How do you bench-test your shocks?

[Coelacanth]

I was wondering how everyone bench-tests their shocks on 1/10 off-road buggies? I got the feeling my fronts are just about perfect, but my rears have too much bounce. I was dropping the car from about 4 to 5 feet and the fronts absorbed beautifully and didn't bounce back, but my rears bounced up about 4 to 6 inches on impact. Even with the stock springs set to minimum tension (collars all the way to the top of the shock bodies), there was still rear-end bouncing (this is on a Turbo Optima).

Should I go with a thinner weight oil or softer springs?

And what do the rest of you guys do to test your suspension before taking a car out to the track, to get it "in the ballpark"?

[shane]

I use a Losi shock tool or I place the bottoms of the shocks end to end together and compress them and observe the rate of rebound by eye. Of course, the shock tool is most accurate, IMO.
If the rear is bouncing, it is to stiff. Maybe try a piston with larger holes or lighter oil.

[Coelacanth]

I use a Losi shock tool or I place the bottoms of the shocks end to end together and compress them and observe the rate of rebound by eye. Of course, the shock tool is most accurate, IMO.
If the rear is bouncing, it is to stiff. Maybe try a piston with larger holes or lighter oil.

Thanks shane. I wasn't sure if the bounce-back would be more a result of too heavy oil/too much resistance inside the shock (piston w/small holes) or overly stiff springs.

[shane]

Could be a combonation of things also.
When you drop your car on your bench, if the rearend bounces back off the bench, it is too stiff. If it bottoms out, it is too soft. Need to find the perfect 'inbetween' The track and your driving style are important also. I have to say, I would try a different mounting position hole for the shocks first, before rebuilding my shocks, IMO.

[Coelacanth]

I don't think changing the mounting hole is an option because they're already mounted in the holes for maximum extension. Mounting the shocks in the more inner holes would increase the spring tension even more. I'll try your other suggestions, though...the Kyosho Golds are easy shocks to work with.

[uzzi]

I think if you are dropping your car at a height of around 4-5 feet , no suspension on a standard 1/10 buggy will be able to handle it. The reason why the rear is bouncing back so much is because the chassis is bottoming out due to the majority of the weight at the rear (motor and batteries). The adjustment of the spring collar does not make the shocks any stiffer but sets the height of the chassis relative to the ground. Stiffness of suspension is adjusted by changing spring rates and the oil is used to control the damping action of the shocks (relative to springs used). Shock angles can also affect its performance, e.g. more angle easier movement the opposite for a more upright set up.

For testing right height, lift the rear of the car then drop it without liting the front tyres let the suspension settle. If the arms are angled inwards then the ride height is not correct, adjust the spring collar to lift the rear of the car. If the arms are level or slightly angled when it comes to rest it is about ballpark. At most drop the car from a height of 1 foot is more than sufficient.

For testing damping, do the same test as above and note what the chassis is doing. Remember different weight oils are used in order to slow the springs oscillation not adjust stiffness. Oil too light will result in the excessive movement of the chassis even after the tyres have settled.....too hard and the tyres will bounce off the table. Majority of the time you will use between 25-40wt oil for 1/10 buggies. The way you actually build the shocks will also affect the damping, if you do not bleed the oil properly it will result in a stiffer feel.....this is called rebound.

Hope this has helped, it is only a ballpark guide as race tuning suspension is a science on its own imo.

[Coelacanth]

I think if you are dropping your car at a height of around 4-5 feet , no suspension on a standard 1/10 buggy will be able to handle it.

Granted, I was dropping it on a carpet, and these cars jumped further & higher than this in competition on harder surfaces.

The reason why the rear is bouncing back so much is because the chassis is bottoming out due to the majority of the weight at the rear (motor and batteries).

To be honest, I don't think that's the case; it's rebounding before it bottoms out because the shocks are currently too stiff or under too much spring tension. When I drop the rear end only (with front end left on the ground), it doesn't seem like the shocks are absorbing that much. There's even a bounce at this height. And that's using stock Kyosho red oil & probably the smallest-hole piston caps.

For testing damping, do the same test as above and note what the chassis is doing. Remember different weight oils are used in order to slow the springs oscillation not adjust stiffness. Oil too light will result in the excessive movement of the chassis even after the tyres have settled.....too hard and the tyres will bounce off the table. Majority of the time you will use between 25-40wt oil for 1/10 buggies. The way you actually build the shocks will also affect the damping, if you do not bleed the oil properly it will result in a stiffer feel.....this is called rebound.

Good tips there, thanks. At least I know the shocks were bled properly, there were no air bubbles at all. I even popped the tiny ones that appeared at the top rim of the shock tubes with a dab of tissue after running the pistons up/down several times.

[Coelacanth]

Ahh, I got the rear shocks dialed in much better last night! I put in a next-lighter weight of oil and replaced the shock piston caps with one hole to 2-hole caps. Now it's damping beautifully with no bouncing, and not bottoming out either.

Thanks for the tips!

[uzzi]

Sweet!

[Jay Dub]

4-5 Feet, I don't quite know what to say ... There are soooooo many things not right with "bench testing" your shocks this way. This is going to take a while, and I promise I will reply at some point, but I really need to get some sleep. BTW, please don't "bench test" your shocks any more . -Jeff

[Coelacanth]

Interestingly, back in '86 or so when I was initially considering buying a Kyosho Optima, it was one of my fellow hobby store employees--and serious racer--showing off his new Javelin's suspension capabilities by dropping it from torso-high onto a hard-carpeted floor. That really impressed me how it absorbed that drop with no rebound.

Guys, we're talking 4 to 5 feet onto a carpeted floor--not a drop from a 3-story balcony. Frankly, if your car is at risk of breakage after falling from that height onto its 4 wheels, how is it going to survive the far greater rigors of racing?

[kaiser]

a straight drop from 4-5 feet is not the same as a jumping height of 4-5 feet.

when jumping the car is in motion and inertia takes hold. while a car may bottom out in a straight drop it may not when jumping because theres less downward energy when jumping and much more foward energy. (given that you are hitting the jumps correctly and not "airing it out".

but it sounds like you made some progress.

[THEYTOOKMYTHUMB]

I bench test my E-Savage XL from the roof with no bounce back. I see no problem in your system…

Sorry everyone( )… going to bed now…