GB Track Chevron problem

[slothead]

I have 2 GB Track Chevron B19's that I really like but they've developed problems on left turns. There are 2 180 degree left turns on my road course and one 90 degree left hand turn. On the 180 degree turns the Chevrons slow down and creep around the turns. It's not as bad on the 90 degree turn but the cars definitely slow down there. It's not the track because I test drove other cars and they didn't have any problems in those corners.

I fiddled with the braids but it's still happening. I took the bodies off to see if the wires to the guide might be catching and that's not happening. I ran the bare chassis around the track so I could watch and it runs basically normal except on those left hand turns. Thinking it might be due to wonky stub axles such that the front tires caused the guide to be lifted out of the slot on those turns I took the front tires off so the chassis became a tripod - same problem.

At this time this is only happening with the GB Track Chevrons, not with Slot.it, Monogram, or other Fly Can Am cars. This is bugging me and I'm wondering if anyone else has ever had a similar problem with any cars?

[chrisguyw]

First thing I would look for is lateral play in the rear axle,.....allowing the inside of the right rear tire to rub on the chassis plate/pod in left hand corners.

Cheers
Chris Walker

[War Eagle River]

slothead, kinda hard to say with certainty was is going on. If the stub axle fronts are not binding and rubbing, how about the rear! Is there a lot of play that maybe the gear side tire is rubbing on the pinion, or possibly the chassis? Theres obviously something binding/rubbing, especially if you say it’s not a braid/lead issue.

[chrisguyw]

If there is some lateral play in the rear axle........... the spur/wheel/axle would be pushed away from the chassis/pinion in left hand corners.....!!!

[chappyman66]

Two (no three) ideas...
1) you have a broken lead wire that makes intermittent contact in left turns. But if the bare chassis runs ok then that's unlikely unless the body restricts the lead wires somehow. Clip the lead wires and reinstall, see if that fixes it.

2) Like Chris said, you have something binding in the rear on left turns. Axle play or the motor moving to cause binding are the two likely culprits.

3) I have seen tires move sideways on wheels if they are not the right size for the center rib of the wheel. That can also bind.

[Fathead59]

Ok , this is a shot in the dark , but could your guide blade be a little bit to big for the corners , just might be binding .

[Fathead59]

Sorry , that suggestion was alright mentioned

[waaytoomuchintothis]

The only thing I would add is to check the tire on the spur gear side. I have found a pinion chewing on the tire more than once, and the motorshaft will do it, too. Does the car have the stock guide? A longer guide will wedge in a tight turn. I had a Carrera guide that would wedge so bad on my hairpin in the middle of my track, that I would have to slip a narrow stick of wood under to pry it loose. A friend of mine had a track with those awful R-1 turns doubled up on it. Everybody got stuck in the inside lane of the hairpin, or at least slowed down badly.

[chrisguyw]

Check the right hand (not the left) rear tire to see if it is rubbing..........on left hand corners, the left hand rear tire (spur side) will, if anything, move away from the pinion/chassis/pod, but, the right hand tire/wheel may move into the chassis causing rub.

[War Eagle River]

Just goes to show, I have no idea which way I’m going

[Fathead59]

Just a thought , could you sand down the inside of the tire

[slothead]

Thanks for the feedback, I hadn't considered rear axle slop as a possible cause of the problem. When I took the first Chevron apart I noted there was slop in the rear axle and when pushed all the way over away from the spur gear it was possible the tire could be rubbing on the pinion gear or chassis pod. There was a spacer on the axle opposite the spur gear but that didn't address the problem, and when the axle was pushed all the way toward the spur gear side nothing rubbed. I put a spacer between the spur gear and the bushing, put the axle back in the pod, adjusted the braid again and - problem solved! The car ran around the whole track and time trialed well.

Since I don't swap out the axles and plastic wheels on my RTR cars to put a spacer on an axle I have to put a slit in it to slide it over the axle. Generally speaking the space between the bushing and wheel is so small the spacer can't flex enough to come off the axle, so this works. How are others dealing with installing spacers on axles like this? I know I could pull a wheel off to shim it properly, but that would be my last resort. Also, what type of spacers are best to use? When I use the plastic washers I got from Professor motor (for 1/8th inch axles) they often split while fitting over an axle.

[dinglebery]

would love to see pics... ;D

[slothead]

See post #13 below.

[Wobble]

Thanks for the feedback, I hadn't considered rear axle slop as a possible cause of the problem. When I took the first Chevron apart I noted there was slop in the rear axle and when pushed all the way over away from the spur gear it was possible the tire could be rubbing on the pinion gear or chassis pod. There was a spacer on the axle opposite the spur gear but that didn't address the problem, and when the axle was pushed all the way toward the spur gear side nothing rubbed. I put a spacer between the spur gear and the bushing, put the axle back in the pod, adjusted the braid again and - problem solved! The car ran around the whole track and time trialed well.

Since I don't swap out the axles and plastic wheels on my RTR cars to put a spacer on an axle I have to put a slit in it to slide it over the axle. Generally speaking the space between the bushing and wheel is so small the spacer can't flex enough to come off the axle, so this works. How are others dealing with installing spacers on axles like this? I know I could pull a wheel off to shim it properly, but that would be my last resort. Also, what type of spacers are best to use? When I use the plastic washers I got from Professor motor (for 1/8th inch axles) they often split while fitting over an axle.

Splitting spacers to install them is a great idea and something I've also been doing for ages and never had one fail yet. You've caused me to have a closer look at my Chevron but the only rubbing problem I have is the front right wheel rubbing on the wheel arch. Seems it's the only Fly car I haven't replaced the front stub axles with a full width axle.

[SuperSlab]

....to have a closer look at my Chevron ...... Seems it's the only Fly car I haven't replaced the front stub axles with a full width axle.

Mine do not have full axles either because the front body post is precisely between the two front wheels! Only way to fit a full axle is to somehow move the body mounting, which is a fair bit of work.

Cheers

Alwyn

[Wobble]

Ah ha, so that's why I didn't do it ... didn't look closely enough. I did go to the trouble of moving the front body post in a Monte Carlo to 'fix' this problem.

[slothead]

I was able to take some photos to show the rear axle of the GB Track Chevron I worked on. I think this is a car I bought used on HRW. My camera doesn't do a good job with close-ups but...

Here's the axle with foam spacer next to the spur gear. When the axle had slop in it and the axle was pushed so the spur gear moved closer to the motor the pinion gear was so close to the tire I couldn't see a space between them. Not sure this was the problem but the car does run better now.


Here's a picture showing how my spacers start out - as bits of thin (1/16th inch?) hobby foam I use a leather punch to put a small hole in. Then I trim the corners so it ends up looking like an octagon (stop sign shape), cut a slit in it, and slide over the axle. In this case I used a drop of superglue to close up the slit and I think glued the spacer to the spur gear.


Here's the bottom side showing the small gap between the chassis and other rear tire after the chassis was trimmed with a hobby knife and filed to create more space.


Since I did multiple things at the same time while I had the car apart I don't know which made the most difference. But the car now runs much better and doesn't slow down on left hand turns.

Also, just remembered that the way this car ran on left hand turns is like how a Fiat I had once would run if you went around a corner too fast. Something to do with the floats in the carburetor that caused the car to sputter for the next 5 minutes or so before it cleared up. Very quirky little car.

[chrisguyw]

You might want to consider trimming (sanding) the sidewall bulge of your right rear tire....it appears very close to the chassis !!.....this is more likely where the issue is/was, as on left hand corners, the gear side of the axle is pushed Away from the chassis, not into it.
On left hand corners, the right rear tire is pushed toward the chassis, and depending on lateral axle play/clearance can/will cause rubbing.

[waaytoomuchintothis]

Fiat 128, right? My 124 Spyder never did it, but my friend's 128 did it the whole time he had it. Cornering hard in that car wasn't a great idea, so he avoided it until he would get on a spiral expressway ramp, and it would sputter enough to be dangerous entering or exiting the highway.

[slothead]

The Chevron B19 is the blue #6 driven by Niki Lauda (Red Rose Racing).

I did try to sand the tire opposite the spur gear but the tire is glued on the wheel. I put a file in between the chassis and tire and did what I could, but most of the effect was on the chassis.

The Fiat was actually a X1/9. I bought it after reading an article by Brock Yates in which he compared it to driving a go kart. It was fun, but not reliable. Looking back it was risky of me to drive it over 200 miles to see races at the NY State Fairgrounds then back home at night long before having a cell phone.

[slothead]

Some images related to comments above.

The GB Track Chevron (shown with HSRR & Monogram McLarens).


And for those who don't know what a Fiat X1/9 is, here's an image off the internet. The engine is in the rear and the removable top fits under the front hood. Mine was brown.


Now imagine a guy built like an NFL lineman getting into and out of that car. But, since I was in much younger then I was actually limber enough to manage it easily.

[dinglebery]

it reminds me of a TVR

[docdoom]

I had one of those when I was in the Army in Hawaii. Had twin Weber carbs and went like stink. got rid of it before they end up bury me in it. wasnt much bigger than a go cart and corned like one too. I was all ways fighting a over heat problem with it.... mine was silver on black