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Author Topic:   Mid-turn loose..
GnarlyCar
Member
posted April 19, 2000 08:07 PM
OK, guys, I think I'm darn close... 2500# metric Mod, 56.5% rear, 53% left, 52.5% cross, 3" stagger. LF 650# w/ easy out (6-2)carrera, RF 750# w/ 76 afco, RR 200#, LR 175# w/ Bilstien equivalent to 5 valve across the rear. 4-bars at 16" and 20 degrees (upper)and 14" and -5 degrees (lower) both sides. Brake floater rods at 10 degrees both sides. Panhard @ 29" mounted 3" below axle center and approx 8" right of center of rear end, and 3" higher at ch***is (left side). 32" torque arm w/ progressive spring set w/ 1/4" preload and 10/90 braking shock at 28" on torque arm. Running a sliced and diced Hoosier Hard Bozz on RR, Super Bozz on LR, and supers across the front.
The car goes into the corner beautifully, takes initial throttle nicely, but begins to loosen up a little bit as I get through the middle. I wait for it and when it comes back, it hooks up a TON and rockets off the corner. P***ed a bunch of cars with it Saturday, but that was from the back of a B main after cutting a tire in the heat. Not sure if it's enough to run with the dogs in front of the A. I'd like to get it to stay under me a little better through the middle of the corner, as I don't feel I should have to lift off the throttle as much as I did. I'm thinking a small spring rate change in the rear should be the answer, but I've never really had the budget to just go buy things that I wasn't positive would work, so I'm hoping to find a popular opinion in here on which to base my next spring purchase.

Fire off a few opinions, guys..

Thanks,
Matt


bbracer17
Member
posted April 19, 2000 09:21 PM
Not sure how much this would help but I run my easy up on the right front. Try swapping your front shocks, it's free.


jammin
Administrator
posted April 19, 2000 09:41 PM
Sounds like a roll steer issue to me. When the weight is transferred to the right rear the hardest (middle of turn) is when the rear is being pushed back somewhat. You can work on the geometry of your arms to make the right rear either stay the same, or come to the front. If it comes to the front, it will make your car come off even harder.

Hope this helps.

jammin

GnarlyCar
Member
posted April 21, 2000 12:54 AM
Thanks, guys...I had completely forgotten about the adjustments to the 4-bar angles until I was thinking about it at work today. Until this spring all I had driven was a 3-link, so I still haven't gotten used to the idea of having that much more to adjust with.
The problem is that I think the 4-bar angles will affect the way the car goes into the turn also, and I don't want anything to change there.
By swapping the front shocks, I think the car would be a little too tight on initial throttle, as my starting set-up had equal shocks across the front and the LF was replaced w/ the easy out to cure a tight condition on initial throttle to begin with. I can see your point about switching them.. that would probably cure the midturn problem but I think would worsen the entry condition.
I'm a bit leery of changing anything that might affect the entry (braking) and initial throttle conditions, as I've been pretty sold on the idea of working the car through the corner in several steps,ie; you can't fix an exit problem on a car that doesn't get in well. In other words, fix problems in order. First entry, then mid-turn, then exit after the rest is working well. I've got the car going in and getting set nicely, but it just seems to go away a little as it goes through the turn.
As I understand the way springs work, a stiffer spring will take a load quicker, but not take as much sustained wieght on any given corner. By my thinking then, wouldn't a rate increase of 25 lbs or so at the RR make it a bit more loose on initial throttle, allowing me to put my 6 valve back on the LF, then leave a bit more wieght on the LR through the middle, tightening the car up through there? Or, could this be as simple as lowering the ch***is end of the panhard bar?
Forgive my ramblings...it's way past midnite and this whole mess is keeping me awake.

Thanks in advance for your replies..
Matt...way too hard-core..


retired
Member
posted April 24, 2000 01:49 PM
You also may try to drop the panhard bar down 1 hole and see if the car stays under you better
quote:
Originally posted by GnarlyCar:
Thanks, guys...I had completely forgotten about the adjustments to the 4-bar angles until I was thinking about it at work today. Until this spring all I had driven was a 3-link, so I still haven't gotten used to the idea of having that much more to adjust with.
The problem is that I think the 4-bar angles will affect the way the car goes into the turn also, and I don't want anything to change there.
By swapping the front shocks, I think the car would be a little too tight on initial throttle, as my starting set-up had equal shocks across the front and the LF was replaced w/ the easy out to cure a tight condition on initial throttle to begin with. I can see your point about switching them.. that would probably cure the midturn problem but I think would worsen the entry condition.
I'm a bit leery of changing anything that might affect the entry (braking) and initial throttle conditions, as I've been pretty sold on the idea of working the car through the corner in several steps,ie; you can't fix an exit problem on a car that doesn't get in well. In other words, fix problems in order. First entry, then mid-turn, then exit after the rest is working well. I've got the car going in and getting set nicely, but it just seems to go away a little as it goes through the turn.
As I understand the way springs work, a stiffer spring will take a load quicker, but not take as much sustained wieght on any given corner. By my thinking then, wouldn't a rate increase of 25 lbs or so at the RR make it a bit more loose on initial throttle, allowing me to put my 6 valve back on the LF, then leave a bit more wieght on the LR through the middle, tightening the car up through there? Or, could this be as simple as lowering the ch***is end of the panhard bar?
Forgive my ramblings...it's way past midnite and this whole mess is keeping me awake.

Thanks in advance for your replies..
Matt...way too hard-core..




X-1R Guy
Member
posted April 24, 2000 03:52 PM
GNARLY I told u 1 time that it sounded like we think alot alike.
I think you have solved this 1 on your own already.Check your rear shock travel and adjust your r/spring split so your eather
the same or heavier on theL/R as the R/r.


A2KY2K88
Member
posted April 25, 2000 01:02 AM
SINCE STAGGER AFFECTS THE CAR IN THE MIDDLE OF THE TURN THE MOST, REDUCE YOUR STAGGER TO ABOUT 1 INCH ON THE REAR. ITS FREE! 3" IS WAY TOO MUCH. TRY THIS FIRST. ALSO, SWAP YOUR RR AND LR SPRINGS AND YOU SHOULD BE RIGHT IN THE GAME. BOTH OF THESE TOGETHER WILL MAKE A HUGE DIFFERENCE AND SHOULD NOT AFFECT ENTRY TOO MUCH. LET ME KNOW IF THIS WORKS. IT DID FOR ME..


MelFer
Member
posted April 26, 2000 01:50 AM
try taking about 1/2% cross out of the car You may be rolling tooo much off the LR


Sidebite
unregistered
posted May 02, 2000 08:59 AM           
Hey Matt how about an update!

What did you try and did it work?

GnarlyCar
Member
posted May 02, 2000 01:48 PM
Thanks for everything you guys.. All your suggestions were certainly considered, but what I ended up doing was raising the upper bar on the left side to try and drive that tire harder into the dirt. My suspension model showed it to bring only a very small change in rear steer, but a drastic increase in anti-squat.
I went out the week after this was originally posted and hot lapped it as it was the week before just to get a feel for it again, and it did the same thing it had the week before, so I was sure I wasn't just dreaming up excuses for myself. After raising the upper on the left side, I went out for the heat race, started 7th and had worked into a pretty heated battle for 3rd before jumping the cushion and throwing the right rear spring completely out of the car(fixed that..it won't happen again). I finished the race riding on the fender in 6th and was left to run from near the back of the B. After starting 14th there, I had moved to 9th after 3 laps when there was a restart, but the spotters didn't see things the way I did and put me back to 14th again. In the few remaining laps we were given the car worked well wherever I drove it, but there just weren't enough laps to get any closer than 7th.
Since then, my Friday night track opened and we won a heat race from 6th, and ran 2nd in the feature from 4th, being beaten only because after I passed for the lead I stayed low on the track where I had made the pass, and was beat by a guy who was rolling through the black in the middle of the track. After he passed me, I moved up behind him and we had a good race to the end, but I didn't have enough for him out of his groove.
This weekend, I started 2nd in the heat and stayed there for 5 laps, but my RR jack bolt began to move and by the end of the race it had backed out about 1/2"(fixed that too...it won't happen again), making the car nearly undriveable and I finished 6th. After moving it back as best I could on bumpy ground without scaling the car, I ran from 6th to 3rd in the B, and started the main in 23rd spot. Before the main, I had moved the RR upper one hole up (3/4") to try to free the car up a little in the middle of the turn (I know...why's he wanna free it up when it was too free last week?? The fast groove this week was on the bottom, where the track is very flat, as opposed to the top where it's wicked steep..), but it went too far and the car was very loose through the middle and off, and I was only able to get up to 17th. I originally wanted to put a turn into the LF to do this( which, in hindsight, I think would have worked better), but my son figured we had nothing to lose starting back as far as we did and talked me into it, just to see what would happen. Well, I got a good seat-of-the-pants feel for what that change will do, so it wasn't a total loss, anyway.
The car is very close, and after I get all the stupid little problems out of the way, I think we're gonna be able to make some pretty decent runs at some of the hot rods this year.
Aside from raising the RR upper, all the changes have done just about what I'd expected them to, showing me that this style of rear suspension should prove to be quite predictable. I already know it drives a lot smoother than the old 3 link.

Thanks, Matt
PS, see my next post..there's another issue I'm thinking about.

[This message has been edited by GnarlyCar (edited 05-02-2000).]

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