94 replies to this topic

[dc-65x]

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

 

 

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

 

 

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

 

 

 

 

 

 

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

 

 

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

 

 

 

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

 

 

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

 

 

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

 

 

 

 

[Lone Wolf]

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

[dc-65x]

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. 

 

 

I might have to get some of those puppies.  

[don.siegel]

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 

[MSwiss]

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.

[dc-65x]

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

 

 

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.....

[Lone Wolf]

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.

[dc-65x]

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:

 

 

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:

 

 

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

[don.siegel]

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 

[dc-65x]

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.

[don.siegel]

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

 

Don 

[dc-65x]

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

[Lone Wolf]

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.

[dc-65x]

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

 

 

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

 

 

 

[dc-65x]

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

[dc-65x]

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:

 

 

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:

 

 

All the parts ready for assembly:

 

[dc-65x]

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:

 

 

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:

 

 

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:

 

 

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.    But that did the trick. :

 

 

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

 

 

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

 

 

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

 

 

 

 

Since I took these pictures I pulled the motor apart again (including the brushes and springs  ) 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.  

 

 

 

[don.siegel]

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 

[dc-65x]

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.

[Dave Crevie]

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.   

[dc-65x]

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:

 

 

 

 

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

 

 

 

 

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

 

 

[slotbaker]

Beautiful engineering Rick, love it.

[Dave Crevie]

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. 

[dc-65x]

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:

 

 

 

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

 

 

 

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

[Phil Smith]

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