The biggest tire balancing thread I found in the off road section.
http://www.rctech.net/forum/nitro-of...balancing.html

Now back to tuning with camberrrrr.

I finally got some track time with my 210 after switching out my front pistons based on the "hose" test and fred's method of setting pack and oil.

It's been almost a month since I drove the car last so I don't quite remember exactly how it drove then vs how it drove last night.

With everything else the same as it was before except the front pistons and oil, the car had a tendency to lift the inner rear tire in the turns and break loose. It didn't feel neutral or balanced. It jumped and landed great, though. I knew it had to be balanced so I was a bit perplexed and getting frustrated.

I started to go to work on my links. I played with them the whole night making progress after each round of practice. At the end of the night, I ended up with the links on their longest settings both front and rear with 2mm under the rear and no spacers under the front. Going to the longest link in the rear really made the car predictable. Instead of oversteering half way through the turn, the car has a very consistent and predictable feel the whole way through the turn, which is what I want.

Looking back it's obvious that I should have gone to a longer link, but I was so excited about the new front piston setup that I thought the car would just handle better than what it had before without any other changes. That expectation really frustrated me yesterday and kept me from seeing the obvious.

I only had about 10 minutes left on the track after I got the links right, but those were the best 10 minutes of the night. The car was jumping great and felt so much better than the start of the night, and possibly better than it had before I made the piston change. I think now I've got everything in balance; springs, pistons, oils, and roll centers. Next thursday will be a race night so I'll get another chance to drive it then.

double post.

I would like to clear up one thing that a few people on here have repeatedly mentioned backwards and was not rectified and I think its important to know whats going on in the suspension with respect to weight transfer.

Higher RC = higher roll resistance = LESS weight is transferred into the suspension as a roll, MOST weight is transferred directly to the outer tires. Extreme example 90% outer tire 10% inner tire. More extreme example 100% outer tire 0% inner on final edge of traction rolling.

Lower RC = less roll resistance= MORE weight is transferred into the suspension as a roll. Instead of the weight being transferred to just the outside tire it is spread across both. Fair example 66% outer tire 34% inside tire.

This explains and goes back to the opening pages of this thread as Fred describes the differences between the vintage cars and modern cars. Modern cars will have a harder time cornering on vintage tracks. likewise vintage cars will be fairly twitchy with heir higher roll centers compared to modern cars on modern high byte high speed tracks.
The act of the weight being transferred into the suspension as more roll with lower roll center cars is felt as laziness in the suspension, decreasing the edgy twitchy suspension feel, it will feel more stable at speed, which is required for high speed high byte tracks.

Everything has its advantages. I have to mention this before everybody goes out and sets up for lowest RC. With respect to rough tracks, higher roll center causes more camber gain with suspension compression. More camber gain is required for bumps, ruts, woops, moguls, and imperfect surface. More camber gain is more stability for rough track. Also with the higher roll resistance one takes advantage of the stiffer setup and can have much softer springs and lighter oil for the rough stuff.

Another thing mentioned and was of concern about camber and camber gain throughout the suspension compression its perfectly normal and okay for the outer tire to go into positive camber during high speed corner on low rc car (the chassis roll angle exceeds the camber angle gained at max compression), it helps in rotation and minimizes traction rolling. I think you will agree to a certain extent its better to drift sideways rather than traction rolling.


If Im wrong in any part of this, lets sit down discuss and be friends :cool:

In your Lower RC example you substituted "transferred" for "spread" like in your Higher RC example. For consistency I changed the LRC to match your HRC example (I changed the word and emboldened it below).

One of the biggest problems most have with suspension tuning is that mechanical linkage and suspension arm designs engineered into our cars allow a lot of roll center and roll center migration control. But, shocks also control chassis roll and the ability to use those settings correctly for the racing surface. So many of these adjustments can cancel, or at least to some degree lessen the changes we feel.
This is what is interesting when someone says I'm using "most, of _____'s set-up."

These professional drivers are testing, calculating and correcting their chassis' weight control settings and their package works together for their circumstance, reflexes, tire choice, etc.
That means every ball stud location, it's height, shock location, castor, kick up, anti-squat, springs, ride height, wing size, angle and weight, static camber, everything is factored in.

My point is this. If your running rear shock oil at 30wt with the same pistons the team driver is using with 20 weight, your not taking advantage of the anti-squat and roll center settings in the set up. The chassis won't be able to react and give the tires the same leverage in the same period of time.
Of course this also applies to being one hole further out on the suspension arm.

Hope this makes sense.

Which is why I concentrate on driving well and not untuning my car. The most common thing holding racers back is mucking too much with the setup looking for a miracle. As for actual tuning, I use a huge notebook and take a considered approach to each change. You are so right sir.

Well got some more track time and it seems that dual rate springs and bypass pistons prove to be faster for me than straight rate springs
And going the a single x-ring over 2 orings cut .2 of my 7.5sec backyard track record

Thought I'd post my latest experience in mid motor land. All winter long I had been running my buggy with 28g of lead shoe-good to the back of the transmission case. I had it there because I thought it would help with keeping the rear under control, and was willing to accept the trade off of having the weight outside of the wheelbase. This setup, along with my custom chassis, got the car to about 65.4% weight on the rear. It drove ok like this all winter, but I had this feeling the whole time that something wasn't right with the car. Nothing really made me question having that weight there until recently. I had the car just about perfect in terms of having springs, pistons, and oils balanced, but the car was having problems keeping the back end under control. I finally realized maybe the extra weight behind the rear axle might be the culprit.

This past week I removed that 28g of weight and re-balanced my springs and oils. To my surprise, the car still weighed in at 64.9%. I thought I would have lost more than that overall. The car drove much better on the track. The back end was much more controllable even though I removed weight from the rear!

It just goes to show the benefit of mid motor. Keep all the weight within the wheelbase and everything will be alright. Add even just a little bit outside the wheelbase, and it all goes to poop!

Got it to the track last week and drove the truck with the duel springs and got my first first place and had the best lap of the day not bad with a new layout to the track and the qualifier being my only practice

@RC10Nick: This is exactly what I found as well! :D

Anytime I add weight to an MM car, I do it within the wheelbase.

Any time I add weight to any car it is within the wheelbase, low and I have been tending towards the center. AE short course trucks tend to be loose in the rear end and people have gotten to the point where they add a lot of weight (ballast plus 2-3 oz right in front of the ballast). I've found that I like the feel better with the battery all the way forward and the extra weight right behind the battery and a good spring/oil balance. A slab of lead flashing right under the battery seems like it would be the ticket. Then again, it seems like reducing the weight overall along with the spring rates and damping rates plus some roll center adjustments should be able to run even better but I've never been able to make that work as well. Maybe for giggles, I'll try going down that path with my SCB.

More weight = more predictable but not faster sc trucks are so grossly over powered they can have 9 lbs and still go fast but lower the power lighten it up and drive smooth and softer suspension And see the lap times drop

Thanks Fred for telling me how in portent having the right amount of pack
I was happy with my sc10 4x4 and after I fixed the pack on the b44.2 I desided to poll out the truck it was faster than the b44 but I was using the same pistons front and rear I had 2.1 mip shims all around It was balanced interns and it jumped well but on some of the small bumps the rear end would bounce so I went to 2.0 rear and 2.4 front what a dif

learning a lot about pack from this thread and tuning camber. Thanks for the read.