B18C5-EH2

A co worker and I are having a debate, or an exchange of theory.

We are debating if installing a longer or shorter timing belt (let's say 1 tooth extra/less) would actually throw the timing belt off on an engine.

The exact scenario we're using is a 1993 Honda Accord engine. He bought the car with a broken timing belt, and rather than buying a brand new belt we were looking through our shop for "take-off" belts for free to slap on the engine just to make the car mobile until he scavanges parts on the car for another Accord of his.

The Accord belt he would actually need is a 113 tooth belt.

I found a good condition take-off belt that came from a VTEC 2.3L Accord engine that has one less tooth, at 112.

My theory is that installing the shorter belt will not change the timing at all. Sure he'll need to run the tensioner in all the way, and the belt will be tighter than it should be, but I think the timing would stay on time.

For some reason he thinks the change in belt size/length would throw the timing off, or at least he's not 100% it wouldn't throw the timing off.

I likened it to a bicycle chain. Toss a longer chain on, but leave the sprockets the same size, and the ratio remains unchanged. Same with extended swingarm/longer chain motorcycles with stock sprockets - sure the chain is way longer, but the ratio remains the same.

I told him that unless you change the cam or crank gear I can't see how timing could be affected.

Thoughts?

91DA9

I would think that you are correct in that it will keep time, but I do not know from personal experience. Although I would make sure the lengths are really that close and it does not have larger teeth to compensate.

89s1

given your exact situation you are the one that is correct, not your friend.

be sure that the teeth in the belt are the same size and that they sit snug in the wells on the pulley cogs.

sanimalp

I agree with the above posters. its exactly like the bycicle analogy. the only thing that will change the timing is changing the number of teeth on the gear. the timing belt is a 1-1 transfer of motion(as long as tension is retained). the gear teeth on both sides are what cause it to be a 1-x transfer of motion.

court76wi

I wouldn't recommend mixing and matching timing belts, you can get into a world of trouble.

The first thing is that the size of the teeth and the distance between the teeth on both belts have to be the same, otherwise you risk jumping a tooth on one of your pulleys or loosing the belt entirely. And on an interference engine it's not good when that happens.

The length of the belt DOES make a difference. It's similar to when your timing belt stretches, it still works, but your timing starts to get slightly retarded the more it stretches.

In order for that 112 tooth belt to be a completely identical fit belt, in terms of timing angle, it has to be shorter than the 113 tooth belt by a distance of exactly 1 tooth (tooth to tooth length, or one tooth and one valley). If the belt lengths are the same, or the difference in lengths isn't 1 tooth, you just threw your timing off.

Think of it this way. Imagine the distance of the belt from the crank, around the exhaust cam gear, and to the intake cam gear. Now count the # of teeth the belt has in that distance. Now if you put on another belt, and the number of teeth on that belt is different over the same length, say 1/2 a tooth, your intake cam is now off 1/2 tooth rotation from the crank. The exhaust cam will be off as well but by a lesser amount.

As your OEM timing belt stretches, the length of the belt over the same number of teeth gets longer. This causes the cam gears to slowly start falling behind the crank. 1/2 a degree, 1 degree, and etc. as the belt stretches more.

It doesn't cause a catastrophe per say, but why knock the timing off your car and hurt your performance by installing an incorrect belt? Not unless you're trying to save every $ you can. You might be able to correct your ignition timing, but your valve timing is hosed.

Modified by court76wi at 3:42 PM 1/16/2008


Modified by court76wi at 4:15 PM 1/16/2008

sanimalp

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by court76wi &raquo;</TD></TR><TR><TD CLASS="quote">Think of it this way. Imagine the distance of the belt from the crank, around the exhaust cam gear, and to the intake cam gear. Now count the # of teeth the belt has in that distance. Now if you put on another belt, and the number of teeth on that belt is different over the same length, say 1/2 a tooth, your intake cam is now off 1/2 tooth rotation from the crank. The exhaust cam will be off as well but by a lesser amount.
</TD></TR></TABLE>

If the belt has the same number of teeth per foot(i.e. tooth spacing), then the number of feet away the belt is has no effect on the rotational speed of the gears.

You are correct in that if the tooth to tooth spacing is off, the timing might be jacked up. that is because there might be some slip in the belt, or a tooth gets skipped on the pulley which will cause the pulley to not rotate as far as it should if all the teeth are being used on the other one.

Since the op never specified whether tooth spacing was identical, either theory could be correct. If tooth spacing is the same on both belts, the belt would be proportionately longer to incorporate the extra tooth, and not change the timing at all if the tensioner is doing its job. If the tooth spacing is different, then the potential for play in the the belt, or uneven tooth seating might cause timing issues.

B18C5-EH2

Okat let me clarify a few things:

The teeth spacing is 100% identical. Both belts are genuine Honda belts, intended for F series SOHC engines. One for the VTEC, one for the non-VTEC. the belts are literally identical save the one tooth difference.

Also for those telling me I'm risking the engine this engine is more than likely junked already - this is literally to make the car mobile again to pull it in and out of our shop rather than pushing it.

If belt tension is a concern, and if a loose belt causes a change in timing, then if anything this overly tight belt would cause timing to be better than a looser correct belt, no?

court76wi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sanimalp &raquo;</TD></TR><TR><TD CLASS="quote">

If the belt has the same number of teeth per foot(i.e. tooth spacing), then the number of feet away the belt is has no effect on the rotational speed of the gears.
</TD></TR></TABLE>

sanimalp, I didn't say the length of the belt or its distance affected the rotational speed. Differences in spacing become more apparent over a longer distance. So any "visible" differences are easy to notice – it's called a mental image of what is happening. Having a spacing difference of 1/2 a tooth would give you an idea of how advanced or retarded your cam timing is. However the same number of belt teeth still go around the crank per revolution. So yes, the speed doesn't change.

If rotational speed actually changed you would no longer have a 1:1 ratio, your motor wouldn't run.

sanimalp

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 &raquo;</TD></TR><TR><TD CLASS="quote">
If belt tension is a concern, and if a loose belt causes a change in timing, then if anything this overly tight belt would cause timing to be better than a looser correct belt, no?
</TD></TR></TABLE>

the main reason I mentioned belt tension is because if the tensioner can't do its job, then the belt can either slip because its too loose, or be slowly shredded because it is too tight. only one of those issues will cause problems in the short term.

0dyfamily

Just dealt with this yesterday on a 1994 Accord with an F22B2 non-VTEC engine. The owner, who has some disabilities from a bad motorcycle wreck, ordered a VTEC timing belt kit for an F22B1 engine with its 112-tooth belt. I offered to take care of it for him gratis, and I set about working on the car. I've done a few Honda timing belt jobs before, among other foreign car brands.

Will not throw off timing.

I tried and tried to get that 112-tooth belt to fit. Could not do it. The amount of tension on a 112-tooth belt would probably be ruinous. We went out and purchased a proper 113-tooth belt and ran through the shop manual to ensure everything was buttoned up properly.

The Search function on this forum is tremendous. I was tearing my hair out trying to figure why the new timing belt would...not....fit!!!....and finally jumped onto Honda-Tech.

F22B2 engine belt, non-VTEC: 113 teeth.

F22B1 engine belt, VTEC: 112 teeth.

Newly armed with this information from another thread, I set out to counting teeth on the belt.

Both engines use an identical Honda part number for the crankshaft timing belt drive sprocket, which means the belts share an identical tooth and groove shape and pitch (i.e., number of teeth per inch of belt). They would be interchangeable if....IF there was enough adjustment available on the tensioner. I'm here to say there was not enough in our case attempting to fit an OEM-spec VTEC belt to this non-VTEC engine.

This is a great forum. Saved me from throwing my hands up and quitting this one. We finished it, new set of NGK stock plugs (nothing fancy), new water pump and a fresh load of coolant, and he was on his way.

OF

Tyler Dirden

iTrader: (3)

Any synchronous drive belt system can use any length or number of teeth for the system.

No timing change can be made by belt length of similar designed teeth.

v4lu3s

the only time i makes a difference is if the length is so long that the tensioner cannot take up the slack, then you end up with a belt that easily skips teeth....

0dyfamily

Yes. Think tandem bicycle vs. roadbike, both with identical chain rings (gears on the pedal end) and clusters (stack of cogs shifted via the rear derailleur). Ring-for-ring and gear-for-gear paired identically, no change in mechanical advantage. Longer chain makes no difference.

I got here because the vehicle owner purchased a short belt on accident (112 vs. 113 teeth). I thought I was seeing double every time I counted, and found I was "one tooth off" each time. Did not realize my counts were 100% accurate each time. Thankfully, Honda-Tech has a good search engine.

Also, nowhere is it written in any easily available Honda literature that the belt and pulley pitch and tooth geometry on both sides (cog and belt) are identical from one belt to another on all Honda applications, but it's a safe bet Honda does this for parts commonality purposes. I did assume so in this particular case by simply comparing p/n's (note that the F22B1 & B2 engines share an identical crank cog p/n for this model year; they couldn't if there were any sort of pitch & geometry differences). Minor pitch and tooth geometry (belt and/or cog) differences not detectable with our eyes (or even by laying one belt on top of another) will (not can) result in belt destruction in short order.

It's a false economy to use a used belt from a different motor, anyways, being these things are getting so reasonably priced from quality vendors. Just buy the right one and save yourself any installation hassle or worry is my world view on that one.

OF

B18C5-EH2

HA! I've logged in after a looong break, and was looking at my topics sorted by most recent activity. This topic was it.

I asked the question in this topic mainly for theory/debate/settle a discussion purposes. The engine in question was already damaged because of a broken timing belt. The timing cover had been removed to extract the old belt that had wrapped itself/become lodged behind the timing cover. While the cover was off we were trying to toss a belt on it just to make the car mobile. We ended up waiting a day and getting a cheap aftermarket belt JUST to move the car around when needed. The engine had bent valves, and the car ended up eventually getting a JDM engine swap.

Thanks to all for the replies though, and I'm glad the topic served as informational to anyone searching 112/113 tooth belts/differences.

0dyfamily

"Search" is a great tool. The answers are usually already there without having to post another thread.

I would have spent all day thinking I had mis-counted teeth on the belts until I finally went to Honda-Tech and found this one.

One tooth makes a difference in fit, for sure. The VTEC belt will be far too tight to reliably fit the generic motor, and I'm pretty darn sure the generic motor belt will be way too loose from the get-go to safely run on a VTEC motor.

Definitely learned the moral to the story....get the right timing belt for your application, always.

OF