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Old 07-04-2010, 10:33 AM   #1561
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Asphalt setups for the Gen X 10 were recently discussed here and in a few followup posts.

http://www.rctech.net/forum/7590768-post1152.html

Roll Steer
a fellow asked by PM about the 0.040 inch roll steer reccomended on some of the factory setups for the Gen X 10.

You add roll steer by elevating the front of the two side links. When the car rolls the rear then steers out a little. I add a lot of roll steer to my pro cars, 1 degree of roll steer out on my cars. This frees up the rear end in the corners.

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Old 07-07-2010, 08:03 AM   #1562
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As I crash more then I would like to admit. At this time I am looking at adding the 3mm thick top pod plate and adding an additional X-brace to the rear of the car. Was thinking of switching from the aluminum to steel fasteners so that I could torque them down harder.

My question is does adding additional weight behind the axel cause handling defects?

My second problem is my turning grip is not balanced with my rear grip. By adding additional weight to the rear pod will this significantly affect the rear grip of the car. Or should I be thinking about softer side springs and dampening.
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Old 07-07-2010, 08:58 AM   #1563
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Micah-Use the 4 mm CRC top plate or a double stock top plate to get 5 mm. Yes use the steel screws, then you can use blue loctite and they won't back out any more.
I have not broken an X brace. You may just want to keep it stock to avoid the extra weight.

Adding 1.5 ounces (a speed control) to the pod causes unwanted oversteer. Adding steel screws and a heavier top plate will have little effect.

JS Pro 10 report from Barcelona, Spain

"Hello John:

Ive tried the car last weekend. We had a race. The grip was very good and I could win the race. The car (or me with the car) is going faster every day. The last race I was the fastest (including touring cars) and my best lap was near a second better than the next best lap so I think I made a good purchase LOL.
The problem with the shocks was the same so I replaced them.
I think I can go a bit faster but need to drive more the car because the driving of this car is different the other cars I had.

Congratulations for your design!!!"
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Old 07-07-2010, 12:27 PM   #1564
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Good to know the car will not behave strange after I'm done Frankenstein it.

With the heavy duty top plate my motor will hopefully not be able to pop forward. I have broke the rear X-brace by backing the car into the outside boards at the end of the straight usually it also takes the left small bulkhead with it as well.

Beefed up rear Pod

John - Have you played around with the rear roll center of your cars at all. Typically I do not raise the outside connection point for the damper tubes as I like the rear more planted.
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Old 07-07-2010, 01:23 PM   #1565
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Nice-now all you need are the steel screws.

Note the newer 2011 models of my JS Pro cars will come with a top plate that bridges the two side plates and by that fact alone will be much sturdier. They will have one generation older side metal plates with a long left side pod plate. The motor will be more secure with all aluminum slots for the motor screws. Machined prototype parts are on the way to me today.

Roll centers- I have played extensively with the roll center of the rear of the car and this is what I have found. You have absolutely no control of it; it is fixed at the center of the rear axle. I have moved Panhard bars up and down 1/2 inch with no change to the handling whereas a .030" change to my front dual A-arm suspension pivots makes a noticeable change to roll center and handling.

There are some modern Pan car design that strive to get a low roll center by moving the T-plate down or in case of the Hatzenbach by using an elaborate multilink to make a virtual pivot below the chassis. If there is any change in handling, I believe it is from other factors like small changes in antisquat or in case of the lowered t-plates from milling giving a decrease in chassis stiffness.

So play with the pivot heights of the dampers to fine tune roll stiffness, but don't expect some big changes like when you have a handle on roll center. Equally useful will be to just change the viscosity and keep them low.

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Old 07-09-2010, 04:42 AM   #1566
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Quote:
Roll centers- I have played extensively with the roll center of the rear of the car and this is what I have found. You have absolutely no control of it; it is fixed at the center of the rear axle. I have moved Panhard bars up and down 1/2 inch with no change to the handling whereas a .030" change to my front dual A-arm suspension pivots makes a noticeable change to roll center and handling.

There are some modern Pan car design that strive to get a low roll center by moving the T-plate down or in case of the Hatzenbach by using an elaborate multilink to make a virtual pivot below the chassis. If there is any change in handling, I believe it is from other factors like small changes in antisquat or in case of the lowered t-plates from milling giving a decrease in chassis stiffness.
I think the rollcenter is exactly at the lower pivot point of the damper. With 0 droop, the sprung mass rotates around this point. The height of the panhard bar doesnt really matter, then. So, the rollcenter is not in the middle of the car. With a t-bar- or "normal" link-car, the rollcenter is in the middle and the distance between RC and CG is much smaller. A change of the pivot point height has then much more influence.
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Old 07-09-2010, 01:34 PM   #1567
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Note I have played with the pivot height on a center pivot side link car, again with no effect on rear traction. There was a low roll center kit available for the CRC cars.

When there is a panhard bar a virtual pivot exhists at the center of the Panhard bar.
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Old 07-09-2010, 01:38 PM   #1568
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So I got the Gen-X 10 out for practice 2 the other day. Grip was much better, but i'd say our track is a "Medium" at best.
For outdoor asphalt, how would Green rears work? I've never seen them recommended anywhere, but it appears as though they may offer more traction than Pinks.
For tire wear, I have put through about 6 packs, with my 13.5 set-up, and there is almost zero wear on the back.
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Old 07-09-2010, 01:43 PM   #1569
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Quote:
Originally Posted by JR007 View Post
So I got the Gen-X 10 out for practice 2 the other day. Grip was much better, but i'd say our track is a "Medium" at best.
For outdoor asphalt, how would Green rears work? I've never seen them recommended anywhere, but it appears as though they may offer more traction than Pinks.
For tire wear, I have put through about 6 packs, with my 13.5 set-up, and there is almost zero wear on the back.
Greens offer a lot of grip but the wear is very high. Pinks are a good compromise between wear and grip - Jaco also makes (or made) a "soft" pink but it seems a little inconsistent.
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Old 07-09-2010, 05:53 PM   #1570
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Thanks for that. I may give it a go. We only race once a month at our track, and the greens are quite a bit cheaper, so it's not a big outlay if I chew one pair per race meet. If it means more grip it's gotta be worth a nudge!
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Old 07-11-2010, 01:49 AM   #1571
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Well, had the first proper race run with the Gen-X 13.5 car today. The track was VERY cold and a little damp. Track temps were about 3C at the start of the day, air temp 7C. Nippy.
My biggest problems of the day were mainly around getting the right tires. I started with Jaco pink rears and BSR purple fronts. The rears are near new and I don't have a truer, so the rear pod height is about 7mm.
I also tried Jaco Greens with Jaco purples. These were new out of the box, and I couldn't get the rear ride height uder 8mm.
Needless to say, the handling was largely poop.
By the end of the day, I had it going OK, but here is the big issue I need help with:
Coming out of a turn, no power, car going slow, front hooks the car around (I think).
This did NOT happen if I had good corner speed, only when I was in hairpins, or slowed too much.
It was off-power, so it's not an itchy trigger finger.
Any ideas?
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Old 07-11-2010, 02:41 AM   #1572
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Quote:
Originally Posted by JR007 View Post
Well, had the first proper race run with the Gen-X 13.5 car today. The track was VERY cold and a little damp. Track temps were about 3C at the start of the day, air temp 7C. Nippy.
My biggest problems of the day were mainly around getting the right tires. I started with Jaco pink rears and BSR purple fronts. The rears are near new and I don't have a truer, so the rear pod height is about 7mm.
I also tried Jaco Greens with Jaco purples. These were new out of the box, and I couldn't get the rear ride height uder 8mm.
Needless to say, the handling was largely poop.
By the end of the day, I had it going OK, but here is the big issue I need help with:
Coming out of a turn, no power, car going slow, front hooks the car around (I think).
This did NOT happen if I had good corner speed, only when I was in hairpins, or slowed too much.
It was off-power, so it's not an itchy trigger finger.
Any ideas?
That is typical behaviour of a car with rear ride height a lot higher then front.
You never want more than 1mm ride height difference between front and back.

If you have no access to a truer, at least raise the front so you are near level.
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Old 07-11-2010, 10:47 AM   #1573
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I never got to race today, no other GT racers turned up.
Ever since the club took up the British GT10 rules (1s 10.5 & 1s Mod) the class has faded, and although trying to revert back to 2s 17.5 I fear it is too late.
I now have an FF03 near completion, and look like racing that in future, and putting the GT car in to retirement
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Old 07-11-2010, 11:55 AM   #1574
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JR007-certainly try the ride height fix. That corner exit hook is something I experience everytime the traction is on the poor side. I have too believe you are not completely off power at corner exit or the car will have stopped. It requires some power to maintain corner speed. The hook occurs to me when I roll on power a fraction of a second too soon while the car is still cornering, like I do on a touring car. If I wait just a fraction of a second until wheels are straight to roll on throttle, I eliminate the problem. I have to conciously think about it as this is not our normal tendency.
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Old 07-11-2010, 12:29 PM   #1575
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Maybe too much front castor?
that causes the front to pull the rear around out of corners.

Or it could be not enough droop so needing more steering than is needed mid corner?

But then if you are running a Mulsanne shell then change your shell.
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