b4 and lipo , weight ?
 

Hi.
I am racing lipos next week end for the first time and won't have much time to practice since then .
So i am wondering if you guys can help me on where i should put the weights in the car knowing that the lipos i 'll run are 260 gr ( Corally 4200 30c).
I don't have the heavier front bulkhead and i'll race it on carpet .

Thanks to all !

standard nimh cells weigh around 450-470g so when you use lipo you need to add a fair bit seen as your losing around 200g! Get some thin roofing lead if you can (quite a few people on this forum have plenty to sell at low prices if you don't know where to get any and cut out a rectangle the same length and width as your lipo (you can cut it with scissors easily!) and put it underneath the lipo and all should be ok, maybe drop a spring rate front and rear on the car aswell

Thanks mike !

I thought it was going to be something like adding 30 gr on top of the servo, 50 on the battery tray etc ...

Your solution looks very simple, i'll find some lead and cut it to get the 200gr back and put it underneath the lipo then.

Thanks again , cheers .

you won't get the full 200g back you'll only gain about 100g max but it's ok just drop down to a softer spring on the rear and maybe drop down to a softer spring on the front too or lighter oil and it should be ok,

I fitted a lead plate under the battery of around 110gr and the car was planted with the standard Associated astroturf and carpet set-up.

This is the latest set-up from the Associated website for a B4 running LiPo. I know they are trying to prefect a LiPo set-up without the need for adding lead. Maybe an ok starting point?

http://67.199.85.166/racing/setups/b...crcrc_2009.pdf

without adding weight the car is under the legal brca weight though :yawn: and that setup is for american dirt tracks so may not work so well here

I ran almost the same set-up at the Petit RC (carpet), just with lead running down each side of the battery tray to get to the legal weight and blue front springs and was very happy with how the car performed.

Thanks guys for all the infos,

I'll try that setup on a training day, but black springs/rear on a carpet track that must feel kinda weird ?...

oh yeah... I also ran silver springs on the rear!

Where can I find lead plates that fit the B4 & B44?

Have a look at this!! - Made from Brass and has exact 60g weight. Perfect and no nasty weights showing everywhere - Also your name can be put on it. Cheap enough as well. David Burton former National winner and an engineer by trade makes them to order - 5 days and they can be with you. Anyone wanting one, let me know and I can arrange for you.....

nice work DB, could your name not be cut out though? rather than stamped?

But then you'd Lose Weight....

not a great deal though! and would look wayyyy cooler....or groove the name using a lathe etc?

Hi all - the name is engraved on the brass - it can also be cut out if you wish - in fact anything is possible. Some people even like logos etc etc....Brass is expensive as some of you may know and this unfortunately reflects in the price a little - the brace is £12 (plain) and £2 for your name - obviously plus a little for shipping - if you think about it, the weights are some £4-£5 alone! - Good luck with everyones racing by the way - Tony

Added another few pics to show the engraving and the thickness - hope this helps you.....

PM send to those relevant

I've put a sheet of stainless steel underneath my Lipo. My Complete B4 now weighs in at 1581g?

Is that too heavy?

without the stainless steel sheet, it is 1430g ish? what is the ideal weight?

for brca events legal minimum weight is 1474g (mine is around 1530g with minipins, minispikes are a little lighter) with 50g added around the front and rear of the car, run what weight you like, it's more down to how you like the car the to feel, less weight it's more agile and on the edge but with more weight it calms it down abit and keeps the car planted and abit easier to drive/more predictable

Totally agree Mike - with more weight it's also better over bumps etc etc .
The design of the brass brace is there for people that know their set up with heavy cells and now with Lipo they want their car similar. I think it looks good as well.....

Ahh, ok. I guess my current sheet of steel is too thick then. if I use 1.5mm, the weight would be 75g ish, which would bring the car up to minimum weight. I could then tune in the final weight using sticky weights.

Do people still run the weight in the rear of the chassis with Lipo's, as previously with nimh's?

Thanks.

The new Lipos, example the great LRP stick ones, they are the right size so you can't run anything under the battery = no brace will fit if you do that. Like I said our brace not only looks good and is solid but adds 60g of weight exackly in the right place. There are though some Lipos that are thinner and you could do what your doing now.....hope this helps....60g by the way should make a car with Lipos spot on the legal weight limit....mine is 20g under so I add weight either side of 10g and decide whether I want it froward or back depending on the track....this is all choice of course....

What people are also doing is running the GHEA Racing Brass Bulkhead, and rear pivot mounts in brass. This adds substantial weight down low, which is a nice place to have it!

HTH
Mark

Hi there,
I ended up adding 49 grammes on top of the battery tray and softened the rear as Mike advised, the car is around 1500 gr and it was flying.
The race was carpet indoor.
I guess that would probably be better to ad more for a bumpy track .
Would have a try to those heavier front bulkheads !

I would also try to fit the weight as low as possible. Brass bulkhead and anti squat blocks are great, together with a lead plate under your lipo. I tested with adding weight on top of the lipo too, since I have orion 3400's which have a hole on top you can fill up with lead. But I really didn't like the car with that weight this high up! Getting your weight +- the same as with nimhs is a good idea, but mounting it even lower as with nimhs is a big advantage, car is super easy that way. Tried it on high grip carpet only.

PM - sent

Agree that weight as low as possible is correct but to be honest there are so many drivers that can actually tell the difference - I bet that if 2 cars the same were given to a driver - one with weight high and the other with weight low - I bet he could not tell the difference - this actually was tested with a National champion and he couldn't tell - but like stated - the lower, yes the better although very very little difference

True, but that's the case with so many subtle adjustments on these cars. I tested it on an indoor carpet track one heat after the other, and the difference was not that huge, but with the lower weight the car was easier, without being slower. With the high weight the car reacted a lot more to slightly touching the curbs, resulting in many many mistakes. So that's when I decided to put it low and never look back :-)

Just as a matter of interest - some top drivers are now running the brace and feedback is all positive - see you all soon - Tony

Has anybody tried running a low weight lipo setup (1515-1530g), such as the Cactus Classic setup, on low-grip (clay, dirt) conditions? Does these setups work, or will additional weight be needed, in order gain traction?

Zaca, I´m about to try it. As you know I´ve just moved to Asso again (sponsor needs) and copied the cactus set up with minimal changes. Tomorrow I´m gonna practice in CAPA and we´ll see.

Cábrón, tu por aqui!

OK, so tell me how it goes! I think some extra lead will be needed in order to get the back down, nice and low... I will also try some low-weight-low-grip-setups this weekend, hopefully.

While waiting for number 2 shock pistons and 30ºcarriers, I noticed the back a lil bit bouncy and a bit of off power understeering. This weekend I´ll try 30w oil at the back (now 25).
Anyway I´ve been as fast as with my Losi, just less confident overall.

HI, i'm also new to Lipo in my B4... i always run in tracks with low grip (like Collegno just for example), and i always used to weight my "Nimh B4", Weight in front of rear transmission and in the rear quarters of the chassis. The car is good, overall good traction, steering and good driveablity!
I don't want to try a "light" setup, so my idea is to weight the car as it weights with nimh....

Now with Lipo i have to add 160gr. (5.6oz.) to have the same weight as Nimh, my question is:

- is better to place all the 160gr. very low, under the lipo pack (weight in this place tend to lower at maxium the center or gravity)

or

- is better to place some weight in the sides of the battery case and the rest of the weight placed over the battery strap? Weights in this places tend to raise the CG, but this can also increase the roll of the car and maybe more roll give more side bite and pressure on tires on low grip surface...


What's your opinion? It's just an idea, maybe i'm wrong.... let me know if raising the weights can improve roll or lower the weights is always better, thanks! :thumbsup:

It is known and agreed that weight as low as possible is correct but to be honest there are so many drivers that cannot actually tell the difference - I bet that if 2 cars the same were given to a driver - one with weight high (above the Lipo) and the other with weight low (under the Lipo) - I bet he could not tell the difference - this actually was tested with a National champion and he couldn't tell - but like stated - the lower, yes the better although very very little difference - also bare in mind that some Lipos won't allow you to add weight under them as they are simply too high and the brace won't fit - Hope this helps

Hi guys, to add my 2p worth to the conversation.

I ran the B4 all Winter with around 70g added to the Battery Strap (above). This was all well and good indoors until I got the car outdoors at Kidderminster on Sunday. Really struggled for the first 2 rounds until we added another 70g under the LiPo.

We're not running and other weight to normal and the car felt really good to drive, something which I'm hoping will help at Tally this weekend.

Start from scratch, you suggested us to add all weight approx. 160g under the lipo battery in order to keep low CG, keep in mind only for certain lipos battery due the width

Do I need to add extra weight in front of the B4? :thumbsup: It should good enough

Thank you in advance.

Does anybody know what the ideal weight front/rear % is?

The brass 70g straps for the Lipos should be in again this week after waiting for the high quality brass to arrive back in stock.......if anyone wants one then let me know ASAP so it can be reserved for you - see you all soon, Tony E