Weights

[Shannow]

I ran my Madrat at the local club on Thursday for the first time with lipo's and about halfway down the straight the front end would start to lift (looked great, not so good for cornering!) - I don't really want to be putting extra weight on the car unless I have to (it weighs 1.3kg with a 33 / 66 split) as surely one of the main advantages of lipo's is the lack of weight compared to nimh's...

I've reduced the wing angle and I'll trim it a bit too as I think that is the cause of the wheelies, but I was wondering if any of you guys run similar setup (5.5 Ezrun) and found adding weight improves handling?

[sparrow.2]

If the car feels good on the rest of the track and only lifts it's nose on the straight then just catch it with the throttle. That and your rear wing looks massive on your avatar but you've already come up with that yourself.

1.3kg is about 400g lighter than an X6 in full trim. Sometimes adding weight can make a car more settled on bumpy stuff and keep it on the ground better too.

I never liked the approach of adding weight to cars. But then when I started racing we used to drill the crap out of everything to get it as light as possible to get the batteries to last. Making a car heavy just doesn't seem right :)
You don't see F1 cars with anvils tied to them to get the handling right :woot:

[DCM]

I found, without NiMH's in the car, the front end was just too light, and wouldn't pitch into the corners enough, and the front would be really light, especially over bumps on power, or jumps.

The only way around it, is to add weight under the LiPo and around the servo. The car's balance is all out with LiPo in there.

[Battle_axe]

I find that 30 grams in the front is all that is needed running a trakpower 3600 30C lipo in mine but I have also seen some people running upto 120 grams in the front

[Shannow]

I think I'm from the same era as you Sparrow.2 - adding weight just feels wrong!

I ran the car at Bury yesterday which gave me a chance to properly test the car, but unfortunately my driving skills (or lack of) need time to get used to the speed of the car - I broke it repeatedly :-(

I really need to find somewhere locally where I can experiment on it and get used to it.

Thanks for the info guys.

[warped]

if the car only weighs 1.3kg then definitely add weight.

The BRCA weight limit is 1.474kg for 2wd, so if you race anywhere that actually scrutineers the cars then you will have to add weight whether you like it or not.

It will handle better and be easier to drive with more weight.

The wing is nothing to do with the wheelies, and will make little difference.

(Wheelying generally occurs when you accelerate initially i.e when you're going relatively slowly)

Are you sure your figures are correct? I'd be surprised if you have actualy got 66% 33% weight split with a rear motor car weighing only 1.3kg. I'd expect a little more on the rear.

Add some lead sheet under the battery if you can. - It will make the car easier to drive.
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Stability is everything in offroad - especially if your driving's slightly iffy.

[Evsie]

I always found mine to understeer badly due to the lack of weight over the front end; I added a strip of lead under the battery as well as a lot of stick on weights over the front end and it ended up about 1640g and handled much better.

[KBRacing]

My weighers 1540g. and it handleds realy well and jumps great.
:confused: I can not understand why they must weigh more then 1600g +g with lipo....????

[Shannow]

Warped: Cheers for the info regarding the BRCA - The wing was actually the cause of the wheelies (surprised me too) as it started to occur once the car was approaching full speed and not on the initial acceleration. Removing the vertical back edge on the wing solved that particular issue.

Steering has virtually no effect when accelerating hard so you need to be prepared to go in a straight line when doing so, but I think this is pretty much what it's like running a 2wd with a brushless motor... Turns in fine once the speed has dropped enough...

The weight distribution is pretty much as I said, give or take a percentage or two. The lipo cells I've got however are smaller (and the lighter) than than the usual packs I've seen which means I can slide them further forward to help the weight distribution.

Whats the feeling on front wings? I saw quite a number of cars using them on Sunday at Bury (and it's along the theme of Sparrow.2's formula 1 anvil alternative too...)

[Battle_axe]

Warped: Cheers for the info regarding the BRCA - The wing was actually the cause of the wheelies (surprised me too) as it started to occur once the car was approaching full speed and not on the initial acceleration. Removing the vertical back edge on the wing solved that particular issue.

Steering has virtually no effect when accelerating hard so you need to be prepared to go in a straight line when doing so, but I think this is pretty much what it's like running a 2wd with a brushless motor... Turns in fine once the speed has dropped enough...

The weight distribution is pretty much as I said, give or take a percentage or two. The lipo cells I've got however are smaller (and the lighter) than than the usual packs I've seen which means I can slide them further forward to help the weight distribution.

Whats the feeling on front wings? I saw quite a number of cars using them on Sunday at Bury (and it's along the theme of Sparrow.2's formula 1 anvil alternative too...)

i have seen allot of people using the front wings on the CR2 and a few on B4's i have been told they make no difference at all enless you are on a very fast track with sweeping corners but in a straight line they will keep the front end planted

[rob martin]

Only weight im using in mine is the optional aluminum front bulkhead with the brass weight. Beleive or not i went to a milder motor and that was my ticket to stop it from wheelying on the straight. If i had to run more motor though i would probaly experiment with a lil bit of weight over the front end or if the tractions up experiment with a diffrent wing. The tracks i run on are highbite clay and we use slicks. Or depending on your speedo your could adjust your throttle curve/or exp,arc on your radio to smooth the curve out.

[jim76]

i have around 150g of lead in the front of mine. helps with the steering no end. and steering under acceleration is VERY important if you want to gain decent lap times, otherwise your lap will just be accelerate, turn, accelerate, turn. Any fast sweeping turns will always benefit from front end weight.

And as said, you are well under the legal weight anyway. I would sugggest 100g nder the battery, and 100g around the front steering and servo. This will bring the car up to weight and make it far more stable to drive.

[nikos2002]

I would agree with Rob, you don't always need the fastest motor to "drive" fast.

JP Richards used a 9.5 at the CRCRC race in the US and was turning lap times compariable to two different world champions on a big track!! :thumbsup:

[KBRacing]

I agree too, the 2wd Class in Denmark runs 9.5BL and Lipo, and we run as fast as they do in 4wd mod.......