need grt help

[wildchild41]

alright im running a 03 grt with the short upper on the right front, the updated multi hole four bar brackets, on a 1/4 mile medium banked medium traction track.
54.3% rear
52.5 left %
90 lbs. bite
without driver

afco M2s
50# gas across front lf 4-6 rf 4.5-6
35 rr 3-4
125 lr 5-3

4 bars
rights side upper 1 up from std
lower std.
left side upper std
lower 2 up from st.

j bar 8.5 frame 2nd notch on pinion 19.5 long

the car rotates in good but is tight in the middle

how can u tell if the rf is to stiff or too soft?
how much rear steer is to much?
thank you

[Rocket Bonehead]

What type of engine do you have and what springs do you have in the car?


WHEN exactly is the car tight? When you pick up the gas or before you pick up the gas?



RB

[wildchild41]

i start on
500 400
275 225

open engine all aluminum around 700 hp

it tightens up between entry and the middle right before i go to the gas

[Rocket Bonehead]

How much static rear steer do you have in the car?


One thing I would do is to tame down that pressure in the LR shock. That is an awful lot of pressure for a shock that is floated behind the axle.



RB

[ScottyRocket]

I would watch the RR spring.... could be a little low there.

[Rocket Bonehead]

I would disagree... That isn't too soft for a Goat, and I know a number of guys in Goats that are running a 200.


Different cars require different things... WC41, get back to me on that steer...




RB

[billetbirdcage]

i start on
500 400
275 225

open engine all aluminum around 700 hp

it tightens up between entry and the middle right before i go to the gas

You absolutely sure it gets tight before throttle, and not upon throttle?

[bizkit]

That 275, looks like it could cause the problem, if its tight right at throttle..He might be trial braking into the corner a little and not realize it

[wildchild41]

i usually keep the static rear steer around 1/2 last saturday i went up to 5/8 not much help in the midlle but made it eractic when i tried to straighten up.

i see what you are saying about it tightening up in the throttle but what i did was to roll in the turn not at race speed and i stayed off the brakes, the car cut good into the turn but right before it rotated it tried to straighten up so this delays me from returning to the gas.

[billetbirdcage]

I'm wondering if he isn't slightly picking up the throttle and coasting the car at that point and making it tight. Kind of a semi trail braking or just to tight on entry and has alot of rear brake in the car and is releasing the brake at this point thus the car goes tight.

alot of variables here: If you can add anything about braking or dirving at this point would help get you a more correct answer.

[wildchild41]

i do run my brakes to the rear but i dont use alot of brake and it does it when im not on the brake but i may not be completely off the gas, i have had problems doing that before.

[bizkit]

billet can answer you better on what to do on the trail braking issue, ever time I try to learn it, I'm too tight, then when I loosen the car to where I think I can do it and still cut across the center, I always end up in traffic and then I'm too loose off the gas. So I've pretty much ditched trying to learn to trail brake, I think it can be a good tool if leading a race or in qualifying, but I've got no use for it in racing conditons..JMO

[billetbirdcage]

How is the exit when the middle isn't real bad? Just wanting to get I idea as to what adjustment to go with and not mess with or worsen your exit.

Also is the car rolled up on the LR some or is it completely down on the LR on entry (at the point of problem.

[wildchild41]

the exit is fine when i can get through the middle, its on the bars some on entry, what would happen if i went to a 450 or 475 on the left front

[bizkit]

I know I said ask Kent, but you need less compression in the LR shock

[wildchild41]

what about the gas pressure?

[billetbirdcage]

It will loosen entry, but only at the point the LF has some load on it. Meaning if it is carring the LF (or very little load) on early entry it would make a big change here. It the LF started getting loaded (setting down more) at late entry that is when you'll notice the loosening effect.

Moral of story if the track is hammer down and the LF is fairly unloaded all the way around it isn't going to loosen the car, it will loosen at the point that the LF excepts some load.

Couple other choices:

Increase LR bite to loosen entry. This will likley help later in the corner as it will likely be more noticiable when you off the brakes.

Drop the RRU bar: Some will notice the fair difference some not at all.

Raise the RRL: bar: Will likely loosen entire entry.

Have you every run a lighter RF spring then the 400 like a 350??

You likely get several different answers depenting on the way we are interpreting your description.

[bizkit]

I run 125#'s of gas in my ohlins on the left side all the time and 50 right. That's just the number I seem to like. I know I also don't like a gas shock in front of the housing, I run a twin tube 6c3r. On the hook I run my ohlin I adjust the compression and I 3 clicks from closed off on rebound all the time

[wildchild41]

i have been down to a 350 the 375 seems to be the best because one turn is longer and flatter and the other end is tighter and steeper

[billetbirdcage]

So maybe this problem is only on one corner the tighter one?

[wildchild41]

yeah its in the tighter turn im the fastest car at the other end but no one else has this problem, sorry i didnt say this earlier.

[billetbirdcage]

With this being the case, it is much more difficult to get the tight corner correct without messing up the other (too loose). This is where trail braking is going to help. You may need to loosen the car up (correcting the tight corner) and use some trail braking to tighten the other corner (corner your good in now).

Trail braking will tighten the car on entry (or where ever you are doing it more) by removing some of the engine braking. So you may need to loosen car and trail brake on the good corner to tighten entry back up and not trail brake on the bad corner to keep the free.

The more LR bite you have the more trail braking will tighten the car, with you running a low bite set-up you may not get alot of effect from this (lots of variables here). If you don't get enuff effect from this try increasing bite and adjust accordingly.

[ScottyRocket]

RB...Since we run a 2005 GRT, also a 2006 feature winner at our local track, 7 straight heat race wins, 3rd in ALMS 2006 Oakshade race... i guess we don't know so much about GRT's....so I'll shut up now. :roll:

Everybody may like a different setup and have different ideas on how to fix the problem, but the physics stay the same.

You will need to adjust your driving style if it's different on each end, kinda the way it is....just got to find what works for you. Billet is on the mark with setting up for the tighter corner and then figuring out what you need to do at the other end.

[billetbirdcage]

Scotty,

Don't take things so personal. We can all get along and all of us have our opinions and are wrong or not right all the time. RB, simply said he didn't agree. Alot of people don't agree with me at times and that is fine. Even RB and I don't agree at times, but I respect his answers and it gives everyone a different look or more options at the subject.

We all welcome all replies or peoples opinions. Your input is more then welcome even if we disagree. Not everything works the same for everyone, and sometimes people pick up something or read the description of the problem different. I find most of the time the descriptions are usually not fully correct or have important info left out that would help.

While we may state we disagree on something, don't take it as a personal attack or anyone saying you don't know what your talking about. It is just a statement that we don't agree. Funny thing about posts it is sometimes have to tell how it is being said. Alot of times (I feel) things comes across in a derogatory way when that wasn't the intension.

With that being said, I believe the reseason RB said that was he was describing a tight on entry condition. I think we pretty much all agree that stiffening the RR will tighten entry. So upping the RR spring rate would make his entry worse, would it not? If you have a different reasoning behind this could you state that reasoning

[Timmay]

Here's something you techies can take pot-shots at.

If your not using a lot of brake, that's a good thing. The good thing is if you can get your car in and through the middle without the brakes you'll be a lot better off in the long run. Also, it's easier to diagnose problems when you don't use the brakes too much, you get a more accurate assement of what the car wants to do.

If I'm hearing you correctly, the car turns in well but when the car starts rolling in deeper it gets tight before you even pick up the gas. If this is right, then I would SOFTEN THE RR SPRING. This will keep the car turning off of the gas.

Don't worry about this tightening your exit. You need to fix the middle before you can worry about exit. If it does fix the middle, but tightens exit too much, that's when you make some bar changes. You can raise both (top & bottom) RR rods to help loosen the car IF YOU NEED IT. Doing this will mainly effect exit.

As far as what end of the track to tune for, Tune for the end of the track where most of the passing is done. That might be the tighter end or it maybe the more open end.

Good Luck!

[billetbirdcage]

Timmay,

As much as I like giving you a hard time, I would agree with you. Just a different approach. :-D

He is also correct about the corner with the most or possibilty of passing is the corner you want to be the best in.

The only problem I have is with the brake deal, while I agree with timmay if you are stuck to this (no brakes) on certain tracks. I'll guarantee that under the right conditions I'll drive up beside you on entry and steal your line from you. Brakes are a good thing and should be used correctly and not to fix a handling problem all though alot of us do this (me included) .

[racer68]

You better watch out Timmay, billet is forum racing. :-D

[Timmay]

I'll just pull a slide job on the next lap :-D

[billetbirdcage]

Well, the next lap I'm going to drive it in real hard and stomp on the binders so you can't get beside me, so your going to have to SIDE BOARD ME. Well heck that still didn't work very well on my end! :shock: :? :-D

Bench racing sure is CHEAPER then real racing, Oh ya EASIER too! :)

[ScottyRocket]

Scotty,

Don't take things so personal. We can all get along and all of us have our opinions and are wrong or not right all the time. RB, simply said he didn't agree. Alot of people don't agree with me at times and that is fine. Even RB and I don't agree at times, but I respect his answers and it gives everyone a different look or more options at the subject.
...
With that being said, I believe the reseason RB said that was he was describing a tight on entry condition. I think we pretty much all agree that stiffening the RR will tighten entry. So upping the RR spring rate would make his entry worse, would it not? If you have a different reasoning behind this could you state that reasoning

No problem...i've been around the net long enough. Got a little a crazy there...my bad. That's what i get for posting at work.

Actaully we find that a stiffer RR spring isn't that big of a change on entry.... we find that the RR lower bar, RF spring and static rear steer has more of an effect on entry...very little braking. The spring change for us affects more middle and exit. Then we tune exit with the upper bars and bite. We worked mainly with the stagger, j-bar, some lower bars and springs to get it better through the center. The spring change evened out our tire temps, improved lap times and the driver said it was better.

Our tracks are simular to what he described. We are also down on power with our spare engine(iron block)... 650-700hp. We also had the same problem he stated..."tight in the middle". We setup to be the best in the corner that has bite up high and no one is running up there...while in the other corner its pretty much one lane, follow the leader and don't spin the tires coming off.

Once we got it netural, we only make very small changes at most any other track we go to... 1/4 to 3/8ths. Fremont, OH, Oakshade, OH, Butler, MI and Kamp, IN this weekend.

Wildchild, I don't think you mentioned what stagger your running....what stagger are you running?

[Rocket Bonehead]

RB...Since we run a 2005 GRT, also a 2006 feature winner at our local track, 7 straight heat race wins, 3rd in ALMS 2006 Oakshade race... i guess we don't know so much about GRT's....so I'll shut up now. :roll:

Everybody may like a different setup and have different ideas on how to fix the problem, but the physics stay the same.

You will need to adjust your driving style if it's different on each end, kinda the way it is....just got to find what works for you. Billet is on the mark with setting up for the tighter corner and then figuring out what you need to do at the other end.



Whoa man, I wasn't attacking you. I just disagreed with your comment, nothing more. I've helped a few guys out with Goats and they almost always ran a 200 or 225, and with anything stiffer, they complained about the car being too tight and not wanting to take a set.


Each car is different. Billet summed up my thoughts on a stiffer RR spring. That said, it isn't for every car or every driver. I wasn't attacking, bashing, or singling you out in anyway. No offense was intended, so my appologies if it came across as such. Congratulations on your success this year.



Back to the subject at hand, I would agree with Billet on freeing the car up for the tighter corner and driving around that in the larger corner by trail braking. Like Billet said, it is very hard to be good on both ends of the track when you have two different corners (unless you change how you drive them).



I would also agree with Timmay & Billet on using the brakes, and with Timmay on that you should work on your entry & middle before working on exit, but I would use a different approach to fixing those items than he suggested. That all goes back to some different views we have on adjusting the bars (an entirely differnt topic all together, lol).



RB

[ScottyRocket]

RB.... No problem... like i metioned above... i shouldn't post while at work. Sorry i came off the handle some.

My driver(s) doesn't like a bunch of static rear steer and the car does slow down later in the run if we do run more. Dynamic rear steer has just about the same effect on lap times...so we try to run with as little as possible.

We've had pretty good luck on good tack to dry slick tracks.... just getting out motored on heavy tacky tracks and early in the night..at least with the 2005 car. My other driver(2004 GRT) is way tight with a 200-250 in the RR, but he doesn't go in as hard either...both cars react the same to the changes, just the driving styles are completely different. It's hard taking a pavement driver and trying to get them to drive dirt correctly.

I agree.... get it working better on the tighter end and use what you can to make it better at the looser end(driving style/line, braking, etc.). You can sometimes make changes that affect one end more than the other, it's just finding those adjustments that do that.