Shock oil weight

[ahr43]

For my conventional chassis converted to RC drag racing, using a combo of piston and fluid changes. Up front using 3-hole pistons and 25wt fluid. This allows the front end to come up quickly and transfer weight to the rear. In the rear using a 1-hole piston and 45wt fluid. Idea here is to limit fluid transfer and prevent squat. -AC

 

[Lumikko]

Thanks for the info guys!

My racer is a Team Associated Pro4SC10. It's nice. I like it, just want to tune it more. It is RTR, I'd prefer to buy a kit, but who has time for that?

I think I'm going to go down to 30wt. See what happens.

I have the same truck and have tuned it quite extensively.

The stock shocks have plastic bodies and the bores are not uniform through the stroke. I ran a gauge up and down in there and there definitely are tight and loose areas.

Also, the pistons are way undersized. There’s a lot of oil blowing by. The stock 40 wt oil seems thick enough on the bench (low speed damping) but it has very little ”pack” (high speed damping) when you land jumps and hit bumps at speeds.

Further, the spur gear cover in the bottom is in front of the rear but the chassis in front of it is high. This catches the edges of jumps and really tosses the rear around when it hits anything.

To reduce the rear bucking and tossing around, I added anti-squat (flipped C block mod) and used larger pistons all around. I have oversized Team Durango 12.3 mm pistons drilled to 2x 1.5 in the front, 2x 1.6 in the rear. I turned the OD of the pistons down until they had a ”sliding” fit. This helped firm up the rear when going off jumps, and the spur gear cover is less likely to hit bumps – all this without having to increase ride height or use stiffer springs.

I’ve toyed with the idea of making a wedge-shaped profile that runs below the chassis from the steering posts all the way to the spur gear cover. This would decrease ground clearance under the ”belly” but also prevent bumps from hitting the lump in the back at a steep angle. Sort of drag and slide over the bumps, as with a flat chassis.

Get Tekno EB410 pills (TKR6544) so you can fine-tune the hinge pin angles further.

 

[sylentk]

I have the same truck and have tuned it quite extensively.

The stock shocks have plastic bodies and the bores are not uniform through the stroke. I ran a gauge up and down in there and there definitely are tight and loose areas.

Also, the pistons are way undersized. There’s a lot of oil blowing by. The stock 40 wt oil seems thick enough on the bench (low speed damping) but it has very little ”pack” (high speed damping) when you land jumps and hit bumps at speeds.

Further, the spur gear cover in the bottom is in front of the rear but the chassis in front of it is high. This catches the edges of jumps and really tosses the rear around when it hits anything.

To reduce the rear bucking and tossing around, I added anti-squat (flipped C block mod) and used larger pistons all around. I have oversized Team Durango 12.3 mm pistons drilled to 2x 1.5 in the front, 2x 1.6 in the rear. I turned the OD of the pistons down until they had a ”sliding” fit. This helped firm up the rear when going off jumps, and the spur gear cover is less likely to hit bumps – all this without having to increase ride height or use stiffer springs.

I’ve toyed with the idea of making a wedge-shaped profile that runs below the chassis from the steering posts all the way to the spur gear cover. This would decrease ground clearance under the ”belly” but also prevent bumps from hitting the lump in the back at a steep angle. Sort of drag and slide over the bumps, as with a flat chassis.

Get Tekno EB410 pills (TKR6544) so you can fine-tune the hinge pin angles further.

That is good stuff! You have definitely done a ton of work! I have looked into and will continue to look into all this info.

Unfortunately, I am now a part of the "broken front A arm club". Super embarrassed to admit. Was bending over to pick up something and accidentally pinned the throttle, so there went to truck, straight into the side of the house at mach stupid. Could've been worse. No one was hurt in the incident, just my ego I'm still shaking my head in the I can't believe I just did that...RPM replacement arms on the way.

 

[Lumikko]

That is good stuff! You have definitely done a ton of work! I have looked into and will continue to look into all this info.

Unfortunately, I am now a part of the "broken front A arm club". Super embarrassed to admit. Was bending over to pick up something and accidentally pinned the throttle, so there went to truck, straight into the side of the house at mach stupid. Could've been worse. No one was hurt in the incident, just my ego I'm still shaking my head in the I can't believe I just did that...RPM replacement arms on the way.

I tried the RPM arms and went back to stock. They are way too flexy for track use with lots of grip, The handling is all over the place. Great for bashing, though. Can’t snap when you can virtually tie them into a knot!

 

[nino]

I wouldn't put RPM on anything that you want to go where you want it to go
Another thing that I don't like is that the screw holes strip easily, take off the shocks a couple of times and you need a new set of arms.

 

[sylentk]

OK Yeah. I bought both stock and RPM, just in case I go mach stupid again. The RPM's needed a bit of filing to get to fit, so not impressed, but at least the truck is up and running again. We'll see if I can get them to pretzel. Sounds like a challenge

 

[sylentk]

So new shocks. The AE MT10 aluminum. They seem quality. Oil I put in was 30 wt front 35 rear. IDK. Seems like I could go less. Still a bit stiff feeling. I would like to try other weight springs as well. But I can't seem to find any. (I know, I'm a nerd)

And today I broke the other A arm. But you know what? I had fun doing it. HA. Good to get out on the track. Super tight and technical. The challenge to go fast on this track is almost misleading. Like, can I just go as fast by slowing down? But I do love pulling that trigger. Darnit, To be continued

 

[Lumikko]

So new shocks. The AE MT10 aluminum. They seem quality. Oil I put in was 30 wt front 35 rear. IDK. Seems like I could go less. Still a bit stiff feeling. I would like to try other weight springs as well. But I can't seem to find any. (I know, I'm a nerd)

What do you mean by stiff feeling? A stiff feeling in general could be caused by many things not even related to the shocks.

 

[sylentk]

What do you mean by stiff feeling? A stiff feeling in general could be caused by many things not even related to the shocks.

Like the suspension is not moving fast enough to absorb and rebound the smaller, repeated hits. Therefore the truck isn't as controllable as I'd like at the speed I'd like.

If this track was the blue groove type, where all you need to worry about is jumps and smooth corners. It would be fine. But this track is like plywood over carpet. I forget the actual name of the plywood looking stuff, but you probably get the idea. And I know the car is loosing traction, especially in fast corners because of the multiple plywood junctions that are the small, repeated hits. You can see it bounce, therefore loose a bit of control. The "little" cars (regular buggies) seem to be glued to the ground and not affected. And they have smaller tires. So suspension nerdery is my fun.

I also race/ride mountain bikes. We have the ability to adjust compression, rebound, spring rates on our suspension. And if you really want, you can adjust the IFP and shim stacks. But not so much in R/C. I'm just being picky

Any suggestions?

 

[nino]

Adjusting all of that is done in RC too. Spring rates, piston selection and shock oil are the basics. More advanced would be piston kits that offer different rebound/compression rates and choosing between vented/emulsion/bladder setup...

Plus around a million options regarding shock positioning and wheel alignment.

 

[Lumikko]

The irregularities sound small enough that they should be absorbed by the tires alone.

Your shock oils don’t sound stiff for the shocks you’re running, also considering the weight of the truck.

The shock towers on these are pretty flexy though. It’s possible that they act as springs without damping.

 

[sylentk]

I'll have to take a pic next time I'm out at the track. But picture 3/4" plywood stacked and fanned out to make a turn. That's where I feel like I'm loosing traction and control and speed. Sometimes it's banked, sometimes it's off camber. On purpose. You know, just to make things interesting. And it's always different everytime I go, but one thing is for sure, the stacked/fanned out plywood. No worries, I'm still having fun.