring inside that assembly. I have had to remove it during reassembly and start over more then once.

So, try the cables off and see what happens.

HTH,
LarryB

 

[Hagasan]

I hate to say it, but I really think the transmission will need to come out. The only other thing it can be is something with the cable adjustment, but it is a long shot.

What I would do is remove the shift cables and by hand get the trans in reverse, then release the clutch. If it jumps out of gear, the issue is definately inside the trans. If not, the cable is not right. I have not had to adjust the cables on any 5-6 speed swap.

With that said, the reverse gear assembly can be tricky to reinstall. You need to have the mainshaft and countershaft assemblies in the right spot to slip the reverse gears in place. I use some shims to set the shafts then install the reverse gear assembly. The NSX transmission does have a reverse syncro, so something maybe is not right with the syncro, or the syncro spring inside that assembly. I have had to remove it during reassembly and start over more then once.

So, try the cables off and see what happens.

HTH,
LarryB

Hi Larry,

I had already tried the the cables off test and the levers on the gearbox were at the limit of their travel.

The gearbox is coming out today then it has to be transferred to builder....All along it's been my view that the box was faulty internally but the rebuilder seemed reluctant to accept this may be the case....Hopefully an honest diagnosis will be revealed soon.

Another party has also commented that the case rejoining is critical. There comments suggest that if the reverse gear syncro & spring fall out of their natural posistion when closing the case then the parts may well get bent. If so then they will cause the exact problem I am experiencing...

....If so then new parts and another attempt at closing the box correctly!!

Lets hope second time around it's fixed, shouldn't be at my expense though!!

Gary

 

[Larry Bastanza]

Hi Gary,

Please help me understand one thing. Your comments above indicate you have started with a 5 speed transmission and installed 6 speed shafts into the 5 speed case. Is this true? There are MANY differences between the two transmissions so this has got me a little concerned that it will be disassembled and still not correct when rebuilt. The area of the case with the reverse lock-out and the shift linkage, I believe is different.

Regards,
LarryB

 

[NSXGB]

Hi Gary,

Please help me understand one thing. Your comments above indicate you have started with a 5 speed transmission and installed 6 speed shafts into the 5 speed case. Is this true? There are MANY differences between the two transmissions so this has got me a little concerned that it will be disassembled and still not correct when rebuilt. The area of the case with the reverse lock-out and the shift linkage, I believe is different.

Regards,
LarryB

I'll answer that one for Gary to keep things rolling...
Gary bought a complete 6 speed transmission then had the 'R' final drive and input shaft installed...

 

[goldNSX]

Hi, yes it was a 5 to 6 speed upgrade

Gary bought a complete 6 speed transmission then had the 'R' final drive and input shaft installed...

Still confused...

 

[Hagasan]

Still confused...

Ahh, when is English not English? When me, the guy from Scotland speaks it!!

To clear any confusion....

I bought a bulk standard E61 6-speed gearbox. I had the 6-speeder rebuilt with the twin-splined input shaft and the NSX-R 4.23 final drive.

I had the original 5-speeder removed untouched from my car and then the modified 6-speeder was installed...

This is where the story/fun begins :frown: My newly modified 6-speeder is the box with the reverse problem...

Hope that clears it up :biggrin:

Gary

 

[Larry Bastanza]

OK, So let's go inside and find out why the reverse syncro is not working. I am thinking it is the detent spring.

Go here, #6

http://www.acuraautomotiveparts.org...omp=List All&vinnoT=&trim=&trans=&view=normal

Regards,
LarryB

 

[Hagasan]

Well the box is out and back at the shop.....No reports back today but watch this space......

 

[Hagasan]

The gearbox was fitted back into the car yesterday and now reverse works fine.....

Although I asked to be present when the gearbox was opened (by the rebuilder not by the dealer) I was not offered this facility.

The gearbox rebuilder said he took the cover off and could find nothing wrong, he said he dis-assembled the reverse shaft assembly and nothing was wrong with any part. He says it was put back together exactly the same as first time.

The box was then refitted by the dealer and all is now ok. As I said in earlier posts, the cables were removed first time around to make sure the gearbox shift levers could not move any further and better engage the gear.

The rebuilder says the dealer did something wrong first time but I can't really understand what.....He says he couldn't have done anything wrong the first time or the case would not have gone back on....

He is not accepting it is his fault/responsiblity and inferring it's the dealers...

Either way it's not MY fault but I had to pay the dealer today for refitting of the box so that I could get my car back....

Larry specifically or others too, what's you final views on my outcome? I'm thinking I now need to take legal action to reclaim my second set of fitting costs...

Thanks,

Gary

 

[Larry Bastanza]

Based on the information presented it is clear to me the rebuilder "fixed" something, even if he did not realize it. Simply lifting the case off can correct an issue. Obviously being only on the internet and not present as the case was removed it is hard to say what, and even harder to prove.

The fact is there is nothing outside of the gearbox that could cause this issue, especially after removing the shift cables and having the same results.

Frankly, I am not 100% sure where you are located, but any legal action in the US would be more $$ then it is worth.

The lesson here is NEVER have more then one person perform any one job on the car. When things go wrong, and they do, you cannot have two persons to blame, you NEVER win.

BTW, Did the rebuilder charge you?

Was it only the R & R that you had to pay twice?

If so, I do not think the dealer was wrong to charge you, he did his job correctly, twice.

My $.02,

Glad it is fixed

Regards,
LarryB

 

[Hagasan]

Based on the information presented it is clear to me the rebuilder "fixed" something, even if he did not realize it. Simply lifting the case off can correct an issue. Obviously being only on the internet and not present as the case was removed it is hard to say what, and even harder to prove.

The fact is there is nothing outside of the gearbox that could cause this issue, especially after removing the shift cables and having the same results.

Frankly, I am not 100% sure where you are located, but any legal action in the US would be more $$ then it is worth.

The lesson here is NEVER have more then one person perform any one job on the car. When things go wrong, and they do, you cannot have two persons to blame, you NEVER win.

BTW, Did the rebuilder charge you?

Was it only the R & R that you had to pay twice?

If so, I do not think the dealer was wrong to charge you, he did his job correctly, twice.

My $.02,

Glad it is fixed

Regards,
LarryB

Hi Larry thanks for your comments....

I originally asked the gearbox guy to fit the box as well ( I bought it from him) but he said he was too busy without the space to do the work. This is the only reason why I took the gearbox to the dealer for fitting. When there was a problem with the box I offered to take my car to him so that he could see the symptoms for himself but he did not accept my offer, just asked for the box back......

I did not have to pay the builder any more money!?!?

I did pay the dealer again to release the car but as far as I can see/understand what could they have done wrong? They were open in showing me the car in their workshop with the cables off and the fault existing. I can't see where they could have gone wrong?

I think I will have to pursue the builder in the first case....