johnparts
Slammed 1
Well and that is where my intended use and Tory's intended use might be different behavior wise. He drag races I will be doing the twisties and this stuff will get addressed here after I get the prototype.
Ok so lets really talk K-members here Folks
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blown71duster
Well-Known Member
You guys are on the subject of using stock spindles with rear steer. Couldnt a guy mount a center steer rack and fab some steering arms on each side to mount steering linkage to keep the stock mounting points of the inner tie rod ends, keeping rear steer geometry , you would eliminate the center link something like they did on this v10 challenger:
http://www.popularhotrodding.com/features/0902phr_1970_dodge_challenger/photo_17.html
http://www.popularhotrodding.com/features/0902phr_1970_dodge_challenger/photo_17.html
johnparts
Slammed 1
Here is something I was just reading.
Costin &Phipps, "Racing & Sports Car Chassis Design", 1961. For performance and racing cars, they recommended a small amount of anti-Ackerman, and did not discuss any circumstance where Ackerman might be used. "Owing to weight transfer, the outside wheel always runs at a higher loading than the inside wheel, and therefore higher slip angles, which necessitate greater lock".
Carroll Smith, "Tune to Win", 1978. Referring to anti-Ackerman, he writes it "cannot be right". He suggested that racing car steering angles are generally too small for Ackerman to build, and that in the mid corner, the inside tyre is not sufficiently loaded for it to have much affect anyway (meaning for Ackerman effect - in general consideration of inside tyre grip is a major focus for set up). For corner entry he prefered to use small amount of static toe out and/or, interestingly, small amount of bumpsteer toe out in bump. Because of the difficulty of predicting dynamic ride height side to side, it may be preferable to run the static toe out required with zero bump steer. Those teams with wheel position sensors and data logging could tell for sure. "Engineer in Your Pocket", 1998. No mention of Ackerman. This is significant. Twenty years after "Tune to Win" Carroll Smith must have considered Ackerman adjustment still only a small part of set up.
Don Alexander, "Performance Handling", 1991. He writes that anti-Ackerman was used in earlier years. But that by the 90's, "Ackerman steering has returned, often exceeding 100 percent geometry", eg for vehicles with high aero down force. However, he has got his explanation of the slip angle effect the wrong way round, and does not expand further. Finally, he says Ackerman is a design element, not a tuning tool the racer will use.
Paul Valkenburg, "Race Car Engineering & Mechanics", 1992. Taking into account the slip angles, "at first glance it might seem" ..."Ackerman steering may be a disadvantage. On the other hand, scientifically obtained tyre data tends to indicate that the lighter the tyre load, the higher the the slip angle required for peak cornering power. This would indicate that Ackerman is in fact usefull in racing cars. " ........."although there probably isn't enough steering motion to have a significant effect. Only your skid pad or test track will tell for sure."
Allan Staniforth, "Competition Car Suspension", 1999. Writing about inside tyre grip he says "My own view, not applying to Ackerman alone, is that any single thing that helps the contact patch do a better job and enjoy a happier existence has to be worth any trouble to achieve." He does not say when, or under what conditions, he would use Ackerman. Later he did an article in one of the technical mags (or was it Simon McBeath?) where he got very keen on Ackerman, and did some testing on a hill climb car. Unfortunately, I can't find the magazine.
Eric Zapletal, "Race Car Engineering" magazine, August 2001. This is part 3 of a series on "Ackerman Explained". He offers a number of "kinematic steer angle curves", representing steering systems with a lot of Ackerman, for various slip angles. At the end of the article he does give some further clues as to how Ackermen may be used. He points out how the car will turn by braking one side of the vehicle - tanks, bulldozers and other "skid-steer"' vehicles are an examples where it is the only steering mechanism. He points out that modern Vehicle Stability Systems (VCS) use the ABS braking system to brake an individual wheel to counter the yaw motion of the vehicle and control oversteer and understeer. "One of the easiest ways to take advantage of this yawing power (in racing cars) is to use dynamic-toe changes. Dynamic toe out of the front wheels generates just the right sort of differential- longitudinal forces that help yaw the vehicle into the corner." I think he is saying if the inside front tyre drag is a bit more than the outside, this will help turn the car into the corner.
Costin &Phipps, "Racing & Sports Car Chassis Design", 1961. For performance and racing cars, they recommended a small amount of anti-Ackerman, and did not discuss any circumstance where Ackerman might be used. "Owing to weight transfer, the outside wheel always runs at a higher loading than the inside wheel, and therefore higher slip angles, which necessitate greater lock".
Carroll Smith, "Tune to Win", 1978. Referring to anti-Ackerman, he writes it "cannot be right". He suggested that racing car steering angles are generally too small for Ackerman to build, and that in the mid corner, the inside tyre is not sufficiently loaded for it to have much affect anyway (meaning for Ackerman effect - in general consideration of inside tyre grip is a major focus for set up). For corner entry he prefered to use small amount of static toe out and/or, interestingly, small amount of bumpsteer toe out in bump. Because of the difficulty of predicting dynamic ride height side to side, it may be preferable to run the static toe out required with zero bump steer. Those teams with wheel position sensors and data logging could tell for sure. "Engineer in Your Pocket", 1998. No mention of Ackerman. This is significant. Twenty years after "Tune to Win" Carroll Smith must have considered Ackerman adjustment still only a small part of set up.
Don Alexander, "Performance Handling", 1991. He writes that anti-Ackerman was used in earlier years. But that by the 90's, "Ackerman steering has returned, often exceeding 100 percent geometry", eg for vehicles with high aero down force. However, he has got his explanation of the slip angle effect the wrong way round, and does not expand further. Finally, he says Ackerman is a design element, not a tuning tool the racer will use.
Paul Valkenburg, "Race Car Engineering & Mechanics", 1992. Taking into account the slip angles, "at first glance it might seem" ..."Ackerman steering may be a disadvantage. On the other hand, scientifically obtained tyre data tends to indicate that the lighter the tyre load, the higher the the slip angle required for peak cornering power. This would indicate that Ackerman is in fact usefull in racing cars. " ........."although there probably isn't enough steering motion to have a significant effect. Only your skid pad or test track will tell for sure."
Allan Staniforth, "Competition Car Suspension", 1999. Writing about inside tyre grip he says "My own view, not applying to Ackerman alone, is that any single thing that helps the contact patch do a better job and enjoy a happier existence has to be worth any trouble to achieve." He does not say when, or under what conditions, he would use Ackerman. Later he did an article in one of the technical mags (or was it Simon McBeath?) where he got very keen on Ackerman, and did some testing on a hill climb car. Unfortunately, I can't find the magazine.
Eric Zapletal, "Race Car Engineering" magazine, August 2001. This is part 3 of a series on "Ackerman Explained". He offers a number of "kinematic steer angle curves", representing steering systems with a lot of Ackerman, for various slip angles. At the end of the article he does give some further clues as to how Ackermen may be used. He points out how the car will turn by braking one side of the vehicle - tanks, bulldozers and other "skid-steer"' vehicles are an examples where it is the only steering mechanism. He points out that modern Vehicle Stability Systems (VCS) use the ABS braking system to brake an individual wheel to counter the yaw motion of the vehicle and control oversteer and understeer. "One of the easiest ways to take advantage of this yawing power (in racing cars) is to use dynamic-toe changes. Dynamic toe out of the front wheels generates just the right sort of differential- longitudinal forces that help yaw the vehicle into the corner." I think he is saying if the inside front tyre drag is a bit more than the outside, this will help turn the car into the corner.
abodyjoe
Well-Known Member
Yup. I know two guys running that type of set up. One is a hemi Fred with his sox and martian duster the other looks similar but not sure if its exactly the same. They both work awesome on the track in a straight line but would be horrible on the street when ya actually have to turn. You would **** if you saw how the tire flops over when turning into the bleach pit.
I really don't like being the nay-sayer....ask my buddies..I'm the king of "what ifs" (look at some of the stuff I've built)....but it pains me to see my Mopar buddies spend even half the money for something that will not live up to their expectations.
The_night_rider
Sheriff of Rockridge
I had mentioned 500 as what I had been quoted by other builders for a k member. John never said 500.
johnparts
Slammed 1
So if I draw an imaginary line from the rear axle center to each front lower ball joint the steering arm should meet that plane whether in front or behind the ball joint. So since the mustang spindle is the popular one to use do you guys adjust that arm in relation to the difference in the wheelbase and track width on the abody?
johnparts
Slammed 1
Does anyone see anything wrong with the akerman on this suspension?
OK ..one more..most of the adjustment/modification is done for bumpsteer....the mustang spindles....in my opinion...will not give you the ackerman of your stock set-up(almost impossible for a front steer unless you can locate the tie rod mount inside the rim...like a Corvette)... to me at least it gets neutral(outside/inside wheel turn the same)...acceptable for most "streetrod" applications.....that is why i would use the stock set-up if at all possible...for$$$$$ and driveability
USCG CHARGER
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Nice videos... car sounds badass for sure... so with the back up video my guess is that Tory was showing the common issues that other were having while backing? When he was braking hard and using no hands on the wheel that showed the balance under load?
Jason
Jason
man that car is sick!!!
A couple quick video's Tory did today He says he is sorry for the quality but he just threw these together.
Very very informative thread with a lot of good vantage points to the same problem/situation. I would love to build a K-frame that would have it's mounting points for all of the stock components in the factory location. Benefit? probably a little weight and header clearance but the biggest benefit for me would be not having to chase and haggle over a K-frame for a project car that is made out of unobtainium because its for a B/RB A-body or whatnot. Sometimes the beauty of a part isn't weight or brand recognition or "look what I got", sometimes it's ordering a $400 part that you can get your ride back on the road with with the stuff you already got. Of course this is my opinion and I could be wrong :glasses9:
Does anyone see anything wrong with the akerman on this suspension?
Is this a bottom view of a RMS set up??? Do I see anything wrong with the akerman, ummm. no?
actually I have no clue how to spot akerman issues from a picture, but after spending a day talking to you about it I felt I needed to give a response before i go to bed. . . great topic john, I'll catch the updates in the morning, Derek
johnparts
Slammed 1
Derrek Akerman is a term used to describe the turning aspect and it's relationship to handling. As I said in an above post draw an imaginary line from the absolute center of the rear axle to the lower ball joint and the steering link should ride front or rear steer in that imaginary line.
rapidtransitric
LX/LC platform a body swap pioneer
What about the angle of those tie rods? I could be wrong but it looks a little severe
John, I know the term "akerman" and have read a few of the very technical and very confusing (to me) articles written about it. But based on your picture showing only the front wheels you can not draw an "imaginary line from the absolute center of the rear axle to the lower ball joint and steering link" (in the picture you posted) since the rear axle is not shown in the picture and the ball joints and steering link end are hidden inside the wheel. (maybe I'm just getting slap happy)
I honestly have no clue how to determine akerman, I know its important, just no clue how to set it up, hence why i would not personally under take such a daunting task (to me) I would and am leaving it to much smarter folks than I.
I'm just intrigued by the process and open to asking the questions to help develop more conversation. . . anyway great discussions today, I can only imagine what tomorrow will bring.
bad440
everything,all the time..
come on man i'm poor need all the help i can get!and you with your mad fab. skills and turbo setup...making me want to force feed before ever flogging my setup
autoxcuda
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All those books are about race car suspension geometry. When a race car is in a turn, the tires generate higher slip angles (skidding) and throws traditional Ackermann steering theory out the door. But the idea of both front tires turning on different angles like in Ackermann is used in a circle track cars. They use it to manipulate the tire slip angles and have adjustable steering arms for it.
Street cars in normal lawful driving don't have the front end in high slip angles (skidding).
It's described in better detail in Miliken "Race Car Vehicle Dynamic" 1995 pg 128. It terms this street car situation as, Steady-State Low-Speed Cornering Geometry.
Also goes into Ackermann steering geometry on street cars on pg 713 :read2:
autoxcuda
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Does anyone see anything wrong with the akerman on this suspension?
No.
But I can see why most people would.
1970Duster
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Question is that a b/rb engine in that picture right?
abodyjoe
Well-Known Member
1970Duster
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Thanks! that was bothering me because I knew it wasn't a sb but was pretty sure it was a b/rb but could've been a new hemi for all I know, because I've never seen a new hemi from below.
abodyjoe
Well-Known Member
A couple quick video's Tory did today He says he is sorry for the quality but he just threw these together.
ok so what are we looking at? sounds damn good. looks like it goes in a straight line good. now tell him to throw it into a nice S turn at 65 mph and let us see video of that.
Mopar parts have always been more expensive. Always will be. They never made as many Cudas as Cajunkos. Never made as many Challengers as Rustangs. Hell, Mopar didn't make a RWD car for what....26 years? When you have your head up your *** for that long, you lose perspective. They lost it. When you go Mopar, you just have to face reality that your parts are fewer and more costly. If that's too much for you to grasp, buy a Cajunko or a Rustang.
johnparts
Slammed 1
70Duster that's the poisondart built by Schwartz chassis and the engine is a 572 hemi. What I see when I look at that picture is severe angle on the tie rods and a complete lack of Ackerman like everyone is so quick to point out is a must.
Joe, Tory has been street driving with this k-member and suspension for over a year and has been designing it for 3. He has shown his design to some of his peers and they all have commented on how well designed the system is. Even someone who has been mentioned in this thread a good deal has praised this system and commented that it was time he wasn't the only pony at this show.
I know this is relatively unknown and untested (without years of postings and articles) but you guys are very quick to say it's junk when you don't know that much about it. I will be getting a k-member from Tory in about a week/week and a half and after I mock up my motor mounts and send him measurements he asked me to try my best to destroy it. I have a spare factory K-member so I will do comparisons between the 2 side by side pictures and side by side destruction so you can see what this thing is made of.
Joe, Tory has been street driving with this k-member and suspension for over a year and has been designing it for 3. He has shown his design to some of his peers and they all have commented on how well designed the system is. Even someone who has been mentioned in this thread a good deal has praised this system and commented that it was time he wasn't the only pony at this show.
I know this is relatively unknown and untested (without years of postings and articles) but you guys are very quick to say it's junk when you don't know that much about it. I will be getting a k-member from Tory in about a week/week and a half and after I mock up my motor mounts and send him measurements he asked me to try my best to destroy it. I have a spare factory K-member so I will do comparisons between the 2 side by side pictures and side by side destruction so you can see what this thing is made of.
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