Quote:
Originally Posted by PoorMans180SX
Okay, so some more people have to be driving around with the gktech rlca mod by now. Post a review?
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Im hesitant to share my results because I dont trust my data 100%, but I finally did a quick check on how the dynamic alignment has changed after the RLCA relocation kit install. I have to emphasize that this was just a quick check, and I'm sure there were flaws in the way I collected the data. Ill split my post into 2 parts: first part will be about the "data" i collected", second part will be my experiences driving the car after the anti-squat kit.
This is on a KE70 using a full nissan underchassis, and only used for drifting so far. 230whp 1UZ-FE mated to an R32 RB25DET transmission, 4.0 final drive.
Data collection
Setup:
- Driftworks Geomaster 2 spindles
- Fully adjustable arms all around, except for the lower control arm (but has gktech spherical bushings installed)
- Gktech anti-squat reduction kit
- I dialed out some camber and toe from my pre-antisquat kit alignment (from -0.5 to +0.5 camber, and 1mm of toe in to 0 toe)
Results during the (questionable) test:
i set up a simple toe plate using plywood and string, and jacked the rear assembly (without the coilover spring) up and down to see how the toe changed. I measured the distance between the edges of the plywood to the string I had setup.
-I was seeing some toe out under (3cm) of compression-- 1/4" just on this one side. The rearward part of the plywood went inwards 1/4", causing toe out.
-At 2cm droop, I was getting toe out again-- 3/16" worth. This time the frontward side of the plywood went outwards 3/16", causing toe out.
NOTE: I now realize that there were lots factors that might have made my data collection at this point inconsistent (i.e. not measuring either edge of the plywood toe plate at the same exact point, among other possible factors.)
I decided to lengthen the traction rod by 5mm to see what would happen. Lengthening the traction rod to 22cm (center of bolt to center of bolt) fixed the toe change.
-3cm of compression saw same measurements from the plywood edges to the string
-2cm of droop saw same measurements from the plywood to the string again
-4cm of droop started seeing some toe out (only 1/16")
In terms of camber, I didnt even have to setup a rig. During my test days, I started noticing that the inner part of the tire was experiencing more wear that the outside (hence why i changed my alignment to positive camber). Before the anti-squat kit, wear was pretty even throughout the the width of the tire. Jacking the rear assembly up and down confirmed this-- Lots of positive camber at droop and noticeable negative camber under compression.
Driving impressions
NOTE: Test days were before I did any data collection and before changing alignment. This means that I was using the same alignment settings as before I installed the antisquat kit
During the test days, I felt like the car was lacking a little power. The engine was bogging slightly more compared to before. The rear tires took a couple more clutch kicks to keep them spinning.
There was also less "gliding" than before, I would have to really get my line more precise and use more throttle to get to where i wanted to go. Usually for the "typical drift s chassis", you can let off the gas and the car will continue to wash out, gliding towards the outer edge of the turn. with the antisquat kit, it seemed to have more "Side bite", as the drifters call it.
All this made the car a little less fun to drive. I really felt that the
power to grip balance was shifted further away from the "sweet spot". I still believe that I need an extra 30whp to get it back to the same balance it had before. The car was already underpowered, and the antisquat kit setup took that feeling of being "underpowered" a subtle notch higher.
One obvious difference compared to the pre-antisquat kit setup was when launching the car. I could now launch the car off the line with much more traction and stability. I used to have to baby the throttle after popping the clutch because i would lose 1-2 seconds waiting for the tires to telll me that they could take more throttle. Now, I can launch and continuously apply linear throttle off the line.
In hindsight, was the car harder to keep in drift during corners because of anti squat changes, or because of camber gain/ "side bite"?
Compeition
We switched to Sailun tires on the competition day itself as they were our tire sponsor. Unfortunately, it was my first time using the Sailun tire as the supply couldnt be delivered earlier for testing. These were 340TW UHP Sailun ZSR tires on the rear and 180TW Sailun R01 tires on the front. In terms of treadwear, the rear tires were similar to the generic china practice tires i was using, except sailun gave us a slightly wider spec (215/45 R17 practice tire, 225/45 R17 Sailun ZSR for competition). Fronts were the same size as the generic china test tires (215/45 R17), but obviously the Sailun R01 had a much better compound.
The whole day i was struggling to complete the first corner, a medium right hander with a sharp entry. I couldnt keep the tires spinning enough to trace the car along the outside of the corner. Lots of bogging down and consequential understeer. It was one of my worst performances in competition. We pumped the rear tire pressure to 65PSI and I stiffened the dampers in the rear hoping it would help me "shock" the rear tires into maintaining wheel spin. None of it really solved the bogging issues.
If I had to make any type of adjustment or correction in the first corner, I would surely bog down and straighten out. Example below:
https://streamable.com/t9kqx4
Conclusions and my own points for discussion
To put it simply, switching from the S13 to the S14/15 RLCA angle did add more traction. If i had to make up a number to describe the change, I'd say it made my car 10-15% "grippier" in certain situations, namely:
- Launching
- Clutch Kicking
- Loading up one side of the car ("side bite")
Seems like the changes are most noticeable during the situations where you're initially loading up the rear of the car.
This brings me to what i really want to discuss:
What
are you supposed to notice with reduced anti squat?
You can be more aggressive with throttle due to the fact that the rear kinematics are able to move more freely, and in turn let the coilovers "absorb" the shock from aggressive throttle inputs?
Aside from forward traction, how exactly does this affect side to side load transfer?