Building Oil Filled Dampers

[Sammo]

Evening,

This evening I'm going to be building my Tamiya TRF Dampers. They're for my FF01 speed run car. I'm going to be running soft springs on the front and hard on the rear but I have no idea which pistons to use in the dampers. They come with one, two and three hole pistons. What should I be using on each end?

 

[Percymon]

I’d start with the three hole pistons to give the fastest possible response for any given oil weight

[Kingfisher]

The more holes in the piston, more oil will flow through when it goes up and down. The more oil that can flow through, the softest ride or fastest response. The single hole piston will flow less oil during up/down movement, and would be stiffer than the 3 hole. 

I see a 29t pinion. What's your spur going to be? 

[Sammo]

20 minutes ago, Kingfisher said:

The more holes in the piston, more oil will flow through when it goes up and down. The more oil that can flow through, the softest ride or fastest response. The single hole piston will flow less oil during up/down movement, and would be stiffer than the 3 hole. 

I see a 29t pinion. What's your spur going to be? 

It's a 66t spur. 

[Juggular]

1 hour ago, Percymon said:

I’d start with the three hole pistons to give the fastest possible response for any given oil weight

I second that.  Tamiya's instructions often choose stiff pistons.  It seems Tamiya is very afraid of their cars bottoming out. 

[Jonathon Gillham]

Those shocks look like the ones one my TA07 and TRF102. Both manuals suggested the 3 hole piston as the starting point, given the FF01 will be similar weight etc as the TA07 I would start with 3 hole in that too

[Juls1]

All the weight off the ff01 is up front, you’ll need much firmer settings up front than in the rear. Your proposed arrangement will probably handle horrifically particularly if there is no sway bar (which your unlikely to find). The front shocks are mounted upright, and the lower arm position is quite onboard, campared to the back the front wheels have significantly more leverage on the shock that the rear wheels do. 

The factory tamiya oil is about 40wt, I would run a 2 hole piston up front and 3 in the rear. You will need hard springs up front to carry that forward weighing motor. Out back there is almost no weight at all so softer springs are needed to stop the rear passing the front under brakes. 

If the idea is speed then the suspension needs to be fairly slow for stability, one might think it needs to be fast because your going fast but the reality is that will make it incredibly twitchy at high speed. 

Youll want to space the shocks internally to set a suitable droop, my suggestion is to set the length so the arms don’t extend below dead level. You’ll want a small amount of sag in the normal ride height. 

[Sammo]

2 hours ago, Juls1 said:

All the weight off the ff01 is up front, you’ll need much firmer settings up front than in the rear. Your proposed arrangement will probably handle horrifically particularly if there is no sway bar (which your unlikely to find). The front shocks are mounted upright, and the lower arm position is quite onboard, campared to the back the front wheels have significantly more leverage on the shock that the rear wheels do. 

The factory tamiya oil is about 40wt, I would run a 2 hole piston up front and 3 in the rear. You will need hard springs up front to carry that forward weighing motor. Out back there is almost no weight at all so softer springs are needed to stop the rear passing the front under brakes. 

If the idea is speed then the suspension needs to be fairly slow for stability, one might think it needs to be fast because your going fast but the reality is that will make it incredibly twitchy at high speed. 

Youll want to space the shocks internally to set a suitable droop, my suggestion is to set the length so the arms don’t extend below dead level. You’ll want a small amount of sag in the normal ride height. 

Now this is the opposite to what everyone else has been telling me haha!

[Kingfisher]

3 hours ago, Juls1 said:

All the weight off the ff01 is up front, you’ll need much firmer settings up front than in the rear.

Sammo is going for straight line speed. On acceleration, weight transfers to the back, lifting the weight off of the front tires and increasing the chance of breaking traction. Wouldn't you want a firm rear and soft front? That way the rear doesn't squat on acceleration, and instead keeps the weight over the front wheels?

[Juls1]

For straight line that may well work out better, but the moment you try to turn at speed it’s just gonna tuck in heavily on the outside corner, if the rear is too hard that will just exacerbate the issue. I guess I’m thinking more about track use or street bashing where being able to turn without flipping is preferred. If your just drag racing then that said, maybe a soft front back hard arrangement might well be the go for that particular situation! 

I guess the other thing I was alluding to was more the choice of spring, a hard spring up front is likely to feel like a soft spring out back due to the weight balance of the car and the leverage of the suspension layout. Simply putting a hard spring at the back and a soft spring at the front seems like it might achieve a slightly extreme version of a described soft front hard rear suspension setup. 

[Wooders28]

Depends of weight and surface, so it maybe a bit of trial and error. For the DT03 set up, I used the slow motion feature on the smart phone to film the launch to see what was happening.

The shock absorber does the, urm,shock absorbing ,the springs are just for pushing the piston back to its starting point, a stiff spring will push it back really quickly, making it bouncy. Extremely stiff and the chassis will lift instead of absorbing the shock, making the suspension useless.

For a speed run, I'd go for a softish set up,(3 hole, soft springs) but play about at slow speeds to find something that you like / that's predictable.You may need slightly thicker or thinner oil etc.

Also, I altered the steering curve to be less responsive at the start of the steering, as the faster you go, the less steering input needed. (You'll still need to steer, DT03 was all over the place, but big steering movements and you'll crash)

[Kingfisher]

Trial and error. It's the only way to get it to where you like it.

26 minutes ago, Wooders28 said:

The shock absorber does the, urm,shock absorbing

 

 

[Sammo]

45 minutes ago, Wooders28 said:

The shock absorber does the, urm,shock absorbing

Well I'm glad we've cleared that one up 

[Juls1]

I’d leave the factory white springs ok for the moment they feel ok on my ff01. fiddle with the oil weights and holes to get a consistent planted feel till your happy you can hold onto the thing at 50mph+