Post by liteway on Jun 23, 2019 21:57:15 GMT -5
Not getting out of trikes, but converting away from a type of steering I have long used and advocated, to adopt a traditional R&P
Why?
Tired of hearing about and reading the skepticism in the faces of doubters.
Sad that some friends and family found the system too strange and intimidating to even try.
The kicker was continuing to have some stability problems on uneven surfaces at speed. I did not know if this was related to the side stick steering or not, but after never getting it back to an acceptable level after the switch from atv to Spyder components, and trying every mod trick I could, I was ready for a drastic change. After looking around for a quality R&P, I wound up spending a small fortune on the same unit the Captain Has, The Pegasus unit for single seat formula cars. There were other quality units available for less, but they would have required a complete redesign of the frame and body ahead of the front axle to work for me.
Even so, the list of changes was numerous and drastic.
Having designed the cockpit around the stick steering, there was not enough room to get my arms straight to my satisfaction with a steering wheel in front of me. In order to achieve that the seat back angle was changed from about 30 degrees off the vertical to more like 45, and to get that I had to saw away the frame that had been directly under seat and restructure it around the seat bottom. Also had to cut about an inch and a quarter off the lip at the top of seat back. For the third time, the shifter was cut and rewelded for a more comfortable reach. Extensions were added on the gas pedal and clutch.
A substructure was added underneath the dash as that area was built lightly the first time because it did not have to support a steering column and wheel. A bicycle steering neck was welded to that new structure for bearings and their shells and races.
Special ends were fabricated to fit on the ends of the rack to allow routing over the lower inner suspension pivots and get the right length to prevent bump steer. One of these incorporated a mounting for a link to a steering damper, and the damper was mounted on the other end of that link. The rack itself had to be low enough to fit under my ankles with no interference.
The lower lay back driving position left me peering through the distortion of the bubble windscreen that had been installed to look over. That will have to change. Probably will just cut the bubble down for now, but long term I want a full coverage distortion free screen that will allow leaving the helmet at home. I have a temporary windscreen in position in the photos, but it will allow water to enter around the recessed headlight mountings.
Signal switches had been mounted on top of the sticks and were replaced with a double throw toggle on the dash that can operated without taking your hand off the wheel. There is barely 3 inches between the wheel and dash, just enough not to accidentally foul a knuckle or finger.
New steering arms were made even though the old ones should have worked fine as the steering geometry was basically going to be unchanged.
But after The first road trial, I found the steering to be ridiculously light and lifeless, even at 1.75 turns lock to lock, and 7 degrees of caster.
Shorting the steering arms from about 4.25 off the steering axis to 3.25 and adding 2 degrees more caster gave me 1.1 turns lock to lock and much better feel .
So how is it working out? I like it, even if I do miss some of the advantages the sticks had in speed, feel and comfort. With eyes lowered to 36 inches off the payment, the wonderfully twitchy steering(not kidding) a sequential shifter that requires no more than a slight bump, and screaming high RPM engine , its very easy to channel Jim Clark at Monte Carlo. Yimmy never used side sticks. If only they would put curves in the roads of Okla.
The big thing is the gain in stability. Much better than even the atv hardware provided. It is no longer a problem and the steering rarely requires correction in a straight line unless the road is exceptionally bumpy in which case kickback exceeds what I would like and that can have an affect.
With an effective steering ratio of about 7 to 1, there is rarely a need for hand repositioning.
The only complaint I have left is the lack of self return to center, but only a minor gripe with steering this quick. Not sure what to do about that As I already have 9 degrees caster and doubt more would help. I suspect the lack of trail in the Spyder uprights, but heck, the sticks gave just the right amount of pushback.
So why would the R&P help stability when the geometry is basically the same and the rack is the same length as the old center tie rod?
I am guessing the old system was not stiff enough to keep the ends of the tie rods from being displaced vertically under load. That may be why the ATV front worked better as the wheel/hub/brake assembly represented a lot less entia to control when bumps were encountered.
I'm callin this DS 2.5. 2.75 or maybe even 3.0 to follow.
i.pinimg.com/originals/b9/27/5c/b9275c1c1194e1e5255dc04e8011871d.jpg
i.pinimg.com/originals/f9/61/b4/f961b4ad34c50def6e17da45670eccd9.jpg
i.pinimg.com/originals/fc/0d/59/fc0d59b188a9995d56f725bd4dca3ba3.jpg
i.pinimg.com/originals/4e/7a/c0/4e7ac0a648413d745e4cf82517ab20a5.jpg
Why?
Tired of hearing about and reading the skepticism in the faces of doubters.
Sad that some friends and family found the system too strange and intimidating to even try.
The kicker was continuing to have some stability problems on uneven surfaces at speed. I did not know if this was related to the side stick steering or not, but after never getting it back to an acceptable level after the switch from atv to Spyder components, and trying every mod trick I could, I was ready for a drastic change. After looking around for a quality R&P, I wound up spending a small fortune on the same unit the Captain Has, The Pegasus unit for single seat formula cars. There were other quality units available for less, but they would have required a complete redesign of the frame and body ahead of the front axle to work for me.
Even so, the list of changes was numerous and drastic.
Having designed the cockpit around the stick steering, there was not enough room to get my arms straight to my satisfaction with a steering wheel in front of me. In order to achieve that the seat back angle was changed from about 30 degrees off the vertical to more like 45, and to get that I had to saw away the frame that had been directly under seat and restructure it around the seat bottom. Also had to cut about an inch and a quarter off the lip at the top of seat back. For the third time, the shifter was cut and rewelded for a more comfortable reach. Extensions were added on the gas pedal and clutch.
A substructure was added underneath the dash as that area was built lightly the first time because it did not have to support a steering column and wheel. A bicycle steering neck was welded to that new structure for bearings and their shells and races.
Special ends were fabricated to fit on the ends of the rack to allow routing over the lower inner suspension pivots and get the right length to prevent bump steer. One of these incorporated a mounting for a link to a steering damper, and the damper was mounted on the other end of that link. The rack itself had to be low enough to fit under my ankles with no interference.
The lower lay back driving position left me peering through the distortion of the bubble windscreen that had been installed to look over. That will have to change. Probably will just cut the bubble down for now, but long term I want a full coverage distortion free screen that will allow leaving the helmet at home. I have a temporary windscreen in position in the photos, but it will allow water to enter around the recessed headlight mountings.
Signal switches had been mounted on top of the sticks and were replaced with a double throw toggle on the dash that can operated without taking your hand off the wheel. There is barely 3 inches between the wheel and dash, just enough not to accidentally foul a knuckle or finger.
New steering arms were made even though the old ones should have worked fine as the steering geometry was basically going to be unchanged.
But after The first road trial, I found the steering to be ridiculously light and lifeless, even at 1.75 turns lock to lock, and 7 degrees of caster.
Shorting the steering arms from about 4.25 off the steering axis to 3.25 and adding 2 degrees more caster gave me 1.1 turns lock to lock and much better feel .
So how is it working out? I like it, even if I do miss some of the advantages the sticks had in speed, feel and comfort. With eyes lowered to 36 inches off the payment, the wonderfully twitchy steering(not kidding) a sequential shifter that requires no more than a slight bump, and screaming high RPM engine , its very easy to channel Jim Clark at Monte Carlo. Yimmy never used side sticks. If only they would put curves in the roads of Okla.
The big thing is the gain in stability. Much better than even the atv hardware provided. It is no longer a problem and the steering rarely requires correction in a straight line unless the road is exceptionally bumpy in which case kickback exceeds what I would like and that can have an affect.
With an effective steering ratio of about 7 to 1, there is rarely a need for hand repositioning.
The only complaint I have left is the lack of self return to center, but only a minor gripe with steering this quick. Not sure what to do about that As I already have 9 degrees caster and doubt more would help. I suspect the lack of trail in the Spyder uprights, but heck, the sticks gave just the right amount of pushback.
So why would the R&P help stability when the geometry is basically the same and the rack is the same length as the old center tie rod?
I am guessing the old system was not stiff enough to keep the ends of the tie rods from being displaced vertically under load. That may be why the ATV front worked better as the wheel/hub/brake assembly represented a lot less entia to control when bumps were encountered.
I'm callin this DS 2.5. 2.75 or maybe even 3.0 to follow.
i.pinimg.com/originals/b9/27/5c/b9275c1c1194e1e5255dc04e8011871d.jpg
i.pinimg.com/originals/f9/61/b4/f961b4ad34c50def6e17da45670eccd9.jpg
i.pinimg.com/originals/fc/0d/59/fc0d59b188a9995d56f725bd4dca3ba3.jpg
i.pinimg.com/originals/4e/7a/c0/4e7ac0a648413d745e4cf82517ab20a5.jpg
