How critical is a receiver pack?

[Remo]

I'd like to know how necessary is a receiver pack if I run 4 cell mod either with KO or Modeltech mini receiver and a speedo that works with 4 cell? Just wondering as I am thinking of going 4 cell with my RC12L3 with a Fantom 12x3 (thats all I have!)

thanks :)

[MattW]

I think it's more the servo that can be the problem if you don't run a reciever pack. Some are ok, some not so. My Multiplex digital runs ok without a pack, but toward the end of a run i can feel that it is slowing down.

[rice98w]

i ran a KO servo, (947) without a reciever pack all w/e, and was fine

roger also did the same, and both of us normally use an RX pack

it will be fine, with 3000's it was more of a necesity

[Remo]

Servo is a mini futaba...
Do you mean I need one if I use 3000 cells? What wind do you use as I thought a 12x3 would be less juicy. BTW is my motor suitable?
Thanks!

[PDW]

If you use 3000 cells, and run hot winds, the receiver pack is useful as it makes sure the servo continues to operate normally at the end of the run. If you run 3300s, it is less of a problem - almost nil in fact.

I run without a receiver pack all the time and never have a problem. Jim Spencer won at Mold with no receiver pack and almost never runs one.

On a 12 x 3 geared about 40 to 42 mm/rev with 3000s, you should not have a problem - I'd start without one. If you have 3300s, don't even think about it!! A 12 x 3 will be less juicy. The 12 x 3 is a very suitable motor to start with. If you have never raced 1/12th before, keep that motor until you have got the car sorted, can run 8 mins with only one crash - and then think about more power.

1/12th is more about car set-up and driving ability than power. Welcome to the F1 of model cars, I hope you enjoy yourself. :)

[PDW]

Sorry - should read "if you have never raced 4-cell before - you've obviously raced 1/12th as I can see from your post!! 4-cell is the F1!! :D

[KRob]

Hi Remo,

As people have already said, a receiver pack is not really needed now that we have 3300's.

I think Paul Ash is the only guy who uses one out of the regular A final guys, and that's only because his car is so b****y light he uses it as ballast. :o

[Glenn Atterton]

Currently using a Multiplex digital servo, Nosram Dominator, 3300's and motors from 11x2 to 14x3. Haven't used a receiver pack as yet.

Car dumped for 1st time at TRCC on Sunday using 11x2 (on the last lap, a diff ring had slipped so may have been a factor) and heavy on the throttle and servo was still working fine to get the car back to me

[Remo]

cheers for all the help guys... it would be my first time in a 12th... i have raced a 10th L3 touring before against 4wd touring and left them for dead! ;D ;D

i shall work on that 8 mins with 1 crash bit..... LOL

[steven bough]

I don't know why but in the past when i have tried using a receiver pack-i seem to do absolutly sh*tt.

-yet when i don't use one i seem to do o.k
i.e/- better than when i use one,-
But i have no idea why this is,-
Perhaps its all in the mind?

SteviE

[B_Final_Bob]

Make sure your speedo can run 4 cell without a receiver pack. Some can't, such as the MRT VX and possibly the CS Rocket.

I don't use a receiver pack, I got 8 minutes easily out of 9x5 at an endurance meeting I did, that's with un-matched 3300's.

I did manage to dump at the same track last weekend with a 12x2 ??? ???

[Mark Stiles]

When you refer to the MRT VX, do you mean the VX Pro or the VX Sport?. I have a VX sport, and it appears to be fine with no receiver pack. (and it says 4-7 cells (4.8-8.4V) on the data sheet.) ???

[Glenn Atterton]

Modeltech mini receiver

Are your looking at the ProTech receiver ?

Tried two of these and my radio system which is Multiplex hated it. No end of trouble in off-road, on-road & 1/12th with full blown glitching to just a twitch. To be fair to Modeltech they did replace the 1st one and refunded me after the second one refused to play ball.

I know of another guy using the ProTech on KO radio systems who has had similar problems which were bought from another outlet.

[Remo]

Erm... I do have a Protech receiver and come to think about it I tried it with my TC and it was having problems glitching problems... maybe I should call MikeS to see if there has been a batch issue. I may use the KO 297 first... the speedo I am thinking of using is my trusty Novak Cyclone TC2 which the manual says 4-8 cells... hope thats ok... else I will use my LRP F1 Pro which is a bit on the large side!!!

[Dave Treacy]

Remo,

The TC2 is an excellent choice, my son has one in his car. Use program 2 ;D

I have had the same problems with the protech receiver with KO kit. Now it sits on the shelf, I don't even carry it as a spare. Pity really, as it's nice and small, ideal for 1/12th. I use a 297 which works fine.

[B_Final_Bob]

Mark:-

My VX Pro would not work without a receiver pack. Unsure about the VX sport, I thought they were that similiar that they would work with the same number of cells! ???

[Mark Stiles]

I'll try a receiver pack next time I run the car. I don't appear to struggle for speed/power at my local club compared to the other drivers, although the car sometimes feels sluggish when I race on a bigger track like milton keynes (it feels slow along straights compared to other cars with similar motors/gearing). Perhaps this might explain why my cars speed drops off half way through the race at MK? ??? Or is it all in the mind? ???

[Remo]

Slightly off topic, been searching around am I correct to think that 40-42 mmpr is suitable for 6 cell stock as well as 4 cell mod?

[Dave Treacy]

Depends on the track, car setup yada yada...

I start at about 35mmpr with 4 cell mod on a small track, at the weekend I was on 42 at Teeside, but it was a long track

With stock I would start at about 45mmpr and in both cases, work up depending on performance and remaining runtime...the art of 1/12th is to have enough go go juice to finish 8 minute races!

[Terry]

The VX Sport and VX Pro both operate on 4-7 cells. They are identical apart from the MOSFETs (the Pro has higher spec ones as you would expect). They should both work with 4 cells and no rx pack. If you have any problems contact Clive at MRT and he should be able to help.

As has been mentioned in earlier posts 3300 cells have virtually eliminated the need to use a rx pack. You may not have to use a rx pack but no matter what ESC you have, running on 4 cells means you will always be operating your ESC (and rx) on a lower voltage. On 4 cells you're running at the low end of the voltage range for a ESC/rx. If the gains from the weight saving are are worth having then run 4 cells, if not then run a rx pack.

[Remo]

BTW ... raced it last night 6 cell... to sum it up... I'm hooked! ;D

[Dave Treacy]

So we'll be seeing you at Wickham and Chesterfield nationals then? :D

[PDW]

Remo, your question above about mpr... It isn't a cell related thing, mostly it's a weight/set-up related thing. There is an ideal mpr for any given motor/track/set-up combination whether running 6-cell or 4-cell. You just have to find it - usually by asking others and then understanding what works for you.

If you go flat, then the answer is not always simply to gear up (to lower mpr) as this can make things worse. Trial and error, and a good notebook, are the key! HTH :)

[Ben Cosgrove]

gear up to a lower mm/rev???? i reckon glynn's sent you mad! lol

gear up = higher mm/rev

[PDW]

I do a great job of sending myself mad without any help, Ben!! LOL ;D

Remo, simply lowering the gear ratio - going to a lower mpr - is not always the cure to a motor that will not go the distance.

Now, Ben, that is what I said in the first place - NOT!! Thanks.

Peter

[Remo]

Ran it at LRRC indoor tarmac and ended up best with about 37mmpr running Peak Hellfire (this one revs more than a Monster!)... seems high but TC we gear it a bit high too.. took a while to get the handling right...

Dave unfortunately those places are a bit far for me... but I am sure I would like to make at some point...

By the way... is it normal a 6 cell RC12L3 with Novak TC2 can wight up to 1000g in race trim??? with KO297 and PT... :o I guess I'd better solder then 4 cells and get the mod going and buy a mini speedo...

[Dave Treacy]

A BRICK! 6 cell minimum weight is 880g, most come in around 930g

[Mark Stiles]

On the subject of weights, what do people 4 cell cars weigh in at?

My L3 is 856g without transponder and rx pack (I run a lightwieght shell). Is there anything I can do to reduce this? How much lighter are the lightened rear motor mounts?

[rice98w]

my trinity, without PT, but with Rx pack, weighs in at 812g

when i took the rx paxk out, it needed a bit to make it upto 802g! ;D

thinking if using a PT as ballast... expensive ballast though! ;)

[MattW]

My 12M is about 840 with RX pack and PT.

[Mark Stiles]

Paul,

I remember reading somewhere that your L3 is light (compared to mine!). Which parts have you replaced/removed on it to bring it down to min. weight?

Matt & Matt,

What are your tyre diameters with those weights?

[rice98w]

mine are quite small at the mo...

42mm fronts and 49mm rears

[MattW]

About 44 and 50 i would think. This weight was at mould, didnt' take and notice at Teeside!

[KRob]

With 46mm fronts and 51mm rears.
NO receiver pack, my SP12M weighs 855g :o
Bah Humbug!!

I know that Paul has titanium screws on his car.

[PUASHP]

Mark,

I have made the follwing changes to the standard L3 to save weight.

ALL screws are either blue alloy or titanium (inc tweak screws, motor screws etc).

The graphite parts have been carefully trimmed to lighten them (mainly the rear lower pod and centre damper support.

Motor mount has been lightened (4 holes drilled in it)

The servo is laid flat so no heavy servo mounts.

Receiver has the heatshrink removed

I also run a light weight body shell

Cheers

Paul

[Remo]

thats it!!! i amputting my car on a diet >:(!!! will post weights when done!!! 8)

[gaz_d]

Come on Remo, putting the car on a diet is as radical as having your hair cut :o
seem to remember it was going to go if you made the "A". Was that BTCC or 1/12th????

[Glenn Atterton]

Currently using a Multiplex digital servo, Nosram Dominator, 3300's and motors from 11x2 to 14x3. Haven't used a receiver pack as yet.

And forgot to add.

90% of the time the servo speed is turned down to approx 75% using the the transmitter settings to slow the servo response down.

[Terry]

I forgot to add, one good reason to run a receiver pack in 1/12 with 4 cells is to boost the output of your AMBrc PT and get your laps counted ahead of those without a rx pack... but once again, also taking the weight penalty into consideration!! ;D

[Mark Stiles]

Mark:-

My VX Pro would not work without a receiver pack. Unsure about the VX sport, I thought they were that similiar that they would work with the same number of cells! ???


I ran an RX pack in the first race on sun, and it made no difference to the speed of my car at all! (using MRT VX sport)

[rice98w]

are you sure it made NO difference what-soever? if so, i'd recommend you check all your wiring and the routine in which you switch your car on in... it iwll make a difference to servo speed no question about it.

[Mark Stiles]

I meant speed as in how fast the rear wheels move.

[rice98w]

ah right, sorry! :-X

[Mark Stiles]

As you may know, there was discussion earlier in this thread about the MRT VX speed controllers not working properly on 4 cells, unless a receiver pack is used. However, I found it made no difference to the speed at all having a receiver pack in the car.