Shocks Mounted Behind Rear Arms on D4

[4times]

Just curious if anyone has tried mounting the shocks on the rear? I have the new worlds kit, but haven't built it yet. I know Yokomo has done this with some success...so thought the same principal may apply to the D4. Might be a bad idea though....but might make it ever more stable over bumps.

[DarkRedemptor]

I've try this but with new suspension design, your car are more stable on jump, and that give you more rear grip because your dampers (50grams each) are ~30mm more to the rear, and also your wing goes backward.


I know some people that made this on B44, MID44 and TRF501X the result is the same, more rear grip and more stable on jump.

[telboy]

I think (and don't quote me on this), you can't actually mount the shocks to the rear without great modification.
This has been tried by a number of people but it involves swapping the wishbones over and shaving quite a bit off of the rear edge to move the arms rearward enough so that the shocks will mount without any strange angles involved. You also need longer screws and some more washers to mount the shocks.

It sweeps the arms forward shortening the wheelbase and, like you say, mounts the shocks to the rear of the shock tower.

I found that it makes the car twichy and not as good over the bumps (although others prefered it) but when you get the set up good, it makes it really quick through the corners.

But I can't see of a way to mount them behind the rear arms without modding the gear box tops etc. or using the method above, because you'd have to move the shock mount.

[Gayo]

A french driver tried it at the Euros :


Our MiD44 team is testing this mod, but we are not 100% sure that it makes a difference other than moving the wing to the rear, thus increasing stability.

[telboy]

Was this done with the shortened wheelbase?

[DarkRedemptor]

This is my car and how I made this,




It's much easier to do this with the original damper configuration, with my laydown damper I need to add a carbon plate for the wing.
And you need to drill the rear arm for the lower mounting of the damper, but you don't need to modify the wheelbase.

[bender]

That's awesome

Looks like a cross between the old Cat 2000 EC and the 1/8th Piktor buggy!

Can you show some up-close pics of how the shocks are mounted to the arms?

[DarkRedemptor]

Here some more

Overview


Rear shock tower


Front end, with self moulded wing (note the little carbon plate on the shock tower for reinforcement)



The shaft drive are fill with molybden grease then I put plastic film (cellophane use for preserve your food)



Top view without body



Rear view





The aim is to have an ultra progressive suspension work. Actualy the suspension is softer than original one at the ride heigth and firmer than the original one when fully compressed.
That made the car better on jump and bumpy track.

The piston used is losi black with 6 holes in rebound with valve for having only 3 holes in compression (similar to the predator X10-X11 but working in compression, not in rebound)



Enjoy

[Gayo]

Medial Pro tyres! Cool!

[DarkRedemptor]

C'est pour m'entrainer à Montigny Raphaël

(it's for Montigny le Bretonneux training)

[Oliv996]

You've done a great job on your D4, mate !!!!

About Cyrille Baldini at Euro2008, he drove his D4 with rear shocks on the rear of arms and he felt the car much better on this slippery track

[ikey ji]

Great job darkredemptor!
All CAT 2000EC's fans must enjoy...
But is it a french thread or what?

[dan da man]

Cyril Baldinis d4 also has his diffs with lots of grease in. it works well.

[Lindsay]

Originally Posted by 4times

Just curious if anyone has tried mounting the shocks on the rear? I have the new worlds kit, but haven't built it yet. I know Yokomo has done this with some success...so thought the same principal may apply to the D4. Might be a bad idea though....but might make it ever more stable over bumps.

Adam as been trying this mod all year at varios meetings. We last tried it at Indoor Regional but found it was slower overall. To do the job properly there is quite a few mods, ie altering wishbones [ they do not just turnaround] longer studs for shock mountings.
Adam as found most bebefit on dirt tracks.

[Adam Skelding]

The mod I have tried also pushes the wishbones further forward.
Basically you dremel 3mm off the old front of the wishbone. Flip it over and then add 3mm extra of spacers to the back.

You can of course then move the wishbone around in the inner pivots much more.

The main benefit is that you get more drive forward under power on slippery tracks. It's due to the drive shafts being swept forward.

You also have to lengthen the rear shock by 1.5 Turns on the ball end to get the same droop as you had before.

When I tried it on really high bite tracks, I found it made the car too unstable almost like it was fighting itself by having too much grip.

There is an advantage to be had, but it's knowing when you can use it. Like my dad said I tried it a Durham indoor Regional and didn't find it to my liking. I gave it 2 runs (Made some changes between) and couldn't quite get the balance right.

[mark christopher]

does the top of the front gear box fit the rear gearbox? would this move the shock tower back more?

[DarkRedemptor]

Originally Posted by mark christopher

does the top of the front gear box fit the rear gearbox? would this move the shock tower back more?

Yes the front gear box can fit the rear gear box, but you need to do a new rear upper deck.

Cyril Baldini made this

http://www.petitrc.com/setup/hotbodi...ification.html


My personnal feeling about the rear mounted shock tower and damper is not so good :
- the car feel a little better on fast turn due to the more rearward wing.
- the car have more acceleration straight forward due to the 70g of shocks that goes 30mm more rearward.
- the car is more bad in turning out with more oversteer.

In conclude, rearward shock only give advantage on fast track with high speed turn. On "pacman" track it's simply worst than the vanilla configuration.