Kevlar band lining sets

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Theo
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Kevlar band lining sets

Post by Theo » Wed Jul 08, 2020 12:57 pm

Good morning. I'm new to the forum and for that matter the model T. I just purchased a 1922 dr's coupe & the low gear band is shot. What are the pro's & con's of the Kevlar band lining sets.
Thanks for you help
Theo

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Re: Kevlar band lining sets

Post by Steve Jelf » Wed Jul 08, 2020 2:31 pm

Normally I would have recommended Kevlar linings without hesitation. Especially compared to cotton linings, which wear faster and eventually rot, they last forever. The knock on them has always been that they allegedly will overheat and crack drums if you let them slip. My answer to that is don't let them slip. Hold those pedals down tight.

But recently a couple of people have experienced linings unraveling and going to pieces in just a few miles of driving. I haven't seen these linings personally, only pictures. Asking the dealer who sold one of the failed sets, I learned that the company which wove the material for Kevlar bands for many years suffered a loom breakdown last year and didn't think repairing or replacing it was worth the investment. So the companies which sold Kevlar bands to the parts dealers had to find a new source. Apparently the material from the new source is a looser weave and will spread out under pressure. It seems the failed lining began at the proper 1.125" width and in use spread out to 1¼". This caused it to overlap the edges of the new drum, which cut it enough to unravel. Currently the lining companies are waiting for new material made according to the old specs from a new supplier. I expect there will be an announcement on all the Model T pages when new linings become available. I suggested that to the dealer I talked to. Unless you can find Kevlar linings you know are two years old or more, I guess your only choices for now are cotton, wood, or wait. I don't know how the supply of cotton linings is currently, but I believe Jim Guinn makes the wood linings himself, so I assume they are available.
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Re: Kevlar band lining sets

Post by John kuehn » Wed Jul 08, 2020 2:56 pm

Good to know information Steve. Same thing in a sense happened to the Scandinavia band company. The original Scandinavia linings were densely woven and a tight weave. What changed is when the material wasent woven as tight leaving a looser weave. They would tend to wear faster. And yes they were cotton and wouldn’t last as long anyway but a tighter weave band would.
Manufacturing methods will make a difference and so it seems with band manufacturing whether it’s Kevlar or cotton.


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Re: Kevlar band lining sets

Post by OldFord » Wed Jul 08, 2020 5:15 pm

I normally don't get involved with the forum, since I am quite biased toward Kevlar. I and my brother, John have been making bands made of Kevlar fibers since around 1982 or so and sell them under the Nev-R-Wear name. Part of the story above is true, the original weaver of the material that we used died and the machines were sold to a company in China. This occurred about March of 2019. We scrambled to find another source, but we only found one source in England who would make a woven band of Kevlar fibers. After seeing a sample of the work, we rejected it immediately, since it was too thin and the weave was quite loose. After much effort, we located a company in the United States that would weave a band to our specifications and tried it. It was not only as good as before, it was better. Tighter weave and softer fibers. We think our band is far superior to that which is woven in England. We introduced it in Hershey of last year and our customers were very pleased. In Hershey, we wholesaled it to Snyder's, Langs, and Ecklers and they have had excellent results. Joe Bell also uses our bands in every transmission he rebuilds where the customer asks for Kevlar. While I can't speak for other makers and sellers of Kevlar bands, I personally guarantee our band with a money back guarantee, no questions asked, whether you purchase Nev-R-Wear from us directly or from one of our retailers.

Perhaps when searching for American made Kevlar bands, you should do as my ad in the Vintage Ford advises.... Ask for it by name.

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Re: Kevlar band lining sets

Post by DickC » Wed Jul 08, 2020 6:04 pm

It is good to hear that a supplier has taken the effort to do the right thing. I suspect he has incurred expenses that he cannot pass on and he is to be commended for the good will in our T society. I have used Kevlar in some of my cars and have not had a problem. However, I have friends who have had issues (some serious to the point of replacing the transmission housing when the drum let go.). I have chosen to use wood linings and have not experienced any issues. They require less adjustment over time and run smoothly, no chatter. Installing them requires more effort but once done the last a long time, depending on the experience of user and proper maintenance. Just my two cents on a volatile subject.

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Re: Kevlar band lining sets

Post by GrandpaFord » Wed Jul 08, 2020 7:50 pm

I had the Kevlar linings and replaced them with cotton. I just didn't like the feel of the Kevlar and thought that the cotton would be kinder to my new drums. But others swear by Kevlar. I do have to tighten my low band often and I have disk brakes with the transmission brake as a backup. If I loose hydraulic fluid for any reason the brake peddle is adjusted to then use the transmission brake. I try to not let the low band slip any more then necessary and push down hard on the peddle. I thought it took more pressure with the Kevlar to not let low band slip. I do have an oil filter in addition to the screen in the transmission. I sectioned one of the used filters and it catches all the lint generated by the cotton bands so that is not an issue.


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Re: Kevlar band lining sets

Post by Original Smith » Thu Jul 09, 2020 11:42 am

I'm glad to hear they are being made in the USA, and correctly too. The experience I've had is you have to use Crazy Glue on the ends of the band material to keep it from unraveling. I only have Kevlar in one of my T's, and have had very good luck with it. I'm still using old stock Scandanavia in the rest of them.

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Re: Kevlar band lining sets

Post by Tim Rogers » Thu Jul 09, 2020 12:07 pm

Kevlar bands possess the ability to destroy your drums (and transmission)- why risk it?

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Re: Kevlar band lining sets

Post by TWrenn » Thu Jul 09, 2020 12:18 pm

This week I changed the oil from both my Ts. The screen was lint free on both. Had about 650 miles on both. Surprisingly even the oil wasn't black. Point being, I don't know what all the fuss is about. Maybe my bands are adjusted well, I don't abuse the pedals, don't let anything slip, so there's no problems. I like them.

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Re: Kevlar band lining sets

Post by Susanne » Thu Jul 09, 2020 1:21 pm

Point of curiosity...

I have always heard that Kevlar bands caused ruined drums (as in the above picture) and have seen drums such as these which were the result... That the phenomenon happens isn't really in question...

... But my question isn't THAT it happens, but WHY it happens with kevlar and not cotton? Is it a temperature thing? A shock loading thing? An unequal friction thing? Or is it just old drums can't take the same forces that modern ones can? And if this is so, can drums be re-engineered to withstand the whatever it is with Kevlar without creating a situation relying on a transmission rebuild?

I like the idea of bands lasting almost forever... who wouldn't?... but why is it that on THESE particular transmissions they do damage where on others where they have been used for decades, they do not? I know it's not just that it's not cotton - people run wood, people have run asbestos linings, and none of them seem to do the whammy to drums, or at least not that I've heard.

Enquiring minds want to know?

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Re: Kevlar band lining sets

Post by Steve Jelf » Thu Jul 09, 2020 2:05 pm

... But my question isn't THAT it happens, but WHY it happens with Kevlar and not cotton?

I'm not a physicist or an engineer, so my answer is at least partly guesswork. We know that two moving surfaces rubbing together (like a lining and a drum) produces friction, and friction makes heat. My guess is that some property of Kevlar causes more friction than cotton or wood. If that's the case, Kevlar has the potential to make more heat and in some cases enough heat to crack a drum. So why is the broken drum problem relatively rare? I believe it's a question of driving style. As friction comes from two moving surfaces rubbing together, no rubbing = no friction and no heat. I think that people who use Kevlar for decades and never overheat their drums are tromping down hard on their low and reverse pedals as soon as the car is moving, and that overheated drums come from too light a foot on the pedals allowing the drums to slip. But what about brake drums? I figure driving style counts there too. The most common advice on braking is to use the pedal as little as possible, slowing down mostly by engine braking and using the pedal only at slow speed for the final stop, and intermittently to keep the drum oiled.
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Re: Kevlar band lining sets

Post by Tim Rogers » Thu Jul 09, 2020 2:10 pm

Susanne, the answer to your question is simple. The drums were designed to have cotton applied to them- not something like Kevlar which is 5 times stronger than steel. It's not rocket science- cotton and Kevlar are 2 totally different materials.

It's similar to having almond "milk" in the dairy cooler...
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Re: Kevlar band lining sets

Post by Rich Bingham » Thu Jul 09, 2020 5:38 pm

Steve Jelf wrote:
Thu Jul 09, 2020 2:05 pm
. . . My guess is that some property of Kevlar causes more friction than cotton or wood. . .[/size]
I’m guessing with you, Steve. But is it friction in itself, or the amount of heat generated and/or developed by a synthetic material ? Anyone who has worked much with ropes knows synthetics can generate much more heat very quickly than cotton, hemp or sisal do.

Personally, I have no gripe with cotton linings. I have a feeling the same driving habits that contribute to the rapid wear of cotton likely result in enough heat to crack drums when Kevlar is the lining. Anyhow, the “tromp’er down firm” dictum is really hard to hold by when braking.
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Re: Kevlar band lining sets

Post by J1MGOLDEN » Thu Jul 09, 2020 6:04 pm

The simple part is the temperature of a cotton band will cause a burned up band and relieve the pressure on the drum at a much lower temperature than Kevlar.

It is kind of rocket science as Kevlar was used as the exhaust part of the rocket, because it did not burn up and survived much higher temperatures.

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Re: Kevlar band lining sets

Post by A Whiteman » Thu Jul 09, 2020 6:46 pm

Frank - thanks for your post and explanation.

I learned one more thing - that there is more than 1 manufacturer of kevlar bands. I did not realise that.

Taking that on board I would think we should be discussing "xyz kevlar" bands did this to my car or "wqr kevlar bands were used, and avoid the generic "kevlar" to put aspersions on all kevlar bands.

I learned a second thing, that different makers have different weave densities and fibre 'softness' so that only suggests we be more precise when raising concerns about 'generic' products. A bit like saying "one piece spark plugs are rubbish" rather than saying the "Winner M3" was rubbish.

Interesting read and I would suspect that Steve is right - use positive action on the pedals.

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Re: Kevlar band lining sets

Post by Steve Jelf » Thu Jul 09, 2020 10:00 pm

....the “tromp’er down firm” dictum is really hard to hold by when braking.

Quite right. I would apply that only for low and reverse. I apply the brake as little as possible.
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Re: Kevlar band lining sets

Post by Sheri » Thu Jul 09, 2020 10:29 pm

The arguement that kevlar cuases drum failure simply does not hold up. I have taken apart over 100 transmissions in the past 25 years and i found many many cracked drums that had only been used with scandanavia or other period lining materials. The fact is that core shifting was very common on these drums and as a result the drum was often thin on one side and easily broken. After nearly thirty years of kevlar use in my personal cars i have never broken a drum while using them. This includes one cross country tour in 2009 and countless tours in mountian country. Over-tightening and poor driving technique are certainly factors in drum failure, but the fact is that some drums are weaker than others. Wood bands provide a firm pedal, but they can also chatter something awful. I tried them once, never again. Kevlar just works, and thats why it remains so popular.

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Re: Kevlar band lining sets

Post by TWrenn » Fri Jul 10, 2020 8:41 am

I figure driving style counts there too. The most common advice on braking is to use the pedal as little as possible, slowing down mostly by engine braking and using the pedal only at slow speed for the final stop, and intermittently to keep the drum oiled.

I agree with Steve. I let 'er coast a lot, even with the benefit of Rockies. I also think, though likewise not being an engineer or scientist, that maybe part of the reason with Kevlars is perhaps they don't absorb and hold the oil in their material as much as cotton does. Hence not as much cooling effect. However, I've read more than once of how the cotton sheds so much more easily, hence the threat of plugging up the oiler tube for the front bearing. Kind of damned if you do, damned if you don't. Pick your battles I guess.

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Re: Kevlar band lining sets

Post by TWrenn » Fri Jul 10, 2020 8:41 am

See, I can't even figure out how to pull out a part of a paragraph and put it in quotes!! Ba ha ha. :lol: :lol: :lol:

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Re: Kevlar band lining sets

Post by Henry K. Lee » Fri Jul 10, 2020 8:46 am

My Dad and I have bee using Frank and John’s product for 20 plus years, not one problem! 40 plus cars.

Just Saying,

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Re: Kevlar band lining sets

Post by Mark Gregush » Fri Jul 10, 2020 11:06 am

I would think that wood bands would create more heat then Kevlar or cotton if miss used? Kevlar and cotton being woven and can hold more oil then the wood bands.
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Re: Kevlar band lining sets

Post by Thorlick » Fri Jul 10, 2020 11:51 am

Mark,
I disagree. No material in use for bands can create more heat than Kevlar. Wooden bands will ablate if overheated. I did that once going down the grade from Iowa Hill (Long, steep, horrendously dangerous... first I lost my transmission brake, then low, then reverse... I like to think that my adept use of the parking brake lever and lined parking brake shoes saved me, but the reality is that reaching a spot with lower gradient near the bottom did. Even with horrendous band abuse wood liners will not break drums.

Steve is right about stomping on low and reverse bands to prevent slippage with Kevlar bands. You don't do that with the brake but thank goodness the brake drum is thicker.

The reason I don't use Kevlar is that I've broken 3 drums and every broken drum I have seen in other's cars was due to Kevlar. Kevlar is great if it is installed perfectly and driven perfectly correct. But if anything goes wrong and the material slides or rubs against a drum your transmission is toast. Once about two blocks from home my reverse drum blew up... I hadn't touched the reverse pedal at all. I think an end of the Kevlar folded under (which can and does happen to folks who have done everything correctly) and dragged against the reverse drum.

I remember one drum a fellow forum member blew up because his low pedal dragged on a floor board failing to fully return to center causing the band to rub the low drum.

If you use Kevlar bands you may be amongst the many who use and love them. Or you may get the opportunity to part with the cost of an engine and transmission rebuild due to KEVLAR KALAMITY. I much prefer replacing my wooden bands once or twice a year than replacing my transmission and assorted broken parts even once.

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Re: Kevlar band lining sets

Post by SurveyKing » Fri Jul 10, 2020 2:09 pm

I have had good experience with wood bands. No more lint build up in the oil.


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Re: Kevlar band lining sets

Post by Stephen_heatherly » Fri Jul 10, 2020 2:17 pm

I have taken apart probably two dozen transmissions looking for parts or rebuild them for use in a car and have found that there is usually at least one cracked drum in every transmission I take apart. Most of those drums have never seen kevlar bands. I think it depends mostly on driving style. If you abuse the transmission and slip the bands or stomp on all three pedals trying to stop the car, you're eventually going to break something.

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Re: Kevlar band lining sets

Post by John Codman » Sun Jul 12, 2020 5:59 pm

This seems to be a discussion on a par with what oil to use, or do you believe in Marvel Mystery Oil. I really wish that I knew what band material to use in my T. I like the concept of Kevlar, but the troops seem to be seriously divided as to whether it is the ultimate solution or not.

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Re: Kevlar band lining sets

Post by TRDxB2 » Sun Jul 12, 2020 7:16 pm

To summarize what has be said so far and to seek some agreement.
Improper pedal pressure, slipping, will cause drums to heat and possible crack.
Use of the brake pedal requires firm then hard pressure to stop. (slipping)
Wood & cotton bands appear to be less abrasive than Kevlar
There are no statics supporting drum failure by band manufacturer, brand material, drum or by type T
A tight weave of the bands is important (Cotton or Kevlar) Wood is naturally tight
There is sufficient evidence that there were cracked drums before Kevlar bands.
Not mentioned
How improperly adjusted bands can cause failures
The possibility of metal fatigue on 100 year old drums

So..... Heads use K Tails use C

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Re: Kevlar band lining sets

Post by paddy1998 » Tue Jul 14, 2020 9:54 am

I am not an engineer and have no specialized knowledge beyond that of the tinkerer, but having thought about it I do not believe the case has been made that Kevlar bands will (or can) destroy the drums, or at least are any more prone to do so than any other given material.

That Kevlar has a tensile strength 5 times that of steel isn't relevant to this analysis because it's not alleged that the Kevlar is "crushing" the drums; rather Kevlar's high heat resistance can cause friction temperatures greater than the drum can withstand.

Perhaps that's true if it's run dry. It is also true of the bearings and gears, which are metal to metal contact. Run those dry and they will destroy themselves. But they aren't run dry in the car, and neither are the Kevlar bands; they are subject to a constant and overwhelming oil bath at all times.

I don't know the heat resistance of Kevlar bands v. steel. I don't even know how to measure it. What I do know is that I just installed a set of Kevlar band linings and used a propane torch to seal up the trimmed ends; it burned the Kevlar, but the steel band material was unaffected. Not proof of anything, just an observation.

It seems to me that Kevlar bands have been available and in use for a long time, long enough that if Kevlar were more prone to destroying drums in ordinary use we would have more than anecdotal, post-hoc ergo propter-hoc evidence.

If such evidence exists I haven't seen it.


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Re: Kevlar band lining sets

Post by Rich Bingham » Tue Jul 14, 2020 10:50 am

paddy1998 wrote:
Tue Jul 14, 2020 9:54 am
. . . having thought about it I do not believe . . .
Scott, that is the crux of all Kevlar / cotton / wood, “which oil ?”, MMO, water pump or no, regular vs. non ethanol gas discussions. No final conclusions can ever be drawn, because they depend on multiple variables. Some may have good results, while others find failure. If something works, one tends to have faith in it. Our individual preferences pretty much amount to a belief system. Like Dumbo’s magic feather, they give us confidence and add to the fun !

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Re: Kevlar band lining sets

Post by Adam » Tue Jul 14, 2020 11:00 am

The bottom line is this: If you drive correctly, you can get 3,500 miles or more out of a set of good cotton linings. Some people can’t get them to last several hundred miles...

The people who get long life from plain cotton linings will likely NEVER have any problem with Kevlar linings and will be quite satisfied with them (maybe even never having to change linings again). For these people, Kevlar is a far superior product.

The people who get short life from cotton bands are VERY LIKELY to have catastrophic drum failure with Kevlar linings. For these people, Kevlar is a poor choice.

Drum failures with Kevlar bands generally occur on the low drum more often than the rest because the web between the gear and drum is off center, doesn’t heat-sink evenly, and has a very wide gap between webs that easily pops open a crack during rapid uneven heating. Kevlar does not burn, glaze, and fade like cotton does when it is driven outside of its design parameters. It allows a much higher surface temperature at the drum. Drum failures always have a cause. It could be driving style, improper lining installation, improper band alignment or centering, interference issues with the hogshead or pan, incorrect adaptation of later parts in an earlier hogshead, a “big one” is incorrect adjustment; or a host of other issues... The person who has the issue generally says “I’m sure I didn’t do anything to cause it, it must be something wrong with the lining”, while in fact, if a real investigation was made to find the root cause, it would be almost impossible that the lining itself would be the single issue.

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