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citiracer
07-06-2011, 08:02 AM
On one of the tracks we race at we have been fighting an entry push (on or off the gas). We've got the bars in "by the book" position for tacky track which should help it turn. Our springs are LF-500, RF-450, LR-225, RR-225. 54.5% left, 53.8% rear, 80 lbs of bite. J-bar is 1/2" above pinion on pinion side and at 8.5" on frame. Ballast is mounted in reasonable locations that shouldn't be causing the issue.
This track is much higher banked than other tracks we run. We normally run a 425 RF spring at other tracks but it bottoms out at this track so we switched to the 450 which should also help us turn on entry I think.
We were finally able to get it to turn good on entry by moving the lower right bar ALL the way up but this seems like a crutch to me since that is an extreme setup and this is when the track slicked off so I really don't know if that would have worked earlier in the night. Is there anything I am missing for a high-banked 3/8 deal that is causing our problem? Do I need to try raising the entire j-bar a little bit? For what it's worth, the entry push gets worse and worse as the race goes on but we aren't overheating any of the tires and they appear to be working good.

MasterSbilt_Racer
07-06-2011, 08:35 AM
What type of shocks are you running?

citiracer
07-06-2011, 11:07 AM
Afco twin tubes. We've had them done by a very reputable shock guy. We're going to step up to gas shocks all the way around next season.

rubbinsracin
07-06-2011, 11:29 AM
we run the twin tubes and they are a good shock. might lower the LS % just a bit. we had this problem at the beginning of the year with a push...especially on throttle...and we lowered out LS% down to 53.5 from 54.5 and it really made a big difference.

where do you have you bar angles at?

MasterSbilt_Racer
07-06-2011, 11:30 AM
I would lower the j bar at the frame.

jedclampit
07-06-2011, 11:34 AM
Try a 200# spring in the RR
..... make sure camber is correct at rf.
Some big corner banked tracks it takes a lot (150-240#) of bite to get the car loosened up in.
The rr spring change should make a noticeable difference.:cool:

MasterSbilt_Racer
07-06-2011, 11:56 AM
Try a 200# spring in the RR
..... make sure camber is correct at rf.
Some big corner banked tracks it takes a lot (150-240#) of bite to get the car loosened up in.
The rr spring change should make a noticeable difference.:cool:

I was a little scared to suggest that not knowing how bad the push was, shock travels, etc. It will make a big difference though.

citiracer
07-06-2011, 12:09 PM
As far as how bad the push is...it's an actual push and not just a "tight" condition. One of the corners is a little more banked than the other one and the push is worse in that corner.
We are about 2 inches from bottoming out on RR shock travel and the track is kind of rough so it probably isn't traveling that much all the time so I think we may have room for a softer spring there.

35racing
07-06-2011, 01:41 PM
Im fighting the same issue and my setup is almost spot on to yours except im around 130# wedge and Im running a 200# RR. my track has some banking but not extreme and its a 1/2 mile. I moved both LR and RR top bars all the way up and it has helped a fair amount but now pushing in the middle the longer the race goes on also.

It does seem like a crutch to be running these bar angles on a slick track!! Im thinking of going up with the J-bar myself.... running out of ideas:confused:

Good luck

jedclampit
07-07-2011, 12:43 PM
I was a little scared to suggest that not knowing how bad the push was, shock travels, etc. It will make a big difference though.
I went there because he said he can run the rr lower uphill, in slick conditions!

To Citiracer---You MAY not have the correct ride height at the rr, I can't help you with a measurement, although MBR probably can & will.
A 450 in the lf may be worth a try also,some banked tracks require you to load up the cross in the chassis, either statically or dynamic to get loosened up.

Is this an older car?
A full setup may disclose other areas of suspect, :cool:

01racing
07-07-2011, 01:13 PM
do you really think you need a 450 rf spring

citiracer
07-07-2011, 03:18 PM
It's a 2005 with 2011 updates.
Full setup is pretty much in my original post - let me know if there is additional information that might help.
RR ride height is 7-3/8" per MasterSbilt.
The only reason we run a 450 RF on this particular track is because we bottom out the shock on anything softer. We normally run 400-425 on lesser banked tracks and have considered going even lower. This higher-banked track is the only place we are having this push on entry issue although we have been on the tight side most of the year when the tracks are tacky but we've been able to correct it for the most part.
At this point I think we may try the softer (200) RR the next time out at this track.

dualdj1
07-07-2011, 03:29 PM
remember softening rr spring can also tighten you on exit. softening left front will mainly effect entry, but can loosen up overall. just another way to go with it.

racin29
07-08-2011, 12:44 AM
what are your front tire pressures you said its not really a tight condition its more of a push, like wheel slide? is the car on the bars going in or not, also is it a big momentum track

grt74
07-08-2011, 06:23 AM
you could rock the car over some too,on a high banked track the car is pulled more down in stead of to the right,bite,lf spring,rr spring,left side % but we go up on it if the car wont turn,just some ideas also most of the time very little j bar until it slicks off

citiracer
07-08-2011, 07:19 AM
Tire pressures are
8 10
6 8

Car is up on the bars going in but falls a little if I use the brake.

racin29
07-08-2011, 10:35 AM
that might be too soft on the front try going up to 10lf 12rf should help the car turn more positive might just be the right front is to squishy and the tread is loosing contact

JB1K
07-08-2011, 12:32 PM
I read somewhere that standing the RR shock up (more towards vertical) will loosen it up on entry. My car has two different upper mounting points but I havent tried this yet.

rubbinsracin
07-08-2011, 12:38 PM
I read somewhere that standing the RR shock up (more towards vertical) will loosen it up on entry. My car has two different upper mounting points but I havent tried this yet.

be careful with this, because standing the RR shock up can cause the car to "skate" up the track. youre pressures all the way around seem a little low. we run LF 10 RF 12
LR 6 RR 10

dualdj1
07-08-2011, 02:29 PM
I read somewhere that standing the RR shock up (more towards vertical) will loosen it up on entry. My car has two different upper mounting points but I havent tried this yet.

This is correct to an extent. It moves your moment center (roll center) right, which means your car tries to roll over less, which transfers less weight to rr, which loosens. but when you roll less, yes it can skate up on you if you don't have good traction at the wheels.

Rear MC lateral location (left to right) exists halfway between chassis spring mounts. If you want more or less roll, adjust your mounting point. Otherwise leave it alone.

grt74
07-08-2011, 07:33 PM
i see said the blind man after seeing the air pressures your running go up on the rr until it fixes the problem i would start at 10 or 11 psi, if it helps some but you need more go up some more

citiracer
07-09-2011, 09:18 AM
Okay we might try the air pressure but I always thought of air pressure as more of a fine tuning thing. The problem we are having is far from something that a fine adjustment is going to fix. Am I missing something?

racin29
07-09-2011, 10:39 AM
yes you are right tire pressure is a fine tuning thing but it looks like your tires are so soft that they are flexing too much and loosing contact you have to still be at a zero to adjust and you are below zero, two pounds is also alot on these tires(2 pounds on a 10 pound tire is 20%) just give it a try in hotlaps go up two pounds everywhere(to keep stager the same) if it doesnt do anything you can call me bad words when you get home :D

citiracer
07-11-2011, 12:15 AM
yes you are right tire pressure is a fine tuning thing but it looks like your tires are so soft that they are flexing too much and loosing contact you have to still be at a zero to adjust and you are below zero, two pounds is also alot on these tires(2 pounds on a 10 pound tire is 20%) just give it a try in hotlaps go up two pounds everywhere(to keep stager the same) if it doesnt do anything you can call me bad words when you get home :D

Hell I'll try anything once. It makes sense though when you think about it with the high banked deal and pressure being to low. We might just be getting way to much rubber on the ground on the RR.

K15
07-11-2011, 02:48 PM
what engine combo do u have?? aluminum, steel block, all steel?? we run a steel block and run a 500 on the rf

citiracer
07-11-2011, 04:10 PM
Motor is all steel (602 crate). 450 is the heaviest 12" spring we have right now.
At this point I think we're looking at the following options when we go back to this track on 7/16:
1) raise the j-bar up on both sides
2) lower the j-bar on the frame side
3) softer RR spring (200)
4) more air pressure in RR

MasterSbilt_Racer
07-11-2011, 04:51 PM
Motor is all steel (602 crate). 450 is the heaviest 12" spring we have right now.
At this point I think we're looking at the following options when we go back to this track on 7/16:
1) raise the j-bar up on both sides
2) lower the j-bar on the frame side
3) softer RR spring (200)
4) more air pressure in RR

If this track has good banking and you are carrying some decent speed, all your tire pressures are a bit low. Your fronts may be rolling under real bad.

citiracer
07-12-2011, 11:31 AM
Another note...we ran a big flat paperclip 1/3 mile this past weekend that required a lot of brakes getting into the corner. We could never get the car freed up enough on entry and I think this might be because we have the RR brake on the birdcage as opposed to the axle. Now our tight condition at the high-banked place was regardless of whether brake was being used to try to turn the car so I don't think that is the complete solution for that track but I want to try clamping the RR brake to the axle to free entry at places like the flat 1/3 mile where a lot of brake is needed. Does that make sense?

MasterSbilt_Racer
07-12-2011, 12:23 PM
Another note...we ran a big flat paperclip 1/3 mile this past weekend that required a lot of brakes getting into the corner. We could never get the car freed up enough on entry and I think this might be because we have the RR brake on the birdcage as opposed to the axle. Now our tight condition at the high-banked place was regardless of whether brake was being used to try to turn the car so I don't think that is the complete solution for that track but I want to try clamping the RR brake to the axle to free entry at places like the flat 1/3 mile where a lot of brake is needed. Does that make sense?

Yes. That makes sense.