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  #71  
Old 05-27-2010, 08:06 PM
cheeky14 cheeky14 is offline
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Quote:
Originally Posted by Full-Race Geoff View Post
i did what you are suggesting and it was not ideal -- what i am doing now is this:

8.5" traction rod
12.25" RUCA -- adjusting camber with eccentric
toe rod eccentric moved to make the toe rod as *Short* as possible, then toe is adjusted with the rod length


just had a quick question, to verify what you explained about adjusting rear toe arm eccentric to furthest position; you are referring to adjusting the eccentric fat side towards the outside (towards the wheel) in this way the inner pickup point for the toe arm is more inboard in the subframe making the toe arm length shorter & then adjusting the toe arm via the buckle, like you would the front suspension toe arm, correct?

then adjusting rear camber via the eccentric once ruca & trac arm lengths are set

hope to see what you came up with as far as ruca & trac arm lengths in the future

also wanted to verify on the procedure of bump gauging rear, when the gauge/rig is setup the vehicle has to be level to the ground or at the static ride height in other words the rear can't be jacked up only, also i have been told that camber & toe settings should be set before gauging bump, is this correct?

i would assume this is correct, so as to be as close to the goal camber & toe settings to begin with
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  #72  
Old 05-31-2010, 01:04 PM
logr logr is offline
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I have been experimenting with these lengths. Not sure why but my UCA's are different lengths to get the same camber on both sides. I found I was tail happy/ loose one recent weekend. I had one longer traction rod. I measured UCA lengths and put the traction to UCA ratio back to 12/8.25 and things worked much better.
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  #73  
Old 06-08-2010, 12:15 AM
Full-Race Geoff Full-Race Geoff is offline
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sorry it took me so long to get to this post. Ive been meaning to take some pics of a full time attack R34 GTR suspension setup we had at the shop, it really explains a lot. ill get to that in my next post

Quote:
Originally Posted by cheeky14 View Post
to verify what you explained about adjusting the rear toe arm eccentric to furthest position; you are referring to adjusting the eccentric fat side towards the outside (towards the wheel) in this way the inner pickup point for the toe arm is more inboard in the subframe making the toe arm length shorter & then adjusting the toe arm via the buckle, like you would the front suspension toe arm, correct? then adjusting rear camber via the eccentric once ruca & trac arm lengths are set
YES that is correct. You want a fixed RUCA and TRAC arm length!

To adjust camber, do it with the eccentric!! Do not change RUCA length, just the eccentric bolt's position. Use the same lengths on both L&R sides (assuming your crossmember, LCA and bushings are all proper and undamaged, you would be surprised how many cars have bent lcas or subframes).

To adjust toe, DONT do it with the eccentric! run the eccentric so that the toe arm is the shortest possible length, then adjust toe with the arm length.

if the car is going to be lowered substantially, this requires longer lengths for the RUCA and toe arms.

This is how the R34 nismo is all set up -- all that is, is a glorified S14 rear susp. http://www.nismo.co.jp/en/products/c...linebnr34.html


R34 nismo trac arm length +5mm over S14
R34 nismo RUCA length +5mm over S14

due to this thread, i ran:
+6.35mm over S14 trac arm length
+6.35mm over S14 RUCA length

i hope we can get more plots with my toe settings, and +5mm, +8mm, and + 15mm over S14 for final verification.... i just dont have the time lately


Last - if you decide to use any sort of roll center adjuster the REAR LCA MUST BE LENGTHENED, ie moonface ball joints (OR if those hardrace ones are legit, but i think they are bunk? ) but read that again -- roll center adjusters require longer LCA's!!!

so basically what the OP in this thread learned is that for a low car, arm lengths need to be lengthened

Quote:
Originally Posted by cheeky14 View Post
also wanted to verify on the procedure of bump gauging rear, when the gauge/rig is setup the vehicle has to be level to the ground or at the static ride height in other words the rear can't be jacked up only, also i have been told that camber & toe settings should be set before gauging bump, is this correct? I would assume this is correct, so as to be as close to the goal camber & toe settings to begin with
a friend of mine wrote a GREAT step by step tutorial on this, ill ask him to post it up on this forum i think he would be interested

Quote:
Originally Posted by logr View Post
I have been experimenting with these lengths. Not sure why but my UCA's are different lengths to get the same camber on both sides. I found I was tail happy/ loose one recent weekend. I had one longer traction rod. I measured UCA lengths and put the traction to UCA ratio back to 12/8.25 and things worked much better.
use the same length UCA, however do not use the same camber bolt position for anything but the toe rod.

i hope that makes sense

EDIT: FIXED

Last edited by Full-Race Geoff; 06-08-2010 at 10:35 PM..
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  #74  
Old 06-08-2010, 07:23 AM
SoSideways SoSideways is offline
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Quote:
Originally Posted by Full-Race Geoff View Post
Last - if you decide to use any sort of roll center adjuster the REAR LCA MUST BE LENGTHENED, ie moonface ball joints (OR if those hardrace ones are legit, but i think they are bunk? ) but read that again -- roll center adjusters require longer LCA's!!!

so basically what the OP in this thread learned is that for a low car, arm lengths need to be lengthened
Amen to that.

You need to do the same thing up front too.

My FLCAs are... well, lengthened. By a lot.

I haven't set it in stone as far as the length goes yet, so once I do, I will take measurements.

But yeah, FLCAs have to be lengthened too if you have roll center correction via longer ball joints or using longer bolts with spacers, when the car is substantially lowered.
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  #75  
Old 06-08-2010, 07:30 AM
djsilver djsilver is offline
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Quote:
Originally Posted by SoSideways View Post
Amen to that.

You need to do the same thing up front too.

My FLCAs are... well, lengthened. By a lot.

I haven't set it in stone as far as the length goes yet, so once I do, I will take measurements.

But yeah, FLCAs have to be lengthened too if you have roll center correction via longer ball joints or using longer bolts with spacers, when the car is substantially lowered.
Am I correct in thinking that the FLCA/RLCA must be made longer because the longer ball joints change the angle and reduce the "effective length"?
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  #76  
Old 06-08-2010, 07:36 AM
SoSideways SoSideways is offline
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Yes.

The FLCAs actually need to be MUCH LONGER if you don't space it very much and want to lower your car substantially, because if you don't, the angle between the FLCA's bearing cup and the knuckle's bottom will be way off, causing the tapered pin or bolt to bind up on the bearing cup as the arm moves up to get into it's finally position where it will be at static ride height.

Lengthening the arm will help fix that binding issue.
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  #77  
Old 06-08-2010, 08:02 AM
Epstein Epstein is offline
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Quote:
Originally Posted by Full-Race Geoff View Post
if the car is going to be lowered substantially, this requires longer lengths for the RUCA and toe arms.

This is how the R34 nismo is all set up -- all that is, is a glorified S14 rear susp. http://www.nismo.co.jp/en/products/c...linebnr34.html


R34 nismo trac arm length +5mm over S14
R34 nismo RUCA length +5mm over S14

due to this thread, i ran:
+12.5mm over S14
+12.5mm over S14

so basically what the OP in this thread learned is that for a low car, arm lengths need to be lengthened
Great info! So with Nismo adding 5mm to both arms, that's going to be roughly what the 12.25/8.50 plot looks like in my graphs on the first post. It's good to see this data come full circle.
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  #78  
Old 06-08-2010, 09:21 AM
logr logr is offline
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Geoff, Are you 12.5 longer due to a longer LCA?
When I had the ratio off with a longer traction rod, it was amazing how loose the car was. Drifters take note.

Isn't it interesting that the STOCK ration Traction to UCA gives the best/least toe change. Nissan engineers must be fairly sharp.

After lowering my car and looking at everything, it seems that the rear lower control arm is almost level but the upper arms are at quite an angle. Will lowering the ball joint do much for roll center/anything given that it is almost level when lowered? I believe the camber gain will still be there either way and I can't see it helping bump steer either.

Thoughts?
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  #79  
Old 06-08-2010, 12:40 PM
SoSideways SoSideways is offline
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Quote:
Originally Posted by logr View Post
Geoff, Are you 12.5 longer due to a longer LCA?
When I had the ratio off with a longer traction rod, it was amazing how loose the car was. Drifters take note.
Roger that.

I'll try not to have the ratio off.
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  #80  
Old 06-08-2010, 10:49 PM
Full-Race Geoff Full-Race Geoff is offline
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Quote:
Originally Posted by Epstein View Post
Great info! So with Nismo adding 5mm to both arms, that's going to be roughly what the 12.25/8.50 plot looks like in my graphs on the first post. It's good to see this data come full circle.
YES!!! I completely agree - thank you soo much for sharing this with the community. Saved me a lot of headaches and time. Next round of susp work for me will be getting the bumpsteer measurements super precise, and then figure out a legitimate solution for the LCA roll center adjustment. I have a few ideas, but havent settled on what method im going to go with yet.

also, going to try and use the more aggressive Nismo clutchpack kit in my OE gtr rear diff
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