joe diego

iTrader: (3)

Was wondering if this would work on our SCs. It’s from Grannas Racing for the MKIV Supra.

https://www.grannasracing.com/produc...teering-rack-1

KahnBB6

iTrader: (5)

I *think* it should work on an SC as there is little difference between the SC and MKIV LHD racks other than maybe a .1 difference in ratios. But... I would contact Grannas Racing about it to ask first.

His recommendation for a slower than stock 20:1 ratio for street use is probably wise since either car is a bit heavy and big. The 14:1 option is I believe faster than even a UZZ32 Soarer Active which has the fastest of all racks on this platform and faster than any Supra MKIV. It would be far too demanding (14:1 ratio) without any power assist.

joe diego

iTrader: (3)

Honestly, I want to do it because it really cleans up the engine bay.
There’s a video on YT (Supra w/PS delete from Grannas) and he showed little effort turning the steering wheel at very slow speeds.

RXRodger

iTrader: (2)

I deleted my power steering by converting my rack to manual on my endurance racing car, after one weekend at a practice event I put it all back. With larger tires/wheels it was just too tiring to try to run it that way on track. It may be ok for the occasional driven street car with normal size tires, not sure. Keep us posted what you end up doing.

RudysSC

I will say from experience - if you're going to drive it on the street regularly.... Don't do it. These cars have heavy engines, typically fit big wheels and tires up front, and are heavy to begin with... I ran no P/S on my 2jzge swapped Cressida to keep things clean and simple - I ALWAYS regretted it.

Ali SC3

iTrader: (10)

Looks like another nice product from Grannas but I still wouldn't do it on an SC unless I was just drag racing.
It sounds like a good idea at first, but like deleting your Idle air control valve on a FFIM, it quickly turns into a "why did I do that" situation.

KahnBB6

iTrader: (5)

I think a fully decked out drag prepped car with little skinny wheels and tires up front and big meaty M/T slicks in the back is a good point for how an application of a manual steering conversion might make some sense but otherwise I'd find it hard to justify doing on a car like this. It's not a huge chassis but it is kind of "big"... and heavy. SC300's have a 53/47 weight distribution which is good but not quite 50/50.

The manual steer cars that I have driven and had fun with have all been much older 50's-70's designs with very light weight. A 914, 550 replica, MG, Triumph or similar cars are good examples. So are super lightweight FWD cars of the 80's and 90's.

I owned a '69 Mustang once and I'll never forget the day the power steering lines went out on me which gave me an instant manual conversion for a week or so. I hated turning it until I got it repaired. That was *at least* a 3300-3400lb car but it was probably heavier and that's still much lighter than most SC's.

Small, very lightweight vehicles and many mid-engine vehicles get away with having manual steering racks due to their weight distribution. Even so:

--both the SW20 MR2 of 1990-1999 and the 1999(?)-2005 MR2 Spyder both had power steering (though this was electric assisted in both cases). I believe it was only the AW11 MR2 of the 80's that was manual steer only.
--The mid engine Lotus Exige has a manual rack with it being so small and light but the mid engine Lotus Evora got power steering since it was a larger, heavier 2+2 GT style vehicle.

It's very cool that we have a well thought out manual steering rack option for the LHD SC/MKIV but it's not going to be fun to operate in most situations outside of a dedicated drag car or a dedicated track car.

...

Really, the main weak point of our power steering systems is that the Dexron II/III/etc ATF fluid can boil over under very hard use (sustained hard drifting, racetrack course use, etc). Adding a good PS cooler to the system besides just that bundle of steel tubes helps this out a lot.

Bimmerbill

Craig,
Your comment regarding the Dexron brought back a memory from three years ago when I purchased my SC. My friend who is in parts at the local Lexus dealership highly advised me to use Honda fluid in my power steering because it does not foam. I have yet to switch over and cannot recommend it yet but my friend has never been wrong. In the future I will be replacing my high pressure hose and will drain and fill with the Honda fluid and advise at that time.

t2d2

iTrader: (8)

Never has a project gone wrong on the basis of a youtube video making it look easy.

I drove a manual rack Miata once. They don't come much lighter or better balanced than that, and even so, maneuvering at low speeds got real annoying real fast. It felt great at 40+ mph in the curves, but not enough of an improvement to justify the work getting there.

joe diego

iTrader: (3)

Good to know, but if it fits the SC I’m going for it. I’ll post info/vid after install.
I’ve done a few mods to decrease the weight of my SC, so I hope it won’t be that bad.
battery location to trunk
ABS delete
Electric fans
No sun roof (OG slick top)
Supra seats
Carbon fiber hood (soon)
FFIM

t2d2

iTrader: (8)

I'm the epitome of, "your car, do with it as you wish," so I'm certainly not going to judge, but here's an alternative that I think is a much better route than a full PS delete:

https://www.clublexus.com/forums/per...st-how-to.html

I don't have that car any more, but that simple little mod was such a great improvement to the road feel, I sometimes miss it. When I switch from 225 winter tires to 245 summer tires up front, I get back a bit of that planted feel on the current SC. Being able to adjust the PS assist can give you the heavy feeling of a manual rack, while still being maneuverable at low speeds if you feel like turning the dial. I left it set in the middle.

KahnBB6

iTrader: (5)

Not to downplay your friend's experience since it wasn't just the Lexus SC, GS and MKIV Supra which used Dexron II/III compatible ATF fluid in their power steering systems but most Toyota and Lexus models throughout the 1990's but whatever specific type of "Honda fluid" he is suggesting that you use needs to be a Dexron II/III ATF formulation. Common "power steering fluid" does not work with these power steering systems and can cause issues.

What Honda fluid did he specifically name?

Aside, you really have to be giving your power steering system a major workout for it to boil over the Dexron ATF fluid. The solution for that in competition setups is to add a PS cooler to the system. Small temp activated or manual fan on the cooler optional.

RXRodger

iTrader: (2)

Actually it works quite well in these systems. There is nothing special about these pumps and racks. I purged the system and use AutoZone power steering fluid in my white car. Just never got around to swapping it out on any of the others.

Bimmerbill

Hey Craig,
Finally got back to Rusty at the Toyota Lexus dealership and he did confirm that he told me to use the Honda power steering fluid because it does not foam like the Toyota fluid. But I only remembered part of what he told me (old age) . The reason that their dealership uses the Honda fluid is it heavier in viscosity and stops the power steering noise that older Toyota and Lexus cars have. Even though I do not have any noise in my SC I will still convert to the Honda fluid when I install the high pressure line.
Bill

KahnBB6

iTrader: (5)

Interesting. You guys have given me some alternatives to think about. I've always heard it as common lore on SF that you really don't want to put anything but Dexron II/III/IV compatible ATF into these power steering systems. I really should have looked at the TSRM section on power steering to see what it says (other than Toyota's recommendation of the Dexron ATF).

I'm as much a believer in Honda's engineering as I am in Toyota's so I may look into that Honda PS fluid especially if boil-over becomes an issue for me.