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Allan Wakefield
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Derek at slotcarchassis.com produces a small but growing range of CNC cut repacement chassis for 1/32 scale slot cars.

I ordered one for the Viper with all the trimings and this is what I came up with...

One Viper body with lights awaiting a good chassis...


Add Metal Chassis, race bearings all round (supplied),Little Ripper motor, Slot.It starter kit, Slot.It guide...




and you get an awesome race car! well balanced although I added 2 grams of weight to each side just in front of the rear wheels to keep it down on tight corners because those Slot.It P3 tyres have high grip.

A definate improvement over a similar Viper with original chassis and set up. I set this car up with the same components (without race bearings) on a plastic Fly chassis and it was prone to tip over alot more and was alot harder to find good balance.

Not the cheapest of solutions but considering these chassis are faultless and hand made I am more than happy.

Now if the one for the Monogram Cobra is as good


Overall, the slotcarchassis.com car was around 1.6 seconds per lap faster on Suzuka than the standard chassis car.
 

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Nobby Berkshire
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Looks mean! Is there a magnet in that chassis pocket as it looks very small to the original.

Good times as well, but do you think it's the chassis, or the upgraded motor and bearings? I mean, the Fly plastic chassis is good in these cars, isn't it? Mind you, that prop ring and axle bearing support system looks more impressive than Fly's.

Is this car still with the 8:27 gear ratio that stock Vipers come with?
 

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QUOTE (Screwneck @ 23 Sep 2004, 11:43)Looks mean! Is there a magnet in that chassis pocket as it looks very small to the original.

Good times as well, but do you think it's the chassis, or the upgraded motor and bearings? I mean, the Fly plastic chassis is good in these cars, isn't it? Mind you, that prop ring and axle bearing support system looks more impressive than Fly's.

Is this car still with the 8:27 gear ratio that stock Vipers come with?
The pocket in the chassis will accept the stock Neodymium magnet from the Viper.

I'd like to hear a clarification on the setup also. The time difference sounds pretty good. From his description it sounds like he's running the same gear in the plastic chassis.

Derek
 

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Allan Wakefield
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I installed all the running gear you can see above plus the 4 grams of weight (except the race bearings on the axles and prop shaft) in a Fly Viper plastic chassis and did some time trials with that body on.
Then I changed everything onto the metal chassis (NO magnet in either setup) and transferred the body onto it.

The fact I have uprated parts (motor Slot.It stuff etc) makes no odds as I used the same on both chassis.

The whole point was that with the metal chassis I got over a second faster times than with the Fly plastic one using the same parts.

Gearing is set to 10/26.

I think the time difference is a combination of the balanced chassis, race bearings and firmer tolerances of the whole setup.
 

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QUOTE (Swissracer @ 23 Sep 2004, 08:01)A definate improvement over a similar Viper with original chassis and set up. I set this car up with the same components (without race bearings) on a plastic Fly chassis and it was prone to tip over alot more and was alot harder to find good balance.
How much heavier is this chassis? And did you try adding the difference in weight very low on the stock chassis to compare? I just tend to think that some of the advantage comes from added weight and much lower CG, especially if the limit with the plastic chassis resulted in tipping.
 

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Allan Wakefield
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QUOTE I just tend to think that some of the advantage comes from added weight and much lower CG

But thats the whole point! evenly spread weight and lower Cof G of the chassis.
With the best will in the world adding weight to the plastic chassis will not get the Cof G as low.
That and the race bearings which make the whole thing smoother.
 

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QUOTE (Swissracer @ 24 Sep 2004, 00:28)But thats the whole point! evenly spread weight and lower Cof G of the chassis.
With the best will in the world adding weight to the plastic chassis will not get the Cof G as low.
That and the race bearings which make the whole thing smoother.
Also the fact that the motor, drive shaft, and pinion stay in the same position. With the plastic chassis there is so much slop between the motor and rear axle that the pinions angle of attack on the ring gear is constantly changing. Even if you glue everything in on the plastic chassis you still have the flex of the chassis to contend with. I think with the CNC chassis your getting more horsepower to the rear wheels in a much more predictable manner.

Derek
 

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Wow, Swiss. That Viper makeover and Derek's chassis is something I would pay £40 for. Damn, where do you get those skills guys? But, really, with Swiss's makeover and a good few Xenon lights al over the Viper and Derek's chassis, that would look great and go very quick-how much would you sell one for, just curious?!
 

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Hmmmm....Stiffer chassis = faster lap times? Seems strange that loosening the body screws (to allow more flex) on some plastic chassis cars helps lap times too?!?
 

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Allan Wakefield
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Discussion Starter · #13 ·
Yes but that is to create slight flex of the body against the chassis NOT to create flex in the chassis and running gear itself Pete.

Look to most performance chassis out there TSRF, Repro 60s /70s metal chassis, Plafit, Momo (different sclae but same principle) etc. The idea of the set up is to get the running gear and chassis as rigid as possible whilst maintaining slight movement of the body.

Compare it to the atrocious Ninco Pro Race suspension chassis idea - tons of lateral movement, side to side and front to back, of the rear axle due to the suspension springs resulting in terrible performance and excessive wear on running gear.

There are more examples of good/Bad but the general giist is above.
 

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I think I see your point, Swiss, having the drivetrain components stiffly mounted, relative to each other, is good. But by tightening the screws holding the body to the chassis on a plastic car, you are effectively stiffening the chassis by creating a unibody frame, similar to some 1:1 cars. I assume that by allowing a slight movement between the body and chassis, some vibration is absorbed and the tires are kept in more consistant contact with the track surface?

I find the different schemes for creating this limited movement interesting. I have a couple Proslot cars with the partially rubber mounted motor pod, which allows a slight rocking motion in the for/aft axis, pivoting around the rear axle. I also have the SCX Dome LMP, which mounts the drivetrain in a pod which rocks side to side, perpendicular to the motion allowed by the Proslot cars? They both seem to be good cars, but which is the better system, if there is one?
 

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eugh!!! those ninco porsches are CRAP!!!!!!!!!!! its like theres a bloody kangaroo in the boot! we have 9 cars, we had to fix them very 3 secs, broke so easily, no power, no grip... bounce bounce bounce everywhere!!!!!!!!! waste of money!!!

remember in rl racing they ste the shocks up to be harder! so in theory your just making a very hard suspension!
 

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This is a very interesting thread as it raises some rather conflicting questions about chassis design.

There is little doubt that maximum stiffening of the motor/transmission section is absolutely essential to full realisation of any motor's power.

It has equally been proved that obtaining the 'correct' amount of chassis flex between the guide and the back wheels is the NEXT step towards improved performance on track.

Those are two separate concepts and, for success, must to be achieved in the order written - motor/transmission stiffness first, followed by chassis improvements.

However, it becomes a little complicated when we look at what is necesary to achieve this when comparing front motored cars with rear/mid motored cars. In a front motored car, the LONG transmission line has to contend with most of the length of the chassis, whereas a rear/mid motored car has a much shorter chassis length to contend with in eliminating flex between motor and axle. This makes the combination of stiff transmission with slightly flexible chassis MUCH easier to achieve in a rear/motored motored car because the entire motor/transmission/axle combination can easily be incorporated as a pod. This leaves the remainder of the atual chassis freely available for any mods the designer desires to experiment with in achieving the right degree of flex.

Side winders are clearly the best way to optimise these two conflicting needs and that is one (not the only) reason why sidewinders are exclusively used for ultimate high speed racing performance.

Having said all that and returning to Swiss's car and its undeniable superiority over standard: it's clear that chassis flex can never be anything but disadvantageous in a front motored car because flex wrecks the needed rigidity between motor and drive axle. Therfore a rigid chassis is the best possible improvement for this particular configuration - and Swiss has proved this pretty conclusively.
 
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