Power Steering to Sensitive?

[bucketlist]

hello, just purchased a mark III, (very nicely done from illinios)(bought it in sept still trying to title it in NJ!) getting to know it, is has a 1996 4.6 mustang gt motor, with power rack, my question is, it is very sensitive, is there a way to make it less sensitive, it drives straight, handles well, just very sensitive, any help would be great.

[d42davis]

Do you have the As Aligned specs on the front end?

[MPTech]

You can also install a Heidts valve and/or the cut-down spring mod for the rack.

[AZPete]

I agree. Check the front alignment because the caster setting can make it twitchy.

[Greg_M]

As mentioned, check aligment and also the tire pressure, it should be around 24#. A lot of us performed the cut-spring mod where a few coils are cut from the regulator spring in the PS pump to reduce pressure/assist.

Greg

[bucketlist]

no, do not have any specs, 24 pounds of front pressure? it's now 38 pounds! ffr build date is mark iii 2004, the steering is very responsive, needs a light hand, i am used to manual steering on my 1940 ford sedan street rod, maybe just need to get used to it, thanks to all

[d42davis]

Get the tire pressures down to the 24# range first. Toe, Camber and Caster can all affect the twitchy issue. Find out how the car is set up before you start cutting anything.

[Frank Messina]

Start by setting your tire pressure. 23 F 26 R. Next count the number of steering wheel turns from lock to lock just to know what you've got. 3.0 is good and very driveable. 2.5 is very quick and responds in a big way to very small inputs. You need to pay attention to what you're doing with the wheel all the time. 2.25 LTL is rediculously quick unless you are doing autocrossing. Check that you have correct toe setting. 1/16" Toe in total. Toe out will make the car want to take off. If the steering feels light check the caster. FFR says 3 - 5° but many run more. More improves road feel and tracking with power steering. If you have 5+ caster and it still feels light then consider either a Heid'ts valve or cutting the relief spring. I like the Heidt's valve because of it's adjustability.

Frank

[Greg_M]

Originally Posted by bucketlist

any how too's on the spring cutting and how much?

From the buildsite: Gregs '65 Shelby AC Cobra Build (FFR) - Reduced Power Steering Assist Spring Mod - Worldisround photo

Greg

[JKleiner]

All good comments above regarding tire pressure (38 is way high!), rack ratio and alignment. With power steering you can get real agressive with positive caster, like 7 to 9 degrees, to stabilize the car. Your alignment guy might look at you like you have 3 heads when you ask for that but trust us! When you go with the higher caster ranges be aware that you'll most likely need longer adjuster sleeves on the forward links of the upper control arms (SEE THIS). As Frank mentioned be sure that it is set for TOE IN; toe out will cause it to feel darty and too sensitive.

With a proper setup even a car with a 2.25 turn rack will feel stable at full boost.

Good luck,
Jeff

[rich grsc]

Frank, Jeff, the 2.5 and 2.25 rack are the same ratio, the 2.25 has the plastic turn limiters. At least that the story I was told!

[tad240]

Originally Posted by JKleiner

All good comments above regarding tire pressure (38 is way high!), rack ratio and alignment. With power steering you can get real agressive with positive caster, like 7 to 9 degrees, to stabilize the car. Your alignment guy might look at you like you have 3 heads when you ask for that but trust us! When you go with the higher caster ranges be aware that you'll most likely need longer adjuster sleeves on the forward links of the upper control arms (SEE THIS). As Frank mentioned be sure that it is set for TOE IN; toe out will cause it to feel darty and too sensitive.

With a proper setup even a car with a 2.25 turn rack will feel stable at full boost.

Good luck,
Jeff

X2 - Add Caster. Get 2 longer adjuster sleeves (Speedway sells them) as the stock ones will likely be too short and you will not have enough thread engagement. You've got power steering so the caster will really improve stability and will not make your steering feel heavy like it would with a non-assisted car.

[JKleiner]

Originally Posted by rich grsc

Frank, Jeff, the 2.5 and 2.25 rack are the same ratio, the 2.25 has the plastic turn limiters. At least that the story I was told!

That may well be the case Rich. I've never had the two side by side to find out for sure but would be curious to know if it is a mechanical ratio difference or simply a travel limit. Either way it's a pretty small difference between them; one eighth of a turn either direction.

Jeff

[bucketlist]

will do the tire pressure 38 to 28, thanks for all the suggestions, i do know that the rack is out of 96 mustang gt, 3 turns LTL? it does have longer adjuster sleeves. i am used to manual steering on my 1940 ford sedan street rod, maybe just need to get used to it, thanks to all

[Marty Prario]

I have a similar set up. The tire pressure depends on the size of tires you run. 15" tires run different tire pressures. I run 17" tires and run 22 up front and 23 in the rear. These pressures work perfect with my kumo esta xs tires. I am running 255x40x17 on all 4 corners.

Like most have said, alignment, alignment alignment. Lots of Caster.

[rich grsc]

28 psi is still too high. 10 psi per 1000# is a good starting point, then adjust from there. A 1 or 2# change in tire pressure can make difference.

[NiceGuyEddie]

agreed even 28 all around is too high.

38 must be a death trap, i am all over the place at 24. i have crummy Sumimotos, though.

following the 1 psi per 100 pounds general rule, i'd easily recommend 22psi all around, go for a drive, see the HUGE difference, and be happy you have already improved the car for free.

then, bump it up from there.

but please tell us your exact tire sizes, brand, type. e.g. 17", Goodyear, All-season. or 17", Nitto, DOT track

[cChrisM]

Where in NJ are you. I would highly suggest you contact Mark Dougherty (he is right next to Hersey Pa). Talk to him and then spend a day in his shop. He will align the car to how you will drive it and check everything to make sure you are safe. Worth every penny.

Mark Dougherty can build anything! | The Traveling Builder

Many guys in NJ and PA have used him as well as many of the others on this forum. He also worked at FFR.

Give him a shout and you won't regret it.

[hind sight]

Good info given
I too have done the "cut spring" mod as mentioned on Gregs build site. A must if useing the mustang rac kand pump set up.
You also need to increase the amount of caster. Increaseing the amount of caster will make the steering wheel want to return to center faster/easyer. Basicly it will require more effort to turn the wheel the more caster you have.
Once you have the cut spring mod along with correct alignment specs. You'll love the power steering option opposed to manual steering.

[bucketlist]

tried 28 pds felt better, will try even letting out more, running 17" wheels sumitomo tires.

[w4jeh]

I had Sumitomos, and I took them off because I simply couldn't control the car. I went to Nitto NT05s in the front and NT05Rs in the back - a WORLD of difference. Caster also makes a huge difference. Caster adjustment should be specifically done for a power rack if that's what you have. I also agree with the others on tire pressure - for me, 24 Lbs is just about right, 28 is too much. If you do all three things, good tires, correct caster and correct tire pressure, your car will be much safer and easier to drive at speed and under acceleration, IMHO.

[AZPete]

Bucketlist, I still think it is the caster but once you find the solution please let us know - that's how we all learn.

[NiceGuyEddie]

i have Sumis as well, go down to 22psi. that's most of us run on the street for overall handling and tire wear.

(Sumi's are known to wear in the center, even with 22psi on our cars.)

i have found that for autocrossing 22psi hot is the best. 21psi hot for me was understeer and 23psi was oversteer. i didn't experiment front/rear and your suspension setup will come into play.

in any case be careful with the car!

[Chepsk8]

Another rack idea is to use the slowest one available. I use one from a V-6 PS car, and I think it's 3:1 ratio, for even a slower response.

I also have a small crank pulley for reduced pump RPM.

Yes, like all above, alignment is a MAJOR factor.

Also, it is the nature of the beast, light weight, short weelbase, snap-spin.

[bucketlist]

tring 26#'s now, its much better,

[CraigS]

I know it's counter intuitive compared to normal cars but try 22#, just try it!