Author Topic: 2019 New Production Tracks - Taking Pre-Orders  (Read 3615 times)

Darth_Kitten

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #15 on: January 17, 2019, 05:33:32 PM »
So that would mean that you would get a somewhat larger "bite" on the sprocket, and give a minimal change to the overall gearing.
I know it's been speculated before, but I still wonder what the rationale is for this change?
Is there a larger aperture in the track that this is compensating for?
hmmmm. curious.


I measured some of the reproduction flanges and they where 1/4" in diameter smaller
the sprockets  where the same

they may have made a new run of tracks that does not require the new flanges
« Last Edit: January 17, 2019, 09:52:28 PM by Darth_Kitten »

8683jb

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #16 on: January 17, 2019, 05:58:01 PM »
Maybe the track is 1/8” thicker than original and to keep the same gear ratio, the flanges are ¼” smaller in diameter?
« Last Edit: January 17, 2019, 06:03:27 PM by 8683jb »
'42 Autocar M2A1

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steve-0

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #17 on: January 17, 2019, 07:52:28 PM »
if the flanges aren't the exact correct diameter for the tracks the tracks will start hopping over the sprockets

which is why many have speculated that the tracks where made wrong and only work with the new smaller flanges

im sure Kevin will inform us when he finds out why they where needed and if they still are.

Torque

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #18 on: January 17, 2019, 07:57:27 PM »
Don't have any personal experience so I am talking theoretical here. There is a certain radius at which the sprocket matches the designed pitch of the tracks perfectly. The flanges are what holds the track at the correct radius so the teeth of the sprocket match the pitch of the tracks. The teeth on the sprocket of coarse are further apart at the tips of the teeth and closer at the root, this is why it is important to have flanges that are the correct diameter. If the flange is too big the track will be pulled at the bottom of the wrap but held back at the top, this would not be good, if the flange is small the sprocket will be pulling in the center of the track wrap with clearance at the beginning and end of the wrap of the track, this would not be harmful. This may explain why the new flanges are small if that is the case.

Darth_Kitten

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #19 on: January 17, 2019, 09:51:49 PM »
all valid points and good discussion!

I got a kick out of this photo on Facebook.


https://www.facebook.com/photo.php?fbid=776473056038234&set=pcb.1190937114395687&type=3&theater&ifg=1

col.halftrack

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #20 on: January 18, 2019, 09:28:24 AM »
 Hal-Trac-ers,
 While I certainly appreciate the discussion and would, and have, welcomed any reviews of these tracks. Even prior to my involvement in importing these.  I must say; the Europeans have posted several videos both on and off road showing these tracks in use. I have several texts from users of these tracks in the states; all favorable. To my knowledge there have been no complaints made either in Europe or N.America. They have been sold now for four years. Hundreds of sets. While some of these sets may be still in the crate as spares I am confident that we are talking about 50 plus half-tracs some of which have been ran pretty hard and no issues reported.
 I have a limited knowledge as to casting of the drive flanges but I do know that castings in general can vary in the shrinkage during the cooling process. I would be willing to bet that during the original production there could have been quite a bit of variance. Then consider the track manufacture and we can also assume that not every track was the same length or thickness. Just think of the difference in ratio produced by running a new WW2 track and, perhaps even on the same vehicle, running a track down to the crossbars on the opposite side. Perhaps a 2" difference.
 I have been fortunate in that I bought many sets of track long ago out of a old business. So I cannot speak to these tracks personally, I look forward to the opportunity to run a set of these myself. I remember when the IZZY tracks ran out and prices went to over 9k for a pair of track. Thank goodness there is a source for dependable tracks.
1941 White M2
1942 White M4A1 was M4
1942 Autocar M2A1
1942 Autocar M3-75
1943 White M13 rebuilt as M16
1943 Diamond T M3A1

mfrance

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #21 on: January 18, 2019, 01:34:47 PM »
shipping crate is 36" wide x 31" tall from bottom skid to top of crate x 69 1/2" long
both tracks inside with 4 drive sprocket flanges
NEW Flanges are 21-1/8" diameter
(originals are 21-3/8")

steve-0

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #22 on: January 18, 2019, 02:20:41 PM »

 I have a limited knowledge as to casting of the drive flanges but I do know that castings in general can vary in the shrinkage during the cooling process. I would be willing to bet that during the original production there could have been quite a bit of variance.

the flanges are cast then machined to the correct diameter so shrinkage is not a factor

wear on the outside of the track does not affect the geometry of the sprocket and flange.




« Last Edit: January 19, 2019, 12:07:37 AM by steve-0 »

Outsider

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #23 on: January 19, 2019, 08:59:37 AM »
NEW Flanges are 21-1/8" diameter
(originals are 21-3/8")

So they wanted to change the geometry for some reason on the new tracks.

Steve
Lots of green "junk" as my wife likes to call it.
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autocar925

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #24 on: January 19, 2019, 10:08:43 PM »
As I speculated when the tracks first came out, the tracks are most likely made incorrectly.  The pitch diameter of the sprocket must match the pitch of the tracks(the distance between each crossbar).  The pitch of the sprocket is determined by the diameter of the flange.  As the flange gets smaller, the pitch gets smaller.  I think the pitch of the new tracks ended up too small, probably because an old track was copied and the rubber had shrunk.  The new track was made the same size as the shrunken old track so therefore the pitch was too small(or else they just screwed up the design). The smaller new flanges will have a shorter pitch to match the shortened new track pitch.  The molds can’t be modified or changed to correct the problem, you must scrap them and make new ones.  The molds are very expensive so they won’t be scrapped.  Cheaper to make new flanges and throw them in with the deal.  It means you can’t ever use new tracks with old flanges or vice versa

col.halftrack

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #25 on: January 21, 2019, 10:19:34 AM »
mfrance: Thanks for the dimensions. I am attempting to confirm with the manufacturer that they will be crated similarly.  Just don't want a surprise change up.
 Others: I would think that the outside diameter would indeed effect the geometry. That is why you should not run 9.00 x 20s on a half-trac that was intended to run 8.25 x 20s. My point was that you are overthinking this because an original track can wear both on the inner surface and outer surface far more than 1/4" 
 If a shrunk track was used for a mold, the track would be thinner so one would have needed to make a LARGER drive flange to make up for  a thinner track. The new track may indeed be made thicker due to the desire to increase there load rating or wear.
 Last: I think the success of this track on vehicles that routinely run 30mph over all terrain surfaces should be the focus. Speculating on how the ship floats or sinks is fine but if a change improves a design and is itself proven over time I am good with that. The Israeli's changed the design of this track and most feel that it was for the better. As long as the track performs well and retains the look of WW2 style track I am thrilled. I have ran lots of original track from the forties and it certainly will not maintain road speed without failing due to its age.
1941 White M2
1942 White M4A1 was M4
1942 Autocar M2A1
1942 Autocar M3-75
1943 White M13 rebuilt as M16
1943 Diamond T M3A1

autocar925

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #26 on: January 21, 2019, 11:11:30 AM »
Just for clarification, the issue is not shrinkage in the thickness, it is shrinkage in the length.  The rubber shrinks equally in all directions.  The track is roughly 100 times longer than it is thick, so the thickness shrinkage is essentially nothing compared to the length shrinkage.  The inside of the track doesn't wear much since it runs on the bogies and there is no relative motion(grinding or slippage) between the flanges and the track.  The track wear occurs on the outside of the track where it runs against the road and doesn't have anything to do with pitch diameter, so the pitch stays the same over the life of the track.

My intent was not to argue whether the new tracks or old tracks are better.  There have been continuing questions as to why new flanges are needed and I thought I would throw my 2 cents in as to the most likely reason for this.
« Last Edit: January 21, 2019, 06:06:55 PM by autocar925 »

mfrance

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #27 on: January 21, 2019, 02:39:29 PM »
I'm just glad we have new tracks to keep this hobby going,  thank you to those who worked diligently to get these tracks to market so we are all not sitting around with expensive yard art.
Thank you for even taking on this as being a U.S distributor..

WayOffTrack

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #28 on: January 21, 2019, 03:15:15 PM »
I'm just glad we have new tracks to keep this hobby going,  thank you to those who worked diligently to get these tracks to market so we are all not sitting around with expensive yard art.
Thank you for even taking on this as being a U.S distributor..

YES!

8683jb

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Re: 2019 New Production Tracks - Taking Pre-Orders
« Reply #29 on: January 21, 2019, 06:37:56 PM »
After thinking about my question on the track thickness being a possible factor, it came to me that the thickness of the track has no effect on the gear ratio since the flange runs on the inside of the track. The diameter of the flange itself is the only thing that would affect the relationship of the rear and front differential gear ratios. In this case the difference between the diameter of the original and the new flanges is just over 1% - pretty negligible. And as Kevin stated, the difference in wear between the tracks from side to side can be way over that, and certainly tire wear can as well. In any case, as others have said it’s great to have new tracks coming available! Thanks Kevin.
'42 Autocar M2A1

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