Well, it's official, the snap ring has failed and has damaged fifth gear as its fragments have whizzed through the gearbox. Replacing the gearbox casing, the bits of 5th gear, the clutch - while we're in there - and the various odds and ends will probably top £4,000. Here's the text of a letter I wrote this morning to Honda Customer Relations UK.... I'll let you know how I get on 
Dear Sir,
I am writing to you to ask whether you would reimburse, as a gesture of goodwill, the cost of a part required to repair my 1992 Honda NSX.
You may be aware that a manufacturing defect affected a proportion of gearboxes fitted to this model between 1991 and 1992. Transmissions bearing serial numbers between J4A4-1003542 and J4A4-1005978 were manufactured using a three piece bit to cut the groove in which the countershaft bearing snap-ring is sited. As the three piece bit aged some of the grooves were machined outside ( above ) their normal tolerances and the snap-ring was thus free to flex within the groove.
This results in an inevitable failure and the enclosed technical service bulletin 93-010, issued by Acura, who market the car in the United States, give details of the remedial work required as a result.
The gearbox on my NSX ( # J4A4-1003815 ) falls within the reference range. The snap ring has failed, and the countershaft transmits impulses up to the gear stick when second gear is selected and the car accelerates and decelerates. The car has been driven very little since the fault manifested itself so the resulting damage to the gears and shafts themselves has been minimised.
In the USA Acura have accepted that this was a design and manufacturing fault and have replaced the faulty part as a goodwill gesture if it has failed in a gearbox from the reference range.
This problem does not only affect NSXs supplied to the US market. My car was UK supplied when new. Other NSX drivers in the Netherlands and Switzerland have reported identical faults with their 1991-2 cars.
Acura USA have replaced entire transmissions as a matter of goodwill when faced with the problem, but I imagine that the cost of such a response on your part would be prohibitive as the gearbox is priced at over £7500 in the UK.
As the car has just covered its 60,000th mile I am taking this opportunity to replace the clutch, a repair that would entail removal of the gearbox in any event, so the labour costs would be roughly equivalent.
However, the only way to ensure that the snap ring does not fail again is to obtain a new gearbox housing in which the snap ring groove has been correctly machined. This part alone costs £900 and it is this part that I am asking you to supply gratis.
I am told by the mechanics at Guy Salmon Honda that the 5th gear and shaft are showing sings of damage disproportionate to the car’s mileage and that this has probably been caused by fragments of the broken snap ring. If you could subsidise the cost of these parts in addition that would be a most generous gesture on your behalf. The total cost of the entire repair, including the replacement clutch and labour costs, will probably exceed £4000. Even if you are generous enough to subsidise the cost of parts it would amount to little over 20% of the total.
I am told that the parts have been ordered and that repairs could take place soon after January 18th, and so I would appreciate a reply before that date.
Yours sincerely,
Dear Sir,
I am writing to you to ask whether you would reimburse, as a gesture of goodwill, the cost of a part required to repair my 1992 Honda NSX.
You may be aware that a manufacturing defect affected a proportion of gearboxes fitted to this model between 1991 and 1992. Transmissions bearing serial numbers between J4A4-1003542 and J4A4-1005978 were manufactured using a three piece bit to cut the groove in which the countershaft bearing snap-ring is sited. As the three piece bit aged some of the grooves were machined outside ( above ) their normal tolerances and the snap-ring was thus free to flex within the groove.
This results in an inevitable failure and the enclosed technical service bulletin 93-010, issued by Acura, who market the car in the United States, give details of the remedial work required as a result.
The gearbox on my NSX ( # J4A4-1003815 ) falls within the reference range. The snap ring has failed, and the countershaft transmits impulses up to the gear stick when second gear is selected and the car accelerates and decelerates. The car has been driven very little since the fault manifested itself so the resulting damage to the gears and shafts themselves has been minimised.
In the USA Acura have accepted that this was a design and manufacturing fault and have replaced the faulty part as a goodwill gesture if it has failed in a gearbox from the reference range.
This problem does not only affect NSXs supplied to the US market. My car was UK supplied when new. Other NSX drivers in the Netherlands and Switzerland have reported identical faults with their 1991-2 cars.
Acura USA have replaced entire transmissions as a matter of goodwill when faced with the problem, but I imagine that the cost of such a response on your part would be prohibitive as the gearbox is priced at over £7500 in the UK.
As the car has just covered its 60,000th mile I am taking this opportunity to replace the clutch, a repair that would entail removal of the gearbox in any event, so the labour costs would be roughly equivalent.
However, the only way to ensure that the snap ring does not fail again is to obtain a new gearbox housing in which the snap ring groove has been correctly machined. This part alone costs £900 and it is this part that I am asking you to supply gratis.
I am told by the mechanics at Guy Salmon Honda that the 5th gear and shaft are showing sings of damage disproportionate to the car’s mileage and that this has probably been caused by fragments of the broken snap ring. If you could subsidise the cost of these parts in addition that would be a most generous gesture on your behalf. The total cost of the entire repair, including the replacement clutch and labour costs, will probably exceed £4000. Even if you are generous enough to subsidise the cost of parts it would amount to little over 20% of the total.
I am told that the parts have been ordered and that repairs could take place soon after January 18th, and so I would appreciate a reply before that date.
Yours sincerely,
