howard coleman's FD Chassis/Setup
09-11-10, 10:33 AM
#726
I apologize if it has been touched upon in this thread already, but I have done a re-read through and didnt see it talked about in depth.. What are your thoughts on staggered vs symmetrical wheel/tire sizing? Ive had both but have never really tracked my FD, and now that Im looking to get into it a bit more Im wondering what I should purchase for my next set. Ive been very **** in keeping weight down without really "stripping" the car, any my goal weight is 2600lbs with a N/A 20B and lets say ~350whp. Springrates are 9/8k with Zeal coilovers. I was thinking doing a 9.5 rear and 8.5 front, with 265/245 stagger.. but in all reality Id have no problem going 9.5 w/ 265 all around. My thoughts so far have been that I dont want to add the extra weight of the larger wheel and tire up front if I didnt have to, but I know itll be a slight trade-off in lateral grip. Thoughts?
09-18-10, 09:43 AM
#727
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I apologize if it has been touched upon in this thread already, but I have done a re-read through and didnt see it talked about in depth.. What are your thoughts on staggered vs symmetrical wheel/tire sizing? Ive had both but have never really tracked my FD, and now that Im looking to get into it a bit more Im wondering what I should purchase for my next set. Ive been very **** in keeping weight down without really "stripping" the car, any my goal weight is 2600lbs with a N/A 20B and lets say ~350whp. Springrates are 9/8k with Zeal coilovers. I was thinking doing a 9.5 rear and 8.5 front, with 265/245 stagger.. but in all reality Id have no problem going 9.5 w/ 265 all around. My thoughts so far have been that I dont want to add the extra weight of the larger wheel and tire up front if I didnt have to, but I know itll be a slight trade-off in lateral grip. Thoughts?
really good advice from an FD track pro...
09-18-10, 11:17 AM
#729
Been searching through Howards threads for a little while now. Should have done it about 2 years ago and could have saved a LOT of cash. A few years ago, I got big into autocross and started building the car soley for that. After running JIC coilovers, for a few years, I purchased Zeal Super Function coilovers 16KG F/R with Swift sway bars and 285/30/18s at all corners with Hoosiers. Aligned at -2.5 degrees camber all around. Pretty much made the car unbearable on the street. Times have changed and I'm looking to just enjoy the car on the street again. Not as a daily driver, but just to get out and enjoy some of my favorite roads again. My tire/wheel setup consists of 18X9.5 inch RPF1s(+45 offset) with 255/35/18s at all 4 corners. I'd also like to lower the camber down and get the toe back to 0. I estimate my car's weight to be in the 2700-2750lb range + 230lb driver. I'm thinking the Pettit stg. IIs with a 8/6 spring rate instead of the 10/8 will be the most beneficial for my needs now.
10-03-10, 12:16 PM
#731
Howard,
I've pulled apart my front suspension, just to double check everything for soundness, and to my satisfaction, my ball joints feel smooth, free, and firm.
However, I'm noticing that my front arms are very tight to go through their motion, needing considerable effort to move them by hand, and even sticking in place to whatever position i move them. These are Superpro urathane bushings.
Question: How tight should these feel, and what constitutes "binding"?
I've pulled apart my front suspension, just to double check everything for soundness, and to my satisfaction, my ball joints feel smooth, free, and firm.
However, I'm noticing that my front arms are very tight to go through their motion, needing considerable effort to move them by hand, and even sticking in place to whatever position i move them. These are Superpro urathane bushings.
Question: How tight should these feel, and what constitutes "binding"?
10-11-10, 07:28 PM
#732
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i don't have an answer for you as i run rubber everywhere but the Diff and the front of the rear lower longitudinal link. my suspicion is that there is so much motion and force that "binding" is not an issue.
hopefully someone more knowledgable will respond.
howard
hopefully someone more knowledgable will respond.
howard
10-11-10, 08:13 PM
#733
Howard,
I've pulled apart my front suspension, just to double check everything for soundness, and to my satisfaction, my ball joints feel smooth, free, and firm.
However, I'm noticing that my front arms are very tight to go through their motion, needing considerable effort to move them by hand, and even sticking in place to whatever position i move them. These are Superpro urathane bushings.
Question: How tight should these feel, and what constitutes "binding"?
I've pulled apart my front suspension, just to double check everything for soundness, and to my satisfaction, my ball joints feel smooth, free, and firm.
However, I'm noticing that my front arms are very tight to go through their motion, needing considerable effort to move them by hand, and even sticking in place to whatever position i move them. These are Superpro urathane bushings.
Question: How tight should these feel, and what constitutes "binding"?
10-11-10, 08:33 PM
#734
Howard, do you have any idea what the deflection is like on the FDs bushings? Coming from C5/C6 Corvettes we can see significant improvements going to poly and life gets even better with sphericals/monoballs. You can run a much much less aggressive static alignment: http://www.youtube.com/watch?v=nkrH4...layer_embedded
I also noticed you mentioned keeping the stock rubber bushing at the top of the shock, and I'll again pass along as Corvette-based video for discussion:
http://s67.photobucket.com/albums/h2...rubbertest.flv
The way the rubber deflects it's hard to imagine the shock is able to really do its job since the entire assembly is moving?
10-12-10, 08:33 AM
#735
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"but a few [tens of?] pounds of force isn't that much when you've got the weight of the car acting on it."
agree.
"keeping the stock rubber bushing at the top of the shock"
there are rubber bushings and then there are rubber bushings. the FD has significantly less rubber in the front end and has just the right amount at the upper shock mount and of course it has no effect on geometry.
the two bushings i recommend replacing are more similar to what we see in your video, are in critical dynamic areas, and do need to be replaced with something a bit more manly.
wow, the video was a shocker, and a ZO6 too.
hc
agree.
"keeping the stock rubber bushing at the top of the shock"
there are rubber bushings and then there are rubber bushings. the FD has significantly less rubber in the front end and has just the right amount at the upper shock mount and of course it has no effect on geometry.
the two bushings i recommend replacing are more similar to what we see in your video, are in critical dynamic areas, and do need to be replaced with something a bit more manly.
wow, the video was a shocker, and a ZO6 too.
hc
10-12-10, 09:24 AM
#737
As far as the rubber bushings moving around, I suspect that happens with urathane as well, and when it does it'll create momentary gaps around the metal sleeves (since they aren't bonded like the factory rubber), and I suspect that's how dirt gets in or grease gets dried out.
Wondering whether mono ***** wouldn't be effective on the lower arm, which sees most of the lateral forces, with rubber in the upper arms for "comfort"?
Wondering whether mono ***** wouldn't be effective on the lower arm, which sees most of the lateral forces, with rubber in the upper arms for "comfort"?
10-12-10, 10:38 AM
#738
Howard,
I've pulled apart my front suspension, just to double check everything for soundness, and to my satisfaction, my ball joints feel smooth, free, and firm.
However, I'm noticing that my front arms are very tight to go through their motion, needing considerable effort to move them by hand, and even sticking in place to whatever position i move them. These are Superpro urathane bushings.
Question: How tight should these feel, and what constitutes "binding"?
I've pulled apart my front suspension, just to double check everything for soundness, and to my satisfaction, my ball joints feel smooth, free, and firm.
However, I'm noticing that my front arms are very tight to go through their motion, needing considerable effort to move them by hand, and even sticking in place to whatever position i move them. These are Superpro urathane bushings.
Question: How tight should these feel, and what constitutes "binding"?
Peter,
What torque settings are you using for those bolts?
In the Spec Miata world, I encountered a similar scenario using the stock bushings. Spec Miata builders say to torque to factory settings and then back out slightly if there is too much bind.
The bind itself probably won't be something you will notice in handling changes given the force when the car is on the ground and the suspension is weighted. However, the bind and resulting extra heat may wear the bushing and will cause some squeaking noises over time. The poly bushings do need some love now and then.
10-12-10, 10:46 AM
#739
Wow. Interesting video.
The old Yamaguchi book mentioned that the stock bushings were designed to deflect to provide more toe in or toe out to aid in handling. I forget whether it stated how much. Over time the amount of deflection probably increases as the rubber "wears" and ages.
10-12-10, 10:48 AM
#740
In any case, I was particularly interested in your comment because my FC camber plates use a monoball for the pintop mount rather than any rubber at all...
10-12-10, 10:49 AM
#741
As far as the rubber bushings moving around, I suspect that happens with urathane as well, and when it does it'll create momentary gaps around the metal sleeves (since they aren't bonded like the factory rubber), and I suspect that's how dirt gets in or grease gets dried out.
Wondering whether mono ***** wouldn't be effective on the lower arm, which sees most of the lateral forces, with rubber in the upper arms for "comfort"?
Wondering whether mono ***** wouldn't be effective on the lower arm, which sees most of the lateral forces, with rubber in the upper arms for "comfort"?
Have you seen the new rubber encased, heim jointed bushings of the STI? I'd love to have something similar at certain spots in our cars.
10-12-10, 01:57 PM
#743
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Howard,
Got 2 new video of my car at the track. This is MSR Houston. It was my first time there so I was still learning it. I think I did ok consider the car handle very well. Also, I switched from Yokohamas slicks to Michelin Slicks. It was day and night difference. I didn't get any tire temp because the battery was dead and I didn't feel like getting a new one for only a couple session.
http://www.youtube.com/watch?v=6DJJ1h91naQ
http://www.youtube.com/watch?v=oEPOd...e=mfu_in_order
Got 2 new video of my car at the track. This is MSR Houston. It was my first time there so I was still learning it. I think I did ok consider the car handle very well. Also, I switched from Yokohamas slicks to Michelin Slicks. It was day and night difference. I didn't get any tire temp because the battery was dead and I didn't feel like getting a new one for only a couple session.
http://www.youtube.com/watch?v=6DJJ1h91naQ
http://www.youtube.com/watch?v=oEPOd...e=mfu_in_order
12-03-10, 01:00 PM
#745
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Howard you mentioned before that you like the FD chassis because it has a race car suspension with the unequal double wishbone control arms. I thought about it, and realized more what that really means. But I got to thinking...
Don't some other cars like the Honda S2000 also have a double wishbone suspension? They look totally different from the FD's though so maybe they aren't unequal length? I am just wondering because I keep seeing the S2000 up there next to the FD in time attack events in Japan.
Don't some other cars like the Honda S2000 also have a double wishbone suspension? They look totally different from the FD's though so maybe they aren't unequal length? I am just wondering because I keep seeing the S2000 up there next to the FD in time attack events in Japan.
12-08-10, 08:00 AM
#746
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each of the double A arms scribes a different arc. the upper arc is tighter since the A arm is shorter.
this tighter arc pulls the top of the tire in so as to generate more negative camber under compression.
this is what is commonly called "negative camber gain.NGT"
you are entering a turn...
as you turn the steering wheel the body assumes a centrifugal roll attitude... let's say 3 degrees. the outside front tire goes up into the wheel well w roll.
if there is no NGT, and your static camber is minus one degree, your tire is now positive 2 degrees. the car will understeer as the tire is tilted the wrong way.
the FD has more than 1 degree of NGT per inch of tire travel. so if the FD rolls 3 degrees the tires still will have negative camber.
that is one of the key reasons the FD is so special on a road course.
other cars may have a double A arm suspension... that does not mean the camber curve is necessarily similar to the FD. many are not... some are.
as to the Honda 2000. i don't know.
howard
this tighter arc pulls the top of the tire in so as to generate more negative camber under compression.
this is what is commonly called "negative camber gain.NGT"
you are entering a turn...
as you turn the steering wheel the body assumes a centrifugal roll attitude... let's say 3 degrees. the outside front tire goes up into the wheel well w roll.
if there is no NGT, and your static camber is minus one degree, your tire is now positive 2 degrees. the car will understeer as the tire is tilted the wrong way.
the FD has more than 1 degree of NGT per inch of tire travel. so if the FD rolls 3 degrees the tires still will have negative camber.
that is one of the key reasons the FD is so special on a road course.
other cars may have a double A arm suspension... that does not mean the camber curve is necessarily similar to the FD. many are not... some are.
as to the Honda 2000. i don't know.
howard
12-08-10, 08:15 AM
#747
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Thanks Howard that makes sense.
Going through my pictures I found one of my old car, a VW GTI, and it shows exactly what you are talking about. About 2 degrees of positive camber in a corner even though the car doesn't have that much body roll, the tire is not touching the pavement flatly. It seems like such a waste because I tried so hard to improve the handling with this car, but the McPherson strut suspension would never let it handle as good as a stock FD.
Going through my pictures I found one of my old car, a VW GTI, and it shows exactly what you are talking about. About 2 degrees of positive camber in a corner even though the car doesn't have that much body roll, the tire is not touching the pavement flatly. It seems like such a waste because I tried so hard to improve the handling with this car, but the McPherson strut suspension would never let it handle as good as a stock FD.
12-13-10, 11:38 PM
#748
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Macpherson struts for some reason usually seem to be more stable, is this true mechanically? Or is it just that cars with struts are built more understeer prone etc like BMWs and factors other than strut vs a-arm create this stable condition? Can anyone confirm these conjectures?
Also I have long wondered why Porsche doesn't use a-arms in the front suspension of their cars instead of mac struts. They have plenty of room up there so packaging is not an issue and they're supposed to be high performance so a-arms make sense. Which makes me think that the struts are more stable since the germans seem to prefer that (if rear engine cars are ever stable haha).
Also I have long wondered why Porsche doesn't use a-arms in the front suspension of their cars instead of mac struts. They have plenty of room up there so packaging is not an issue and they're supposed to be high performance so a-arms make sense. Which makes me think that the struts are more stable since the germans seem to prefer that (if rear engine cars are ever stable haha).
