Snap ring repair

[696]

I have a few questions about snap ring repair. My car is a 1992 with ~31,000 miles that is in snap ring range. The transmission feels fine. The repair is just to have the potential for future failure taken care of.

I just purchased a new case. I was going to send my transmission to SOS to do the case replacement/snap ring repair. The local shop I was planning to use thought they (my local shop) may be able to replace the case in the car, but the technician doesn’t remember because it’s been 10 or 15 years since he’s done it. Does anyone know if that is possible? The shop quoted me 1,200 to pull and replace the transmission. If I didn’t send the whole trans off it will obviously save me time and money, but I like the idea of a shop doing it that is experienced. Maybe thats not valid if it’s a simple job. Also the shop send they would need to charge me for storage if the car is on the lift for a couple of weeks. I guess the other option is to skip the repair and just hang onto the case so that I can have the transmission repaired if it ever failed.

I live in OKC and there aren’t many local options for NSX work. Any input is greatly appreciated

 

[Old Guy]

The story goes that Acura's official position is that NSX transmission repairs are to be replacements because their opinion is that the repair is not within the skills of the typical master technician. You can take that for what it is worth because it is hear-say. If that is true, you probably don't want somebody who can't remember whether they have done this trying it. That said, the service manual does detail transmission case removal (so the hear-say about Acura techs not being qualified might just be repeated 'internet wisdom'). A superficial review of the service manual suggests that you might be able to do a simple case replacement without actually messing with the main and countershaft which means you dodge all the messy measuring stuff. That should be technically simpler. If you want to go in and freshen up some synchros while the cover is off, that changes things.

Is your local shop an Acura dealer or just a general automotive repair shop? If they are a generalist and don't even have a copy of the service manual you may not want to trust that they think they might have done this before.

Somebody who has done this may be able to advise whether simple case replacement is easy / straight forward or a high skills activity.

As to waiting for failure or relying on the 'if it ever failed'. Some snap ring range transmissions do not suffer from the failure problem. However, if the snap ring does fail and the pieces of the snap ring come out, drop into the case and get tossed up into the gears you have likely gone from case replacement to case replacement plus replacement of gears and other moving parts. You might not get sufficient warning of failure to prevent further damage to the transmission. That is a risk assessment.

 

[Miner]

I'm about 99+% sure that one has to remove the gearbox from the car to replace the case. I don't believe there isn't enough room to slide the case off the rest of the gearbox. But I'll be honest, I just followed the service manual instructions so trying to remove the case wasn't ever a thought.

 

[Old Guy]

I'm about 99+% sure that one has to remove the gearbox from the car to replace the case. I don't believe there isn't enough room to slide the case off the rest of the gearbox. But I'll be honest, I just followed the service manual instructions so trying to remove the case wasn't ever a thought.

If you are referring to my comment, I was unclear. My reference to transmission case removal described in the service manual referred to, with the transmission out of the car, being able to separate the transmission case from the clutch housing presumably leaving the main and countershafts and various other bits in the clutch housing undisturbed. Presumably if all you are doing is the case replacement, you install your new case, deal with the bits and pieces and voila, easy, peasey snap ring problem fixed (sez the guy who has never had to do it).

Actually, my comments were more directed to the narrative in the Prime Wiki which suggested that Acura's fix for the snap ring problem was complete transmission replacement rather than repair, the reason being that repair was beyond the capability of even master service techs. That doesn't necessarily ring true for me when you look at the factory service manual and the details for the case removal process.

I went through this about 8 years ago when I was trying to decide between a very low mileage 1991 red & black NSX versus a 2000 with higher mileage. The 1991 was in the snap ring range and I was trying to factor in transmission repair into the purchase price. I chickened out and bought the 2000.

 

[Miner]

I was only referring to the OPs comment that the shop thought they could replace the case without removing the gearbox.

All your comment seemed accurate, Old Guy.

 

[91 X]

If it ain't broke don't fix it.....

Just cuz it's in range didn't mean it's going to go anytime soon.

Waste of money if it is still in perfectly good condition and working properly

 

[drew]

I'm 100% certain that it is not financially feasible to do a snap ring repair in situ. Crazy stuff would have to be done to get the casing off inside the engine compartment, let alone install it competently.

I did my own snap ring repair in my garage. Just changing out the case is reasonably easy and quick (2-hours max) if you are not changing out any of the internals.

However, on my car was a high mile car, 125K miles, when the snap ring went out. At that point, I made the decision to go ahead and refresh the transmission because of the high miles. Otherwise, I would have just R&R'd the casing.

I kept driving for a day...75 freeway miles and about 12 shifts total...until I could secure alternate transportation as the NSX was my daily driver. The snap ring was completely shattered and I had to cut the case apart to remove it. It took a day and a half to knock out and replace the bearings and synchros. I left the diff alone.

Honda recommends end-play measuring and shimming. Getting shims from Honda is a real pain and quick call to Mark Basch stated that his experience indicated no effective need as he hasn't had to change out the shims on all the transmissions he has done. So far so good and another 40K miles, before I sold it.

FYI: The replacement casing should have an ink stamped eight-digit number see attached along the top ridge. This is visible by looking down on the transmission from the airbox.

There is so much value and anxiety on the snap ring issue that I would engrave the details on the new casing. Document "proof of life" style with a dated newspaper, VIN number and the disassembled transmission in a few photos. Keep the old casing, or at least cut it down to the part that has the snap ring shoulder, because few will believe you. Include the newspaper with your documentation. Just this information alone is worth some $10K.


If the snap ring issue concerns you: I recommend on the next clutch change go ahead and change out the casing. It will add in a couple of hours to the job but document it to a very high degree or it will be assumed to have not been performed (Or performed wrong by just replacing the snap ring...which was also done to my car before I purchased it).

Or just keep the casing until you do need it as @91_X advises.



edit: It is rare for any dealership to break open a transmission. Just R&R the whole unit. I did have a Mazda dealership rebuild an FD transmission, but it is rare.

 

[99NCNSX]

Here's my 2 cents. From what I have read about the snap ring issue....the odds of failure for transmissions within range, driven under normal street conditions, on an NSX with low miles are VERY, VERY LOW. If this were my car, I would accumulate the parts needed for repair, and then store them until such time that you might experience snap ring failure. I'm betting that sometime in the future you will end up selling these parts at a profit.

 

[696]

Thanks for the input so far. I purchased the car with snap ring repair planned. I’m the type of guy that likes to care of any issues ahead of time. To me it was a no brainer to go ahead and buy the parts to fix it. I wouldn’t want to have a failure and not be able to easily fix it, and if I were to sell the car, having parts to be able to repair it would probably increase the value.

I wouldn’t think twice about doing the full fix now if I had a local shop with a lot of NSX experience, but I Haven’t found a shop with a lot of NSX experience. I’m starting to think maybe I should just keep all the parts on hand as a precaution and be ready to fix it if something happens. I will probably only put 1,000 or so miles a year on it.

 

[asylum]

Remember that the snap ring problem comes from the groove machined in the case. Only a small percentage of the cases within the snap ring problem range are badly machined. It is only the ones that have been machined just before the periodic replacement or adjustment of the tool making the groove. 3/4 of the cases that are in the snap ring range will not cause any problem. Store the case and wait you have something else to do in the gearbox (synchros, bearings, ...).

 

[nis350]

Is there any document/statement from Honda regarding the percentage and estimated number of the transmissions were actually effected? I don't recall seeing anything...

I recalled reading long ago that most of the effected transmissions failed with fairly low miles and some at higher miles.

IMO, I would wait til it fails or when you replace the clutch to do the case replacement.

Remember that the snap ring problem comes from the groove machined in the case. Only a small percentage of the cases within the snap ring problem range are badly machined. It is only the ones that have been machined just before the periodic replacement or adjustment of the tool making the groove. 3/4 of the cases that are in the snap ring range will not cause any problem. Store the case and wait you have something else to do in the gearbox (synchros, bearings, ...).

 

[nis350]

Thanks for providing the image of the replacement case.

Do you know if ALL the replacement cases have that stamped 8 digit number?

FYI: The replacement casing should have an ink stamped eight-digit number see attached along the top ridge. This is visible by looking down on the transmission from the airbox.

 

[drew]

>Do you know if ALL the replacement cases have that stamped 8 digit number?

I stay away from absolutes when I don't control the source and even then I qualify my statements.

This observation came from Mark Basch, who seems to be long gone now, who rebuilt quite a few transmissions.

My personal kb is N = 2 and the conjecture holds up.

A poll is in order.

 

[696]

I’m planning to go ahead and preemptively do the repair instead of storing the case. Does anyone have the dimensions for the transmission. I’m planning to have it removed locally and shipped to Science of speed for the repair. The local shop doesn’t want to pack it for shipping so I would like to know how big a case I need to build for shipping.

 

[Miner]

I’m planning to go ahead and preemptively do the repair instead of storing the case. Does anyone have the dimensions for the transmission. I’m planning to have it removed locally and shipped to Science of speed for the repair. The local shop doesn’t want to pack it for shipping so I would like to know how big a case I need to build for shipping.

The whole gearbox is about 6-8 inches longer than the replacement case, if that helps. It’s weight is about 150 lbs.
there are a couple for sale in the classified section, may have some photos for reference. Give a shout to SOS, they probably have exact dimensions as well as a best method to crate.

 

[NSX_n00b]

I’m planning to go ahead and preemptively do the repair instead of storing the case. Does anyone have the dimensions for the transmission. I’m planning to have it removed locally and shipped to Science of speed for the repair. The local shop doesn’t want to pack it for shipping so I would like to know how big a case I need to build for shipping.

Maybe give this a shot...looks like you'll need an extra large heavy duty box from HD:

https://www.youtube.com/watch?v=u_epZyj68f4

 

[MotorMouth93]

Just measured my NA1 5mt since it's sitting on the floor in the garage.

It's roughly 18x22x16 inches. If you're looking at it from the bell housing it's 22" wide, 16" tall, and 18" deep. Best thing to do would probably be to build a wooden crate for it.

 

[696]

Just measured my NA1 5mt since it's sitting on the floor in the garage.

It's roughly 18x22x16 inches. If you're looking at it from the bell housing it's 22" wide, 16" tall, and 18" deep. Best thing to do would probably be to build a wooden crate for it.

Thanks for the info!!! The plan was to build a 2x4 reinforced plywood box on a pallet base to protect it. Sounds like a pallet should be big enough

 

[onilink]

Since you're in OKC, a very good/cheap option would be to drive to Houston and get the transmission case replaced by our NSX Master Tech Carl. He has done a bunch of our cars including mine (preventative as well) locally.

Also a good time to consider swapping your USDM gears for shorter JDM gears/final drive. Save all the labor since the trans will be out and one of the best mods IMO for the NSX.

 

[696]

Since you're in OKC, a very good/cheap option would be to drive to Houston and get the transmission case replaced by our NSX Master Tech Carl. He has done a bunch of our cars including mine (preventative as well) locally.

Also a good time to consider swapping your USDM gears for shorter JDM gears/final drive. Save all the labor since the trans will be out and one of the best mods IMO for the NSX.

pm sent

 

[drew]

> It’s weight is about 150 lbs.

I ran into this issue and it was costly. I built a wooden box that sent the weight a couple of pounds over the maximum that was able to be sent over the counter shipping (I do think 150 lbs). I had to pay significantly extra for Truck Freight (or similar) and shipping was a different process that was a bit miserable in comparison.

I recommend going to a transmission shop and buying a crate for your transmission. It should keep it safer and a lot more inexpensive as the weight of the transmission is just under the maximum allowed for normal shipping.

 

[gene3x]

I also have a car within snap ring range and my plan is to add a twin turbo to it.

What is the max hp and more importantly max torque that these transmissions will handle? Is it not a good idea to run a Turbo with this tranny within snap ring range?

I want to to go ahead and do the short gears and final drive when I do all of this anyway so switching the case out shouldn't be a big deal but figured I would ask where the weak link is when you start adding mods that add torque.

 

[696]

Update:
In the end I decided to go ahead and do the repair. Even though the transmission felt good, I didn’t want to risk possibly destroying my transmission. It took awhile for the case to come in from Japan and arrive at Science of Speed. Then it took 6-8 weeks for me to be able to get my car into the local shop. Unfortunately for me the closest shop that knows how to work on an NSX is 100 miles away. A forum member who lives inTulsa recommended 4 Star Imports. They took the transmission out and then I shipped the transmission to SOS for the repair. SOS turned it around quickly and the shop got my car back to me quick. I was really happy with 4 Star in Tulsa and SOS.

It was a bit of a hassle getting the repair done and possibly a waste of money, but now I won’t have to worry about it and if I ever sale the car I won’t have people freak out over it being in snap ring range.

 

[drew]

I would engrave the new and old case with vins, dates and miles. Keep the old case as proof of repair, you won't believe the amount of naysaying that will go on if/when might sell your car...

 

[696]

I would engrave the new and old case with vins, dates and miles. Keep the old case as proof of repair, you won't believe the amount of naysaying that will go on if/when might sell your car...

It’s interesting. The new one does seem to have any number on it from me peeking down, but it’s shinier.

You may be right that some people could question the repair, but if they wouldn’t accept repair receipts and how it looks, I would probably not want to deal with them anyway.