# AFX Chassis Noise with McLaren Body



## Grandcheapskate (Jan 5, 2006)

I am having a problem with an original Aurora AFX non-mag chassis and the Aurora McLaren XLR body.

When I run the chassis with no body, everything is fine. When I put the body on, there is an occasional grinding which I believe is (at least) one of the gears hitting the underside of the body. The noise usually occurs as either the car is slowing down after a long straight, or on acceleration into the straight. It is the same noise you get from lack of oil. If you run around at a constant speed, you rarely hear the noise.

My guess is that on acceleration, one of the gears is rising just enough to hit the bottom of the body. But, I have no idea how to either pinpoint the problem or correct it. Suggestions?

Thanks...Joe


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## jeremy1082 (Apr 27, 2004)

How about putting a little colored marker on the gears then running it? If the gears are touching the body, it should show you where.


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## twolff (May 11, 2007)

A strip of adhesive tape on the underside of the body might show where the interference is.


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## Bill Hall (Jan 6, 2007)

Should be a rub spot if ya look close. If it's making noise under accel and decel I'd have to ask if the body fits tight or rocks north to south in the mounts.


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## AfxToo (Aug 29, 2003)

The McLaren is one of the early A/FX bodies that does not have upper detents on the side mount tabs. It relies on a front post and standoffs molded into the body to keep the chassis secure in the body shell. If the front post is removed or trimmed the body will sit lower in the front and tend to rock fore and aft. This can cause the armature pinion gear to rub the underside of the body and the front tires to rub. The standoffs molded into the rear of the body are designed to ride on the side rail of the gearplate. If these are broken or worn down the top gears can rub the underside of the body. Finally, if the armature pinion is not pressed on flush with the top of the armature shaft, the gear may stick up too high and rub the body. Since you are experiencing the problem only under certain running conditions it sounds like the body is moving around a bit. 

If the body has all of its original parts it may have just loosened up due to age and repeated mount/unmount cycles (it's a tight fit) and tightening up the body may fix the issue. The first thing to do is to make sure the armature pinion is flush, or swap the gearplate with another chassis that has a better fitting gear. If the front post is intact you can try putting a screw in it since the A/FX chassis has a hole that allows you to do this. Just make sure the screw head sits flush or recessed in the bottom of the chassis. If the rear standoffs are missing you can fabricate new ones. If they are worn down you can try building them up a little bit with epoxy or black max. A tiny drop of epoxy or black max applied with a toothpick on top of the existing standoffs is all you need. Make sure it's thoroughly cured before mounting the body on a chassis.


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## rodstrguy (Feb 14, 2002)

I have found some of those bodies are too tight! They generally are hard to get on and squeeze the chassis and then they make noise...


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## resinmonger (Mar 5, 2008)

I remember that the Lola T-260 was also a very tight fit back in the day. All of the early Can-Am cars with front body posts were problematic. If my memory serves corectly, I ended up putting a couple of layers of masking tape on the top of the chassis clip to promote some clearance for the gears. I did this after removing the front posts because I thought those made it too hard to get the body on or off. This was when I was in either 8th or 9th grade so you can imagine a total lack of sophisicated mechanical skills or tools. I think I took the posts off with nail clippers...

:drunk::hat::freak::dude:


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## Grandcheapskate (Jan 5, 2006)

Guys,
Thanks for the input. I had not noticed that the side tabs on this body are missing the upper half. I have check the gears and the armature shaft is flush with the top of the armature gear. The armature is still loose enough to have a little up/down movement, which I believe is normal and necessary. 

I was aware of the tab "problem" on the Porsche 917; that body must be used with an AFX chassis (no G Plus or Super Mag) and will tend to rock back and forth.

The McLaren body I have is in perfect condition. Even though I've had the car since the early 70s, I never ran it much. But you guys bring up another great point - the body is VERY tight on the chassis. It is difficult to remove and install the chassis. I was wondering whether this tightness could contribute to the noise. I tried a second McLaren body on this chassis and it did the same thing. I don't think I want to grind the underside of the body, so I may try to put a small amout of tape on the clamp and see if that helps.

Thanks...Joe


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## AfxToo (Aug 29, 2003)

A number of the early A/FX bodies relied on the A/FX chassis geometry to fit the body on the chassis. Beside the McLaren, the Camaro, Porsche 917, and Ferrari 612P all used a similar mounting arrangement, which effectively keeps these bodies from being used on other chassis without modification. Other A/FX bodies, like the Ferrari 512M have the detents, but don't have sufficient clearance underneath for mounting anything except the original chassis. 

Using an upper detent on the side tabs could have resulted in an ill fitting body. The AW McLaren and AW Camaro both use an upper detent and the result is ... less than desirable compared to the Aurora versions. 

The interchangeability of Aurora A/FX and Tomy AFX bodies across the various Aurora and Tomy designed chassis is not nearly as universal as the common mounting tab system implies. Some of the nicest Aurora bodies, like the Porsche 917K and Ferrari 512M, will not mount on any Tomy chassis without major modifications.


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