Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: noturbo999 on February 06, 2018, 01:49:13 PM
-
Hey folks,
Does anyone have knowledge they can share about sway bars? I have a Mazda RX7 I'm building with a Chevy LS swap (C/GC). The oil pan interferes with the front sway bar, so I'm contemplating removing it completely. I'll hopefully be working my way up to 200mph, so I certainly want stable handling.
Thanks
-
By "sway bar" I am assuming that you are talking about the stock anti roll bar. Anti roll bars actually only work when turning, going straight they are just along for the ride. Although I am sure that you will be loosing some roll stiffness you can probably get most of it back by increasing the spring rate of the front springs, which you will probably do to compensate for the extra weight of the LS over the Mazda rotary, so my vote is to just not run the stock anti roll bar. What year is your RX7? All of them seem to work pretty good on the salt.
Rex
-
I'm not familiar with the RX7 front end but I assume it's McPherson strut type.
The change to an LS engine plus all the added structure & safety equipment you need will significantly raise the CG then you add into that the extra torque from the LS, you should expect to see some body roll under power. With variation in traction &-or you coming off the power, that will change & that will likely create a yaw situation. On the salt that can mean you are looking at the start line or getting 360 views & a trip to re-inspection before changing your shorts. :-o
I know of some door slammers that have huge sway bars from box trucks & motorhomes under both ends.
Go to the junkyard with you tape measure & find something you can adapt.
Sid.
-
I remember an RX-7 that cut in line in front of us at SW in the 90s. It made quite a journey on its lid. It was pretty stable in that configuration.
-
It is always good to know the most stable configuration for your vehicle... :roll: :cheers:
-
Do you mean sideways isn't it ?
Ron
-
No. It was on its top. They dragged it off that way. We then qualified. Didn't hurt the track much on that smooth top.
-
Cut in front of you in line? Ended up on his top? Ice pick in the left rear? 8-)
-
Naaa. This was in the stupid year of pre-staging. They told us to move up. I hadn't towed the race car before, so I went carefully and leisurely up to the back of No. 1. Apparently they wanted to be 9 back instead of 10 back and I wasn't going fast enough, so they went around me. Big hat with some imported cattle. Karma.
-
Was that the white one the starting line crew had a hard time communicating to the non-English speaking crew that the car had spun and crashed?
-
This one?
Sid.
https://www.youtube.com/watch?v=o8b8oYuftYk
-
Notice that the driver was able to extricate himself from the upside down car, see the flames, and reach back into the car and presumably hit the fire bottles before the crash crew arrived. Think how much harder if the new head restraint rules for cages and swing out bars etc made that much harder. Maybe we should have bail out tests with the car upside down...... :evil: :evil:
-
Looks to me like he also needed a lot more parachute for that one....
-
Numbah 10, GI !!! :x
Regards, Neil Tucson, AZ
-
Liked the shot of Al early on in the video.
At 1:33, right behind the Mazda, there's Steve Batchelor's stock-bodied Monza C/CFALT that ran 243 for the record right after. That Bonneville record and his 213 El Mirage record still stand 25 years later.
I had the very important duty of pushing him off at Bonneville.
-
That vid was great! Pretty obvious that the color wasn't the problem, he spun in both black and white! My guess is that a three rotor, peripheral port rotor motor with a big hair dryer could probably make north of 900 hps. I think the problem was in Medder's right foot.
Rex
-
I'm not familiar with the RX7 front end but I assume it's McPherson strut type.
The change to an LS engine plus all the added structure & safety equipment you need will significantly raise the CG then you add into that the extra torque from the LS, you should expect to see some body roll under power. With variation in traction &-or you coming off the power, that will change & that will likely create a yaw situation. On the salt that can mean you are looking at the start line or getting 360 views & a trip to re-inspection before changing your shorts. :-o
I know of some door slammers that have huge sway bars from box trucks & motorhomes under both ends.
Go to the junkyard with you tape measure & find something you can adapt.
Sid.
This response makes the most sense to me. Thanks for sharing your insight.
-
I've no idea what the correct overall approach might be for LSR, but trying to add roll stiffness by increasing the spring rate(s) is the wrong way to get there. If you need to increase roll stiffness you need to increase the size of the anti-sway bar or shorten it's lever arms. Adding spring rate not only doesn't work, but now your damping is off and the tires will have a harder time following the surface of the track thereby decreasing available traction. That said, it could be that for LSR a spring rate increase is desirable.
If you do remove the front bar and there is a rear bar it needs to come off too. Not removing an existing rear bar when the front is removed will result in a car where the rear wants to pass the front. Probably an undesirable trait in LSR......