lawndoggie

I totally understand! Who would want to wait 5 months!!
Check out Harmony and World Model. They'll both give you the same price. World Model is the distributor here in HK, where I bought the 705:
http://www.worldmodel.com.hk

but they might just ask you to get it from you LHS!

fmolzer

I usually allow for this by just plugging the stinger and the pressure fitting. (run fuel tubing from one to the other) Then, fill the pipe with water, but leave the hole uncovered (connection at manifold) Stand the pipe up in the freezer so no water spills out. The ice will start to form on the uncovered hole first, creating an ice cover, then inside the pipe so the dings gets pushed out. The ice cover will start to push up if the ice inside the pipe can't expand the pipe itself anymore. This happens way before the pipe would become damaged from the expanding ice. Works every time

lawndoggie

kool kool! got to try it tonite!
Whats the "chariteristic" of having front tires harder than the rear? for example 40 front and 37 rear? comparing to say 40/40?

Thanks

MichaelS

Well, the problem with rear toe is that it takes away steering! No matter if you are on or off throttle! It also takes away top speed!
So the goal should be as little as possible.
With the 705 my problem was usually turn-in oversteer, never on-throttle. Of course this also depends on the differential settings.
So again: a loose diff will make your car turn in faster but will create understeer out of the turn.
More rear toe will creat more understeer (or more rear traction) off and on-throttle.
Caster is more difficult. With more caster the inside rear wheel will lift more, when you turn the wheels. Because of that effect you actually gain steering (or loose rear traction). On the other hand you have less front rubber touching the surface because the inside wheel will run more on it's edge.
If you gain steering or not with more caster may depend on your diff settings. If you run a tight diff or solid rear axle, you will gain steering on and off throttle, because the lifted inside rear wheel will help the car to turn. With an open diff you don't need to lift the inside wheel, in that case the car may turn better with more front rubber on the street, which means less caster.
Something to think about!

InitialD

Agreed.

Agreed.

Ummm, on throttle understeer yes but off throttle understeer with more rear toe in is new to me..

So when do you use more rear toe in then? Larger tracks? Wouldn't that take away top speed?

Agreed.

Woow, yes... Definitely something to think about ! Read it a few times to digest.

The last info is totally new to me. So what you're saying is the drag on the harder rear diff (or solid axle) when off power will assist in steering the car, which will be greatly amplified when you have more caster? This is with one way front right? Cool. What about turning radius?

So what you're also saying is the caster's characteristics only apply conventionally when the rear diff is loose?

When you say more steering (off power), how would you describe it? Faster and more responsive turn in with smaller turning radius? I always thought this was a function of the caster (i.e. less caster, faster turn in) regardless of the rear diff setting.

Julius

When you run rear toe in two things happen.

First realise that when cornering the outside wheel does most of the work. That means if you run toe-in on the rear the outside wheel will be pointing to the inside of the corner.
Because of this the car rotates less aound the top axis but also moves sideways. Therefore the front will need to turn more to compensate this effect = less steering.

On throttle toe-in has a stabilising effect. Now the wheel not only points to the inside of the corner, but the acceleration force of the wheel will also be directed that way. This counteracts in part an oversteer situation.
Under braking unfortunately things are reversed. The braking force in this case actually pulls the rear out of line. So more toe-in will not help a car that is unstable during braking.

It has not a lot to do with big or small tracks. I set toe to be a compromise. I will try to run as little as possible and use it to balance the car under acceleration.

Solara

iTrader: (17)

Hey InitialD.......any idea where is "ammdrew"..? Back then at HPI forum and here, he was very active and I found him very helpfull on Impulse....did he jumped the wegon to Mugen or NTC3 or Retired...?

markp27

Hi Julius,

Is there some basic rules about downstop settings for small tracks?

Cheers, Mark.

Julius

Here also two things interact. The diff and caster work together.

Caster makes the car roll sideways. This is because when you turn the wheels part of the rotation is in an up and down movement of the wheel (more with a lot of caster, less with small caster angles).

If you run a solid axle and have no caster and turn the front wheels in a corner, the car will have difficulty to turn in. This is like a flintstone car. If you were to use a lot of caster, the chassis roll will lift the inside wheel off the ground and the car will turn in much easier.

If you run a loose diff the car will turn in easy because the diff allows the rear wheels to turn at different speeds. If you would run a loose diff and a lot of caster, the turn in wouldn't change so much but you could lose a lot of drive out of the corner. The caster lifts the inside wheel and the loose diff will put all the power to the wheel that is off the ground.

So caster and diff will need to work together.

Julius

First of all downstop means the limit on the downtravel of the suspension (droop limit). I saw somebody using up and downstop the other way around (that is maybe more logical but not the "widely used" explanation).

Rear downstop has most effect on braking. In general more downstop (less rear downward movement of the suspension) gives more stability under braking. But limiting suspension movement is generally less good in bumpy conditions.

Front downstop effects the on power steering. If you run more front movement you get a little more on power steering (the front wheels stay on the ground longer). But if you go too far the car's response slows down and could get vague out of the corners.

In a small track with lots of corners you'd expect more downstop (less suspension travel) gives best results because the car responds quicker. Try to always keep the car "in the springs" so if the car is stationary on the table you can lift the chassis a little before the wheels come off the ground.

markp27

So is it common to use more rear downstop when running with a oneway? I always have trouble getting my car to break straight when running a one-way, even though I check for tweak with a tweak station. InitialD already pointed out that I should check the downstops to make sure they are perfectly equal. Any other tips there? I should mention, that I do run very little break, so I'm not really hitting the breaks hard either


Thanks for the tips!

J_Longbrake

iTrader: (20)

Great Info! Thanks Michael and Julius, keep it coming.

serpentracer1

Thanks for the info yall gave us I was almost on track with the car and it was getting quicker and the handling was smoothing out really well .Cant wait for the 710.I see all kinds of possibilites!!

Diesel Racer

Thanks for the link lawndoggie.

Diesel Racer

A question for Michael, Rene or Julius.

As a matter of interest is there any reason why the fuel tank wasn't reshaped on the 710 to gain a lower profile and hence a lower CG, much like the TM G4's, I know the throttle servo is in the way to the right and to move that out would change the polar moment, but surely the tank could have extended forward, it's just with the rest of the low profile design the tank sticks up like a flag pole which looks pretty crap.