Timing Belt Shelf Life?

[bullithollywood]

So looking at Gates recommendations about shelf life of a timing belt they say this? "Timing Belt when properly stored is good as new up to 8 years. Life expectancy is reduced 10% per year for every year thereafter." With that said I'm concerned how old the stock of NSX timing belts out there really is. Anything mfg after 2014 is on the downhill slide. I've got two Gates belts in reserve with date codes 111 and 708. Based on when I purchased them I assume they're from Nov 2011 and Aug 2017. So the one is passed 70% life and the other is technically OK till 2025. Does anyone at Acura/Honda even dispose of stock that has timed out? Based on how the mft date code is made I think Gates intends belts to be retired after 10 years from the mfg date. Anybody have better insights on this?

 

[Honcho]

That's a really good question. One thing to note is that Honda packages its timing belts (at least the JDM ones) in sealed bags. This no doubt slows the degradation of the rubber compared to a belt just sitting on a shelf exposed to changes in humidity.

 

[Superhatch]

Gates, which is a great OEM and aftermarket belt maker notes up to 6 years, with a LOT of qualifiers (humidity, temp, sun exposure, etc).

https://www.gatesaustralia.com.au/~/media/files/gates/industrial/power-transmission/white-papers/old-proper-belt-handling.pdf

 

[bullithollywood]

Its a fact of life all rubber degrades over time with the most common causes being light (UV), oxygen (ozone) and heat. The molecular changes caused by these environmental conditions can significantly affect the mechanical properties of the rubber and therefore you have a recommended service life for rubber products. Oxidative rubber degradation can cause hardening OR softening. Hardening, which I think is our major concern, is more common vs softening because free radicals produced due to heat, oxygen and light change the makeup of the rubber reducing its flexibility and making it prone to cracking, which leads to breaking. I've stored my belts in vacuum sealed bags in a dark closet against the day when the dealer says "unavailable". I think their life is extended somewhat but at the dealer I wonder if they take as much care with monitoring the life of whats on their shelves.

 

[Superhatch]

I think their life is extended somewhat but at the dealer I wonder if they take as much care with monitoring the life of whats on their shelves.

My only thought about dealership belts is they likely don't sit for very long as stock on the shelves means $$ stored and not in use. With today's just in time business models, and dealerships holding less and less parts on the shelves it falls back to the distribution centers and ultimately Honda of Japan's production levels. I've waited on some parts from Honda that were on back order, and some that are still on back order which means (I think) they are still being produced but out of stock.

I'd wager there are around 5200 NA1/NA2s left on the road (assuming 2% loss per year)...So that is just a guess but then after some digging there is a study that was done in 2006 by Duke called the NVPP. It's a dataset that's available for purchase I think so I emailed them to track it down.

Anyway...with 5-6k left on the road, and at least half of them driven infrequently were looking at probably 2k putting down decent mileage, and maybe 500-1k putting daily driver mileage on them? My point is there aren't that many belts in rotation because there just aren't that many timing belt jobs being done yearly in the US. 10-20 maybe, 50 world wide (our belt doesn't fit any other NSX as per the Acura parts websites)?

Honda is likely having these made in small numbers and upon request if their yearly orders are nearly getting sold out. All just guesses, but I would say a belt you get at the dealer is a year old at most.

 

[acuhon]

Gates, which is a great OEM and aftermarket belt maker notes up to 6 years, with a LOT of qualifiers (humidity, temp, sun exposure, etc).

https://www.gatesaustralia.com.au/~/media/files/gates/industrial/power-transmission/white-papers/old-proper-belt-handling.pdf

On the right is Gates NSX timing belt. It has 17 strings of reinforcement. The OEM has 27 strings and feels much stronger.
I would trust more 10 years old OEM belt than new Gates.

 

[Old Guy]

I am fairly confident that in Canada, you don't have to worry about the timing belt 'timing out' by sitting on a shelf at a dealership or at an Acura Canada parts warehouse. The only part that is ever on the shelf at my local dealership is the oil filter and crush washer and the only part that I was ever able to get through the warehouse was the air filter. They probably also have fuel filters; but, I have never checked. Everything else is pretty much 'factory fresh' from Japan if it isn't a shared part with another Honda product.

I find the material ageing discussion interesting, primarily because it was a question on the application of Arrhenius reaction rate theory to ageing that allowed me to ace a 3rd year materials science engineering class final exam. However, I am mindful that in over 10+ years of hanging around NSX Prime I don't recall any reports of in-service failures caused by failure of the the timing belt on non tracked cars (harmonic damper failures and tensioner failures that toast the timing belt don't count). The other thing is that a timing belt that has been sitting on some shelf for 5 years is still better than the 1-12 year old timing belt in your engine.

I would worry less about seeking perfection in timing belts because the anecdotal evidence on Prime suggests that it is something else that is likely to stop you in your tracks.

 

[bullithollywood]

My only thought about dealership belts is they likely don't sit for very long as stock on the shelves means $$ stored and not in use. With today's just in time business models, and dealerships holding less and less parts on the shelves it falls back to the distribution centers and ultimately Honda of Japan's production levels. I've waited on some parts from Honda that were on back order, and some that are still on back order which means (I think) they are still being produced but out of stock.

I'd wager there are around 5200 NA1/NA2s left on the road (assuming 2% loss per year)...So that is just a guess but then after some digging there is a study that was done in 2006 by Duke called the NVPP. It's a dataset that's available for purchase I think so I emailed them to track it down.

Anyway...with 5-6k left on the road, and at least half of them driven infrequently were looking at probably 2k putting down decent mileage, and maybe 500-1k putting daily driver mileage on them? My point is there aren't that many belts in rotation because there just aren't that many timing belt jobs being done yearly in the US. 10-20 maybe, 50 world wide (our belt doesn't fit any other NSX as per the Acura parts websites)?

Honda is likely having these made in small numbers and upon request if their yearly orders are nearly getting sold out. All just guesses, but I would say a belt you get at the dealer is a year old at most.

Umm, 10-20 TB/WP jobs per year...50 world wide? Since 9 out of 10 NSX belts are done on time not mileage I'd wager SoS does at least a dozen a year by themselves. But whatever the number done if mother Honda is having new belts in batches based on consumption emptying the "just in time" shelf stock then chances are the belts are new. But how many people have ever had a dealership do a TB/WP job and been told their was a backorder for TB belts?

 

[bullithollywood]

On the right is Gates NSX timing belt. It has 17 strings of reinforcement. The OEM has 27 strings and feels much stronger.
I would trust more 10 years old OEM belt than new Gates.

Thats very interesting since Gates and Unitta (the name on the OEM belts) are literally the same company.

 

[bullithollywood]

I am fairly confident that in Canada, you don't have to worry about the timing belt 'timing out' by sitting on a shelf at a dealership or at an Acura Canada parts warehouse. The only part that is ever on the shelf at my local dealership is the oil filter and crush washer and the only part that I was ever able to get through the warehouse was the air filter. They probably also have fuel filters; but, I have never checked. Everything else is pretty much 'factory fresh' from Japan if it isn't a shared part with another Honda product.

I find the material ageing discussion interesting, primarily because it was a question on the application of Arrhenius reaction rate theory to ageing that allowed me to ace a 3rd year materials science engineering class final exam. However, I am mindful that in over 10+ years of hanging around NSX Prime I don't recall any reports of in-service failures caused by failure of the the timing belt on non tracked cars (harmonic damper failures and tensioner failures that toast the timing belt don't count). The other thing is that a timing belt that has been sitting on some shelf for 5 years is still better than the 1-12 year old timing belt in your engine.

I would worry less about seeking perfection in timing belts because the anecdotal evidence on Prime suggests that it is something else that is likely to stop you in your tracks.

All good points, and I can't remember a TB failure either. And, as Superhatch assumes, there ARE new belts being mfg for Honda by GatesUnitta (Gates says they no longer make their T231 from Acuhons post) then as the global stock is depleted then its a non-issue. But if there are no new belts being made for the NSX, other than those from some large LAST run from some past year, like so many other things, then the stock of NSX timing belts are sitting somewhere aging, just maybe not at the local dealer.

 

[Wild Turkey]

I am fairly confident that in Canada, you don't have to worry about the timing belt 'timing out' by sitting on a shelf at a dealership or at an Acura Canada parts warehouse. The only part that is ever on the shelf at my local dealership is the oil filter and crush washer and the only part that I was ever able to get through the warehouse was the air filter. They probably also have fuel filters; but, I have never checked. Everything else is pretty much 'factory fresh' from Japan if it isn't a shared part with another Honda product.

Same here. No parts, and 4x the price of other vendors. It's a vicious circle and I feel for my dealership. Brick & mortar, so they have to charge a markup to stay in business, so fewer sales (for a car <1% of customers, only 2 at my dealership) so the parts sit, and the dealership decides it's a poor business model to stock the parts...
They did have the fuel filter and air filter in the warehouse so I got it next-day.

 

[Superhatch]

Since 9 out of 10 NSX belts are done on time not mileage I'd wager SoS does at least a dozen a year by themselves.

I thought the time-frame was 7 years? I would still imagine that's still a really low number of belts. Even if you double or triple my original guess it's still just going to be a JIT order from Honda every month and my original point that NSX belts don't sit on shelves very long still stands.

 

[Superhatch]

On the right is Gates NSX timing belt. It has 17 strings of reinforcement. The OEM has 27 strings and feels much stronger.
I would trust more 10 years old OEM belt than new Gates.

Gates OEM belts are fine for normal cars, but I've always used OEM Honda belts for normal replacements, and Honda is known for their belt quality. I mainly know them from their 'Blue' belt line which I get requested on some of the engine builds I do.

Gates 'blue': https://www.gatestechzone.com/en/product-info/racing-belts

 

[DA NSX]

Just had full timing belt/water pump/gaskets/belts service done in November 2022 along with shocks/struts, trunk/hood/glass support struts, and a couple of marker lights. Had to wait only a week and dealer told me all parts were coming “from California”. I suppose that could mean from Japan via California but when I set up the appt the service advisor didn’t express any concern about availability.

 

[Chris_Lum]

Thats very interesting since Gates and Unitta (the name on the OEM belts) are literally the same company.

Definitely interesting! Actually a lot of people think OEM parts are exactly the same as aftermarket parts provided by the same manufacturer when that's only sometimes the case. Many times an OEM will get something produced by a manufacturer but the manufacturer will sell a different part to the aftermarket, either because the manufacturer doesn't have the rights to sell the OEM part to the aftermarket (think OEM paid tooling, specifications, etc.) or the manufacturer wants to sell a cheaper part. The latter could be the reason for the difference in reinforcement strings--Gates may have decided that 17 was perfectly acceptable (and cheaper to produce), but Honda may have said 27 is the requirement, thus the variation.

 

[corpuzd]

So looking at Gates recommendations about shelf life of a timing belt they say this? "Timing Belt when properly stored is good as new up to 8 years. Life expectancy is reduced 10% per year for every year thereafter." With that said I'm concerned how old the stock of NSX timing belts out there really is. Anything mfg after 2014 is on the downhill slide. I've got two Gates belts in reserve with date codes 111 and 708. Based on when I purchased them I assume they're from Nov 2011 and Aug 2017. So the one is passed 70% life and the other is technically OK till 2025. Does anyone at Acura/Honda even dispose of stock that has timed out? Based on how the mft date code is made I think Gates intends belts to be retired after 10 years from the mfg date. Anybody have better insights on this?

Vacuum seal the belts to keep them from air.