107 replies to this topic

[Bill from NH]

The old stock can motors ran counter-clockwise at the endbell, If you check a Russkit Carrera chassis, they had right side spur gears. The timing of these motors was slight, but it wasn't neutral.

[Mad Mark]

Made it to the track finally and got to test some cars. had to swap to a testers 26d and after three different sets of tires and some gear changes I got it to run ok. my dynamic inline 36d with silicone sponge tires was running the same lap times on a flat track and was super easy to drive so my scratchbuild probably isnt super great! Haha. maybe it will work better on a hillclimb or something. also I did some light wall hits and the front end held up fine with no broken solder joints.

[Eddie Fleming]

It looks good on the track.

[Mad Mark]

Updating with new rainy day project. Almost sacrificed previous black hot rod for parts since it doesnt work very good but ended up using whatever spare parts I could find.

making a jaildoor out of a space frame style motor bracket was sorta tricky. didnt want the motor stuck in the chassis for when it melts down so I made front support removable. not super solid but enough to keep motor from moving too much. i would have rather used threaded inserts or collars but didnt want to take more than a day thinking up ideas.


Soldering tip was starting to go so pretty terrible solder joints!


drop arm is under built but seems solid might have to add some rods for future weight.

[Dave Crevie]

Cool chassis. I see projects like this and I get enthused to start building again. Feeling a bit better the last couple of months, so maybe.

[Carter]

Very cool looking build. You need to come over a pick up some parts whenever you want let me know.


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[Mad Mark]

Went testing today. the old russkit motor is the slowest motor I’ve ever had in a car. can’t even tell if the chassis handles good it’s so slow! i installed a Hong Kong motor that will be way faster.

[dc-65x]

Hi Mark,

 

Rodney and I have had the copper brush springs in these 50 year old motors take a set and loose most of their tension.

 

I was looking at the pictures of your very cool build and noticed this when I zoomed up:

 

 

Is the spring post partially melted into the brush spring? That could really seize up the spring and cause a problem.

 

A Russkit 22 should run better than what you are experiencing.......not a rocket ship but not a complete turd either.  

[Mad Mark]

Hi Mark,
 
Rodney and I have had the copper brush springs in these 50 year old motors take a set and loose most of their tension.
 
I was looking at the pictures of your very cool build and noticed this when I zoomed up:
 
post-7497-0-81701300-1679414492.jpeg
 
Is the spring post partially melted into the brush spring? That could really seize up the spring and cause a problem.
 
A Russkit 22 should run better than what you are experiencing.......not a rocket ship but not a complete turd either.

i was wondering about the brush springs. i actually fixed up another blind bushing 16d and the brush springs where totally worn out. and yeah looks like someone bumped the post with an iron and melted it. Guess I’d have to find a way to grind down post to get spring off. it’s for sure slower than my NOS non heat sink endbell russkit 33’s which are my slowest motors besides this one.

[old & gray]

Just a guess.

Cut the post off (the spring may have melted in).

Drill (VERY carefully) and tap.

Use a Group 12 screw and spring cup.

[Mad Mark]

New mill, bracing, and further motor box work. dont mind the crazy rear tires thats what I could come up with for the electric dreams wood 1/32 track.


also I did end up sacrificing two cars for parts including the previous rainy day project 32 ford. i have a pretty good pile of motor brackets and 26Ds to make some stuff out of now. underperforming cars get the iron.

[Mad Mark]

Track test with new mill and while a whole second faster is still slow. sheesh cant catch a break. i now installed the third motor which is another Hong Kong motor that I disassembled, cleaned the comm, set end play, adjusted brush holders, and checked spring tension. i then broke in underwater for couple minutes to get the old brushes to take a seat. this motor has blue winding and a green paint on the laminations so maybe this ones better. Im not a motor builder so I dont know how to tell if its going to be a dud or not. sounded pretty good after water break in so well see. good thing I didnt solder motor end plates on and trap the motor!

Seems to handle really good. waaaay underpowered for how it performs so far.

[Mad Mark]

well its raining so that means rainy day project #3! still learning as this will be around my fifth or sixth chassis. trying to have everything bent up and ready to solder instead of bending as I go and burning up my iron.


Obligatory messed up body to build off.

Hmmm wonder what I can fill in that hacked out area with???

[Mad Mark]

Finished!

[Bill from NH]

The chassis looks great & the dump tubes cover nicely for the missing body panel. 

[olescratch]

  Awesome chassis work!  How long did you say that you've been doing this?  Looks like it's been for years.  Good job!

[dc-65x]

Gotta love a Cheetah.       Nice job Mark.

[Pablo]

Really bitchin', especially the pipes!     

[Mad Mark]

Awesome chassis work!  How long did you say that you've been doing this?  Looks like it's been for years.  Good job!

Thanks! Built first chassis like 10 years ago. just recently started up again last couple years.

[Mad Mark]

i have an assortment of cheetah bodies now. who can name the brands?? Obviously tinted body is dubro. guessing clear one is lancer.

[Dave Crevie]

Ya got a handle on it.

[Mad Mark]

so I had a feeling this cheetah would be a hand full and it seems to be. on flat track S curves the back end hops off the ground while switching directions and wants to understeer in turns. Also does acceleration hops. the guide was about a 1/16 higher than it should be and the guide lead is really short.

I’ve extending the guide lead a 1/8” and am now able to fit a guide post retainer/weight. i trued down the front tires a little further to get it lower and put a guide spacer. i went ahead and put slightly lower profile rear tires that are less grippy and narrower too. All these should help a bit with handling. sometimes just different tires or a different motor will make these cars a whole different handler.

happy to say the red chaparral jaildoor handles like a dream and is easily my best handling easiest to drive vintage car. the new motor is way better speed as well.

[Mad Mark]

Well tried cheetah again and it still does same thing really bad chatter and hopping in turns. tried different rear tires, axles gearing, wheelbases, front wheels, and tried .1oz lead behind each front wheel and nothing seemed to really help. only thing left i can think is solder bushings into motor bracket to get it more solid and get any slop out. either that or their is just a chassis design flaw and it’s too stiff or too flexy. tried to make this chassis extra stiff and solid around motor bracket.

[Bill from NH]

Yes, solder in your axle bushings to see if that helps. You could try rounding the edges of the rear tires a bit more. I wouldn't think this chassis was too stiff or had too much flex. It's just a short wheelbase chassis that handles more like a womp than a 4" chassis. If you built the same design, but with a longer wheelbase, depending upon how it handled, you could tell if your basic design is good or defective. Not all chassis handle the same or drive well. 

 

Do those green rear tires mount with setscrews or are they threaded?

[Mad Mark]

Yes, solder in your axle bushings to see if that helps. You could try rounding the edges of the rear tires a bit more. I wouldn't think this chassis was too stiff or had too much flex. It's just a short wheelbase chassis that handles more like a womp than a 4" chassis. If you built the same design, but with a longer wheelbase, depending upon how it handled, you could tell if your basic design is good or defective. Not all chassis handle the same or drive well. 
 
Do those green rear tires mount with setscrews or are they threaded?

thanks for the advice. all the tires and axles I tried are threaded. some of the tires I tried had very rounded edges. yeah it is pretty much like a womp style handling. figured such short wheelbase would be hard to tune especially with a 26d which is probably to much power for a short car.