Anyone know why we don't use a rear bar? (video added)
- bertvorgon
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- Location: White Rock, B.C. Canada
Re: Anyone know why we don't use a rear bar?
Actually, I kinda did mention the rear toe, a very common thread of mine, which does tend to get lost in a lot of discussions. If one reads the suspension thread, it gets talked a lot about there. I guess I could have been more specific as to what that does during travel
One of the best root mods one can do, no matter what "package" you have, is correct the rear toe issue..PERIOD!
While I mean no disrespect to anyone here, it seems like that some that throw together fancy smancy anodized suspension bits and sell a "package", have NOT understood what the suspension really needs to work on a 510. Great if you are just futzing around and cruising to car shows, but, REALLY WORK the suspension and WHAMMO, it does not work.
The rear toe issue is a fundamental problem that until that is sorted out, "tuning" is almost impossible. Shops like Baz and Specialty, who are actual racers themselves and understand suspension, get that.
First thing someone needs to do BEFORE they ask a suspension question, is read that thread, as it discusses that, and various setups that have proven to work. While not gospel, it can save one some time and let them formulate an educated question.
One of the best root mods one can do, no matter what "package" you have, is correct the rear toe issue..PERIOD!
While I mean no disrespect to anyone here, it seems like that some that throw together fancy smancy anodized suspension bits and sell a "package", have NOT understood what the suspension really needs to work on a 510. Great if you are just futzing around and cruising to car shows, but, REALLY WORK the suspension and WHAMMO, it does not work.
The rear toe issue is a fundamental problem that until that is sorted out, "tuning" is almost impossible. Shops like Baz and Specialty, who are actual racers themselves and understand suspension, get that.
First thing someone needs to do BEFORE they ask a suspension question, is read that thread, as it discusses that, and various setups that have proven to work. While not gospel, it can save one some time and let them formulate an educated question.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
Re: Anyone know why we don't use a rear bar? (added video)
Here's a video I made this past weekend. I tried to see if my tire was lifting and am surprised at what I saw.
I'm also surprised at how little suspension travel I'm using. It was suggested at the track that I need to greatly soften both the spring rate and the damping rate of my rear suspension, to get more rear traction.
Do you think I actually have a Torsen that isn't working properly or did I get screwed and actually buy an open diff.?
http://youtu.be/PyEoSr3jcAg
I'm also surprised at how little suspension travel I'm using. It was suggested at the track that I need to greatly soften both the spring rate and the damping rate of my rear suspension, to get more rear traction.
Do you think I actually have a Torsen that isn't working properly or did I get screwed and actually buy an open diff.?
http://youtu.be/PyEoSr3jcAg
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- tire lift test screen shot.JPG (82.35 KiB) Viewed 4103 times
Last edited by S15DET on 20 Jun 2013 06:56, edited 1 time in total.
Re: Anyone know why we don't use a rear bar? (video added)
Don't Torsen diffs require special fluid? Maybe check that. It really looks like the LSD isn't working properly, or that you have an open diff. It also looks like you might have a bit much negative camber.
Re: Anyone know why we don't use a rear bar? (video added)
I've determined that I do, in fact, have a type-2 Torsen in my R180.
However, from Wiki:
"When a Torsen has a 3:1 TBR, that means that one side of the differential can handle up to 75% while the other side would have to only handle 25% of applied torque. During acceleration under asymmetric traction conditions, so long as the higher traction side can handle the higher percentage of applied torque, no relative wheelspin will occur. When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential."
In other words, the torsen is not a locker and can't work miracles. It amount of torque it can transfer is limited by the Torque Bias Ratio (TBR). If the inside tire has 100 lb of normal load and the outside tire has 2000 lb of normal load, assuming coefficient of friction of 1 and TBR of 3:1, the inside tire is limited to 100 lb of tractive force and the outside tire is limited to 300 lb of tractive force. Any extra force will result in spinning the inside tire, like I'm experiencing. The only solution is to transfer LESS weight to the outside tire, easier said than done.
However, from Wiki:
"When a Torsen has a 3:1 TBR, that means that one side of the differential can handle up to 75% while the other side would have to only handle 25% of applied torque. During acceleration under asymmetric traction conditions, so long as the higher traction side can handle the higher percentage of applied torque, no relative wheelspin will occur. When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential."
In other words, the torsen is not a locker and can't work miracles. It amount of torque it can transfer is limited by the Torque Bias Ratio (TBR). If the inside tire has 100 lb of normal load and the outside tire has 2000 lb of normal load, assuming coefficient of friction of 1 and TBR of 3:1, the inside tire is limited to 100 lb of tractive force and the outside tire is limited to 300 lb of tractive force. Any extra force will result in spinning the inside tire, like I'm experiencing. The only solution is to transfer LESS weight to the outside tire, easier said than done.
- bertvorgon
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- Joined: 04 Aug 2003 20:45
- Location: White Rock, B.C. Canada
Re: Anyone know why we don't use a rear bar? (video added)
That's why I elected to stick with my LSD, specially for solo use. We just felt we wanted the full control under full-on throttle applications, so I could really steer the car with no issues of splitting power, or lack thereof.
Even with the VSLD in my G35, there is a weird feel to it before it comes into play. I guess I'm just used to the 100% connection in my 510.
Even with the VSLD in my G35, there is a weird feel to it before it comes into play. I guess I'm just used to the 100% connection in my 510.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
Re: Anyone know why we don't use a rear bar? (video added)
That's interesting. Only way to decrease weight transfer any significant amount is to lower the car or to increase the track width...so yeah...sucks.S15DET wrote:In other words, the torsen is not a locker and can't work miracles. It amount of torque it can transfer is limited by the Torque Bias Ratio (TBR). If the inside tire has 100 lb of normal load and the outside tire has 2000 lb of normal load, assuming coefficient of friction of 1 and TBR of 3:1, the inside tire is limited to 100 lb of tractive force and the outside tire is limited to 300 lb of tractive force. Any extra force will result in spinning the inside tire, like I'm experiencing. The only solution is to transfer LESS weight to the outside tire, easier said than done.
Other thing which would help would be to increase the amount of traction available. That's why I brought the camber issues in my previous post. If you have an adjustable crossmember, I would revisit your camber settings. Even when that tire was loaded, it appeared to be a bit negative. When it was unloaded, that black mark it left was pencil-thin.
Re: Anyone know why we don't use a rear bar? (video added)
My old KA510 with Penultimate, prior to any sort of alignment. Too much negative camber in the rear:HudsonMC wrote:If you have an adjustable crossmember, I would revisit your camber settings. Even when that tire was loaded, it appeared to be a bit negative. When it was unloaded, that black mark it left was pencil-thin.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson
Re: Anyone know why we don't use a rear bar? (video added)
Nice video. I went from a r180 clsd, to the same torsen 3.55 (08STI), and now back to a 3.90 CLSD (04STI). I never had much luck getting the power down with the Torsen. My testing was limited to auto-x, no track experience. The car was way too easy to oversteer on the power. Sweepers were the worst. I do run a lot of front/rear bar and relatively soft springs. I tried wider rear tires and softened the rear springs but the could not get the car to power out of turns. After reworking my powertrain last winter, I found an clsd unit, and swapped it in. The car finally works like it should. I'm back to square tire setup, and basically a very neutral balance, with very controlled power oversteer if I push it hard at auto-x. 200ft/185r springs, 1-1/4ft bar (long arms), 3/4 rear (full soft), -2f/ -1.5r camber, triangulated strut bar. I'm running some Ridetech adjustable rebound rear coilovers now, that seem to work well. Dialing the rebound down on the rear will help.
www.machinedspeed.com
Re: Anyone know why we don't use a rear bar? (video added)
Wow guys, thanks for all the feedback! A few of your suggestions I can do right away with little cost. First will be to re-visit rear toe and camber. I may be at the limit of my slotted crossmember, so the next step will be Byron's brackets. You're right that the inside tire is only touching at it's inside corner, leaving the pencil-thin black stripe. Getting the tire more square will help. I talked to a tech guy at QA1 yesterday about softening my rear shock. He thought that the 4-6 valving I have in there now is appropriate for my car's weight and a 200lb rear spring. However, he did recommend that for my usage (non-dirt track) I need to drill out the low speed bleed hole from 0.042 to 0.059. This will quicken up the compression and rebound response. So maybe that's the only things I'll change before the next outing. I don't want to change too many things at once or I won't really learn anything.
Chuck is selling a clutch-type R-180 right now in this thread...
http://www.the510realm.com/viewtopic.php?f=10&t=25672
Anyone know if it would be a direct swap for my Torsen, including the axle stubs?
Chuck is selling a clutch-type R-180 right now in this thread...
http://www.the510realm.com/viewtopic.php?f=10&t=25672
Anyone know if it would be a direct swap for my Torsen, including the axle stubs?
Last edited by S15DET on 20 Jun 2013 07:20, edited 2 times in total.
Re: Anyone know why we don't use a rear bar? (video added)
Here's another video, taken from the dash of a nice '69 GTV. His was a stock-ish motor so I needed to slow on the straights to allow him to stay close for the turns. I was hoping to get close enought to watch the inside tire, but never really happens. Still a cool video.
http://www.youtube.com/watch?v=Jn4cmgBw ... e=youtu.be
http://www.youtube.com/watch?v=Jn4cmgBw ... e=youtu.be
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- gtv lead follow.JPG (43.7 KiB) Viewed 4101 times
Re: Anyone know why we don't use a rear bar? (video added)
Best advice in this thread. One thing at a time. Just sucks we're all amateurs. Track time is expensive and infrequent!S15DET wrote:So maybe that's the only things I'll change before the next outing. I don't want to change too many things at once or I won't really learn anything.
Re: Anyone know why we don't use a rear bar? (video added)
Yeah, seriously! This track, CMP (Carolina Motorsports Park) is only 45 minutes away and they have a 200ft skidpad separate from the track. I need to find out how one goes about gaining access to it. I could learn a lot that way, and it's much easier on tires than full-on track days. Anyone here ever spent time on a skid pad?HudsonMC wrote:Just sucks we're all amateurs. Track time is expensive and infrequent!
EDIT: Thinking about it, I'm confusing the issues. This thread is about rear sway bars and overall handling balance, and also about rear traction. The skidpad probably won't tell me anything about accelerative traction, putting the power down. It will, however, tell me somethign about overall balance, and that was the initial reason for starting this thread.
Last edited by S15DET on 20 Jun 2013 17:53, edited 1 time in total.
Re: Anyone know why we don't use a rear bar? (video added)
It was part of the requirement for the VARA racing school that I did. One of the things they had you do was just go out and run big circles getting progressively faster until you could feel the slip angle of your car. It allowed you to really feel what it was like to almost loose control and correct and then loose control with no possibility of correction. Very good for car/driver feedback and better there than in a pack of 40 cars.S15DET wrote:HudsonMC wrote: Anyone here ever spent time on a skid pad?
- bertvorgon
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- Joined: 04 Aug 2003 20:45
- Location: White Rock, B.C. Canada
Re: Anyone know why we don't use a rear bar? (video added)
That's what we used to do at Boundry Bay during our solo years. I spun my 510 more times...
But, as you say, it gives you the ability to run the car to it's cornering limit, FEEL that, and then be able to balance the over/understeer with the throttle, or...back to the drawing board to do some more suspension adjustment/mods.
With today's tires the limits are so high, you cannot flirt with that on the street, at least without some prior experience of what and how it is going to do.
But, as you say, it gives you the ability to run the car to it's cornering limit, FEEL that, and then be able to balance the over/understeer with the throttle, or...back to the drawing board to do some more suspension adjustment/mods.
With today's tires the limits are so high, you cannot flirt with that on the street, at least without some prior experience of what and how it is going to do.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
- PoorMtnKid
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Re: Anyone know why we don't use a rear bar? (video added)
When I did my track day a few months back they had us do the same thing while the pad was wet down. It was a real good learning experience. That was done by the Porsche club of America
looking for pass. side arm rest