Cutting tire foams

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Old 09-30-2013, 09:35 PM
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Default Cutting tire foams

I know I'm killin you guys with all of these newbie questions but I'm trying to learn as much as possible about buggies. So while I was following the worlds i noticed some pictures of the drivers cutting all of the edges off of the foam inserts. What does this do? Different contour of the tire? Grip? Just make the tire easier to mount?
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Old 09-30-2013, 09:58 PM
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I just trim the inside edges of my foams at a 45* angle to make gluing them up easier. Haven't experimented with trimming the outer corners...
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Old 10-01-2013, 06:21 AM
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I was told that trimming the edges gives the tire a rounded contour as opposed to mostly square. Makes the car more predictable to drive and less likely to catch an edge at the expense of some traction. The sugared track had infinite traction so there you go.

The first time I drove a rounded carcass I found that it was easier to save bad landings than previously.
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Old 10-01-2013, 08:02 AM
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but how are you cutting it evenly?
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Old 10-01-2013, 10:23 AM
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Old 10-01-2013, 10:49 AM
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Originally Posted by ebay007 View Post
but how are you cutting it evenly?
To cut the inside edges, it helps to roll them inside-out.
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Old 10-01-2013, 01:52 PM
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I think (correct me if I am wrong) what the OP was referring to was photos of the racers cutting open cell rear foams down to fit in front tires.

Rear tire foams used are usually the closed cell type (usually red or blue, depending on brand and firmness). For the front tires, most will take a full size rear tire open cell foam (usually white or beige) and cut about 1/4-1/3 off and squeeze it into the front tires. Gives a firmer front tire.

Hmmm...reading the original post again, I may be wrong as to what he was looking for. Oh well.
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Old 10-01-2013, 05:05 PM
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They may have been cutting the rears to fit the fronts better but I was actually referring to the guys cutting the edges to a 45. But I appreciate the info, I didn't know that some guys cut the to me down for the front either.
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Old 02-17-2014, 06:20 PM
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How do you cut the open cell foams for the front tires. I have some Jconcepts front barcodes that I want use with the included foams but not sure what method to use.

I use to trim the edges at an angle to contour them but someone also told me they just cut the foam to the width of the wheel and then install them.

Which do you do?
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Old 02-17-2014, 06:39 PM
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Originally Posted by Racing4Evo View Post
How do you cut the open cell foams for the front tires. I have some Jconcepts front barcodes that I want use with the included foams but not sure what method to use.

I use to trim the edges at an angle to contour them but someone also told me they just cut the foam to the width of the wheel and then install them.

Which do you do?
I personally usually only run closed cells in the rear. It feels more planted for me. second i only run open cells in the front because when i tried a few sets of broken in fronts with C.C. foams it seemed like a grocery cart effect, just very little steering control. Third, i trim about 1/4 in. off of a full size rear buggy open cell foam for my front tires. I found that if you use the pre cut half size ones there just simply isnt enough foam in the tire to keep its shape very long.
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Old 02-17-2014, 06:43 PM
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normally, I cut the tire foams only when they bow the tires out too much. An example is one of my local tracks, Larry's RCs, is a rubber surface. In stock buggy class, we normally use the Custom Works Street Trac tire. Now, I know all of this is what most people would call a load of bs, but here's the catch. These particular tires are very tight fitting to the wheels. And also very thin, for the 2wd buggy front. You need to cut the foams in order to make these tires fit or else they won't actually mount on the wheels. This is just a common example of when we would need to cut the foams
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Old 02-17-2014, 07:45 PM
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OK thanks for your replies. Im not sure if i was clear but the open cell foam inserts included in the package are not for the rear tires. They are precut smaller for the front but obviouslwould likey...

I wonder if I should trim only the edges to round out the insert OR should I cut a portion of the entire insert to match the width of wheel? I would like to know more what others are doing.
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Old 02-17-2014, 09:11 PM
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if they are front foams, don't cut them narrower, otherwise when the foam compresses after some time, the tire "goes flat". If they are rear foams and you want to use in front, cut -1/2 off of the width, and use the remainder in front. for rear, don't cut, or just use closed cell foams.

if using open cell...do the 45 degree cut on the edges.
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Old 02-18-2014, 06:42 AM
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Let's start from the basics:

Tire foam is the "air pressure" analoge to full scale racing. If you've ever listened to a nascar broadcast you know that a lot of tuning is done with air pressure.

The firmer the foam, the firmer the tire and thus the less compliant to the racing surface. The more the tire forms to the track the larger the contact patch and the more grip... to a point. A soft tire will deform under a certain load and break free in a very unpredictable manner. The high the traction, the high the speeds, the firmer the tire. The tire also acts as part of the suspension. A rough track will typically calls for a softer tire, smooth can run firmer.

So in summary softer tire build equal more grip, firmer tire build equals more predictable.

please note this is tire build and not the compound listed on the package.

now the foam plays a big role in determining the firmness. The more foam you pack in there or the harder the foam is, the more stiffer the tire is going to be.

also take note, open cell foams tend to break down over time, especially if you use a lot of tire sauce.

so go forth and experiment. do like the rest of us and copy shamelessly from the fast guys at your track.
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Old 02-18-2014, 07:31 AM
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depends on the foam, the tire, the application
Change any one of those three and it all changes.
You really can't teach the secrets of this subject online.
Gotta be hands on if you really want to know it.
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