IndyRC_Racer

iTrader: (9)

The HPI Vintage Tires when new have (-) negative camber designed into them. I'm not sure if this was intential or just a result of having a larger diameter inside rim on the wheel as compared to the narrow diameter outisde rim on the wheel. Either way, you should account for this extra camber when using new tires. You may in fact be running -3 camber (with new tires) even though your gauge is showing less.

If you haven't factored in the built in (-) negative camber, it will have a tendency to wear out the rubber faster on the inside edge of the HPI Vintage tires. If this is the case, you will notice the tread on the inside of the tire wearing out much faster than the outside. You will also notice that the outside edge of the tire will have a tendency to balloon up as the tires wear. It will also cause the outside edge to be more rounded than square and may contribute to too much grip or even traction rolling.

If you have factored in the built in (-) negative camber of the Vintage Tires, then the tread across the entire tire will wear at a fairly even rate and the edges will stay fairly square. You may still notice that the front tires will wear out faster than the rears. While this may be in part due to a poorly setup car, you also have to consider the rear tires are also wider (26mm front vs. 31mm rear). If you are running primarily on carpet, even a poorly setup car should get at least 12 weeks (3 months) of racing before there is any noticeable tread wear. Even then, the tires should still provide plently of traction to be competitive.

So next time you glue up a set of HPI Vintage tires, place them on a flat/level surface and you will notice that they don't sit at a 90 degree angle. Use your camber gauge to find the angle and you will be able better measure the real camber angle when mounting that tire to your car.

Hope this information is helpful.

Marv

iTrader: (2)

So, the camber is built into the tire and not the rims,wheels?

Is there different values for the front & the rear?
What is the value of this built in camber for the front?
What is the value of this built in camber for the rear?

Are the values different for the vintage performance tires, the vintage slick tires and the vintage racing tires?


Thanks

IndyRC_Racer

iTrader: (9)

If a track/event is using USVTA rules, then only Novak 25.5 motors are legal/allowed. Real world USVTA racing/results have proven that the performance of all the Novak 25.5 motors on the track are effectively equal. Many people will adjust the timing or FDR to find the "sweet spot" of an individual motor, but having a well setup car is much more important than finding the best Novak 25.5 motor.

If a track/event is using ROAR VTA rules, then any ROAR approved 25.5 motor is allowed. At this time there aren't very many non Novak 25.5 motors available. However, real world VTA racing/results have proven that a fully legal USVTA car is able to compete and/or beat a legal ROAR VTA car.

---------

The current USVTA rules have resulted in a class where setup and driving are more important than new technology. While the latest generation chassis or brand new electronics may offer a slight advantage, they are not required to be competitive in USVTA. In fact as you read through this thread you will find many examples of podium finishes with outdated chassis, less than 5000 mah batteries, and cars that are well over the minimum weight.

The bottom line is get the car on the track and have some fun.

IndyRC_Racer

iTrader: (9)

Off the top of my head, I would say the (-) negative camber has more to do with the design of the plastic wheels. Therefore I would assume it would affect all of the vintage tires when mounted.

I have never actually measured the amount of (-) negative camber on a set of newly mounted wheels/tires. However, I usually start at around -.5 to -1degrees when measuring with a camber gauge when using new wheels/tires and adjust according to tire wear. I cannot say what the best setting would be for every track or racing condition.

Kevin K

iTrader: (32)

Personally I dont think there is any camber built into the wheels(rims) or tires. If the tire isnt sitting flat after you build it that would be because its a round tire and its not really going to sit 100% flat or depending on which side you glued first you might also induce some camber into the tire that way.

One thing you might be seeing is that not all the rims are made out of the same plastic. The chrome rims are of a softer plastic then the non-chrome rims. If you are using the chrome rims you might get the inside edge to wear more because of rim deflection then over non-chrome rims.

Camber gain will have the biggest effect outside of a car that pushes as far as wearing out the inside of the front tires. The use of a spool will also speed up this process as well.

To check your camber gain you measure your camber at your ride height then push down on your chassis until it bottoms out and then you measure your camber again. The difference between the two is how much gain you have. Most times I have had the most luck with less then 1 deg of camber gain in the front.

IndyRC_Racer

iTrader: (9)

I need to post a picture to better illustrate what I've experienced. However, I've been able to duplicate the (-) negative camber on every Vintage wheel/tire that I've glued over the past 2 years. I've also seen the same result on other people's new wheel/tires. I will try to get something posted in the next few days.

howardcano

iTrader: (37)

I agree with your observations.

I always run a very free front differential, as it suits my driving style. My car is noticeably better on turn-in and corner speed than other cars I've seen using spools, but has more on-power understeer than a car with a spool. The lap times are similar, assuming the driver knows how to get the best out of either setup. (I'm a mess with a spool.)

The spool is much harder on drivetrain components.

Going with a more viscous front differential works better on my 17.5 TC, where the extra grip means the inside front wheel can get very light in corners, and the extra horsepower then results in wheelspin on that wheel. It also makes the car more stable when trail-braking.

3D-Seth

iTrader: (36)

Camber gain is simply how much the camber changes, as the suspension compresses.

Does that make sense?

Alan,

FWIW, John ran a diff in the front this past Saturday when he kept breaking spools. When he switched, he did say the car handled pretty poorly with the same setup. I'm sure you could get both setups there, but it does seem like a spool is still a little better than the diff from what John experienced.

Seth

IndyHobbies.com

+1!

I do too. For me, and I stress ME, putting the gear diff in my TC6 with Associated's recommended 40 wt shock oil to start made a huge difference in how well my car drives. I was told by a other racer that I needed to "ignore Associated," and to put million weight goop in the gear diff. But that would have just turned it into a spool more or less. I love the way my car drives now just following Associated's procedure. The front gear differential is free to do its thing and my car is much better behaved.

swantrevor

I am new here. Basically have been bashing with my son and our 2WD Slash Trucks. Looking at getting him and I into VTA. Looking to enter without breaking the bank.
Is anyone running the HPI Sprint 2 with a different motor and speed control? I know stock its not eligible but with a different motor and speed control I think it may be. Please advise.
Link: http://www.hpiracing.com/kitinfo/106130/

slashdriver

iTrader: (84)

does anyone else run the hot bodies "Cyclone S" in VTA? I am still using mine and happy with it, but one of the challenges of the car is that it can't accept a full height (25mm) lipo hard case pack. I'm still using three year old SMC 4000 28c packs (they are 20.9mm tall and fit fine) but the wiring is breaking down on them due to high use.

So the question is, if anyone else is using this chassis (or another chassis that can't fit a full height lipo), what other vta legal lipos are out there that are around 21mm tall?

There are modifications I could make to the car to make it fit/work...like custom fabrication or spacing the motor/center pully upwards for clearance, but I'd rather just find 21mm tall lipos.

GP40X

iTrader: (10)

Here you go. Read the following thread started by Marv on HPI Sprint 2 Mods- Making a silk purse out of a sows ear. HTH

BLKNOTCH

iTrader: (10)

By any chance is there a place to find VTA setup's that can be looked over for my TC6.1? I am new to the VTA racing and would think some things would be much different then 17.5 blinky with the different bodies and offset tires, I am currently running box stock TC6.1 setup with very good results as I have managed to place in the A main at my local track against some very solid drivers. I need to find another .5 per lap if I want to have a chance against the top guy's and I feel this may be in the setup, I found myself traction rolling in the final race of the day but I am sure it is more due to my adding weight to the top deck on the chassis more then a setting issue as I had to add 40grams to make weight so I used stick weights on the top deck lol. I will be installing the weight set for the coming races on the chassis so this will not be a factor.

Thanks for the help people.

Sean

Marv

iTrader: (2)

Kevin, what do you do to compensate for the camber gain:
Adjust in the opposite direction?
Install stiffer springs to eliminate/reduce chassis roll?
Do nothing?

As per http://www.rctech.net/forum/11621077-post3570.html

Just changing the camber that little +1° in front and +1/2° in rear moved the wear from the outside edge to the inside edge... ????

Is this just the nature of the beast?


The car runs and handles great with either setting.


Thanks

oceanhighz

iTrader: (49)

what droop is the stock setting?
and what hole on the front and rear shock tower?
What is your tire prep before the race?

if I remember correctly, when I had traction rolling issues it was generally fixed by droop/ride height changes and changing how I prepped tires.