changes for different tracks?

[mbaker76]

Going from a dry stop and go type track, to a fast grippy momentum type maybe with a little more banking, would it be typcial to stiffen the right side springs some because of the higher speeds? Talking almost from 1 extreme to the other, the dry track is dusty dry and slick and you use the brakes a lot, then the tacky track is heavy and barely out of the gas, maybe never even touch the brakes.

What other changes would be typical.

[Rocket Bonehead]

A stiffer RF, yes, and possibly a stiffer LF as well (to help stabilize the front of the car on corner entry). Adjust the RR if the car is rocking back on the RR too much and/or you have too much/little RR drive.


Other than the RF spring, I would start off with your neutral setup, hotlap it, and then adjust from there. Typical changes in going from one type of track to another (such as you described) would probably revolve around getting the front end stable, adding RR drive, or removing LR drive (or all of the above). If you have a good, balanced, setup in your car now, you will probably find that you won't need to change much from track to track (regardless of which brand of car you run).



RB

[mbaker76]

All of this happened last weekend. We decided to try it as is friday night and it was way tight all around, in thru and off, didnt have a lot of time so lowered teh LRU 1 hole and put more stagger in, better but still tight in, he said unless he got it sideways getting in it was screwed through the middle. Saturday we decided to loosen it up, raised the jbar 1" at pinion, went down 50# on the LF spring, up 25# on the LR spring and raised the RRL 1 hole. Was better in but on the gas still got tight in middle, raised LRL for 'b' feature, was better but still tight off. Then as he moved down to the middle and inside groove, he said he would be going along (on the gas) and all of a sudden it felt like the RR just dug in and the car then pushed up the track, to me it looked like the point he is talking about was right about the apex and the RR gave up and just collapsed. Looking back I think what happened was the RR was taveling so far that the bars were leveling out out so much it lost all drive.
Thats why i thought maybe a stiffer spring would help hold that corner up and keep some more angle in the bars, and possibly put more angle in the RRU bar when we raised the RRL. We never bottomed out the RF but maybe the stiffer spring would have freed the car enough to turn better getting in and the stiffer RR would help free it some on the gas to offset any tightness on exit from the stiffer RF.

[pinionangle]

I fight this problem going from a hooked up 1/2 mile to a dryslick 1/4 mile track. This is what I do and its starting to work really good for me.

Tacky half mile i'll take left rear out, raise RU two holes higher than LU and maybe go up on my RF spring 50 lbs. I dont mess with my stagger much and I hardly ever get off my standard springs unless the track has a ton of banking. My car seems to respond best to bar angle changes and as of late taking leftrear out seems to make my car better. My standard left rear is 80 lbs. This is what I leave the shop with and I may go up a touch but usally I leave it alone. I cant tell you the last time I moved my j-bar. I've thought about it plenty but my whole game plan this year was to make little changes from hot laps to feature. If I do make changes there small and few.

When I go to a track I know is going to slick off i'll start with 120 lbs of left rear, LU bar up and RU down one hole. Usally I start with my bottom bars level and work from there depending on the feel of the car getting in.

I've also added Right front castor in the last few weeks thats helped from the middle off. Kinda makes it a pain at low speeds but it sure seems to help when im back stearing.

Im no expert at this but these things seem to work for me right now. Next Sat I might be scrathing my head yet again.

Good luck.

[Rocket Bonehead]

All of this happened last weekend. We decided to try it as is friday night and it was way tight all around, in thru and off, didnt have a lot of time so lowered teh LRU 1 hole and put more stagger in, better but still tight in, he said unless he got it sideways getting in it was screwed through the middle. Saturday we decided to loosen it up, raised the jbar 1" at pinion, went down 50# on the LF spring, up 25# on the LR spring and raised the RRL 1 hole. Was better in but on the gas still got tight in middle, raised LRL for 'b' feature, was better but still tight off. Then as he moved down to the middle and inside groove, he said he would be going along (on the gas) and all of a sudden it felt like the RR just dug in and the car then pushed up the track, to me it looked like the point he is talking about was right about the apex and the RR gave up and just collapsed. Looking back I think what happened was the RR was taveling so far that the bars were leveling out out so much it lost all drive.
Thats why i thought maybe a stiffer spring would help hold that corner up and keep some more angle in the bars, and possibly put more angle in the RRU bar when we raised the RRL. We never bottomed out the RF but maybe the stiffer spring would have freed the car enough to turn better getting in and the stiffer RR would help free it some on the gas to offset any tightness on exit from the stiffer RF.


A stiffer RF spring would help from the center out in that application, but it might make the car tigher on entry. The entry part is hard to say for certain as if the RR is already locked down getting in, the stiffer RR might help the car cut better which will help it turn better as well. 50lbs stiffer would be a good starting point for a change (to see a very noticeable effect).


A stiffer RF would also help the car cut better getting into the corner.


I would agree with PA that adjusting your bars to help promote RR drive will help as well. I stated in my first response that adding RR drive or removing LR drive would be some of the first things I would do, but I neglected to mention how. I was refering to adjusting the bars to accomplish that.



RB

[mbaker76]

RB quote:
A stiffer RF spring would help from the center out in that application, but it might make the car tigher on entry. The entry part is hard to say for certain as if the RR is already locked down getting in, the stiffer RR might help the car cut better which will help it turn better as well. 50lbs stiffer would be a good starting point for a change (to see a very noticeable effect).

A stiffer RF would also help the car cut better getting into the corner.
------------

In the first line did you mean stiffer RR would help, but may tighten entry???


So was the jbar a bad move then? My thinking there was that since normally our track is slick and you have to generate traction we had it lower and less left% in the car to get the car to set on entry. Then with grip in the track either home or somewhere else, there is already traction there so we dont have to create as much overturning force because the car does it on its own. Thats why i thought moving teh panhard bar up would take some of the excess transfer out of the car and balance it out better. Maybe this track is just so different that wasnt enough though.

What i dont get is how we can run a 200# RR on 4 bar and the thing rolls like it does and acts like it needs to be stiffer, yet some of the local guys are running 175# on top the housing with a 2 link?

It makes sense that since your barely get out of the gas on entry then hammer back down a stiffer RR in that case could loosen the car late entry, possibly along with more RR bar. I can also see where the stiffer RF would help but would be afraid it would get tight off, even with taking LR drive out but maybe not.

maybe evening up the front springs and stiffening the RR would have been the way to go?

[Rocket Bonehead]

RB quote:
A stiffer RF spring would help from the center out in that application, but it might make the car tigher on entry. The entry part is hard to say for certain as if the RR is already locked down getting in, the stiffer RR might help the car cut better which will help it turn better as well. 50lbs stiffer would be a good starting point for a change (to see a very noticeable effect).

A stiffer RF would also help the car cut better getting into the corner.
------------

In the first line did you mean stiffer RR would help, but may tighten entry???


So was the jbar a bad move then? My thinking there was that since normally our track is slick and you have to generate traction we had it lower and less left% in the car to get the car to set on entry. Then with grip in the track either home or somewhere else, there is already traction there so we dont have to create as much overturning force because the car does it on its own. Thats why i thought moving teh panhard bar up would take some of the excess transfer out of the car and balance it out better. Maybe this track is just so different that wasnt enough though.

What i dont get is how we can run a 200# RR on 4 bar and the thing rolls like it does and acts like it needs to be stiffer, yet some of the local guys are running 175# on top the housing with a 2 link?

It makes sense that since your barely get out of the gas on entry then hammer back down a stiffer RR in that case could loosen the car late entry, possibly along with more RR bar. I can also see where the stiffer RF would help but would be afraid it would get tight off, even with taking LR drive out but maybe not.

maybe evening up the front springs and stiffening the RR would have been the way to go?



Yes, I meant the RR...


I think you were on the right track with raising the J-Bar at the pinion. That will free the car up all the way thru the corner. Like I said before, it could simply revolve around the R side springs just being too soft.


If you are on the gas a lot, then yes, the stiffer RR will free the car up all the way around. Even in the slick, when you find the right balance, a stiffer RR spring can lead to better overall traction thru the corner (including off). That of course is my opinion, based on my experiences, so others may vary.


The reason you can run a softer spring on top of the housing is because the spring is standing straight up (or close to it) and it is only subject to the force applied down upon it from body roll (weight transfer). When you run a spring 'tilted in' like most 4-link cars do, the spring rate 'acts' softer than the listed rate (there's an equation to figure it out, but I don't have it in front of me). Also, when you run it floated on the front of the birdcage, you have both the body roll (weight transfer) pushing down AND the indexing of the birdcage causing the bottom of the spring to be forced upward (due to the movement and force applied thru the bars). The more force you have that is trying to be applied, the more spring rate you will need in order to control it (to a point).


In my opinion, a 2-link RR won't have the side bite, or forward bite, that a 4-link RR will have, thus the car will be less affected by changes in track conditions (tacky/slick, smooth/rough), and it should be good and consistent in the tacky/rough. With a 2-link, all of the force is strictly applied thru the spring (the link is simply a locating device, like a PH Bar), where in contrast, with a 4-link the force is applied both thru the spring and thru the bars. If you find the proper rate needed for your situation, you can be just as comfortable and fast with a 4-link RR in all conditions, including when it is tacky/rough.



If you had a 200 in, I'd try a 250 and see how the car responds.




RB

[mbaker76]

In my opinion, a 2-link RR won't have the side bite, or forward bite, that a 4-link RR will have, thus the car will be less affected by changes in track conditions (tacky/slick, smooth/rough), and it should be good and consistent in the tacky/rough. With a 2-link, all of the force is strictly applied thru the spring (the link is simply a locating device, like a PH Bar), where in contrast, with a 4-link the force is applied both thru the spring and thru the bars. If you find the proper rate needed for your situation, you can be just as comfortable and fast with a 4-link RR in all conditions, including when it is tacky/rough.

RB

I think thats part of the problem, trying to convince the driver that we need to change something. I think he feels like the car should work the same all the time, and maybe with a 2 link car it would be less noticeable like you say, but when we get our 4 link car right on one track then go to the complete opposite its going to take some changes.

I searched and searched through some notes and found last year at the same track we were runnin straight up springs across teh front, and a 225RR with spring rubber

last year
650/650
250/225R

this year
750/650
200/200

then went to this
700/650
225/200

the reason we didnt start that way is because this was a different car, similar but different and this one was working better for us weekly, and we felt we had it setup better, so we thought we would try it as is.

Another thing came up when i talked to him, he said it felt like the car wouldnt set right away, like it would slide just for a second then the right side would grab and set, at first thought is from raising jbar, but maybe the stiffer springs would have helped that too. the track had dried some by this time so maybe it was just a little loose now...i dont know.

He also said that whenever we take angle out of the LRU, even when its grippy, it feels like it loses forward bite. Not necessarily loose like to much RR drive just not as much forward drive. could that be beause of teh softer RF, maybe we could run less bar angle with a stiffer RF and let the car cut better getting in but still come off good? Im talking moving 1 hole, 3-4* thats it.

[Chris Steele]

What kind of car are you running those front springs on? Wow, that's stiff!

[mbaker76]

sorry should have mentioned its a mod..... just not much info in that section yet.

[Rocket Bonehead]

I think thats part of the problem, trying to convince the driver that we need to change something. I think he feels like the car should work the same all the time, and maybe with a 2 link car it would be less noticeable like you say, but when we get our 4 link car right on one track then go to the complete opposite its going to take some changes.

I searched and searched through some notes and found last year at the same track we were runnin straight up springs across teh front, and a 225RR with spring rubber

last year
650/650
250/225R

this year
750/650
200/200

then went to this
700/650
225/200

the reason we didnt start that way is because this was a different car, similar but different and this one was working better for us weekly, and we felt we had it setup better, so we thought we would try it as is.

Another thing came up when i talked to him, he said it felt like the car wouldnt set right away, like it would slide just for a second then the right side would grab and set, at first thought is from raising jbar, but maybe the stiffer springs would have helped that too. the track had dried some by this time so maybe it was just a little loose now...i dont know.

He also said that whenever we take angle out of the LRU, even when its grippy, it feels like it loses forward bite. Not necessarily loose like to much RR drive just not as much forward drive. could that be beause of teh softer RF, maybe we could run less bar angle with a stiffer RF and let the car cut better getting in but still come off good? Im talking moving 1 hole, 3-4* thats it.



As far as the LR angle goes, he could be correct in that the car doesn't like running the LRT rod any lower, but it could also be a 'mental' thing too. It is hard to say without seeing it first hand.


As for the entry problem, it sounds as if the R side is just a little lazy on entry, and that could be due to the soft R side springs. I'd try stiffening them 50lbs each and see what happens. That said, if you ran the PH Bar up on the pinion when it started to slick off, that too could be part of the cause of that problem.



RB

[mbaker76]

to kind of back up his thoughts on the LR, most times we have lowered the LRU we have lost heat out of the tire. I also wonder if taking out the angle takes out enough steer that it wont turn and he busts it loose in the middle. maybe the lower angle with more steer would work too? migh be something to try?

Maybe our car just likes that bar angle in the LR and if we need to free it on the gas, we need to put more RR in it instead of taking out LR?

On the entry you could see the car slide just a little bit, it didnt just roll over and up on the bars like before. I wouldnt say it was slick yet but getting there, and it was kind of spotty, around the track. Like you said maybe too soft of springs, and maybe too stiff of shocks, at least on RR.

[Rocket Bonehead]

Maybe our car just likes that bar angle in the LR and if we need to free it on the gas, we need to put more RR in it instead of taking out LR?




That is what I would do.



RB

[mbaker76]

i think thats what i will do, i feel like we are ok on the left side bars (LRU 24, LRL 2-5) but the right side seems shallow (RRU 14 RRL 0 to -3). It doesnt take much roll on the RR to level out the top bars. Makes sense now why the guys on the Z links were freer, as there cars rolled they gained a lot of bar angle to free the car, whereas our 4 bar RR with similar travel were losing so much bar angle. Thats prob what saved us last year on the tack was we were getting less travel so we were losing less bar angle. I think i will raise both right side bars 1 hole to 17 and 0 and see what happens this weekend. We are going to a similar track where its hard to turn the car and plenty of banking as well.

I know other guys running the same car as ours, but seems like with less bar angle, but i hear that they are stiffer (50#) on the RF. Could the stiffer RF make up for less bar angle and keep the car tighter off the corner.

I have been working under the idea of trying to get as much travel on the RF without bottoming it out as possible, to let the front end work and move through the corner. And at the same time keep it free on the gas in the middle. We have been using 3 1/2 of 4"max travel consistently, occasionally if its rough we'll bottom out but usually a little stiffer shock from a 4-6 easy down to a straight 5 will take care of it. Maybe the stiffer spring with the easy down is a better deal all around?

[billetbirdcage]

i think thats what i will do, i feel like we are ok on the left side bars (LRU 24, LRL 2-5) but the right side seems shallow (RRU 14 RRL 0 to -3). It doesnt take much roll on the RR to level out the top bars. Makes sense now why the guys on the Z links were freer, as there cars rolled they gained a lot of bar angle to free the car, whereas our 4 bar RR with similar travel were losing so much bar angle. Thats prob what saved us last year on the tack was we were getting less travel so we were losing less bar angle. I think i will raise both right side bars 1 hole to 17 and 0 and see what happens this weekend. We are going to a similar track where its hard to turn the car and plenty of banking as well.



Going off a LM it appears you have to much split between the L and the R sides. With 24 & 2-5 on the LR, I would suggest 17 to 18 on the RRU and +2.5 on the RR. Then use the lower bar to loosen or tighten entry.

So raising both right side bars would be what I'd start with and go from there.