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-   -   Touring Car F/R Weight Balance Thread (https://www.rctech.net/forum/electric-road/444377-touring-car-f-r-weight-balance-thread.html)

Owen RaCing 10-17-2010 01:36 PM

Touring Car F/R Weight Balance Thread
 
Alright, I searched, but I wanna talk a little bit about weight placement in touring car. This will focus on front to rear balance, since all cars should be side to side balanced. I wanna hear views on the subject, as with how light cars are now days, some of us have to add a lot of weight to get the car up to 1400-1425. And with all that weight added, you can really change the car. Ive had a car go from good to bad, just changing weight a few inches forward/back.

Let's hear scenarios, how it effects tire heat, corner entry and exit, ETC. We need this all this info in one place.

Discuss. :nod:

gonzo416 10-17-2010 07:31 PM

I think this is a great thread so we can learn how to get the car balanced at all four corners so when a setup change is made we should be able to feel the change in handling.

andrew-01 10-17-2010 07:49 PM

Would definietly like to see others opinions on this matter. I need to add weight to make the minimum and any info would be appreciated.

I did just come across this post from Paul L in his thread:

"... for low bite i like to run more front weight, this gives the car a more natural traction feel, especially on exit. maybe try shifting some weight forward on the chassis. you could try less caster or just a bit of anti-dive also."

Zac_with_no_K 10-18-2010 12:56 AM

I have a TA05v.2.. It's really heavy but I've seen youtube videos of people balancing them perfectly on top of the 4 sided wrench tool provided with the kit. supposidly stock.
I'm going to try doing that tommorow

HarryLeach 10-18-2010 01:30 AM

I use 4 scales as part of my initial car setup.

I'll take notes and try some things for the benefit of this thread once I get a T3'11 built and start dialing it in, as I know it's going to take quite a bit of weight to bring it up to legal.

I will say that with a 4wd platform, 50/50 f/r is a good starting place, if you're using scales. If you're not, you'll have to go by feel.

More weight forward usually "feels" more stable due to a less dramatic weight transfer when transitioning on/off power. When I'd played around with this before, it felt similar to running more front droop, but without the edginess that can creep in with large ride height changes at one end or the other in the car.

More rear weight can actually make more entry steering, as the front tires don't put up with as much weight, and the car "pivots" around the rear tires a bit easier. Too much rear weight and the car doesn't like to stop rotating between mid-corner and exit, though.

I've been slack keeping setup notes the last year or two though, so I'm trying to go by memory, if I messed up, I'll post back again when I try again. :lol:

2wd is a lot different, and a f/r balance of 40/60 is pretty common. 1 or 2 percent can change grip balance a fair bit, all other things being equal.

gonzo416 10-18-2010 09:57 AM

I'm going to be picking up some scales today and I'd like to know how to use them to get the car balance at all 4 corners. I'll be picking up 4. 1 for each corner.

sosidge 10-18-2010 10:20 AM

Quote:

Originally Posted by gonzo416 (Post 8087962)
I'm going to be picking up some scales today and I'd like to know how to use them to get the car balance at all 4 corners. I'll be picking up 4. 1 for each corner.

Working out weight distribution is easy...

Flat, level surface. Car at running weight. Scale under each wheel. The sum across the front axle is a constant, as are the sums across the rear axle, and the sums on the left and right side. Use those to work out weight distribution front/rear and side/side.

You can also use them to tweak the car (corner-weighting), although I find that I get some slightly odd results, probably because of the small scale and light weight involved, and prefer the "knife trick". Basically the aim is to get the cross-weights (sum of LF+RR and sum of RF+LR) as equal as possible (I would be happy with 5-10gm difference). Adding preload to a spring will add weight to both that wheel and the one diagonally opposite, so it is a process of experimentation.

If the car's fundamental weight distribution is good, you should also be able to get the weight on across each axle fairly even at the same time (I'd be looking at within 5gms difference between FL and FR, or between RL and RR). If one wheel always seems lighter than another, no matter what you do, then that corner of the car needs a little more static weight on it - better to shift stuff around if possible rather than add weight.

Hard to explain in words... it will all become clear to you when you have the car on the scales in front of you!

PS on actually setting the car's F/R weight balance, I'm on the side of putting more weight on the end that needs more grip. But by no more than 1% at a time. The inertia effect can be overcome with damping and setup.

gonzo416 10-18-2010 12:37 PM

was thinking of making 4 links the length of the shocks and replace the shocks with them to get the weight balanced then put the shocks back on.

sosidge 10-18-2010 01:02 PM

Quote:

Originally Posted by gonzo416 (Post 8088617)
was thinking of making 4 links the length of the shocks and replace the shocks with them to get the weight balanced then put the shocks back on.

You can do that, and it gives an immediate result, but ultimately it's something you will learn while doing the corner weighting with the shocks on anyway.

Jochim_18 10-18-2010 01:21 PM

If you have an iPhone download cross weight APP this is very usefull in balancing LR/FR of the car together with the scale.. I like the car 50/50 all they way around if gives the car a neutral feel all you have to do is play with spring/oil weight... But this all depends on your chassis some car like more weight on the rear some like more weight on the front...

I always have this problem with the traditional 2 belt chassis.. But now I'm running the team magic E4 it's a lot easier to balance the chassis since the E4 chassis layout is all down the centerline.

bukil 10-18-2010 01:29 PM

Here is a good thread about weight distribution.

alcyon 10-18-2010 06:24 PM

Quote:

Originally Posted by Jochim_18 (Post 8088808)
If you have an iPhone download cross weight APP this is very usefull in balancing LR/FR of the car together with the scale.. I like the car 50/50 all they way around if gives the car a neutral feel all you have to do is play with spring/oil weight... But this all depends on your chassis some car like more weight on the rear some like more weight on the front...

I always have this problem with the traditional 2 belt chassis.. But now I'm running the team magic E4 it's a lot easier to balance the chassis since the E4 chassis layout is all down the centerline.

but old school cars like the Xray T1 and the HPI pro2 also have the weights along the center.

Azr 10-18-2010 07:00 PM

now we need to buy 4 digital scales?:weird:

skypilot 10-18-2010 08:42 PM

8 bucks a piece at harbor freight:D

HarryLeach 10-18-2010 11:54 PM

Quote:

Originally Posted by Azr (Post 8090282)
now we need to buy 4 digital scales?:weird:

You don't "need" scales at all. If your method of balancing and tuning works for you, keep doing it.

I've been around full size racing for over 2 decades, so scaling out my RC stuff is natural. :cool:


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