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Old 11-01-2008
adam lancia adam lancia is offline
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Default Question on battery placement (theory)

Hi all,

I've got a mid-motor converted RC10T (yes you read that right, there are no numbers after 10T) and I am unsure of how I want to orient the batteries. The chassis is originally setup to have the cells 6 across the chassis but I would think that it will slow left-to-right transitions and make it feel a little sluggish. I have a machine shop at my disposal so milling the chassis to accept the cells won't be a problem. The other option is having the cells right up the center of the chassis like on the T4 but that has me thinking that there will be a lot more weight on the front end (with the motor pushing the battery forward) and I'm not sure if that's going to make it twitchy steering-wise.

Do you think that the 6 across arrangement will settle the truck canceling out the potential oversteering I may see with the mid-motor setup? I'm using a T4 front end on this and will be bolting the front portion of the T4 chassis to the new chassis (I lopped off the front of a broken T4 chassis, front brace, bulkhead and all!) so I have some flexibility as to how far forward I bolt that section on. Does that give me any wiggle room to tailor my weight distribution?

Any help is greatly appreciated! I'll try to get some posted so you can see what I'm talking about. Thanks in advance!
Attached Images
File Type: jpg Tekin Mid-Motor 10T_T4 001 small.jpg (22.9 KB, 55 views)
File Type: jpg Tekin Mid-Motor 10T_T4 002 small.jpg (40.4 KB, 20 views)
File Type: jpg Tekin Mid-Motor 10T_T4 004 small.jpg (29.3 KB, 26 views)
File Type: jpg Tekin Mid-Motor 10T_T4 005 small.jpg (35.0 KB, 58 views)
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Old 11-01-2008
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i'd go for the 4 & 2 configuration of the X6

those guys have already done the R&D for you on this conversion
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Old 11-01-2008
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super__dan super__dan is offline
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When I tried 6 cells across the back on my X6 (UK high grip track) it went alright, better than I thought infact, but not as sharp as the 4+2. On clay in Austria I found the car wanted to hang onto the turn and not pull itself out, therefore I never run the 6 across the back now. However, if/as/when I get to go Lipo I will defo go with the 6 across the back as with the dramatic reduction in weight I think the forward/rear weight balance will be maintained and the extra weight further out will be negligible.

The complication to this is that it’s a truck and I don’t know how/where the cells are and how this fits the effective weight distribution. So my advice above is maybe not correct. I’d run it as Tekin intended to try it before you start machining the chassis!
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Old 11-01-2008
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sosidge sosidge is offline
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Is that some kind of vintage conversion? Never seen one before, very interesting part!

I'll echo what super dan said and say it would be a shame to start machining the moulding. I'd run it as it is, and if you have a machine shop then you shouldn't find it too hard to run up an alternative chassis to your own design.

Weight distribution is really something you need to do testing with. Having the stick across the width of the car could make the car a bit less responsive, BUT sometimes that makes it easier to drive too.

Looking at the design of the conversion, if you were to make your own chassis you could probably move the cells back closer to the motor, maybe run them as a narrow 3+3 or a 4+2, maybe run a longer wheelbase on the truck for extra stability and to get more weight over the rear wheels again. Lots of options. Lots of fun to be had.
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Old 11-01-2008
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terry.sc terry.sc is offline
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Don't say you're attempting to start modifying a Tekin conversion kit! My god man leave it alone, if you want to rearrange the batteries put the Tekin kit on ebay and buy a sheet of carbon fibre with your profits.

The Tekin chassis was fairly well balanced as it was, not many people used it as it didn't put as much weight on the rear as the stock chassis with the rear mounted motor. Rather than ask what to do about the battery arrangement now, surely it would be sensible to run it first and see how it handles?
Use the mounting holes that are already in the chassis to mount the T4 front end, start drilling your own holes in the chassis and it will be worth nothing.
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Old 12-01-2008
adam lancia adam lancia is offline
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Hey guys, thanks for all the input!

I don't *think* I'll machine the chassis, I was thinking out loud more than anything...

The sheet of carbon is a good idea Terry, I could use the Tekin chassis as my template and bolt the T4 front end onto the carbon then goof with battery position from there. I'm starting to think that 3x3 is the way to go in order to keep weight on the rear.
I won't be able to drive it until March as there isn't an indoor track within a reasonable driving distance which is why I'm trying to get as *close* as possible before hand.

Keep the input coming!
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Old 23-01-2008
Jonny_H Jonny_H is offline
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Switching between a stick arrangement across the car and along the centreline won't change the yaw inertia. Across will have more roll inertia; along will have more pitch inertia; but I suspect those will have very little effect on the car.

If you wanted less yaw inertia then closely-positioned saddle packs (3+3) would be the way forward, but mostly I think you're only changing the weight distribution.

HTH!
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Old 27-01-2008
adam lancia adam lancia is offline
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Thanks for the input Johnny. Is there a reason that you think the 6 across arrangement won't effect the chassis dynamics very much? It just seems like a lot of weight to be hanging so far from the center line of the chassis compared to the newer cars. Thanks!

Ok, the next part to this is finding a body that will fit. The rear shock tower bulges on the newer bodies seem to put the wheel wells ahead of where they should be when you drop the body onto the chassis. I was going to try an old Associated Toyota Prerunner body but it's too wide at the wheel flares Does anyone remember what bodies were used on these kits back in the day? I'm going to head to the LHS tomorrow and see if he's got a few bodies laying around that I can try. Thanks guys!
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Old 30-01-2008
Jonny_H Jonny_H is offline
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Quote:
Originally Posted by adam lancia View Post
Thanks for the input Johnny. Is there a reason that you think the 6 across arrangement won't effect the chassis dynamics very much? It just seems like a lot of weight to be hanging so far from the center line of the chassis compared to the newer cars. Thanks!
It would still be hanging in front of / behind the centre of mass, if it wasn't hanging out to the sides. The yaw inertia doesn't change (unless you fit the stick vertically!)

Hold the pack in your hand, pointing side to side, then twist it from side to side (yaw) as though steering the car. Now hold it pointing straight ahead and do the same thing... no difference in the inertia.

As I said, the only effect (apart from front:rear weight distribution) is that you'll swap some roll inertia for pitch inertia.

If you're not sure about yaw, roll and pitch: Google it!
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Old 03-02-2008
adam lancia adam lancia is offline
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Thanks John, I'll give that google thing a try
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