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RAM and Kemtron motor mashup - the RAMtron 850


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#1 dc-65x

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Posted 27 July 2020 - 11:50 AM

One of my favorite builders of the 60's, Bob Braverman, wrote an interesting motor "hop up" article combining the Kemtron X-503 motor..........

 

Ramtron 850- (8).JPG

 

...........with the big and potent RAM 850 armature:

 

Ramtron 850-(35).JPG

 

Below is the February 1965 Rod & Custom magazine article (click on the picture to enlarge):

 

R&C Kemtron Hop Up (1).jpg

 

R&C Kemtron Hop Up (2).jpg

 

R&C Kemtron Hop Up (3).jpg

 

R&C Kemtron Hop Up (4).jpg

 

R&C Kemtron Hop Up (5).jpg

 

The RAM armature is only .4 ohms resistance compared the the 6 volt Kemtron's .8 ohms:

 

Ramtron 850-(31).JPG

 

Why not just use the RAM 850 motor? The RAM is quite a bit heavier:

 

Ramtron 850-(30).JPG

 

Ramtron 850-(32).JPG

 

The powerful RAM is also taller.........

 

Ramtron 850-(33).JPG

 

............and quite a bit bigger overall:

 

Ramtron 850-(34).JPG

 

Time to get to work and have some fun with a motor mash-up.

 

 

 

 


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#2 Lone Wolf

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Posted 27 July 2020 - 03:48 PM

Very cool. RE: step #5. What the hell is an orange stick :o


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#3 dc-65x

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Posted 27 July 2020 - 04:15 PM

Hi Joe,

 

I didn't know what an "orange stick" was either. Luckily Google did:

 

An orange stick is a manicure tool used for cleaning fingernails and pushing back cuticles. 

 

716om+gWUbL._SL1000_.jpg

 

I might have to get some of those puppies.   :)


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#4 don.siegel

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Posted 27 July 2020 - 05:20 PM

Another great project Rick. And I must admit I didn't remember that article. 

 

Didn't realize the weight difference was that much either, should be interesting! I'll be curious to see what you do about that "1/16 tubing front bearing support"... doesn't seem all that reliable...  

 

Don 



#5 MSwiss

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Posted 27 July 2020 - 07:07 PM

I had never heard of an orange stick, either.

Also, looking at post #1, it appears Ram had 2 different Chicago area locations, back in the day.

I remember a Northlake(a close Chicago suburb) address, on the Ram trinket I had.

Mike Swiss
 
Inventor of the Low CG guide flag 4/20/18
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17B West Ogden Ave., Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

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#6 dc-65x

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Posted 27 July 2020 - 08:14 PM

I won't be doing the pin tube bearing holder that Bob made Don.........because I have this unknown (to me anyway) doohickey  :crazy:

 

Ramtron 850- (10).JPG

 

And I'm spacing the doohickey out from the motor with machined bar stock spacers to account for the RAM's longer armature length. I've added a ball bearing and Pittman brush plate too.....


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#7 Lone Wolf

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Posted 28 July 2020 - 08:16 AM

Thanks Rick. Now I can die a happy man. I found some of those in some old slot boxes I bought in the past. Guess they read the article.

 

I was going to comment that you would never do that caveman bearing support.

 

Guess you beat me to it :)

 

I imagine the 7 pole would be smoother than the 5. Makes a nicer running car I would think.


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#8 dc-65x

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Posted 28 July 2020 - 09:53 AM

The new motor end plate doohickey also upgrades the brushes and springs from the original Kemtron pieces on the left to the larger Pittman items on the right:

 

Ramtron 850- (6).JPG

 

There's another feature of the doohickey compared to the Kemtron piece on the left. Notice those aren't just mounting holes on the new doohickey:

 

Ramtron 850- (11).JPG

 

Those are slots that allow it to be rotated to advance the motors timing.   :dance3:


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#9 don.siegel

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Posted 28 July 2020 - 10:12 AM

Very interesting... Rick, do you or Joe have any idea who made those? Have never seen any reference to something like this in any of my magazines, and had no idea anybody made hopup parts for these motors! 

 

Don 



#10 dc-65x

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Posted 28 July 2020 - 10:34 AM

I don't know who made it Don. It was just in a box of parts I bought. It took a while to just to figure out what motor it was supposed to fit.


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#11 don.siegel

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Posted 28 July 2020 - 10:46 AM

Thanks Rick; does it only fit the Kemtron, or can it go on the Pittman 65 or 85? 

 

Don 



#12 dc-65x

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Posted 28 July 2020 - 10:52 AM

I just checked Don and it's not even close to fitting a 65 or 85.


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#13 Lone Wolf

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Posted 28 July 2020 - 02:40 PM

Don't know who made that part. Maybe Ram as they made things to use their arms in different motors. Rambuchi for example.

 

Kemtron incorporated some of this stuff into the Bronco and Mustang motors. 7 pole arms and a cast endbell opposite the brush side. 2 different shaft sizes etc. Wonder if they did this in response to this magazine article.


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#14 dc-65x

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Posted 28 July 2020 - 02:44 PM

I'm beefing up the other motor end plate with a 1/16" thick hunk of brass:

 

Ramtron 850- (7).JPG

 

This will be an inline configuration car and this end plate mounts to the chassis motor bracket:

 

Ramtron 850- (3).JPG

 

 


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#15 dc-65x

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Posted 28 July 2020 - 02:48 PM

Sorry Joe I didn't see your post.  I'd like to know the story behind that mystery end plate too.


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#16 dc-65x

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Posted 28 July 2020 - 08:16 PM

I decided to turn down my RAM arm from .735" to the same diameter as the Kemtron's .710". My little hobby lathe with a carbide bit worked like a charm:

 

Ramtron 850- (30).JPG

 

The wires near the comm are thread wrapped, the arm coated with epoxy and hit with a heat gun to thin the epoxy and help it soak in the windings. Finally a static balance job and the arm is as ready as it will ever be:

 

Ramtron 850- (13).JPG

 

All the parts ready for assembly:

 

Ramtron 850- (4).JPG


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#17 dc-65x

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Posted 30 July 2020 - 11:29 AM

With the motor assembled it got another good ZAP. The Big Dog zapper also got a pair of cool thumb screws to adjust the pole pieces. No more messing around with an allen wrench:

 

Ramtron 850-(37).JPG

 

Running the motor on the power supply the revs sounded uneven. When I applied pressure pushing the brush harder against the comm the revs definitely increased. The little Pittman 196 brush spring wasn't up the job so I tried one of these Simco torsion springs:

 

Ramtron 850-(38).JPG

 

That worked better but the motors revs still increase with more pressure on the brushes. Next I used the strongest RAM 850 spring from their hop up kit:

 

Ramtron 850-(39).JPG

 

The small Pittman spring was still needed to align the little T-shaped plungers and the big RAM spring was shortened a bit and slipped over them for a double spring arrangement. Talk about a pain to install.  :shok:  But that did the trick. :

 

Ramtron 850- (27).JPG

 

Finished up the motors weight increased only .15 oz...........

 

Ramtron 850- (28).JPG

 

..........and it still weighs an ounce less than a RAM 850:

 

Ramtron 850-(36).JPG

 

I'm a sucker for the older "non-can" style motors and I think this thing looks really cool  :sun_bespectacled: :

 

Ramtron 850- (24).JPG

 

Ramtron 850- (25).JPG

 

Ramtron 850- (26).JPG

 

Since I took these pictures I pulled the motor apart again (including the brushes and springs  :dash2: ) to modify the brush plate and the heads of the screws holding the motor together. This allowed me to rotate that doohickey for more timing. I also had to file the corner off the doohickey because it was now hanging down below the bottom of the motor.

 

The motor is ready to go in a car.   :dance3:

 

 

 


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#18 don.siegel

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Posted 30 July 2020 - 11:37 AM

That looks great Rick, a franken-motor in the best sense of the word. 

 

Could you tell how much the advanced timing helped? Are the Kemtrons neutral advance to begin with? 

 

Don 



#19 dc-65x

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Posted 30 July 2020 - 11:53 AM

Thanks Don. Just listening to the motor the revs definitely increased as I increased the timing up to a point. It really wasn't dramatic but it did help. 

 

I don't know about Kemtron arms but Gene Hustings spoke of RAM 850 arms having advanced timing. I can barely see a bit of CW advance on the comm of a RAM.


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#20 Dave Crevie

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Posted 30 July 2020 - 02:35 PM

Kemtron and Pittman arms were generally neutral timed. Some Ram arms ran a little advance. If I rewound an arm, I would usually eyeball in about 15 to

20 degrees advance, which is all you would want in a seven-pole motor. And we usually wound two brush springs together to get more brush pressure. 

 

Rick; This has been a great thread, replicating what a lot of drag racers were doing back in the day.   


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#21 dc-65x

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Posted 30 July 2020 - 06:09 PM

I'm glad you like the project Dave and thanks for you insights.   :)

 

My chassis is going to be an inline and I'm starting out with this Kemtron chassis kit:

 

Genie (10).JPG

 

Genie (11).JPG

 

Genie (12).JPG

 

So far I'm planning on only using the motor bracket from the kit:

 

Genie (16).JPG

 

Genie (17).JPG

 

Genie (15).JPG

 

I'm working on coming up with a brass pin tube space frame design (my favorite)....

 

 


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#22 slotbaker

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Posted 30 July 2020 - 06:43 PM

Beautiful engineering Rick, love it.

:heart:


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#23 Dave Crevie

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Posted 31 July 2020 - 08:50 AM

OMG! Haven't seen one of those kits since I can remember. They were sold with different mounting holes to fit other motors. The parts were very nice lost

wax castings with the tube and axle holes reamed. Some guys actually epoxied aluminum tube between the front and rear castings. 



#24 dc-65x

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Posted 31 July 2020 - 01:42 PM

I love that Kemtron cast bracket too. You don't see things like that often. But the holes for the axle bearings are way oversize and the bearings really slopped around in them. The solution was to machine up a pair of custom "duffies". It also gave me an excuse to play with my little hobby lathe:

 

Genie (7).JPG

 

Genie (13).JPG

 

The duffies soldered in place and the motor tapped up to protect it from acid flux:

 

Genie (18).JPG

 

Genie (19).JPG

 

Time to figure out a pin tube space frame chassis design........


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#25 Dallas Racer

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Posted 31 July 2020 - 03:04 PM

Damn that looks nice! That's going to be a good looking car. No body required.


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