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I know this has been discussed (and I have researched a lot) but hoping for some input regarding my alignement specs and how bad a de-powered rack would really be?
Car is a 99' running Xidas and 205/55/15 Falken Azenis 200 treadwear.
I'm doing timing belt/water pump/header install and decided now would be the time to do some other items. Just finished gutting AC out and am seriously considering de-powering my rack to make more space in the engine bay and save some weight of the power steering system. This would be done as the simple looped de-power for now as I am not interested in pulling the rack and paying for a new alignment right now (just had this thing corner balanced and aligned in the fall). I would eventually do a proper pinion weld and depower in a year or two the next time i pull the motor and do a new large project on it. This car is NOT a daily driver. I use it mainly as a HPDE track toy and the occasional fun driving around town.
With a de-powered rack people usually recommend somewhere around 3.5* caster for ease of steering. The following is my alignment which is mostly influenced from 949 racings recommendations for dual duty cars.
FL:
-2.49 degrees camber
6.72 degrees caster
0 degrees toe
FR:
-2.49 degrees camber
6.68 degrees caster
0 degrees toe
RL:
-2.05 degrees camber
.10 toe
RR:
-2.04 degrees camber
.10 toe.
Car is exactly 50% weighted.
Any thoughts on how brutal a de-powered rack would be with these specs? I am SO close to pulling the trigger and gutting the power steering but am worried I'm running WAY too much caster to make the car feel decent with a de-powered rack?
You have the right word, "brutal". I have a de-powered NB2, similar specs, and have a proper de-power, with welded pinion, etc. For some reason, even tho it has not been in a wreck, and A-arms are straight, etc., the minimum caster I could get, and still have the rest of the alignment specs OK was around 4.5 deg. It is a street car, but has pretty heavy steering until out and at speed. I really notice it a low speeds, in subdivision, etc. I also have a de-powered '93 NA, and it has a nicer ratio, feels damn near perfect at 3.8deg. caster. Also just doing the loop on the P.S. still leaves some fluid and seals in the rack, and makes it even more resistant to steer. You'v read all this probably, but you can paint witness marks on the alignment, or toe, and pull the rack, to do a better gutting job, and have a better feeling rack afterwords.
My settings are below, I run 225 rc1s on track, depowered (looped lines) rack, sparco 383 steering wheel. Alignment feels great on track but takes a lot of steering effort at low speeds. I wouldn't run it on a car I used on the street.
3.5 is too low and the steering will dart on rutted or uneven pavement. 5.5 was a little heavy at slow speeds but felt more stable at high speeds. 4.5-ish was a sweet spot for me. Wheel size and offset probably effect feel a lot too, so YMMV.
As expected, I am now more confused than ever. I see that personal preference plays a huge roll into what is acceptable/driveable. We have people ranging from 3.5-7 degrees caster and statements from brutal to perfectly fine.
For now I will be leaving power steering in the car. I'm too worried about cutting/looping lines and wishing I had left it alone.
Will most likely go with a proper de-powered rack and look for approx. 4 degrees of caster before my next alignment.
As expected, I am now more confused than ever. I see that personal preference plays a huge roll into what is acceptable/driveable. We have people ranging from 3.5-7 degrees caster and statements from brutal to perfectly fine.
For now I will be leaving power steering in the car. I'm too worried about cutting/looping lines and wishing I had left it alone.
Will most likely go with a proper de-powered rack and look for approx. 4 degrees of caster before my next alignment.
Having driven a looped-lines depowered car and a properly welded pinion rack, the difference is stark. Looped lines felt like ****. Also, FWIW, its very easy to remove the rack with the motor in the car, especially if you've already removed the AC compressor. And not to start anything but if you've pulled weight off the front end removing AC, your corner balance has already gone out the window, so may as well go for it on any other weight savings before realign and rebalance.
There's also a big difference in how much preload you put on the rack after reassembling it. I don't remember the FSM procedure, but it was some torque plus an angle. I didn't have an angle gauge so I had to SWAG it. After properly depowering the rack and going for a test drive it was freakin heavy. A couple degrees makes a big difference. Felt like a rope climb just backing it into the turn around. I noticed steering was fairly heavy even on jackstands, so I loosened up the jam nut and started loosening the preload adjuster in increments as small as I could get it to budge with a wrench. It didn't take more than a couple degrees to drop steering weight dramatically, without adding any additional slop.
FYI I run 7deg of caster.
Not an issue on track. NCM is the most physical track I run and it feels like a good arm workout after a weekend. It's mainly due to the high speed/high g sweepers. I'm a thiccc 5'-11" / 175lbs.
In the words of the great 21st century philosopher, Chopper Read, "Harden the **** up."
I hadn't considered messing with the adjustment bolt on the steering rack for preload, and I know once upon a time I did fiddle with it in diagnosing a steering rack related noise. Now I am curious if I over pre-loaded it a few years ago.
I hadn't considered messing with the adjustment bolt on the steering rack for preload, and I know once upon a time I did fiddle with it in diagnosing a steering rack related noise. Now I am curious if I over pre-loaded it a few years ago.
According to the FM depower guide; "After inserting the parts in the correct order, torque the [preload nut] to 43 in-lb three times, then back it off 25 degrees. Holding it in place, attach the locknut." They called the preload nut an "adjusting cover" thus my edit. I followed this and it felt fine, and still does 2 years later.
4.5 degrees caster with a properly de-powered rack. I have problems shifting coming out of a turn when the steering effort is too high; taking my right hand off the steering wheel makes the car wiggle at times, even at my slow speeds. A properly de-powered and set up rack is key.
I have a manual rack and 4.5 degrees of caster and 15x9 225 Rivals and it's heavy. It's great driving along but doing u-turns or in parking lots it definitely takes a lot of effort. Enough that I'm considering going with an electric booster. I'm a baby and want it to be more comfortable than needed, though.
I have a manual rack and 4.5 degrees of caster and 15x9 RE71s and it's heavy. It's great driving along but doing u-turns or in parking lots it definitely takes a lot of effort. Enough that I'm considering going with an electric booster. I'm a baby and want it to be more comfortable than needed, though.
I too have a manual rack with 195 RSR's on 15x8 and the best way i can describe it is that you have to plan all of your parking lot driving ahead and steering when the car is rolling. Caster is set to 4.2 on both sides and essentially zero toe in the front with a touch in on the rear. As soon as its moving its a dream and i never have any issues, but parking lots definitely suck between that and the 949 1.6 4 puck clutch lol. my buddy runs a properly depowered rack with similar setups overall and its about the same effort the main difference is that the steering ratio is very noticeable faster.
12-14-2019, 03:49 PM
High Caster Settings and Depowered rack
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