Review of Bumspteer kit, diff collar, and axle spacers
10-09-2011 | 11:16 PM
#11
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From: Emmett
The Exedium diff collar is basically a collar that goes where the rubber is on the stock diff mount. Making it rigid. We installed it, but to tell you the truth, I can not tell any difference. However, I can tell that this might benefit older cars with old cracked rubber on their mount. I might leave it in the car cause, I couldn't feel any difference and it might prolonged my rubber from cracking. I know, I've read Mac, review saying he felt a great difference. He might feel it, but I don't.
I only have like 57 thousand miles on the mounts and they looked fine. I hope you feel the difference with the engine mount rings
my fillings sure did notice a difference 
10-09-2011 | 11:38 PM
#13
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Joined: Sep 2007
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From: Yee!
Ive felt a difference in throttle steering with the diff collars on MY00 with 110K as well as my recently sold MY00 with 49K - less motion/play/movement; it wasnt an extreme black & white change; more of a subtle, refined touch.
10-09-2011 | 11:56 PM
#15
Joined: Nov 2010
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Either way the install for this ended up being a total pain in the ass. There is no way in @#$@#$ those are EVER coming off my car.
10-10-2011 | 01:04 AM
#16
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Joined: Mar 2002
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From: Concord, CA
Sorry I am well aware that the front suspension is the same on both the AP1, Ap2 and the concept behind bumpsteer etc. What I was interested in was a bit more clarification as to why NOT to use an anti bumpsteer kit. I did read above but I was hoping the OP could explain more in detail the benefits of using an roll center adjuster vs bumpsteer kit etc. Hope this helps and sorry for my retarded post earlier =P
One other thought and THIS one might actually be dumb. But since our cars utilize a double wishbone suspension x4 why would it not / or would it be advantageous or disadvantageous to apply a similar principle of changing camber during compression rather than merely applying static camber in the rear end of the car as well rather than simply doing so in the front? Or are you intending on doing this in some other fashion?
One other thought and THIS one might actually be dumb. But since our cars utilize a double wishbone suspension x4 why would it not / or would it be advantageous or disadvantageous to apply a similar principle of changing camber during compression rather than merely applying static camber in the rear end of the car as well rather than simply doing so in the front? Or are you intending on doing this in some other fashion?
The car I used to measure, already have roll center on the front and back.
On this case, you need bump steer correction. However, the bump steer kit that are readily available do not work to satisfaction. Factory arm actually yield to closest to zero through out the 2" bump I measured. Notice I say close as it is not actually zero. The Wicked Tuning or J's racing kit, replaces the tie rod with a stud and rod end. The studs has few spacers to lower the rod end or making it further to the mount on the knuckle. We found when measuring that the rod end should not be spaced further, in fact it needed to brought in closer to the mounting point on the knuckle. Someone with a lathe can easily make this happen by cutting the stud closer. Again, this was done on a car with 10mm roll center installed. Bump steer can also be modeled with kinematics computer modeling. But it is more involved as you need to transpose all the coordinate to the spreadsheet. I've done this with my TSX race car, but don't have time to do it on the S2K.
What created bump steer? The 3 arms connected to knuckle are all connected on different part, top, middle, and bottom, and all are in different length. The top, being the shortest in most double wishbone car provide rapid change in camber compare to the bottom. The middle one is not exactly dead in the middle. Depends on the location, the ratio of movement has to match of the top and the bottom to follow the dynamic camber gain in order to achieve zero toe change throughout the range of suspension movement that we will be using at the track.
The rear of this particular AP2 is also fitted with a 15mm roll center. The Wicked Tuning bump steer kit on both front and rear comes with a pre set spacers. 5mm, and 10mm. This means you can position them in 4 different position. zero (no spacers), 5mm, 10mm, or stack them together to 15mm. Ideally the spacers should be a bunch of washer with 1mm increment for fine tuning. We found out we need this for the rear as the correction would fall in between 5mm spacers and 10 mm spacers. We didn't have any washer handy, or I would have tested it and found out for sure.
This bump steer measurement is a tedious process and take quite a long time to do. We also ran out of time.
Now, the exedium front bump steer kit is a spacer, to be put under the steering rack. Raising the steering rack by 20mm. There are no adjustment on this. Ideally it should be shim by 1mm thickness increment. This has the same effect as lowering the tie rod (the approach that Wicked Tuning and J's uses)
While there are obvious advantageous of moving your roll center, by adding spacers or lengthen your knuckle, it is a bit more complicated than that. Installing the spacers, means you lower the car by the thickness of the spacers since the spacer is located at the bottom of the knuckle. Advantageous includes, Lower center of gravity while maintaining the same bottom arm angle. Increasing the rake of the top arm, which means as the suspension moves under bump, the top arm gets shorter really fast giving you more negative camber (dynamic). However, the problem with roll center, is it doesn't remain static. As the suspension moves, the roll center moves around. Making calculation very complex. At this point I believe testing is the easiest solution to figure out how much is too much. Or I will have to consult with people smarter than me to figure it out.
Hopefully this helps. If not, there are few books I would recommend you to give a read. The complete Carroll Smith "How To" books, and few other more complicated suspension books like Milliken & Milliken.
10-10-2011 | 01:07 AM
#17
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Joined: Mar 2002
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From: Concord, CA
Originally Posted by Andrie' timestamp='1318205387' post='21054609
The Exedium diff collar is basically a collar that goes where the rubber is on the stock diff mount. Making it rigid. We installed it, but to tell you the truth, I can not tell any difference. However, I can tell that this might benefit older cars with old cracked rubber on their mount. I might leave it in the car cause, I couldn't feel any difference and it might prolonged my rubber from cracking. I know, I've read Mac, review saying he felt a great difference. He might feel it, but I don't.
I only have like 57 thousand miles on the mounts and they looked fine. I hope you feel the difference with the engine mount rings
my fillings sure did notice a difference
10-10-2011 | 01:38 AM
#18
Joined: Nov 2010
Posts: 1,096
Likes: 2
Originally Posted by Fujin' timestamp='1318226785' post='21055305
Sorry I am well aware that the front suspension is the same on both the AP1, Ap2 and the concept behind bumpsteer etc. What I was interested in was a bit more clarification as to why NOT to use an anti bumpsteer kit. I did read above but I was hoping the OP could explain more in detail the benefits of using an roll center adjuster vs bumpsteer kit etc. Hope this helps and sorry for my retarded post earlier =P
One other thought and THIS one might actually be dumb. But since our cars utilize a double wishbone suspension x4 why would it not / or would it be advantageous or disadvantageous to apply a similar principle of changing camber during compression rather than merely applying static camber in the rear end of the car as well rather than simply doing so in the front? Or are you intending on doing this in some other fashion?
One other thought and THIS one might actually be dumb. But since our cars utilize a double wishbone suspension x4 why would it not / or would it be advantageous or disadvantageous to apply a similar principle of changing camber during compression rather than merely applying static camber in the rear end of the car as well rather than simply doing so in the front? Or are you intending on doing this in some other fashion?
The car I used to measure, already have 15mm roll center on the front and back.
On this case, you need bump steer correction. However, the bump steer kit that are readily available do not work to satisfaction. Factory arm actually yield to closest to zero through out the 2" bump I measured. Notice I say close as it is not actually zero. The Wicked Tuning or J's racing kit, replaces the tie rod with a stud and rod end. The studs has few spacers to lower the rod end or making it further to the mount on the knuckle. We found when measuring that the rod end should not be spaced further, in fact it needed to brought in closer to the mounting point on the knuckle. Someone with a lathe can easily make this happen by cutting the stud closer. Again, this was done on a car with 15mm roll center installed. Bump steer can also be modeled with kinematics computer modeling. But it is more involved as you need to transpose all the coordinate to the spreadsheet. I've done this with my TSX race car, but don't have time to do it on the S2K.
What created bump steer? The 3 arms connected to knuckle are all connected on different part, top, middle, and bottom, and all are in different length. The top, being the shortest in most double wishbone car provide rapid change in camber compare to the bottom. The middle one is not exactly dead in the middle. Depends on the location, the ratio of movement has to match of the top and the bottom to follow the dynamic camber gain in order to achieve zero toe change throughout the range of suspension movement that we will be using at the track.
The rear of this particular AP2 is also fitted with a 15mm roll center. The Wicked Tuning bump steer kit on both front and rear comes with a pre set spacers. 5mm, and 10mm. This means you can position them in 4 different position. zero (no spacers), 5mm, 10mm, or stack them together to 15mm. Ideally the spacers should be a bunch of washer with 1mm increment for fine tuning. We found out we need this for the rear as the correction would fall in between 5mm spacers and 10 mm spacers. We didn't have any washer handy, or I would have tested it and found out for sure.
This bump steer measurement is a tedious process and take quite a long time to do. We also ran out of time.
Now, the exedium front bump steer kit is a spacer, to be put under the steering rack. Raising the steering rack by 20mm. There are no adjustment on this. Ideally it should be shim by 1mm thickness increment. This has the same effect as lowering the tie rod (the approach that Wicked Tuning and J's uses)
While there are obvious advantageous of moving your roll center, by adding spacers or lengthen your knuckle, it is a bit more complicated than that. Installing the spacers, means you lower the car by the thickness of the spacers since the spacer is located at the bottom of the knuckle. Advantageous includes, Lower center of gravity while maintaining the same bottom arm angle. Increasing the rake of the top arm, which means as the suspension moves under bump, the top arm gets shorter really fast giving you more negative camber (dynamic). However, the problem with roll center, is it doesn't remain static. As the suspension moves, the roll center moves around. Making calculation very complex. At this point I believe testing is the easiest solution to figure out how much is too much. Or I will have to consult with people smarter than me to figure it out.
Hopefully this helps. If not, there are few books I would recommend you to give a read. The complete Carroll Smith "How To" books, and few other more complicated suspension books like Milliken & Milliken.
Great! Thanks for clarifying. I personally do better with that level of detail and great to know I wasn't super nuts to think about a rear roll center adjustment. I'll check out those books and this should help me in my suspension set up planning.
10-10-2011 | 07:41 AM
#19
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Joined: May 2006
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From: Emmett
Feeling is very subjective. I don't feel it, it is simply a statement. I don't doubt that you feel it. You might have a better feel than me in that aspect. I however, have not test it on the track to see if it has any performance benefit on the track. Right now, the benefit I can see is probably to extend the life of the rubber on the mounts.
and yes feel is very subjective One thing I've noticed, is a low ride height also seems to have a negative affect on bumpsteer and after reading your post I'm thinking it might be rear bumpsteer since the rear seems to gain more dynamic camber than the front or at least it seems that way to me.
10-10-2011 | 11:19 AM
#20
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Joined: Mar 2002
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From: Concord, CA
I should have a disclaimer. I'm currently sponsored by Wicked Tuning. They make really good products, some I helped design. My Civic Race car had a lot of pieces that I made which end up to be a production by Wicked Tuning. My TSX race car also has lots of Wicked Tuning products.
I have no relation with Vex Motorsports and/or Exedium, other than they supplied me the parts for me to test.
I have no relation with Vex Motorsports and/or Exedium, other than they supplied me the parts for me to test.