# What material is this gear made of?



## Suzuki4evr (Feb 11, 2021)

This is a gear for a Volvo amazon, a timing gear I think. Does anyone know what material this gear made of and is there a substitute material that can be used? It's not metal but more like a fiber  something like bakolite, but I am not sure. I haven't taken any measurement on it yet and don't know if it is metric or imperial,cause I must still figure out if I must get a module or DP cutter. But first I must get the material issue sorted.

Don't worry about the aluminum parts you see,because I think that was a fix for the gear before. Apparently they can't get a gear anywhere. 
	

		
			
		

		
	






Can someone shine some light.


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## jbobb1 (Feb 11, 2021)

Kind of looks like phenolic. Can you see any signs of fiber strands in it?


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## Suzuki4evr (Feb 11, 2021)

No not that I can see. I looked up on the net and it only say "fiber"


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## RJSakowski (Feb 11, 2021)

Measure the OD in mm and divide by the number of teeth plus 2.  If the result is a nice number like 1.5, 2.0, etc. or close, then it is likely a metric gear and the answer will be the modulus.  If not, the number of teeth plus 2 divided by the OD in inches would be the diametral pitch.

Bakelite with some sort of material  added for strength was used in some automotive applications.  McMaster Carr lists several types under the trade name Garolite.


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## jbobb1 (Feb 11, 2021)

Garolite is another type of phenolic. This link explains all the different types.





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						American Plastics Corp :: Phenolic
					






					americanplasticscorp.com


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## benmychree (Feb 11, 2021)

I would think that linen reinforced phenolic would be appropriate for a timing gear, General Electric product, Micarta, Garolite is the same product, both come in several grades, for Micarta, grade L is linen cloth reinforced.


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## Bi11Hudson (Feb 11, 2021)

*Theoretical meanderings* by an old man, maybe or maybe not useful. I am officially an "old man", turning 70 this year.

First of all, a Volvo built in Sweden will *most likely* be metric. Being an automotive part specific to an engine, it might well be any thing. I would be disinclined to think "micarta" since, in electrical parts, micarta is usually a warm brown color. Bakelite is a very old process, one of the earliest incidents of plastic, if not the oldest. It is common as an electrical insulator, is very black, and is *very brittle*. Those two plastics aside, there are many plastics in use the last 30 odd years that I have no knowledge of.

Theorizing on the engine; if it is a clearance engine, in that the crankshaft can come to top dead center with a valve open, most any material could have been used. If it is a "zero clearance" engine, having the camshaft get out of time with the crankshaft could cause considerable damage. 

In either case, using a molded (plastic) gear is a significant reduction to assembly costs and time. It can also possibly be used as a "weak link" to reduce other, more serious damage on failure. In any case, a replacement could be constructed of any material, most easily aluminium. The issues here are "non critical" being primarily increased weight, more affected by corrosive chemicals, and less likely to fail when failure would "save" another part.

The instructions, formulae, system, whatever, for determining metric vs imperial (Modulus V Diametrical Pitch) given above would be most useful. There are many other factors involved in making a gear. First and foremost is what the gear interfaces with. Another gear, timing chain, timing belt, short rope, whatever. If indeed another gear as it appears, perhaps research into that second gear will provide further insight into pitch, pressure angle, et al. Worst case, research and careful measurement would provide enough information to construct something that works. It may not work 100%, but well enough to refine the measurements closer so a second gear could be constructed that was 99.99% useful.

Last but not least, the gear appears to be a "taper" gear. Such is not easily reproduced in a hobby shop environment.  It could be theoretically be printed, given enough time and a strong enough medium. My preference would be to find a similar machine in a junked condition to salvage the gear. Possibly having it built by a machine shop but the cost of that would be enormous. Again, this is mostly theoretical meanderings by an old man, maybe or maybe not useful. Just a little "out of the box" thinking to try to assist.

.


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## CluelessNewB (Feb 11, 2021)

> First of all, a Volvo built in Sweden will *most likely* be metric.


I would have thought that also but from what I understand Volvo used a significant amount of UNF & UNC fasteners prior to 1974.


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## eugene13 (Feb 11, 2021)

Ford used a phenolic timing gear on the flathead V8.


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## FOMOGO (Feb 11, 2021)

Ford also used nylon timing gears in some FE series engines.  They were known for shearing off teeth in high milage engines, and the teeth in turn jambing in the oil pump gears, and toasting said engine. Mike


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## Nutfarmer (Feb 11, 2021)

My 1958 544 Volvo had all metric fasteners. The 1986 Volvo station wagon also was all metric.


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## Asm109 (Feb 11, 2021)

Ford did not limit the lunacy to the FE family of engines.  The small block V8 suffered as well. My old mustang jumped timing at about 90,000 miles.
Luckily the Nylon chunks did not take out the oil pump.


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## Suzuki4evr (Feb 12, 2021)

Bi11Hudson said:


> *Theoretical meanderings* by an old man, maybe or maybe not useful. I am officially an "old man", turning 70 this year.
> 
> First of all, a Volvo built in Sweden will *most likely* be metric. Being an automotive part specific to an engine, it might well be any thing. I would be disinclined to think "micarta" since, in electrical parts, micarta is usually a warm brown color. Bakelite is a very old process, one of the earliest incidents of plastic, if not the oldest. It is common as an electrical insulator, is very black, and is *very brittle*. Those two plastics aside, there are many plastics in use the last 30 odd years that I have no knowledge of.
> 
> ...


I think the pictures maybe a bit misleading concerning the taper,it is not. I will speak to the client as soon as I can and ask if it runs on another gear,and I also think it does,and what it is made of and post that information too.


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## johnnyc14 (Feb 12, 2021)

GM used a similar looking phenolic camshaft timing gear on a 2.5 litre 4 cylinder engine nicknamed the "iron duke" from 1978 to 1990. The stated purpose given at the time for using phenolic was to reduce engine noise caused by the normal backlash in the timing gears and the rapid loading/unloading of the camshaft caused by valce spring pressure. It was fairly common to replace a failed phenolic gear with an aftermarket aluminum one at the expense of more noise.


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## Cadillac (Feb 12, 2021)

I also have a Volvo and it’s all metric. Timing belt would most likely be a standard belt. I had recently looked at me me to check condition and from what I can remember it’s a straight tooth gear. I would also agree that getting a junker would make me sleep alittle better. You don’t want that timing off!


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## Buffalo21 (Feb 12, 2021)

Fords V-6 (German sourced Mercury Capri) had a phenolic timing gear, I had to replace mine 3 different times, the third time was an aluminum gear, expensive, but never replaced it again, sold the car 60,000 later.


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## Suzuki4evr (Feb 12, 2021)

Cadillac said:


> I had recently looked at me me to check condition and from what I can remember it’s a straight tooth gear


This one is definitely not straight.


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## Tim9 (Feb 12, 2021)

Most of the timing gears I have seen which were “plastics “ did appear to have a fabric reinforcement so I’d guess phenolic also. But, that’s just a guess. I have see nylon timing gears and yeah.... I too have seen that they degraded and snapped


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## Suzuki4evr (Feb 16, 2021)

RJSakowski said:


> Measure the OD in mm and divide by the number of teeth plus 2.  If the result is a nice number like 1.5, 2.0, etc. or close, then it is likely a metric gear and the answer will be the modulus.  If not, the number of teeth plus 2 divided by the OD in inches would be the diametral pitch.
> 
> Bakelite with some sort of material  added for strength was used in some automotive applications.  McMaster Carr lists several types under the trade name Garolite.


The gear has 42 teeth,the OD=148.50mm =5.846". So 148.5/44=3.37mm and 44/5.846=7.52. So I am still not sure if it is Module or DP. Would that M3.5 or DP7. Not sure about the presure angle also and another question is at how do you determine the angle of the teeth correctly although it looks like 45dgr. Could you perhaps assist me with this?


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## Suzuki4evr (Feb 16, 2021)

Or could it be DP7.5?


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## Lo-Fi (Feb 16, 2021)

Helicals are notoriously difficulty to reverse engineer. Even measuring the helix angle is not trivial, and this has a bearing on many other dimensions. The formula for the pitch diameter D, for example is: D = N/(Pn cos@)

Where @ is the helix angle, Pn is the normal diametral pitch (defined as being perpendicular to the tooth face) and N is the number of teeth. Note too that everything is calculated from the pitch diameter, meaning that you need to measure the helix angle at that diameter. It's really, really not easy to do accurately.

Try running some numbers through a calc or two, or consult the Machinerys Handbook to get a feel for it. Your chances of successfully making a high speed, highly stressed gear of that type based on measurement are not high, I'm afraid. Making a pair based on the centre distance you're tied to... that's another matter and probably more achievable, though still a fair task in a home shop. When you know and control every aspect of both gears in mesh, you're in a much better position.

A extract relevant overall from the excellent KHK primer here:






						Helical Gears | KHK Gear Manufacturer
					

Helical Gears have teeth with a helix angle for higher torques and noise reduction. KHK produces various standard/special helical gears.



					khkgears.net
				




"The helical gears made by KHK can be classified into two groups by the reference section of the gears being in the rotating plane (transverse module) and normal plane (normal module). If the reference section is in the rotating plane, the center distance is identical to spur gears as long as they are the same module and number of teeth. This allows for easy swapping with spur gears. However, in this case, they require special hobbing cutters and grinding stones, leading to higher production cost. On the other hand, if the reference section is in the normal plane, it is possible to use spur gear hobbing tools and grinding stones. However, the same module and number of teeth in spur gears no longer match the center distance of helical gears, and swapping becomes very difficult. In addition, the center distance is usually not an integer."

I don't mean to blunt your enthusiasm, more to hopefully guide your decision on whether it's an achievable job.


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## Papa Charlie (Feb 16, 2021)

You might try contacting this company. They specialize in timing gears and ship world wide.






						4.) Timing gears - We ship worldwide!
					

Dear customer, To make it easier for you, please click on the picture below to make it bigger. Open it in a new tab or new web browser while looking around in our web store.




					www.cvi-automotive.se
				




If nothing else, they may be able to put you on the right track.


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## RJSakowski (Feb 16, 2021)

Suzuki4evr said:


> The gear has 42 teeth,the OD=148.50mm =5.846". So 148.5/44=3.37mm and 44/5.846=7.52. So I am still not sure if it is Module or DP. Would that M3.5 or DP7. Not sure about the presure angle also and another question is at how do you determine the angle of the teeth correctly although it looks like 45dgr. Could you perhaps assist me with this?


The calculations you made are baffling.  The gear appears to be neither a metric or inch standard gear.. I looked at both the KHK and Boston Gear product catalogs and nothing is close.  The formula for module or diametral pitch  based on number of teeth and O.D. is exact, not an approximation.  The measured O.D. may be off due to wear or machining variation but the calculations should be much closer.

Since this is a gear is from a Volvo, it is possible that they defined their own gear specification.  A major automotive manufacturer would have the resources and possibly motive to do so.  It would certainly discourage aftermarket parts.  Your issue will be to try to finf appropriate tooling.  Standard gear hobs won't work.  It would be possible to cut the gear with a CNC mill and 4th axis capability.  You still have to determine what the  correct geometry is and that could be a difficult task.  

Reverse engineering is bad enough when we can make some assumptions as to the intent (e.g., if a measurement comes out to 2.005, it might be safe to assume that the designed dimension was 2.000.  Given your numbers, it doesn't appear that you can make any such assumptions.  Maybe check the width of the gear.  See if it comes out a nice number in either metric or inch.  It's a stretch but it may provide a clue.  The KHK metric gears have a 20º P.A. while the Boston Gear inch gears have a 14.5º P.A. The KHK gears have a 21.5º helix angle while the Boston Gear gears have a 45º helix angle.
Good luck!


			https://khkgears.net/pdf/3015/helical-gears.pdf
		



			https://www.bostongear.com/-/media/Files/Literature/Brand/boston-gear/catalogs/p-1930-bg-sections/p-1930-bg_helical-gears.ashx


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## Suzuki4evr (Feb 17, 2021)

RJ and Lo-Fi, thanks again for trying to guide me,but I think that I am must reconsider this project and rethink if this is worth persuing taking in consideration that the client added in the beginning that money was a problem. So I do not think it is worth spending a lot of time and money to help THIS time,although I am sorry that I can not help him. Spur gears are one thing,but helicals seems to be a different beast. I hate giving up on something I started,but it is what it is. Thanks again for putting things in perspective for me. Have a great day.


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