Approximate spring rate for 1/8 on-road and GT?
 

I am converting my Jammin buggy to an on-road GT. I will be using Revo shocks, and between the Revo and Jato springs I have a ton of selection to choose from, but not really sure where to start. I know the low and high extremes aren't right, but there are still many in the middle that I'm unsure of.

Can anyone give me an idea of a good starting point? Like what does a Serpent use, or a DM-1 spec, anything similar will do. I have been able to easily find spring rates for 1/8 off-road buggy, but none 1/8 on-road. Looking for values in lb/in or N/mm.

Thanks in advance for any help, it will be greatly appreciated!

OK as usual I find a few things the minute after I make a thread asking about it... :rolleyes:

The numbers I've found for Mugen 1/8 on-road seem very high though, like 30-60 lb/in. The stock springs that came on my Revo shocks were around 25-28 lb/in and they just seem way too stiff to me, can't imagine going even higher. Do 1/8 on-road springs really have that high of rate? Maybe I'm just too used to off-road springs?

Judging by how the Revo springs felt I was guessing I needed closer to 10-20 lb/in?

Off road cars need to be able to handle jumps and landings and run longer springs and higher ride heights.

On-road cars are run much closer to the ground and run shorter springs that are much stronger (stiffer). This is because on-road cars don't need or want the long shock travel and all the suspension movement. On-road is about controlling weight transfer and handling it quickly. Sway bars or anti-roll bars are also used to control across car weight transfer.

I run a Kyosho GT2 car and my shocks are set-up to be extremely stiff due to the use of heavy shock oil. I am running the Kyosho stock black springs but I have the ride height collars cranked down all the way on the shocks and I control the ride height with the droop screws that are located in each lower arm.

Lee

Thanks for the reply.

I understand the basic differences in suspension setup between off-road and on-road, but what I really am looking for is the spring rates used. I know the on-road springs must be shorter and firmer rate, but wondering by how much.

Most off-road springs are in the range of like 3-10 lb/in, so when I saw on-road springs listed at 30-60 lb/in it seems like a big jump. I just want to make sure I have the right range, because I need to order springs to finish my conversion.

P.S. Is it common practice to set ride height with the droop screws? Or is it just the way you prefer to do it? Again I'm mainly used to the off-road side, using droop screws to limit the downtravel of the suspension rather than ride height. Seems like you would still need some downtravel in on-road, even if it's only a few mm, but using the droop screws to set ride height won't allow that.

Using droop screws to set ride height takes away any down travel. Plus this will not stiffen the spring rate since this is a constant of the spring not dependent on tension on it. It is better to find a stiffer spring. A little down travel ia very usefull in less than perfect track condition since in a bumpy track you need the tires planted on the road surface as much as posible and bouncing looses traction.

Setting ride height is done by the shock collars or preset things - droop screws change the way the car reacts on different values.
using the droop screws as ride height makers changes the tension of the springs if combined.

This attachment (poor quality) may help you determine what springs you want to start with.

Lee

Good info Lee...

here is a chart that i've had for a while,it is a 1/10 so it may not help

The GT class that I race in started off as a STOCK car class. When we found that the brakes faded and the 2 speed stripped the rules were changed to allow us to use aftermarket brakes and upgraded 2 speeds. Later we opened up the engine rule to allow street value $200 and below engines.

It is in that context that I my car is set-up. Because it would be illegal for me to change springs I haven't. If I could put stiffer springs on the car I would and that change might allow for the droop screws to handle droop instead of ride height.

My car handle great as it is set-up.

Lee

Thanks for that chart Lee, exactly what I needed.

I understand now why you are using the droop screws to set ride height. Since I am not limited by any rules (I make my own rules LOL :lol:), then I can set ride height with the shock collars and keep a little downtravel in the suspension.

As it turns out the stock springs that came on the Revo shocks I'm using are right in the middle of the chart you posted, so should be a good starting point. 31 lb/in front, 28 lb/in rear. I'll give those a try before buying anything else.

How long are the sprngs and the completed shocks? I'm working on a special project and maybe these shocks can help me out.

Wow Lee, no spring changes! I knew something was off about the droop screws, and now I understand. Our rules are very open compared to yours.

Revo shocks are about 85-87mm depending on how far you screw on the end. The springs I have now are actually the "long travel" Revo springs and they are 52mm. Not sure how long the standard travel springs are, but they should be slightly shorter. I might end up using the long travel in the rear, and standard travel in the front.

I'm also going to play around with the Variable Damping Kit.