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Old 08-28-2013, 04:05 AM   #121
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http://www.ebay.com/itm/270844596217...84.m1438.l2649
Howard...what about this 10 tooth bell with a 58 tooth spur?..I have old Associated 58 tooth spur gears (24 pitch) and they don't stick down below the bottom of the chassis like my 63's do.......which limits how short you can run the rears before they need replaced......one of my problems when I was trying to run my RC300 last year....donuts just cant be found.........
That's very interesting! But is it 24 pitch? I'd like to use available spurs for the ball diff, and the only appropriate ones I can find are 32 pitch.
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Old 08-28-2013, 06:13 AM   #122
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That's very interesting! But is it 24 pitch? I'd like to use available spurs for the ball diff, and the only appropriate ones I can find are 32 pitch.
.i'll try to contact the seller and see if they are 24...I would assume they are since it says 1/8 bell...never saw a 1/8 that uses 32......but you are correct the 32 pitch would be way more plentiful....
just found this page under REDCAT's site....scroll down ..there are 10, 11 and 12 teeth bells in the 1/8 category...I bet they are 24 pitch...1 MOD..
http://www.redcatracing.com/Search#kw=clutch%20bell
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Old 08-28-2013, 10:49 AM   #123
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Hmm............screw-on adapter with a smaller shaft (5mm?) for more standard pinions? I'll have to dig my TRC/Composite Craft/RC10L nitro car out and take some pics of the clutch and pinion arrangement.
Scott,
two issues: The very fine thread would require machining skills far exceeding most. Also you still have the length issues.....
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Old 08-28-2013, 11:07 AM   #124
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That's another very pretty way of doing it! But do you think it would be less complicated to just make a pillow block for a jackshaft? The shaft, gears, and bearings are all cheap and available.
You are correct...Mine has a smaller parts count, but likely harder to make. Just holding on to single reduction for historic reasons I guess.

As I said before, the production on-road cars probably point to the best way. lol

I suspect the reasons include: being able to use smaller tires (An aside here-ROAR does not specify a minimum. SAD...look at 1/12 scale ); Larger bearings in clutch; larger, more efficient pinion gears; better weight distribution; more efficient brake (although some of the newest cars are going to a rear axle brake); etc. There are probably more that I can't think of...
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Old 08-28-2013, 11:15 AM   #125
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Default 24p Pinions

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.i'll try to contact the seller and see if they are 24...I would assume they are since it says 1/8 bell...never saw a 1/8 that uses 32......but you are correct the 32 pitch would be way more plentiful....
just found this page under REDCAT's site....scroll down ..there are 10, 11 and 12 teeth bells in the 1/8 category...I bet they are 24 pitch...1 MOD..
http://www.redcatracing.com/Search#kw=clutch%20bell
Matt, Good find! Those pinions would be a very good start on a direct drive power pod. Like you say probably Mod 1.0 but it seems to work with 24p spurs. The main issue becomes the spur and what type of brake to use. If you use a clutch bell brake it's simple and lets you use any spur that you can find. Probably not the best brake but if it was required, it would be the same for all.
If you go to a disk brake you have to find essentially Associated 300BD spurs or try to clone it...I don't think it is as easy as it needs to be.

Looks to me like I scratch the "Direct drive" requirement off my design specs and move on using 32p gears and double reduction...

I think Howard is right on the nail head...
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Old 08-28-2013, 08:39 PM   #126
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Default GRP (Gear Reducton Pod)

Howard,
Took a few hours tonight during the Atlanta Ballgame to start on what I hope to be an eighth scale gear reduction pod to eliminate some of the issues that have been identified with other approaches. It should answer some other questions also, will an .18 small block O.S. motor be fast enough and how will 32 pitch gears hold up.

Next I need to make a bottom plate and a rear axle/diff assembly to use current 1/8th scale wheels. May be able to clone an Associated type disk brake or try a band brake first to hopefully answer another question or two!

Have you gotten the push rod tubing yet? If it fits some bearings ok, I'm going to get some to fab the axle for this experiment. One thing that worries me is that the push rod I found on Ebay (Very quick look) was only 7" long. I would like 9" or so.

Spec 1/8 Pan Car .21 no frill's racing-grp1.jpg

Spec 1/8 Pan Car .21 no frill's racing-grp-2.jpg

Spec 1/8 Pan Car .21 no frill's racing-grp-3.jpg

Spec 1/8 Pan Car .21 no frill's racing-grp-4.jpg

Spec 1/8 Pan Car .21 no frill's racing-grp-5.jpg
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Old 08-28-2013, 10:09 PM   #127
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Howard,
Took a few hours tonight during the Atlanta Ballgame to start on what I hope to be an eighth scale gear reduction pod to eliminate some of the issues that have been identified with other approaches. It should answer some other questions also, will an .18 small block O.S. motor be fast enough and how will 32 pitch gears hold up.

Next I need to make a bottom plate and a rear axle/diff assembly to use current 1/8th scale wheels. May be able to clone an Associated type disk brake or try a band brake first to hopefully answer another question or two!

Have you gotten the push rod tubing yet? If it fits some bearings ok, I'm going to get some to fab the axle for this experiment. One thing that worries me is that the push rod I found on Ebay (Very quick look) was only 7" long. I would like 9" or so.

Attachment 1106046

Attachment 1106047

Attachment 1106048

Attachment 1106049

Attachment 1106050
..I like the setup Ned...Phil Cring and I had also discussed this arrangement at the track...looks like it would also solve the header to tire clearance issue on the 300's...

I know...I know... pricey pushrods....but longer rods can be had...
http://store.440source.com/Cut-to-Fi...info/105-1022/

http://www.dougherbert.com/cams-valv...-of-22910.html
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Old 08-29-2013, 08:16 AM   #128
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..I like the setup Ned...Phil Cring and I had also discussed this arrangement at the track...looks like it would also solve the header to tire clearance issue on the 300's...

I know...I know... pricey pushrods....but longer rods can be had...
http://store.440source.com/Cut-to-Fi...info/105-1022/

http://www.dougherbert.com/cams-valv...-of-22910.html
Thanks Matt. That's been a possibility for ever but I wanted to stick with direct drive. This seems to make the parts I have to make myself a bit easier.

Unfortunately your push rods are 3/8" dia. Way over kill for this set-up. IMO. If the 5/16" ones are too short, I'll go to something like 0-1 which may be good enough in a lighter weight car.
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Old 08-29-2013, 02:07 PM   #129
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Howard,
Took a few hours tonight during the Atlanta Ballgame to start on what I hope to be an eighth scale gear reduction pod to eliminate some of the issues that have been identified with other approaches. It should answer some other questions also, will an .18 small block O.S. motor be fast enough and how will 32 pitch gears hold up.

Next I need to make a bottom plate and a rear axle/diff assembly to use current 1/8th scale wheels. May be able to clone an Associated type disk brake or try a band brake first to hopefully answer another question or two!

Have you gotten the push rod tubing yet? If it fits some bearings ok, I'm going to get some to fab the axle for this experiment. One thing that worries me is that the push rod I found on Ebay (Very quick look) was only 7" long. I would like 9" or so.
Hi Ned,

I was going to put the spur on the left side of the car, with a very short jackshaft entirely to the left of the clutch bell (between spur and bell). That saves weight, and I can use very small gears on the jackshaft (since it doesn't need to clear the engine block), saving more weight. The motor just needs to shift to the right about 1.5" to make room.

Pushrods and bearings have arived. The 5/16" pushrod I got is 10.1" long. Also, the wall thickness is 0.063", so an 8-32 threaded rod will fit inside. The 10-32 won't quite fit due to the seam on the pushrod ID. The 5/16" pushrod slides right into the 8mm bearings!

My internet connection is down at the moment. (I'm standing here at the library typing this.) When I get access again, I'll post the sources for pushrod and other parts. New pushrods are darn cheap on Ebay! I paid $7, shipped.
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Old 08-29-2013, 03:32 PM   #130
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Hi Ned,

I was going to put the spur on the left side of the car, with a very short jackshaft entirely to the left of the clutch bell (between spur and bell). That saves weight, and I can use very small gears on the jackshaft (since it doesn't need to clear the engine block), saving more weight. The motor just needs to shift to the right about 1.5" to make room.

Pushrods and bearings have arived. The 5/16" pushrod I got is 10.1" long. Also, the wall thickness is 0.063", so an 8-32 threaded rod will fit inside. The 10-32 won't quite fit due to the seam on the pushrod ID. The 5/16" pushrod slides right into the 8mm bearings!

My internet connection is down at the moment. (I'm standing here at the library typing this.) When I get access again, I'll post the sources for pushrod and other parts. New pushrods are darn cheap on Ebay! I paid $7, shipped.
Howard,
I guess I got suck in the box! Lots of advantages, weight, compactness, easier to make, keeps the brake and throttle linkage together... I bet it was as obvious to you as it wasn't to me!

Glad the push rods will work. I'll try to braze the thread (10-32) into the shaft on both ends to use on for the diff adjustment and the other to hold the wheel on. The adapters I make for the current wheels to the vintage axles. Too lazy to fit the QR parts!

Later,
Ned
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Old 09-02-2013, 03:04 AM   #131
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Glad the push rods will work. I'll try to braze the thread (10-32) into the shaft on both ends to use on for the diff adjustment and the other to hold the wheel on. The adapters I make for the current wheels to the vintage axles. Too lazy to fit the QR parts!
Do you have a photo of your wheel hubs for putting new wheels on old axles? Do you sell them?

Here's a link to the 5/16" pushrod I bought on Ebay:

http://www.ebay.com/itm/1-PUSH-ROD-1...a74e07&vxp=mtr

And here is the stainless threaded rod:

http://www.ebay.com/itm/Threaded-Rod...item4d0fbd8f29

I paid $5 for the 5/16" pushrod, with free shipping!

Anyone wanting to purchase a pushrod for cheap should do a search on Ebay for "pushrod 5/16". There are many, with several ranging from 9" to over 10" long.

Both the 5/16" and 3/8" pushrods I received are oversize and out-of round by a few thousandths. (I no longer own a micrometer, so I can't give more accurate numbers.) The 8mm ID bearings fit nicely on the 5/16" pushrod, but the 3/8" axle won't fit into 3/8" bearings . The 5/16" pushrod was 10.14" long including the balls, which gave plenty of length to cut off both ends (which is necessary as their OD is larger by a few thousandths than the rest of the rod for the first 1/2" or so, due to the balls being pressed in the ends).

The 3/8" pushrod will be plan B if the strength is necessary, but then the inner diff ring support and wheel hub on the other side of the axle will need shoulders machined on them to fit into larger bearings, since the axle is too big for 3/8" ID bearings. Or I could use bushings pressed onto the pushrod to build up the OD to fit into larger bearings. But all of this will add more weight!

By the way, I thought of another advantage to using a jackshaft: the gear ratio can be easily changed by swapping out the jackshaft's drive gear rather than the clutch bell, and these gears are a heck of a lot cheaper than the clutch bell.

Here are the parts that I'm considering for the drive train, in sequence from the spur gear to the clutch bell:

54T 32p spur for ball diff (the larger sizes aren't designed to capture the diff balls, which is a pain in the ass): http://www3.towerhobbies.com/cgi-bin...?&I=LXXLP1&P=7

9T 32p 0.125" bore jackshaft drive gear: http://www3.towerhobbies.com/cgi-bin...?&I=LXEW94&P=7

1/8" jackshaft, about 1.5" long, with 1/8x5/16" bearings

23T 32p 0.125 bore jackshaft driven gear: http://www3.towerhobbies.com/cgi-bin...?&I=LXAGWJ&P=7

20T MOD.8/32p clutch bell: http://www3.towerhobbies.com/cgi-bin...?&I=LXXBK7&P=7

These parts give a ratio of 6.9, which should be short enough for the smallest tracks. As I mentioned, I can get a taller ratio by playing with the jackshaft gears.

The jackshaft and its gears and bearings can be easily changed to 5mm if necessary to handle the power of a .21 engine, as all of the parts are readily available. I'll prototype with the 1/8" parts, as I have them already, they will be a bit lighter, and they should be okay for a .15 engine. The 5mm jackshaft also enables use of MOD1.0 driven gears to match up with 1/8 scale, MOD1.0 clutch bells.
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Old 09-02-2013, 06:49 PM   #132
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Howard,
I guess I got suck in the box! Lots of advantages, weight, compactness, easier to make, keeps the brake and throttle linkage together... I bet it was as obvious to you as it wasn't to me!

Glad the push rods will work. I'll try to braze the thread (10-32) into the shaft on both ends to use on for the diff adjustment and the other to hold the wheel on. The adapters I make for the current wheels to the vintage axles. Too lazy to fit the QR parts!

Later,
Ned
wow you guys are busy, will send pics of my idea at some point. what i'm considering is taking the 2 speed edam clutch removing 1st gear, making something that looks like a clutch bell that threads onto it with a 5mm shaft for a mod 1 pinion. just a thought since the edam clutch works good and is a great price.
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Old 09-02-2013, 08:45 PM   #133
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[QUOTE=howardcano;12506965]Do you have a photo of your wheel hubs for putting new wheels on old axles? Do you sell them?

By the way, I thought of another advantage to using a jackshaft: the gear ratio can be easily changed by swapping out the jackshaft's drive gear rather than the clutch bell, and these gears are a heck of a lot cheaper than the clutch bell.QUOTE]

Howard, I'm half afraid to get back to you because my usually bullet proof computer died soon after you had your issues!!! LOL

Anyway, thanks for the push rod info. I'll be ordering a couple soon. (have some traveling to do in the next couple of weeks so I wont get much done for a while. Plus I hope to make a couple of races in Ohio in late Sept and October.)

I was discussing the shaft layout with a buddy, NutDriver, and he mentioned alternate locations for the brake disk which would be a big improvement. I'm going with 1/4" jackshaft. I'm sure 1/8 would work, but just looks to wimpy to me! lol It helps to have a lathe, even if it is a small one! I see where you are coming from, being able to use unmodified parts. I believe you should aim your basic gearing closer to 5.5 to 1. 6.9 would really rev the motor!!!

My adapters are simple as I use a nut or screw to attach the wheel. I'm to lazy to add the QC parts and they are not cheap! Some guys a so spoiled that they complain about un screwing a nut to remove a wheel!!

The Diff side is always a bit tricky. I have made adapters for Associated diffs and MRP but they attach to the existing adapter. I expect to be able to make a one-piece adapter for this project. If you get me a sketch I'd be glad to try to make a set up for you. Have you decided what diff rings and thrust washers you will use? Right now I'm planning on using the Kimbrough gear and 1/10 scale rings.

I'll try to get you some pix before I leave.

Ned
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Old 09-02-2013, 08:52 PM   #134
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These clutch bells look interesting
http://www.rbproducts.com/mainEn.php...equete=0230415
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Old 09-02-2013, 10:55 PM   #135
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These clutch bells look interesting
http://www.rbproducts.com/mainEn.php...equete=0230415
Pretty nice workmanship, but I still think the issue is the gear ratio. I'm certain we need close to 5 to 1. I'm shooting for around 5.5.

The smallest pinion I see there is 14 tooth which needs a 70 tooth spur to get to 5 to 1. A 70 tooth spur is probably something like 3 inches O.D. That's pretty big for an 1/8 scale tire diameter.

If you're going to use double reduction with a jack shaft then you likely would want something like 2.5 to 1 on both gear sets similar to what is used in 4wd and belt drive pans (I think most are nearer 2 to 1 using mid 20's pinions.)

But there's always more than one way to skin a cat!!!

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