UCA, LCA and relocation brackets
11-30-2008, 07:56 PM
#1
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UCA, LCA and relocation brackets
I have steeda tubular LCA and I just ordered a non adjustable BMR UCA/3rd link. Paid only $65 on another forum for the BMR UCA. Now looking at my LCA, I see they are slightly lower in the front. Question is, can I still use a relocation bracket even if I don't have adjustable LCA or UCA? My car is not lowered, but maybe because I only have 25.8" tires it played a role in the pinion angle.
11-30-2008, 08:42 PM
#2
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Hi gman73,
I don't have direct experience to say for sure, but my guess is that you will experience a pinion angle change trying to use the brackets. But before getting into that, I'm not sure I understand your question. If you used non-adjustable upper and lower control arms, they should have been the same length as stock arms. That means you should NOT have experienced any pinion angle changes (you did say you're not lowered, yes). Finally, the S197s come stock with LCAs that are lower in the front than in the rear. Is this bad for hard launches? Yes. Does this also make the car safer under hard cornering for inexperienced drivers? Yes. So there's your OEM-style justification.
The bottom line is that if you were worried your switch to the tubular arms had an ill-effect on the LCA pitch and pinion angle, don't worry. The stock arms were already that way, you probably just didn't notice.
If you're asking a different question, then I'm sorry for the wasted response. To make up for the waste, let me suggest that the answer to whatever question you are asking is going to have a bunch of "maybe, you have to measure this or that on your car" type variables in it.
Using stock length arms and a relocation bracket will likely induce a pinion angle change unless you're able to get the pitch of the new arm position to mirror the original pitch from horizontal. So, for example, on my car I measured the arms in stock form and got a 3 degree angle (down in front: call that negative). Had I used relocation brackets to drop the axle pick-up point down so that the arms were at 3 degrees up (in front: call it positive), then the pinion angle should not have changed at all. There is a HUGE "if" here. This only works if the relocation bracket is perpendicular to horizontal (it is easier to draw this on a napkin than explain it in words). If the bracket is not perpendicular then this "mirror the original angle" won't work, and you'll get a change in pinion angle.
One more thing, even if you get a pinion angle change, the question is "how much?" The OEM pinion spec is defined within a range, and you may still fall within that range. Backup another step; since your new control arms have stiffer bushings you can run a tighter pinion angle, as you don't have to compensate for as much deflection of the pinion angle. Again, some wiser and more experienced person than I should chime in, but my guess is that you would be well served to know what your current setting is at and then see what change you can live with running the brackets.
Best,
-j
I don't have direct experience to say for sure, but my guess is that you will experience a pinion angle change trying to use the brackets. But before getting into that, I'm not sure I understand your question. If you used non-adjustable upper and lower control arms, they should have been the same length as stock arms. That means you should NOT have experienced any pinion angle changes (you did say you're not lowered, yes). Finally, the S197s come stock with LCAs that are lower in the front than in the rear. Is this bad for hard launches? Yes. Does this also make the car safer under hard cornering for inexperienced drivers? Yes. So there's your OEM-style justification.
The bottom line is that if you were worried your switch to the tubular arms had an ill-effect on the LCA pitch and pinion angle, don't worry. The stock arms were already that way, you probably just didn't notice.
If you're asking a different question, then I'm sorry for the wasted response. To make up for the waste, let me suggest that the answer to whatever question you are asking is going to have a bunch of "maybe, you have to measure this or that on your car" type variables in it.
Using stock length arms and a relocation bracket will likely induce a pinion angle change unless you're able to get the pitch of the new arm position to mirror the original pitch from horizontal. So, for example, on my car I measured the arms in stock form and got a 3 degree angle (down in front: call that negative). Had I used relocation brackets to drop the axle pick-up point down so that the arms were at 3 degrees up (in front: call it positive), then the pinion angle should not have changed at all. There is a HUGE "if" here. This only works if the relocation bracket is perpendicular to horizontal (it is easier to draw this on a napkin than explain it in words). If the bracket is not perpendicular then this "mirror the original angle" won't work, and you'll get a change in pinion angle.
One more thing, even if you get a pinion angle change, the question is "how much?" The OEM pinion spec is defined within a range, and you may still fall within that range. Backup another step; since your new control arms have stiffer bushings you can run a tighter pinion angle, as you don't have to compensate for as much deflection of the pinion angle. Again, some wiser and more experienced person than I should chime in, but my guess is that you would be well served to know what your current setting is at and then see what change you can live with running the brackets.
Best,
-j
11-30-2008, 09:35 PM
#4
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Thanks for the responses. The pinion angle is ever so slightly lower in the front, so it may fall within the acceptable range set by the manufacture.
Last edited by gman73; 11-30-2008 at 09:43 PM.
11-30-2008, 10:24 PM
#5
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I believe the Steeda LCA did help reduce wheel hop, but I still have some. My 60's times use to be in the 2.2 to 2.4 range with a best of 1.9. With the Steeda my 60 times are in the 2.0 to 2.2 times with a best of 1.88
12-02-2008, 09:45 AM
#6
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Join Date: May 2008
Posts: 167
Hello, our relocation brackets will not change your pinion angle. The holes are drilled on an arc so the only thing that changes is the angle of your lca's and the instant center of your car. The addition of relocation brackets will stop any wheel hop issues that you have. Our brackets are an easy install and allow for up to 3 inches of adjustment.
Last edited by BMRFabricationSales; 12-02-2008 at 01:11 PM.
12-02-2008, 11:08 PM
#7
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For now I may keep the pinion angle since it's almost parallel and just added the UCA. If that doesn't improve wheel hop, then I will get relocation brackets. I will have the UCA installed this Friday and take it the track on Saturday.
12-03-2008, 01:29 PM
#9
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OE LCA chassis-side pivots are intentionally slightly lower (by about 3/8", IIRC) than the axle side pivots. So what you noticed is normal for an unmodified (and unloaded) S197.
Your shorter tires have given away a little of your anti-squat, meaning that the amount of immediate rearward load transfer isn't quite as much as OE. And I think it also comes in a tiny bit slower than with the OE tire size (which isn't a big deal although it still is one more effect that's going in the "wrong" direction for you).
Relo brackets would probably solve this issue unless it's a huge, axle-threatening hop that you're trying to lose. But if it's a fairly mild case and swapping in a UCA with stiffer bushings is all that it takes to make it go away, you don't need brackets just yet.
Norm
Your shorter tires have given away a little of your anti-squat, meaning that the amount of immediate rearward load transfer isn't quite as much as OE. And I think it also comes in a tiny bit slower than with the OE tire size (which isn't a big deal although it still is one more effect that's going in the "wrong" direction for you).
Relo brackets would probably solve this issue unless it's a huge, axle-threatening hop that you're trying to lose. But if it's a fairly mild case and swapping in a UCA with stiffer bushings is all that it takes to make it go away, you don't need brackets just yet.
Norm
Last edited by Norm Peterson; 12-03-2008 at 01:59 PM. Reason: added missing word
12-03-2008, 04:34 PM
#10
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Prior to installing the steeda lca, crappy tires (Nitto 450 extremes) and bad launching, I would have major wheel hop. Sometimes my 60' times were 2.6 to 2.7 sec. LCA, better tires and better launching techiques reduced the wheel hop and have helped my 60' times. This Saturday or Sunday I'll see if the UCA help even more.
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