Inside Wheel Spin. Howd you fix it??
10-18-2017, 02:28 PM
#11
I don't know if you'll be at Chuckwalla next month, and we've never met, but you're welcome to try the car if you're there just to get the feeling of a pretty different setup than what you're on, and I get to find out if my setup is whack as hell and I just don't realize it.
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f20kills (10-18-2017)
10-18-2017, 04:53 PM
#12
Thread Starter
Front RCA will definitely add front roll stiffness but not exactly in the same way that a stiffer sway bar will but could definitely work. Quite a few variables between cars but I have front and rear RCA (J's S1 with 9mm in front and 12mm in rear, with relatively soft ASM sway bars) and I can't say I experienced inside wheel spin/lift when I was on the stock diff.
Is it limited to tight right hand corners or is that just the particular track you were on? Maybe get to a skidpad and test both right and left? Are you lighting up the inside rear for sure?
Might be able to adjust pre-load to increase rebound travel on the rear dampers?
Is it limited to tight right hand corners or is that just the particular track you were on? Maybe get to a skidpad and test both right and left? Are you lighting up the inside rear for sure?
Might be able to adjust pre-load to increase rebound travel on the rear dampers?
. I’m 225lbs so the added weight I’m sure plays a big part if my car isn’t balanced properly. Some added preload might not be a bad idea too in the rear.
10-18-2017, 04:58 PM
#13
Thread Starter
I have the same issue as you and I have:
AP2
Full Cage
Tein Driving SpecControl Master Type Flex Coilovers (lol)
Whiteline front Sway,
Stock rear sway,
BuddyClub RCA front
Spoon Rigid colar kit Front & rear
Hasport 88A Engine & Diff Mounts
Hoosier R6/7 squared setup
My next steps are:
1. Getting a much better coilover setup with much stiffer springs
2. Corner weight the car
3. Wider tires
My guess is that my springs/shocks are too soft and the front end dips, thus kicking up the rear. Corner balancing the car would help quite a bit as well.
AP2
Full Cage
Tein Driving SpecControl Master Type Flex Coilovers (lol)
Whiteline front Sway,
Stock rear sway,
BuddyClub RCA front
Spoon Rigid colar kit Front & rear
Hasport 88A Engine & Diff Mounts
Hoosier R6/7 squared setup
My next steps are:
1. Getting a much better coilover setup with much stiffer springs
2. Corner weight the car
3. Wider tires
My guess is that my springs/shocks are too soft and the front end dips, thus kicking up the rear. Corner balancing the car would help quite a bit as well.
i agree that a corner balance should be next.
10-18-2017, 05:06 PM
#15
Thread Starter
think we’re on to something...we’re too fat lol jk lefts never happens so corner balance is next. I’ll get that done ASAP and report back
10-19-2017, 10:51 AM
#16
Registered User
More caster will increase jacking forces on the rear which will unload the inside and increase inside wheel spin. Because this is a recent change, I'd suspect your corner weights are off or you have a failed sway bar end link, failed suspension bushings, or binding sway bar. I tried dozens of combinations of spring rates, bars, and alignment and could never find a solution to inside wheel spin without causing push. Reduced caster (~5 degrees) did help but didn't solve it. Ultimately, I replaced the diff with a salisbury style unit and I can now run whatever roll rates I want.
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f20kills (10-20-2017)
10-19-2017, 02:15 PM
#17
More caster will increase jacking forces on the rear which will unload the inside and increase inside wheel spin. Because this is a recent change, I'd suspect your corner weights are off or you have a failed sway bar end link, failed suspension bushings, or binding sway bar. I tried dozens of combinations of spring rates, bars, and alignment and could never find a solution to inside wheel spin without causing push. Reduced caster (~5 degrees) did help but didn't solve it. Ultimately, I replaced the diff with a salisbury style unit and I can now run whatever roll rates I want.
The dampers. Used OE motorcycle units, sprung / valved them properly yourself, CNC'd upper and lower mounts in inverted position. Is that a close guess?
10-20-2017, 08:37 AM
#18
If it didn't before and does now, what changed? Driving faster? Different line? Any changes to the car? What else feels different?
Is the tire unloaded or is the shock picking it up? Is it in just righthand turns, just lefthand turns, or both?
If it is unloaded, why? Have the cross weights changed? Did a spring or bar go bad or bend a link? That would preload the bar causing different lefthand/righthand characteristics. It would also change the static cross weights.
The post seemed to indicate this is a new problem--"This past event I had too much inside wheel spin", "I've never experienced this before"--so looking for something that changed rather than a chronic problem seems like the right track, at least to me.
Is the tire unloaded or is the shock picking it up? Is it in just righthand turns, just lefthand turns, or both?
If it is unloaded, why? Have the cross weights changed? Did a spring or bar go bad or bend a link? That would preload the bar causing different lefthand/righthand characteristics. It would also change the static cross weights.
The post seemed to indicate this is a new problem--"This past event I had too much inside wheel spin", "I've never experienced this before"--so looking for something that changed rather than a chronic problem seems like the right track, at least to me.
10-20-2017, 11:28 AM
#19
Thread Starter
If it didn't before and does now, what changed? Driving faster? Different line? Any changes to the car? What else feels different?
Is the tire unloaded or is the shock picking it up? Is it in just righthand turns, just lefthand turns, or both?
If it is unloaded, why? Have the cross weights changed? Did a spring or bar go bad or bend a link? That would preload the bar causing different lefthand/righthand characteristics. It would also change the static cross weights.
The post seemed to indicate this is a new problem--"This past event I had too much inside wheel spin", "I've never experienced this before"--so looking for something that changed rather than a chronic problem seems like the right track, at least to me.
Is the tire unloaded or is the shock picking it up? Is it in just righthand turns, just lefthand turns, or both?
If it is unloaded, why? Have the cross weights changed? Did a spring or bar go bad or bend a link? That would preload the bar causing different lefthand/righthand characteristics. It would also change the static cross weights.
The post seemed to indicate this is a new problem--"This past event I had too much inside wheel spin", "I've never experienced this before"--so looking for something that changed rather than a chronic problem seems like the right track, at least to me.
I may just end up buying a diff too
10-20-2017, 01:52 PM
#20
Corner weights would be a good start. Checking for something that is bent would be next. Anti-roll bar preload has a direct effect on corner weights. Those would show up in corner weights.
The corner weights might also show a weak spring. If the shocks are high pressure mono-tubes, a loss of pressure won't affect the spring rate, but will reduce a static 50# or so the shock is supporting.
What was your theory behind changing the diff bushings?
Added:
This reminds me of two Spec Miata stories. In one, the wedge of the cross weights was specifically adjusted to put more weight on the inside rear wheel in order to limit wheel spin on entering the most important straight. I believe that is in a popular Spec Miata setup guide. In another, using wheel travel data (this is from Aim's data analysis evangelist, his son won the first SCCA Spec Miata national championship) that a problem was traced to a directional change in the bump steer curve. That problem was fixed by changing the ride height so it didn't travel through that part of the curve in the turn.
To you have speed and lateral/longitudinal acceleration traces around the track on the days in question and earlier times? If so, have they changed?