Dear HPI

Sounds to be a set up question and I had to throw in my 2 cents in for you. HPI cars have alot of front bite. You can run different compounds, But changing the suspension can and will work too.
Harder springs up front with heavier weight oil will create push for you, and stop the rear whip. Of course you could go for softer spring in the rear and lighter oil too to get the whole car to hook up.

You can acomplish the same thing with compounds and inserts.
And or ride height, toe in, rear wing, etc...
So now you have the knowledge to react to what the car is doing.

See what you think about this set-up.

Front
Progressive Red springs 32.5wt oil and 1/2 deg toe-in. Mount the bottom of shock on the inside hole.

Rear
Progressive White Springs 25wt oil and 2 deg toe-in (stock) Mount the bottom of shock outside hole. With the green sway-bar.

Set the car with 5.5mm ride height all the way around, and 0 deg camber all around

Note; To get 5.5mm you might need to cut a coil off the springs

With this set-up I run x-patterns up front and slicks in the rear both the pro compound.

This is the best the car/baby has worked in 3 months of testing
Let me know what you think

Im2lazy

if you put 0 degrees of camber on your car, your tires are going to wear negative (i think), meaning that the outside of tire is wearing faster than the inside of the tire. This decreases grip due to tire wear and also due to the fact that the contact patch will be smaller b/c the HPI car has a lot of roll due to your extremely soft setup. As I've said before, HPI's swaybars are not truly effective when the car is put at race height. Also HPI pro compound tires while they wear fast, have less traction than a general temp-specific tire combo. With tires like HPI's temp specific tires or Take-offs or Sorex's or Yokomo's, you would be able to run a stiffer suspension that will allow your car to react faster and have a looser setup that would actually work. Realize too much traction can be bad as not quite enough.

Fiream

Dear HPI,

That Sound like an interesting setup, I may try it. What about like wider tires in the back???

popsracer

Most experienced HPI racers will tell you that the RS4 Nitro 1 & 2
(don't know about #3)
work best with little or no camber in the front and just a little in the rear.
0 to - 0.5 deg. in the front. - 0.5 to - 1.0 in the back.
Zero toe in the front.
45 wt oil in front, 40 wt oil in the back.
Black or green spring in front. Red or yellow spring in the back.
Ride height somewhere around 5mm is good +/- 0.5mm.
Don't cut springs, you can get ride height with shock position.
Try 2 - 3mm droop in front. 3 - 5 mm in back.

White springs are way too soft. Try using heavier oil in the shocks.

With everything, balance is the key to a fast and easy to drive car.

Has any one measured the width of the car front and back. The front is 5mm narrower than the rear. This will create more front grip. Try some Super Nitro wheel hexes in the front to even things up.

Im2lazy

yeah, definitely go with no toe up front or go with a little toe out. it will make you turn in faster and you car will have less steering coming out of the turn...a good thing for this car. I've tried using toe-in at the front of the car in order to keep my car more stable, but the truth that I had found was that toe really doesn't affect the car much on the straightaway, but in the corners. Your car may wander an extra foot to one side when comparing toe-in to toe-out, but you can easily correct that with no sweat, but realize again that the difference between the main your in now and the main you hope to be in ( unless your in the A main) is in the corners and notthe straights.
Personally I use 50 and 45 weight shock oil. It keeps the car from wanting to roll as much. Also I like to dial a little bit of traction out with springs one step harder than I want to run, b/c again, too much traction will make you go slower than a loose setup.

To get 5 mm of ride height, what I do is I either bottom out the shock eyelet, and then adjust out in order to achieve equal shock lengths if they are not yet equal. This should get you down to 5mm. If not, trim the top of the shock eyelet where the shock shaft threads in. Don't cut the springs unless you have the linear set offered by HPI. The thing about the linear spring set is that they are hard to come by.

popsracer

Im2Lazy reminded me of something to add.
The HPI nitro cars are VERY sensitive to tweek. Make absolutely sure that each pair of shocks is exactly the same length. I have a digital caliper with ballends mounted that can measure the center to center of a shock.
Center to cntr. is more precise because the the shock ends tend to have nubs that vary from one to another.
If your shock length varies by more than a few thousandths at the same end of the car. It will cause the car to pull to one side under power.
Don't cut the springs.
There are other ways to get ride height. Unless you can cut each spring to the EXACT same length ( +/- .002) you will cause different installed pressures on each shock which will have to be corrected some other way.
Some Pro-racers measure dozens of springs to get a pair exactly the same length and rate.

Dear HPI

These are what I have tried and have not experienced any unusual tire wear, camber links have alot to do with this. I am running the same tires for three race days and they are still in good condition.

As for sway bars not having any affect, they will with a soft set-up, they decrease the unloading of the car under left right left situations. This will in turn stop alot of the loose rear end feel in the car which HPI cars have.

Tires are a major key in set-ups alot of racers say "I needed newer tires for the main the car is loose" in fact in this situation
the car was set-up to stiff for the tires for the main. Do you want to have to run new tires all the time? You will notice after a 20 minute main the car falls off in laptimes and the tires loose their grip. I would rather start the race with a car that has a little to much traction and be happy with the traction at the end.

All in all you need to tune your car to the track, and the tires you have to run. Knowing what you don't like about the car and the way to fix it. I was trying to help firearm with his loose rear condition and that set-up is what I have found to work.

Sure this is a soft set-up, I have not tried foams on this car and I am sure that the set-up would change alot, but why buy new tires if you don't have to and have to change your whole set-up. Stay with a tire and a set-up it is easier that way

popsracer

All of the set-up recommendations are for rubber tires on asphalt, which I believe the average person will probally race on.
I almost always get 4 to 6 weekends of racing consisting of two
5-min qualifiers and a 5 or 10 minute main each weekend.
For the most part, HPI sway bars are useless (they look good) because of the sloppy mounting at the arms.

Try the next firmmer spring in the front or back. I think you will find that the car handles better overall.

Dear HPI

The reason I cut the springs is to get ride height and droop correctly. Set the droop first then ride height. I couldn't get both so cutting the springs was the only option. I had no more settings, the collars were all the way up. And true tweek is important however it is not as sensitive as you say. Do you set the tweek with a full tank or an empty tank? As for the pro racers measuring springs Remember they get payed by the hour. But if you had a dozen springs the same, some have runs on them some don't, this would be something to look at. Agree.
I do agree with the shock length this has to be correct it will kill the car

Dear HPI

I have been there and done that. This loosens tha car up too much on the tires/track I am running. As for the sway bars, Yes they are sloppy so tighten them up, or make your own mounting hardware. A small piece of an aluminum can works great but does wear out.

Also, Aren't rubber tires for sedan racing?, are foams roar legal?

Dear HPI

Yes it is not a normal set-up but it has corrected all of my problems with my car. Wider tires can give you more traction in the rear however it wound change the geometry of the car. It might cause the car to push/not turn. Just try softening the car up with lighter oil in the rear and see if you are going the right way. It is alot cheaper than a set of tires, and you won't have to cut the body to fit the larger tires.

PS: this set-up is for a parking lot, swept, and sugered down with soda. Not for a fixed track/professional track. However this set-up will work for a unprepared surface too.

popsracer

Try using CA to hold the pivot balls onto the arms. Most racers who have run HPI cars for years will tell you the same about the HPI sway bar set-up. I like my Super Nitro with a front bar, but I have taken the slop out of the pivot ball mounts with CA.

If the car is loose, maybe you need a different tire. What is the surface you are running on?
Hpi, non "R" series tires are poor in overall available traction compared to what else is out on the market.

Set the ride height first with spring preload and shock position, then adjust droop with shock length and down stops (if your chassis has then) Threaded shocks makes this so much easier.

I believe that most Pro drivers are on salary and are not paid by the Hour to race.

popsracer

What kind of "Wider" tire are you talking about?
If a wider tire is availible to fit then it is usually in a hard "Basher" compound that is no good for racing. This would apply to the difference between 24 and 26mm tires also. Most of the racing compounds come only in one width (24mm) with HPI and Pro-Line being the exceptions.
You are much better running the same tire insert at both ends of the car as it makes for a more balanced set-up. I have tried the mixed tire thing myself. But changed years ago to running the same at both ends of the car. The car drives better and it's easier to set-up the car.

Dear HPI

My swaybar rubs the inside of the pivotballs to glue them I think wound bind them. but yea, they need some help.

A different tire would be the way to go but it took me two months to get it to work right on these tires when they are gone is when I will change. Being unemployed puts the spending on hold. Gas only + broken parts. The surface is school parking lot swept and blown, then treated to a spray of soda.

Ride height is just my problem, I could have raised the tops of the shocks up but then I would lose all the droop, unless I leave the shock ends loose on the shaft. But then in a crash they would pull out. So cutting the springs was in fact the only way to get to 5.5mm ride height and 5mm droop BTW I was not using any spacers on the shocks, inside or out. PS; HPI 's have no down stops.

Yes pro's are paid salary but who's to say they weren't wasting time, I guess if I had three to four sets I guess I would check them too.

No need to put up a battle cry, I see what you are saying, But not all of us have the greenbacks to do what we want. If I did I wouldn't be running an HPI. I just try to win with as little as possible, and help others do it cheaply...Not all the big toys win.

PS: I know it says "rookie" next to my login but it is far from the truth. BTW Can I change this??? How.... Anyone???

popsracer

BATTLE CRY was just a funny way of saying we have different opinions on somethings.

Sorry, I didn't know about your $$ situation. I've got so many useless tires that I don't know what to do with them. Hate to throw anything away that I spent money on.

Don't glue the swaybar ends to the pivot balls. Just the pivot balls to the arms. Set the car on a flat surface, make sure everything is even, then add a drop or two of CA and let dry.

With a better tire you will benefit from a slightly stiffer set-up.

I've never had to cut springs to get ride height. Just takes alot of patience and time.
I could re-measure everything on my HPI and post it if you would like to try something different.
You shouldn't have to unscrew the shockends more than a turn or two for the droop setting.
You can also run the 25mm HPI springs.