'91 Composite Craft/RPM Worlds build

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JK Racing
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Re: '91 RPM Worlds build

Post by JK Racing »

That car looks better and better...shoot that vid and get it posted up.
--Joey --
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vsefiream
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Re: '91 RPM Worlds build

Post by vsefiream »

Thanks JK

Now for one last update before the weekend... I was adjusting the slipper last night and found that I was still having issues with slipping. The stupid thing is I never checked the diff adjustment!!! I wanted to swap to a B4 slipper but never really needed to! I re-adjusted the diff last night and the slipping is gone, go figure. Part of me wants to go back to the B3 slipper. Last thing to do is switch the batt connector to a Deans style for my Lipo battery
I also made some updates to my last post to keep a rolling log of what has gone wrong or right so far

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vsefiream
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Re: '91 RPM Worlds build

Post by vsefiream »

Sunday was an epic failure.
I was all prepared and pumped up to run my car this weekend. All tests were done in the house in a small area but seemed just fine. When I got to the track Sunday I was experiencing difficulty with part throttle. I retraced all my steps concerning what was changed. All the upgrades checked out OK. It's either the speed controller or the motor. During bench testing I swear I saw the motor spit a few sparks but work fine through the entire throttle range. I reset the Novak neutral and HS settings and made sure the current limit was all the way at max. Everything tested fine on the bench. I put the car on the ground and had the same issue. It almost seemed as if there was a bad spot in the motor, it would work from a dead stop them sometimes it wouldn't, all I would get was full throttle and occasional sparks. I pulled the motor out, took it apart and tried to clean the comm as best as I could. I really didn't come preparred for this and had no tools to clean or test the motor. I borrowed the world's worst DMM from somebody and tested the poles. All seemed OK from what I could see but I could not get a very accurate resistance on each pole with this DMM. So my race day was done.
I did the daddy pit crew support for my son's Stampede which broke an axle but made it through the day otherwise unharmed (a small miracle). I managed to get a video of him "racing". Both Kids class and Novice were combined and it was a crash fest, fun to watch but a bear to marshal! I'll post the video on my photo bucket account soon if anybody is interested.
Tonight I'll pull the motor apart again, give it a good cleaning and testing. I'll put it back together and find someplace to give it a good testing. I may still be looking at a bad ESC.
In all I was very impressed with the Sonic's arm, it has a very beefy comm, the balancing looks to be very well done, it has a neat intregal fan on the core, and it was perfectly shimmed. I just hope it's OK and I can continue to use it. This problem may have been part of my issues last week and I assumed it was all slipper related.
I just hope to get this all sorted and be able to get the car on the track! I am really looking forward to running this car regularly at the track.

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Re: '91 RPM Worlds build

Post by DennisM »

That sucks -
Have You tried testing the ESC with another motor of same or nearly the same windnings, it could be a defective "cold" soldering in the ESC?

Bench testing doesn´t really pull any Amps compared to full contact. A cold soldering will burn when Amps increase and make the contact gap even wider.
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Re: '91 RPM Worlds build

Post by mikeymp »

Hello All , and Merry Christmas I have an original complete composite craft worlds 91 chassis that needs a new top brace, where can i get one?

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Re: '91 RPM Worlds build

Post by scr8p »


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Re: '91 RPM Worlds build

Post by minimini »

Thanks for the link....:)

I did email them a few months ago....asking for the CC RC10 double decker chassis...... but they said they need to get "enough" orders before they will press on the machine button.....then I asked how many is enough......but no further reply...... :(

I think it is quite reasonable......businessman is running a business......who cares about that few bucks by selling just one to two sets of graphite chassis ??..... it is a pity but it is real life......:cry:

Seems that they are now selling knifes.....as I can see in their FB photos.....no more R/C...... :(
mini@vintage Team Yokomo/Associated
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vsefiream
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Re: '91 RPM Worlds build

Post by vsefiream »

DennisM wrote:That sucks -
Have You tried testing the ESC with another motor of same or nearly the same windnings, it could be a defective "cold" soldering in the ESC?

Bench testing doesn´t really pull any Amps compared to full contact. A cold soldering will burn when Amps increase and make the contact gap even wider.
I did all the soldering but one joint where the positive branches for the motor. I have yet to check it but it's on my radar.
I pulled the motor apart a few nights ago and polished the comm. There is a bit of pitting on the leading edge of each section so the comm does need to be turned. I have no shorts to the arm and no opens, all fields measure out at .5 ohms and all looks well. I cleaned the brushes and reassembled. It runs great and I really do not think it's the root of my problem. I will check the one solder joint I didn't do.
I have one other thought, the Novak troubleshooting guide does mention a studder issue on acceleration could be caused by a sharp drop in BEC voltage. I may try a cap or auxilary battery pack to test this theory.
Last resort, I have a Novak 410-M5 and a Novak Duster sport (with purple heat sink :D ) to test with or to replace the 410 MXC.
Other changes, I found a new RPM yellow front bumper for $5.00 shipped so I installed it up front. I really like the yellow/purple/carbon look, I plan on carring that theme into the body when I do up a new one for this car. I'll post a pic when I have the electronics sorted.

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Re: '91 RPM Worlds build

Post by vsefiream »

Quick update, just added the pics to this post last night.
I recently picked up a $25 CL RC10 that came as a complete RTR with Lipos. It had a Traxxas package in it including the blue XL5 ESC with the internal low voltage cutoff. I tested that ESC and it works great, installed it in my RPM worlds car and what a difference! First of all, it completely cleaned up the car, much less wiring etc. cluttering up the car. Secondly it was smooth. It just doesn't have the retro look I want but I still like it's performance.
So I took it racing yesterday. My son and I had a pretty good day. My son came in 4th of 7 in his kids class and I took the second heat and main in Novice class. I felt bad as I was the only adult in Novice out of the four drivers. They still gave my poor driving skills a run for the money :shock:
The car was still having some issues with turning in the first heat, I ended up 2nd or 3rd. The car seemed erratic and did not turn very well all the time. I know the Futaba s132H servo was acting a little bit odd so I took the Airtronics servo from the CL car and stuck it in. It was still a little darty feeling but much smoother for the second heat. One thing I have been battling (but much less so with the new servo) was ball cup seperation. Even with the RPM ball cups, they are popping off very easily in a slow speed crash. I either improve my driving style or change them out. I am going to work on my driving first then we will see :roll: The turning on the car was much improved with the new servo, it will whip the back end around if I want it to do a 180 degree turn in very little space. The Reedy Sonic is blazing fast. I geared it down quite a bit, I don't remember tooth counds but it's the stock B4 spur and one of the smallest pinions I had on hand. It keeps the temps in check.
I am very happy with the car right now. I got a kick out of people at the track recognizing it as "an old RC10". Another guy came up to me offering to sell me a bunch of RC10 parts for cars "just like that". He stopped at my pit area when I had the body off and said, "I don't think I've ever seen an RC10 set up like that".
In the future, I may opt to change to a flysky radio and a good quality servo. I think the XL5 ESC may stay for a bit. Tax time might also bring a new body for it.
I'm a bit off the pace of the cars in 2wd buggy class but my best lap time was right in line with a few of their average lap times so it's not impossible....
Hopefully next time out (~3 weeks) I will get some video for you guys. In the meanwhile I will take some pics and post them here tonight.
For anybody interested, results are posted at http://makintraxxrc.com

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vsefiream
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Re: '91 RPM Worlds build

Post by vsefiream »

Well, I've had the car out to the track a few more times since my last post. Just thought I'd update on how things have ben going with this vintage racer.
I was bumped up out of Novice class with the car, not because I won a few races, but because the track owner really thought I could hang with the newer 2wd buggies. I did alright but no where near their pace. I think that if I can get a handle on turning this car I would do much better, of course.
Grip rolling is a problem for me. I found an odd quirk that I think is related to my brushed motor setup. In a corner if I stay on the throttle, I can usually carve a half way decent line but I'm not always that good. I've found that when I completely let off the throttle, I get rear wheel lock up and the rear of the car whips around in a turn. It's been a learning curve to try and get through this. It's like running a ton of drag brake in a brushless motor. If I get it sideways in a corner like that, side grip gets to be an issue and the car barrel rolls. I think If I had a BL setup in this car, it would coast a whole lot better. I geared the car down a bit last month to keep the motor temps down, I'm sure this made my problem worse. Anyhow, I have a hard time lining up one of the jumps that is heading back towards the drivers stand. Twice I missed the line and came off the ramp into one of the poles. I ended up breaking the front bulkhead and the brace that supports the upper chassis plate. It was the end of the day so no big deal. I fixed it the next weekend and took my son out to open track. Wouldn't you know I did the same freakin thing and broke the new upper chassis support I just made. It's catch 22, I need the practice but when I practice I break! I would like to have a one piece nylon or delrin front bulkhead made up much like the one on the '91 stealth cars. I think that would shore up the front end very nicely. So right now I am in the process of drawing something up for that and returning to the build on my "OIN" car. I'll update that thread soon. This car might get a little time off for now. Oh and I know I promised video, I just haven't had anybody free to help take some footage. Hopefully I make good on that some time soon.

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Re: '91 RPM Worlds build

Post by JK Racing »

a trick I always use when the rear is locking up is put some "roll" in the radio. on the bench, rear wheels in the air, slowly move your throttle trim until the tires just barely roll. this should help you in the corners.
--Joey --
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JKRacingRC.com

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Re: '91 RPM Worlds build

Post by fredswain »

Look on eBay for an RC10GT aluminum front bulkhead. I've got one. You'll never break it.
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vsefiream
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Re: '91 RPM Worlds build

Post by vsefiream »

fredswain wrote:Look on eBay for an RC10GT aluminum front bulkhead. I've got one. You'll never break it.
I thought about one of those but I'm not a big fan of aluminum parts. Sure they are strong and won't break but they also transfer the force elsewhere. I'd rather have something plastic that, if stressed in excess, will break before the chassis does. That's what's so great about RPM parts. Did RPM make a truck bulkhead?

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Re: '91 RPM Worlds build

Post by vsefiream »

I made some improvements to the front end (aka truck bulkhead) setup. I made and installed a heavier brace bar and installed a few small sections of nose tube brace in the bulkhead recesses to provide support. If this fails to hold up I may go the aluminum bulkhead route or have one made out of a material such as delrin. I just worry about snapping the upper deck if I get in a crash.

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I raced it last Sunday and it held up really well, no problems other than the chronic ball cup disconnect (when I hit something of course). Nobody can seem to pop them back on but they sure pop off easily enough! I will be changing to the captured ball end links soon.
The car ran really well but I still cannot seem to really turn fast. Tuning is something that comes slowly to me as I don't have really good enough driving skills to know what the car is doing. So... I had one of the better drivers take it a few laps around. It was squirrly for him as well. Obviously everybody is different in setup preference so he was reluctant to say what he thought about it's set up. I feel lost seting this car up but I do feel that the front suspension needs some help. It doesnt feel smooth, almost binding when I push down on the front end. If I activate each arm by itself, off the ground, it feels smooth. I'll be looking into that soon.

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Re: '91 RPM Worlds build

Post by slotcarrod »

What is with you guys racing these gems? JK! :mrgreen: If I could I would too! Lovely car btw!

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