Quick Ratio Steering Rack

[mgar88]

I will spare you all my nine-month saga of trying to diagnose my imprecise and inconsistent turn-in issues. After two steering rack rebuilds, each with incremental improvements, my steering still doesn't feel laser-sharp. This is after the installation of tarett bump-steer kit and fresh wheel bearings.

While I'm going to have my local porsche suspension/steering wizard take one more look at it before I officially rule the rack the culprit and FUBAR, I am already pricing out how much a replacement rack assembly is.

I came across the following product: http://www.patrickmotorsports.com/part/quick-ratio-steering-rack-assembly-911-912-914-930/

Has anyone here installed this? Or have any comments? I'm intrigued but I am unaware of whatever potential downsides that come along with a quicker rack...

[Elombard]

some one installed one several years ago and raved about it. try searching a few ways to see if you can find the thread.

[ClickClickBoom]

Me:
Quick Ratio 911 rack

[chris_seven]

What caster angle are you using as I suspect that the issue is the geometry.

I don't think a quick rack will help turn-in behaviour as basic geometry will not be altered.

I do like 'quick' racks but they won't improve a set up that isn't quite 'right'.

[ClickClickBoom]

Originally Posted by chris_seven

What caster angle are you using as I suspect that the issue is the geometry.

I don't think a quick rack will help turn-in behaviour as basic geometry will not be altered.

I do like 'quick' racks but they won't improve a set up that isn't quite 'right'.

This!
Trying to adjust a 911 without a manual and correct measuring tools is as close to impossible as you can get. Being able to adjust toe-in and out, camber, caster, and ride height and finally, corner balance means, while if done correctly, it's fairly easy to get your car to handling exactly as you like. Done incorrectly, it just won't handle well at all, and might be downright dangerous under heavy braking. My car was a hundred lbs out on corner when I got it and was a handful under slightly heavy braking. Tire wear was horrible. Now with a good corner balance and string set up, I can go to threshold braking from 100 mph with fingertips only on the wheel. Having a shop do your alignment will not be cheap, but it will be worth every penny. If you procure the tools and do it yourself you will be on track to mastering a phase of sports car ownership.

P.S. You location would help with suggestions on a good set up shop. Throwing parts, seldom fixes the problem on the first throw. Also exact set-up of your car would help armchair diagnosis. One un-mentioned possibility is your tires, brand, age, and tread wear. My car, for my driving conditions and style wears my Falken Azenis 200 tread wear , almost flat across the tire in the rear, and the front insides will show cord as the outside tread goes smooth. Tire wear patterns tell a lot about your set up. My tires last for about a year of aggressive street mountain driving.

[mgar88]

Thanks for the input, guys. CCB, your thread on the quick ratio rack is awesome! I'm pretty enthused by your review.

I'm located in southern california. Car has a fresh set of rubber (Exaltos) They are about 6 months old with minimal visible wear. I do some spirited driving and canyon runs. Once my steering is in order, I'd like to do some AX events.

Car has been corner balanced and aligned by Joey Seely in Costa Mesa. He's the former owner of BBI, suspension builder for the Safari cars seen at Luft, and known as an all-around P-car wizard. He's helped me through the two rack failures. When I let him know that things still didn't feel quite right, he offered to take a look at it again, but essentially told me that the rack needs to be replaced with a new unit.

While I hope there's a simpler (cheaper) solution/explanation for my inconsistent turn-in and weak return-to-center symptoms (toe-in settings?), I couldn't help but do some new rack research, which landed me here and on your thread. Will keep you posted on what the diagnosis is when I can bring it to him next week.

[76FJ55]

May be worth posting a copy of your alignment printout, and any other details of your setup. Tire/wheel size, offset, ride height..

[panzerfaust]

Originally Posted by mgar88

Thanks for the input, guys. CCB, your thread on the quick ratio rack is awesome! I'm pretty enthused by your review.

I'm located in southern california. Car has a fresh set of rubber (Exaltos) They are about 6 months old with minimal visible wear. I do some spirited driving and canyon runs. Once my steering is in order, I'd like to do some AX events.

Car has been corner balanced and aligned by Joey Seely in Costa Mesa. He's the former owner of BBI, suspension builder for the Safari cars seen at Luft, and known as an all-around P-car wizard. He's helped me through the two rack failures. When I let him know that things still didn't feel quite right, he offered to take a look at it again, but essentially told me that the rack needs to be replaced with a new unit.

While I hope there's a simpler (cheaper) solution/explanation for my inconsistent turn-in and weak return-to-center symptoms (toe-in settings?), I couldn't help but do some new rack research, which landed me here and on your thread. Will keep you posted on what the diagnosis is when I can bring it to him next week.

i have quaife quick rack too but haven't sourced a 930 rack yet to put in my car since the 911 are slightly different.

did u try maxing out the caster? it should help turn in on tight corners by pitching the car more unloading the inside rear and also adding more neg camber to the outboard fronts.

folks get light (low caster) nervous steering feel mixed up with the ability for the car to dive in a corner with heavy steering. high caster will increase steering efforts noticeably since it weight jacks the car more. it will also help in assisting "the return to center" and straight line stability since the elevated weight wants to return back to it nominal position.

most newer performance cars have ample caster now since they mostly have powered steering to deal with the excessive efforts at parking speeds. if memory serves, the latest 911 or other sports cars are nearly double of what a old school G body 911 has at 5-6 degree maxed out caster.

[Trackrash]

A quick ratio steering rack may be great on an autocross track, but I don't know if I would want one on the street or the track.

The steering on my 911 is almost too sensitive on the street even with a stock rack. See my garage for all the details.

There are a multitude of things that will make your steering more precise and improve your turn in.

You sould post your alignment and ride height specs.

It is possible to enlarge the upper strut mounting holes and gain a little more caster.

Have you driven any other 911s for comparison?

If it was me, I would make absolutely sure that all the bushings, ball joints, tierod ends, and strut inserts are perfect before doing the rack again.

[ClickClickBoom]

Originally Posted by mgar88

Thanks for the input, guys. CCB, your thread on the quick ratio rack is awesome! I'm pretty enthused by your review.
While I hope there's a simpler (cheaper) solution/explanation for my inconsistent turn-in and weak return-to-center symptoms (toe-in settings?), I couldn't help but do some new rack research, which landed me here and on your thread. Will keep you posted on what the diagnosis is when I can bring it to him next week.

The weak return to center says to me you might have a caster issue. TRE is in your neck of the woods. These cars aren't that complicated, but the adjustability throws more than a few techs a curveball. Everything effects everything else, so you can't just make one adjustment and call it good, I use the multi phase approach, get everything close, then remeasure and adjust as necessary, keep checking until everything is where you want it. I tend to run almost no toe in front and rear, I like the car a little nervous, but run stock caster and about 1deg more camber than stock. I also run 215 fronts and 245 rear the widths ratio changes the handling as well. Don't forget the 25MM spacers on the rear either. I do have 3 different widths of spacer, all have small effects on the handling.
I like fussing with the car....

[Trackrash]

Go to 7" front and 8" rear Fuchs.

[panzerfaust]

does anyone know what the quaife quick ratio ratio actually is?

2.5 lock to lock but whats the ratio? stock one is 17ish to 1 from what i recall. i did a quick search on the forum and there is alot of talk of which aircool longnose swb-lwb/G/964/993 had the quickest rack with turning radius and lock to lock. most of the ratios are well document with the exception of the early 3.0 turbo which there is a dabate if there is a quicker rack. i have a buddy with a couple of them 76 930 that we will measure when i get a chance.

hey click click can u measure your quick rack for us when u get a chance? its pretty easy... just turn the steering wheel on full rotation at 360 degree. Measure the degree angle of the wheel or hub (perhaps with an iphone). Then divide the number back into 360. say if its 24 degree angle from straight, divided 24 into 360 = 15:1 ratio. i would guess the quiafe rack its somewhere between 13-15:1?

if the steering overly sensitivity i reckon isnt attributed to the stock steering ratio though a quicker ratio can exasperate it. The layout of the aircooled 911 being rear engine, short wheelbase and an unfavorable center of pressure from the pontoon fenders coupled with a low tail aero wise makes the car inherently less stable. It is akin to throwing a dart backwards.