Rocket Scaling vs Racing Radius Rods

[RacerX10]

Question for the guys running Rockets .. the Rocket book suggests scaling with bars in a "neutral" position, and racing with the bars in the "race" position. I don't see any other builders suggesting that.

Just curious. do you guys actually bother with that or just scale in the "race" position. It seems you could make an argument along the lines of "scale it like you race it", etc.

Thanks !

[Punisher88]

I scale mine it the position I start off with at the beginning of the night. One important thing that it may not say is to pull the lr axle out until the splines are no longer engaged on the drive flange. That way it doesn't load the lr as you roll it backwards or forwards on amd off the scales due to stagger.

[RacerX10]

I scale mine it the position I start off with at the beginning of the night. One important thing that it may not say is to pull the lr axle out until the splines are no longer engaged on the drive flange. That way it doesn't load the lr as you roll it backwards or forwards on amd off the scales due to stagger.

You're right, it doesn't say that anywhere in the book. Thanks for the tip !

[toloud]

scale position

Scale position for top rods is in the bottom holes . From the looks of the bottom brackets scale position for the bottom is either 2 or 3 up from the bottom. Call rocket to make sure. The reason to scale in these positions is any scaling numbers you get from rocket will have been done in them.

[RacerX10]

Scale position for top rods is in the bottom holes . From the looks of the bottom brackets scale position for the bottom is either 2 or 3 up from the bottom. Call rocket to make sure. The reason to scale in these positions is any scaling numbers you get from rocket will have been done in them.

I hadn't thought of that. I almost never call the chassis vendor though .. I usually come here first when I have a problem

[talclipse]

The neutral position for the rods will vary depending on which 4 link rackets you have. There is a full page that describes the different brackets as well as the neutral positions. Like others have said the neutral position just gives you an apples to apples comparison when discussing numbers.

Another tip is to remove the LRF shock when scaling.

[Matt49]

Another tip is to remove the LRF shock when scaling.

I've seen/heard this many times but I've never quite understood it. The LRF shock typically has so much rod pressure that it provides quite a bit of LR bite. Why would this not be something you want to measuew on the scales?

[TheJet-09]

While on the subject, do most people (or does Rocket say to) take out all the rebound in their shocks while scaling? I never looked for a change in numbers but certainly did notice a difference when bouncing the car to settle it.

[keeks]

With regards to doing your setup, ie; setting ride heights, do you do that with or without the driver in the car?

[Dzona1]

With driver weight in seat

[Matt49]

Regarding shocks, I think it is a good idea to take out any super aggressive rebound or compression when scaling. It will just give you more consistent results when shaking the car down.
Regarding ride heights, they are to be measured with the driver in the car.
I use 2x2 wood blocks cut to the exact length and this is how we set it initially. Then I get out of the car, shake it down, and make new "without driver" blocks so that I can do it myself going forward if I don't have my normal help around.
The wife doesn't mind reading and writing down scale numbers but she isn't climbing under the car to check ride heights :-)

[RacerX10]

Regarding shocks, I think it is a good idea to take out any super aggressive rebound or compression when scaling. It will just give you more consistent results when shaking the car down.
Regarding ride heights, they are to be measured with the driver in the car.
I use 2x2 wood blocks cut to the exact length and this is how we set it initially. Then I get out of the car, shake it down, and make new "without driver" blocks so that I can do it myself going forward if I don't have my normal help around.
The wife doesn't mind reading and writing down scale numbers but she isn't climbing under the car to check ride heights :-)

Why not just weigh with the driver's weight in the car every time ? My driver (me) is just about the same as (4) bare small block chevy steel cylinder heads

[Matt49]

Why not just weigh with the driver's weight in the car every time ? My driver (me) is just about the same as (4) bare small block chevy steel cylinder heads

Because putting all the weight in the seat isn't accurate. Legs are heavy.
There's nothing wrong with knowing what the percentages are without driver as a reference. But I would not use this to set bite. I've found the effect the driver has on bite depends on spring rates and bar angles.

[zeroracing]

I put drivers weight in the car, typically put most in the seat then some halfway down and some at the pedals. I would do just the driver himself but being a one man band most the time makes that a bit hard. I just make sure I do it the same every time.

[RacerX10]

I put drivers weight in the car, typically put most in the seat then some halfway down and some at the pedals. I would do just the driver himself but being a one man band most the time makes that a bit hard. I just make sure I do it the same every time.

That's kinda what I do. I sit (1) SBC cylinder head on the floor right in front of the seat, and the other (3) heads actually in the seat. That has to be a 99% approximation of me actually sitting there.