Power Steering options for the Gen2GTM?

[dreabrown]

I'm hoping to receive my kit in the next few weeks and get started on my build. What's the pro/con on finding a power steering solution for the Gen2? What configuration works? Not looking for unnecessary hassles, but I'd like to think about the performance upgrades now as I map out my build. Thanks.

[Jason Lavigne]

I'm a big fan of power steering, particularly in a modern car like the GTM, so I sold my manual rack on Ebay and spent $140 on a '93 Mustang GT power rack. In addition to that, at the recommendation of Jim Schenck here at FFR, I installed the power steering rack extensions (pt# 14687 for the pair) and cut down the tie rods to bring the toe back in. From there, you'll just need a power rack adapter (pt# 14554) for the end of the GTM steering shaft, and it all bolts right up. Lastly, you'll need a pump. I got a Subaru pump, and I think others have used pumps from MR2s and some others. Youll also need to run a couple of custom lines once the rack is in and the pump is mounted. Give a call if you want to discuss, and also I'm sure others who have switched to power steering will weigh in as well.

Congrats on getting started!

Jason @ FFR

[crash]

Don't forget eeny's speed sensitive adjustable power steering controller that should be available soon at www.myraceshop.com. ;)

[bobzffr]

Get the best MR2 pump you can find on e-bay instead of the Subaru pump. Be sure to get a late model MR2 pump that has the power transistors built in to it. The cheap ones on e-bay are older models and you will need a controller box. If you go with the Subaru pump you will have to build a driver box if you want to use eeny's controller. I learned all this from experience.

[FRANKRAT]

I'm a big fan of power steering, particularly in a modern car like the GTM, so I sold my manual rack on Ebay and spent $140 on a '93 Mustang GT power rack. In addition to that, at the recommendation of Jim Schenck here at FFR, I installed the power steering rack extensions (pt# 14687 for the pair) and cut down the tie rods to bring the toe back in. From there, you'll just need a power rack adapter (pt# 14554) for the end of the GTM steering shaft, and it all bolts right up. Lastly, you'll need a pump. I got a Subaru pump, and I think others have used pumps from MR2s and some others. Youll also need to run a couple of custom lines once the rack is in and the pump is mounted. Give a call if you want to discuss, and also I'm sure others who have switched to power steering will weigh in as well.

Congrats on getting started!

Jason @ FFR

Thats a great solution, thanks for posting all the part numbers

[artistwantab]

When you say late model MR2 Pump what exact year because based on what I can tell they have changed every 2-3 years.

[crash]

From my experiences so far, anything from 2001-2005 Toyota MR2 will work just fine.

[VD2021]

I'm hoping to receive my kit in the next few weeks and get started on my build. What's the pro/con on finding a power steering solution for the Gen2? What configuration works? Not looking for unnecessary hassles, but I'd like to think about the performance upgrades now as I map out my build. Thanks.

I have been researching the PS Mod as this is something I may add in the future. There is a lot of info on the other forum. I can tell you that the manual rack is not difficult to turn. My ten year old son can turn the wheel very easily from stop to stop.

Some Pros;
The mustang power rack used in the mod is faster.
Daily driver like easy wheel turning for need maneuvers like parking.
Driver dependent, but likely better control on road course.

Some Cons;
Added cost. Rack, Electric PS Pump, Controller, misc parts.
Minor mounting fabrication.
Added build time. You'll soon discover that every mod or addition turns into more time spent on the build. This may be just what some are looking for, but I for one, want to enjoy driving my creation sooner than later.

HTH

[VRaptor SpeedWorks, LLC]

I've driven.....I think 3 different GTM's with power steering so far. To be perfectly honest, I can tell absolutely no difference between driving with the manual rack or the PS installed. High speed.....low speed....stopped. I just plain can't tell if it has PS or not. They feel the same to me as far as steering effort. If anything, I would say the cars with PS feel much heavier at low speed than without PS. JMHO.

[crash]

Interesting Shane. I would assume that the rack ratio is why the power steering setup felt heavier at low speeds.

Were you utilizing a PS electronic controller?

If you were, did you mess with the assist curves at all?

[VD2021]

I've driven.....I think 3 different GTM's with power steering so far. To be perfectly honest, I can tell absolutely no difference between driving with the manual rack or the PS installed. High speed.....low speed....stopped. I just plain can't tell if it has PS or not. They feel the same to me as far as steering effort. If anything, I would say the cars with PS feel much heavier at low speed than without PS. JMHO.

Shane,
That's valuble information. It definitely pushes me to stay with the manual.

I wonder if there are any others who have had the opportinity to drive both and give feedback?

[VRaptor SpeedWorks, LLC]

Interesting Shane. I would assume that the rack ratio is why the power steering setup felt heavier at low speeds.

Were you utilizing a PS electronic controller?

If you were, did you mess with the assist curves at all?

Yes....using Ian's controller with MR2 pump. It's been awhile, but I think we did play with the curves on JimO's car a bit, but I didn't play with the curves, then drive, then play with the curves, etc....enough to really get any feel for any difference that the settings were making. I left that up to JimO as I figured he would dial it into what he felt worked best while tracking the car. Other than that car, no I did not play with the curves at all.

[kabacj]

I think the logic behind the power steering is its more if a track mod. After doing lots of research on the pump and rack options I found that while folks have had success with the manual on both the street and track the power setup was helpful when you get the car sideways. As many can tell you the mid engine gtm only gives you so long to catch it before you loop. The power rack will give you a few more milliseconds to catch the rear before it becomes the front.

Now all that said..... Who NEEDs a super car? A variable assist power rack is a really cool feature to build yourself with components built with and by other GTM builders. A handful of production cars allow you to adjust the power assist. None allow you to program it. I look at it as another way you can one up every production super car with the car you built yourself.

John

[VRaptor SpeedWorks, LLC]

I think the logic behind the power steering is its more if a track mod. After doing lots of research on the pump and rack options I found that while folks have had success with the manual on both the street and track the power setup was helpful when you get the car sideways. As many can tell you the mid engine gtm only gives you so long to catch it before you loop. The power rack will give you a few more milliseconds to catch the rear before it becomes the front.

John

And that scenario is just as much part of the problem as it is the solution. If you turn the PS pump speed down for more feel/less assist at speed, you can easily out-flow the pump by trying to quickly turn the steering wheel. So you start to get sideways and try to quickly correct with the steering wheel.....only to find that the pump is running too slow to flow enough oil to operate the rack.

[crash]

Thanks for bringing that point up Shane.

It is one of the top things I am working on with AGR to address. That is, trying different combinations of components so that the pump can be turned down to an amount of flow capability that allows fast inputs, yet makes sure that the feel is still there. In other words, the speed of the pump, and corresponding volume of fluid capability, can't go down to the point where the rack can not be turned quickly. There are actually a number of different ways to address this.

I feel, after extensive discussion, that this isn't a situation of "it will never work", but rather a situation of fine tuning components to get the desired results. :)

[VD2021]

And that scenario is just as much part of the problem as it is the solution. If you turn the PS pump speed down for more feel/less assist at speed, you can easily out-flow the pump by trying to quickly turn the steering wheel. So you start to get sideways and try to quickly correct with the steering wheel.....only to find that the pump is running too slow to flow enough oil to operate the rack.

Shane,
Great point.

[VD2021]

Thanks for bringing that point up Shane.

It is one of the top things I am working on with AGR to address. That is, trying different combinations of components so that the pump can be turned down to an amount of flow capability that allows fast inputs, yet makes sure that the feel is still there. In other words, the speed of the pump, and corresponding volume of fluid capability, can't go down to the point where the rack can not be turned quickly. There are actually a number of different ways to address this.

I feel, after extensive discussion, that this isn't a situation of "it will never work", but rather a situation of fine tuning components to get the desired results. :)

If only there were a smart device that increased/decreased pump rate with the speed of movement of the steering wheel.

[crash]

One of the functions of the torsion bar is to regulate pressure and flow rate defined by resistance to steering input.

Balancing the torsion bar, flow rate capability of a given pump, and immediate pressure available based upon electronic control of the pump is the basics to the balancing act.

Again, I am studying this RIGHT NOW in order to possibly improve upon the system that was initially concieved, designed, and tested by myself, Ian Atkinson, and David Borden. While I concede that my initial involvement in the technical issues involved in this product were minimal at most for the original product, and it is a great product with great functionality as designed and originally built by Ian, I AM working hard to refine the entire system to be more user friendly and to perform it's function "better". One of the things I define as "better" is the ability of the system to function more efficiently through a wider range of conditions.

[dbusa]

Hi Mike - as people are using different sourced racks, it should be noted that Agr modifies the rack for the gtm - it is not the same as the stock mustang ll rack. At the time I got mine Matt was working with feedback from the cobra guys and the few gtm guys , and modifying the internals based on the feedback. To this point all I've been able to do is go kart the car, in a limited area, so no high speed corners yet. The system works great at low speed, driven with the pwr disconnected and connected - noticeable difference in steering effort at low speed. I would venture to say that for most people it would be an asset, at least for the street. On the track , if you are in a high speed corner, and have to put that much steering input and effort ( overpowering the pump) it may be an issue - but you've probably overcooked the corner and sometimes skill just isn't enough to save it anyways ...that's where the lucky rabbits foot comes in, lol Ians controller with the agr rack is a step up - and there is probably room for improving even further. Will be glad to give my impressions after doing a track day - that's if the bodywork ever ends. lol

[crash]

Don- Yes, this is why I am working to build a plug and play kit. There are many variables, and getting them right for a GTM will definitely improve the performance of this system.

I ground out, glued, body filled, and sanded again last night. SSDD! It is coming along though.

[VD2021]

The Toyota MR2 electric power steering pump has been a part of the DIY EV seen for quite some time now. The MR2 steering sensor, PS pump ECU and driver are the parts that make it all work in the MR2. Maybe these parts can be reworked for the GTM.

[mikespms]

I looked into the mr2 pump with the controler box and the agr rack i talked with Matt at agr acording to him the rack he modifies works without the need of the cotroler the heavier torsion bar and valveing work well . I oderred a rack from agr and priced a new pump from toyota @565.00 . after a two week wait agr had not started working on the rack and could not give me a delivery date. I had been lookig into using an engine driven pump with the agr rack but after waiting for the rack and no delivery date, i decided to use the corvette variable efort power steering out of my donor car since i am using the ABS and traction cotrol the steering is controled by the EBCM and uses all the imputs from the system. i took some measurements from the corvette front end and made brackets that mount on the gtm frame to mount the corvette rack with the same spacing and location as the corvette. I allso made a bracket to mount the corvette power steering pump on the engine and it fits in the gtm frame with no problem i ran steel lines to the front to rack and ps oil cooler the system has the oem look 6202 i am havig problem with the photos

[mikespms]

I looked into power steering using the mr2 pump with the control box and the agr rack, after talking to matt at agr he said that the cobra guys are using his rack with engine driven pumps with good results if needed you could regulate pressure with a valve but he said the modified valve and torsion bar would do the job fine. I allso looked at a low flow variable press pump from flaming river, the higher the rpm the lower the pressure for a 189.00 vs. 565.00 from the local toyota dealer. I ordered a rack from agr was told two weeks but after two weeks he had not started working on it,so I canceled the order and decided to use the variable efort power steering from my donor since Iam using the ABS and taction control the magnasteer unit from the corvette uses the same sensor and is contoled by the EBCM . I made brackets to mount the corvette rack to the GTM rack mounts maintaning the corvette steering geometry, allso made a bracket to mount the engine driven pump. It fits over the alternator with a couple of idlers like the a/c compressor for the proper rotation . the resevoir is mounted by the fire wall next to the cooling system resevoir and ran steel lines to the front to the rack and ps oil cooler and got that oem look. I should be ready to go kart in a few weeks and see how it works.

[artistwantab]

If you could manage some pics I would be curious to see.

[David]

Mike, the issue with the corvette rack, is its width based on a conversation with Jim S, the engineer on the GTM. Being to wide, it may create bump steer challenges.

David

[David]

I've driven.....I think 3 different GTM's with power steering so far. To be perfectly honest, I can tell absolutely no difference between driving with the manual rack or the PS installed. High speed.....low speed....stopped. I just plain can't tell if it has PS or not. They feel the same to me as far as steering effort. If anything, I would say the cars with PS feel much heavier at low speed than without PS. JMHO.

Hey Shane ... The primary reason I went with PS, was to get a quicker rack. The GT rack is quicker despite the manual is supposed to be 15:1. Otherwise I agree you don't need the boost.

David

[VRaptor SpeedWorks, LLC]

Hey David.....good to hear from you! Yes, I did remember your reasoning for going PS to get the quicker ratio, and I can definitely see that would be an advantage for doing auto-x like you had done with your GTM. Did you ever get yours dialed in to eliminate the problem of the rack out-flowing the pump?

[txbuilder]

Is anybody running the power rack with the MR2 pump and not using the variable speed control? I am building a car, not a GTM, for a customer and he wants power steering. I will be using a Mustang II rack and am wondering how it will work without the controller since I don't have any speed sensors for the variable control.

[crash]

You can definitely run a power rack without the controller. The issue will be tuning the torsion bar to the weight and handling characteristics of the particular car, and the fact that "road feel" will be deminished at higher speeds.

These are the two main benefits of the electronic controller. It allows fine tuning, and it gives good assist at slower speeds, yet you don't lose road feel at higher speeds because the assistance is turned down.

Think 70s type power steering as opposed to the current OEM type of power steering. :)

[artistwantab]

Hey Shane ... The primary reason I went with PS, was to get a quicker rack. The GT rack is quicker despite the manual is supposed to be 15:1. Otherwise I agree you don't need the boost.

David

Do you mind explaining what a quicker ratio gives you? I have never cared or thought about the rack in any car I have owned but WHEN I raced it was more street racing and straight lines.

I imagine this is needed primarily for track racing? I wont be track racing but may go to a track just to see what the car can really do without getting arrested for "Exhibition of Speed".....again. Sigh.

[artistwantab]

You can definitely run a power rack without the controller. The issue will be tuning the torsion bar to the weight and handling characteristics of the particular car, and the fact that "road feel" will be deminished at higher speeds.


I think that is exactly what I need because I only want power steering for traffic and parking lot situations.

[txbuilder]

You can definitely run a power rack without the controller. The issue will be tuning the torsion bar to the weight and handling characteristics of the particular car, and the fact that "road feel" will be deminished at higher speeds.

These are the two main benefits of the electronic controller. It allows fine tuning, and it gives good assist at slower speeds, yet you don't lose road feel at higher speeds because the assistance is turned down.

Think 70s type power steering as opposed to the current OEM type of power steering. :)

Can you explain what is involved with tuning the torsion bar?

[crash]

The torsion bar is the component that controls how much assistance is given to the rack, and with how much input force.

In other words, the lighter the torsion bar, the lighter the input that is needed to kick in the power assist.

With a very light torsion bar, and enough pressure behind it in the hydraulic system, you could potentially have a system that you could turn with one finger in a 12,000 truck...at a stop.

The problem is that this vehicle would also become uncontrollable and unstable in the steering when driving at speed due to the relatively light force to activate the assistance and the large amount of pressure behind it.

The other extreme would be to put in a "heavy" or stiff torsion bar. This is undesirable because it would take a large amount of input, both in force and angle, to initiate the assistance from the hydraulics. If the ratio of the rack is decreased to take advantage of the power steering, but the torsion bar is too heavy, this will multiply the issue of having to put in large force/angle into the steering wheel.

So balancing the torsion bar to the weight of the car, pressure of the system, tires that are on the car, size of the steering wheel, what the car will be used for, etc, etc is the trick, yet nothing about the all mechanical torsion system has anything to do with adjusting to varying speeds of the vehicle. That's where the electronic controller comes in.

Yeah, it adds another variable to the equation, but it isn't by any means the dominant piece of that equation.

So, like with many systems that try to work over varying conditions, mechanics can take you only so far, and while the mechanics have to be right, and "balanced", the electronics make the system much more precise, as far as meeting the desired performance goals.

So with the electric variable pump, the "balance" is to try and not over pressure or under pressure the system at any given time under any particular situation.

:)

[VRaptor SpeedWorks, LLC]

Do you mind explaining what a quicker ratio gives you? I have never cared or thought about the rack in any car I have owned but WHEN I raced it was more street racing and straight lines.

I imagine this is needed primarily for track racing? I wont be track racing but may go to a track just to see what the car can really do without getting arrested for "Exhibition of Speed".....again. Sigh.

Quicker ratio means you have to turn the steering wheel less distance for an equal change in the angle the wheels turn. Assuming the wheels turn to the same angle "lock-to-lock", a quicker ratio rack will have less rotations of the steering wheel to get from full-lock-left to full-lock-right.

[artistwantab]

Thanks guys for a very clear explanation.

This will be my first kit and in previous cars I basically kept it stock and never gave a thought to power steering options.

[Roger Reid]

The torsion bar is the component that controls how much assistance is given to the rack, and with how much input force...

So the torsion bar is part of the steering rack? Is it tunable in the Mustank II power rack? Does the Mustang II rack need to be tuned for the GTM application?

[txbuilder]

Crash,

Thanks for the explanation. Is the torsion bar adjustable or does it need to be replaced to change the rate? I have had power racks apart but I am not familiar with what that part is. Does anyone know where to find a drawing or something that show this and how to change it?

[The Stig]

Hey Shane ... The primary reason I went with PS, was to get a quicker rack. The GT rack is quicker despite the manual is supposed to be 15:1. Otherwise I agree you don't need the boost.

David

I'm interested in upgrading to the power steering configuration at some point in the next few months. The main reason, is that my wife is interested in driving the GTM from time to time, and while the steering seems somewhat light to me, it probably wouldn't for her. I'll be planning a power steering layout for her cobra as well. This thread really pulls all the elements together and makes it easier to wrap your head around what needs to be done.

[mikespms]

Hi Dave Before deciding to use the corvette rack I posted on the other forum for advice and called factory five as well I was told by ff that they had no knowledge of anyone doing it but there was no mention of negative affect from using it no mention of affecting bump steer, also there was no replies to my post. I had seen Dons car, he's using the mr2 pump and agr rack and had taken some measurements there is about 1 inch diferens tie rod end to end between the corvette rack and the agr setup on Dons car . The mounting point on the mustang rack is about 15.5 inches and 17 for the corvette, the body of the corvette rack is wider . The pivot point is inside the pivot point of the upper control arm, the mustang pivot is 2 inches different but it pivots out side of lower control arm. I don't know how much travel the suspension has at ride height but hope it won't have an adverced result. I had allso fitted the corvette front and rear swaybars and they would work but was concerned that they would be to stiff that would limit the suspension travel, would need to look more in to it maybe a lighter bar don't know if the after market has them but they would esealy be installed with minor modification. Worse come to worse i can use the agr rack with the engine driven pump, but would prefer to use the magnasteer.

[VD2021]

the mustang pivot is 2 inches different

If you are going to have bump-steer issues this will be the cause. I would remove the coil-over, move the suspension through it full range and take some toe measurements. Better to know now than later.

[mikespms]

Hi Vidal. I spoke to Jim at factory five today went over the setup and the way I mounted the rack he thinks it will work . nothing that can't be corrected with a bump steer kit if needed,as soon that i can get the car on it's wheels i will check the toe thru the travel of the suspension. I am going to instal swaybars front and back as well.We talked about the shock mounts he is working on a bolt on fix won't have to take the panels out to do.

[kabacj]

For the sake of completeness, this is what I ordered from Toyota to complete the MR2 based setup

[VD2021]

Mike, PM.

[dreabrown]

Do you have parts #'s and source info on the lines connecting the pump to your rack? This is great info, thanks.