Jerobee Corvette

Rodie, The hook of the brake rod is out of the hole and sits just below the servo horn. It just catches in the hole but need refixing.

This picture of another car shows the set up. Look at the small fan to cool the engine!



Lieven

As it's a calm period at work, I decided to give my Jerobee Corvette a clean. With a cotton bud and alcohol, I cleaned the chassis and all corners. I removed the engine for further cleaning. The tube to which connects the fuel pipe from the tank is the standard Cox pick up tube with the spring.





I removed the heat sink and head. The cylinder has 1 bypass port. The flyweights, clutch shaft and bell house bearing were in good condition. The hexagonal rear axle turns in plastic bearings that you have to pry open for fitting around the shaft. There is a little play on the rear axle gear. No play was found on the rear wheels. They are secured to the shaft with C clips. The brake band is a tie wrap from an electrician.







After assembling everything back together, I tested the servos. The steering servo was OK but the throttle servo was totally dead without giving any noise at all. Both servos are glued with époxy to the chassis. I tried to cut around the bottom edge of the servo with a knife to remove it without success. Not wanting to damage the chassis, I left it on there and decided to cut off the plastic servo shaft and to use the servo as a bracket for the replacement servo. This new servo is a lot smaller and fixed with a tie wrap to the original one.  This meant I had to make a new throttle shaft and extend the brake lever. Before, the brake lever was also fixed to the servo wheel. I decided to just make a hook: when the servo is turned the other way, it pulls the hook and brakes will be applied without significantly change idle.



IDLE



FULL THROTTLE



BRAKING



I just filled the tank with some fuel and will let it sit during the night to loosen residues. To be continued.

Lieven

wow nice! vettie i would love to have one of those

I can't get over what a mechanical marvel this model is.. and it's luckily in the hands of a fine hobbyist!

Looks to be cleaning up good for you , that will put some pep in you step . looking good Lieven , getback

Lucky duck Overlord, what a mechanical marvel in deed and in such great shape!
Awesome find and now in the safety of a skilled hobbyist that will take care of it and bring it back for all to see and enjoy.

Cheers!

Nice jerobe! I've seen one of those years ago. BTW you know that you can get a gear set for that S3001 servo right?
Part number is FUTM3400 same gear set as the futaba S148 and the servo is still in production bope this helps! (Bandit)

Thanks guys, you're all very kind.

Thanks Bandit for the info. The reason why the servo stayed on the chassis as it was, is the fact that I can't get it off in a way that wouldn't damage the chassis. And because I can't remove the servo, I can't get to the bolts underneath to take it apart. The servo doesn't have a gear problem, I think it's an electronic failure or maybe just a loose wire on the circuit board!!

I had a look at the steering today. Not exactly Akkerman!!





To get tru rolling of the front wheels in a curve, the inner wheel should be more at an angle than the outer wheel. The pics above show the opposite. It's all in the linkages and connections to the steering arms. On original factory pictures, the steering rod is fixed between the servo and the most forward hole of the steering arm. On my model, both steering linkages are fixed to the rear hole in the steering arms. This makes a big difference. I uncoupled the ball joints at each side and put the servo in both left and right end positions. I then put each end of the steering linkages on the forward hole of the steering arm and that gives a better result:





Both ball joints will be moved forward and the I'll adjust the linkages to get a slight toe in for stable driving.

Lieven

As said above, I removed the ball joints from the steering arms to move them forward and obtain a better wheel position while steering. The left one screwed out all right, but when I was half way on the right right ball joint... oh malheur!!!!... a part of the steering arm fell off. It seems to have been broken already before just in way of the enlarged hole for the ball joint. I discovered some glue on the steering arm.



I made 2 new steering arms from a sheet of ABS to glue on the original ones for repair and to reinforce.









I stuck both steering arms on with époxy. It is still drying until tomorrow.

There was plenty of rubbish in the fuel tank so I removed the plug. The rubber gasket is "slightly dated". I'm thinking of replacing the complete tank.

Lieven.  A picture that you posted earler (which I have attached) shows a different steering set-up with a rigid tie-rod joining the steering arms at the outer hole and the control rod (drag-link) coming from the servo to the inner hole on one arm.  This would maintain a better geometry than the set-up you are using.  The trouble with your system is that as the servo rotates the relationship between the two steering arms changes, effectivily altering the toe-in as the rods raise and lower due to the rotation of the servo.

I'll try to explain what I mean.  The two ball joints attached to your servo appear to be about 20mm apart when set straight ahead.  As the servo rotates, the ball joints move together in the horizontal plane.  At 90° of rotation, the gap is completely gone in a horizontal sense.  This is reducing the toe-in by 20mm at "full lock".  

I hope I explained it ok, but I think you need to change the design to what is pictured here.


Rod.

Thanks Rod, yes I know; that's the original Jerobe set up with a proper track rod between both wheels. On some pictures, the track rod is connected to the forward holes and on others, to the rear ones. On my model, a previous owner mounted the servo saver and the more recent setup with 2 linkages. I just connected the linkages and did a test but it's still not the way it should be. I'll try to make a a proper track rod with only 1 linkage from the servo saver to the left steering arm.

Swapping the track rod from the front holes to the rear will not seriously alter the steering geometry, but will alter the ratio significantly between the servo and the wheels. It depends on how sensitive you want the steering. There will probably be a little bit of difference to the "toe-out on turns" as we call it, if you use the different holes, but it would be negligible.

I have had to try to rectify a couple of vehicles (full size) which had steering geometry faults and I can tell you for sure, you will nevr make the system that you have work correctly if you continue to allow the tie-rods to have up & down movement at the servo end due to servo rotation. Some type of bellcrank arrangement may help, but I would definitely use a common track rod to join the two sides to each other.

Just throwing this out there... how about installing a linear servo and/or a small mixing tray.. if you could build one to fit? Is the steering servo glued to the chassis too?

Here's a small one..



buy it here

or this.. which fits the Futaba S3003 servo.



buy it here

Yes this servo is also glued onto the chassis. That's a nice little servo. Just as in the early days of RC but much smaller.

I made a track rod and a new linkage from the servo to the left steering arm.

Nice job Lieven! The fuel tank looks like it could be a Sullivan #435 1oz./29.5cc slant-type.



You can obtain a stopper kit #S482 which is for glow-fuel.



This might be nice too.. #S469

Save the old clunk! It looks like the tapered bullet/cone shaped clunk. You might want to reuse it as it will drain the tank a little more effectively.

All the same clunks can be cleaned and reused with no worries.

Phil

That's the tank. I'll buy a complete new one. They are sold by Scientific France. I'll save the tapered clunk.

OVERLORD wrote:That's the tank. I'll buy a complete new one. They are sold by Scientific France. I'll save the tapered clunk.

The small tanks are also sold by a Chinese company, i will repost later from my PC, and include everything including the clunk. They were taking offers and i picked up a couple for less than $4.00 each shipped to U. S. 60cc and 360cc tanks.

edited 1-3-2016 2:23p.m. PST - to add link to tank.

sorry can't seem to post a pic of the tank


generic picture for tank


link:
http://www.ebay.com/itm/111641213018?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


P.s. The linear servo could never stand up to the stress of a crash without a servo saver of some sort. It may be hard to implement with the linear type servo.

Happydad

Thanks for the link!!

With the body on

Hoot Hoot man that's NICE ! she is going to bee Sharpe when done , I like that body style lots of curves . Are you waiting on parts now ? what radio are you going to use ? getback

Thanks Eric, In the first place, I'm wating for some descent weather. Yes, I need to buy a ne tank but I fitted another temporary tank for the first trials. My radio? I bought one this year, not a super expensive one: a T2M Pilot 6G , 6 channel 2,4 Ghz.



I just had a good look. It says "T2M Racing Products"!!! You can imagine how fast that car will go with that radio