Soft Springs/Shock oil/Droop?

[H2Ohaze]

This is sort of a 3-4 part question from a newbie, I thought best to be posted in LNC specific forum. Starting to mod my new stock LNC 2.0, I'm using a battery that only weighs 3.8 oz, and I have my eye on another that will come in at about 5 oz. I'm getting about 45 min runtime so far.

I was using the gold springs (1.4 Lbs/in, 2.75 free length), and with the collars all the way to the top of shock, min preload, the chassis was just starting to droop. I read the thread here about droop and I guess it's desired to have 40%-50%. That can be question #1:

1) Is droop desirable in the LNC, and if so how much?

Anyway, I experimented with a spring that fits the shock like it was made for it, almost same diameter, except 3.00 inch free length, and 0.8 Lb/in rate:
Compression Spring S-1681 - Compression Springs - Compression

With spring on all four shocks and collar again at min pre-load (recognize that since free length is 0.25 longer, even though rate is lower, initial force is extra 3.2 oz), I took a few measurements of skid plate height above floor. With chassis lifted so wheels just touch floor, no weight on springs, distance is 3.5 inches or so. With the 3.8 oz battery, settled height is 2.7 inch. With a battery that weighs 6.4 oz, height is 2.5 inches.

If I do the math right, droop is between 22 and 29%. And I'm sure I can decrease this simply by moving the collars down. So next question:

2) Is this a good improvement to the LNC, or will the droop and lower rate mess up it's crawling ability?

Finally, the shock dampening. I don't know what the stock comes with. I bought both extra 20 and 30 Wt Losi oil. The shocks seem to recover and settle into drooped state within 10 seconds or so. When I list the chassis from side to side, it tends to stay there-either due to low rate or shock oil viscous.

3) Should I be changing out the shock oil for something lighter? Whats in the stock LNC?

Not to lengthen the list, but a fourth question might be, as a newbie, (4) what is the best procedure to change/top up shock oil?

I don't mind if the answer is simply to go back to the gold springs, but I had a chance to try this new spring out, so just put them on last night, thought I would get ideas from you folks that know more.

 

[jgrim]

First off, everybody is going to have a different opinion on the ideal setup.
1. I am a believer that soft springs improve crawling ability. My general approach is that you should be able to lift any tire to full shock compression without any of the other 3 tires lifting. I do have external spacers on the shock shafts (3/8" rear, 1/2" front) to limit the compression stroke of the shocks.
However, if you are using the battery tray at the top of the chassis, a 0.8 lb/in spring rate might be a little soft. I run 0.9 lb/in springs. but my battery and electronics are mounted on trays mounted to the front and rear upper links. The trade-off is run time, since space limitations require that a smaller battery be used. Getting the CG down low is one of the best improvements you can make.
My clearance at the skid is 2 5/8 inches (with 5 1/5 inch dia tires). Again the trade-off is lowering the CG vs hanging up on the rocks. There is no "right" ride height. See what works for you in the area you run.
2. I use either 30 or 35 weight in the shocks. Fill to the top with the shock shaft fully compressed and screw on the top.

 

[H2Ohaze]

I think Century had a spring that was close to 0.9 Lbs/in, but I wasn't sure that the ID would be small enough to not slip off.
I think getting the battery on the links is a good idea, I had done some initial poking around in there, but was having issues trying to figure out how to insert/remove it. It is small enough to fit. It seems to me that it would still be riding on the shocks tho.

I guess what I can do is do a run as it is now, 4 softs with whatever shock oil is in there now. From there either increase preload or put the golds back in the rear, run more. As far as changing the oil though, it would be first good to know where I am starting from, IOW, what does Losi put in at the factory?

Thanks for your reply

 

[jgrim]

The Comp Crawler users manual recommends 30 wt. Since the LNC is probably assembled in China, who knows what they put in. If I sound a little cynical it's because the technical specs in the LNC Gen 1 users manual had some major errors. When I queried Losi, they would not even respond to my emails.

 

[H2Ohaze]

Well I took it out for a run on a rock filled trail. I guess that's the real way to tell-change something and try it real world.

The body rode like a jack-in-the-box toy head on a spring...IOW most of the time it flopped to the passenger side and stayed there, a few brief times it was flopped to drivers side. Maybe only 20% of the time did it sit straight wrt chassis. I put more preload on it through collar, it was the same. I wonder why it favored pass side, I thought weight was fairly balanced.

I ran it previously in another area with the gold springs and it behaved itself well. I just can't remember whether I put the collars at min preload, or slid down 1/4 inch. I put the gold ones back on. I'll leave the shock oil in as is for now. Now I'm wondering about even a light battery so high up in stock position, the battery and body weight had such a visible effect.

So now I'm wondering what physical size battery people have used on the links to lower COG. It's pretty tight in there.But I thought I would start another thread on it, since it seems to be a separate topic, not directly a shock question.

I want to thank everyone for answering and tolerating all the newbie questions.

 

[Rattzo1]

Well I took it out for a run on a rock filled trail. I guess that's the real way to tell-change something and try it real world.

The body rode like a jack-in-the-box toy head on a spring...IOW most of the time it flopped to the passenger side and stayed there, a few brief times it was flopped to drivers side. Maybe only 20% of the time did it sit straight wrt chassis. I put more preload on it through collar, it was the same. I wonder why it favored pass side, I thought weight was fairly balanced.

I ran it previously in another area with the gold springs and it behaved itself well. I just can't remember whether I put the collars at min preload, or slid down 1/4 inch. I put the gold ones back on. I'll leave the shock oil in as is for now. Now I'm wondering about even a light battery so high up in stock position, the battery and body weight had such a visible effect.

So now I'm wondering what physical size battery people have used on the links to lower COG. It's pretty tight in there.But I thought I would start another thread on it, since it seems to be a separate topic, not directly a shock question.

I want to thank everyone for answering and tolerating all the newbie questions.

More than likely it was leaning more towards the side the motor is on . That or it is leaning toward the torque side of the motor.
You should just dump out the oil that comes in them and fill with the oil you want because losi won’t say what’s in the the lnc stock shocks.

 

[Rattzo1]

More than likely it was leaning to the side the motor is on that and or leaning more to the torque side of the truck . As for the oil in the shocks losi won’t specify what weight is in them so ide recommend just changing it out for a weight or viscosity that you want to run. It’s cheap in hobby shops and cheaper on line but to guess what they run and top off would be just that a guess. Good luck and have fun.