FFR Mark I Steering

[puppster]

My fathers FFR Mark I is set up with 17" wheels and tires, the rest of the combo is pretty much what you would expect on a Mark I. The problem is the steering, it is very scary turning in to corners. You had better be ready when you turn the wheel. There is nothing between going straight and making a right angle turn it seems. The car does not have any sway bars, although we want to add a front bar to help with this issue. I have wondered if it could be a problem with the (probably fox mustang) rack and pinion, but I have not read of any others experiencing the same problem.

The car has been to an allignment shop, and set to fox Mustang specs.

Any help would be greatly appreciated.

Jeff

[Seagull81]

What are the Mustang spec.s they set it to? Have you set it to the FFR spec.s? I am sending you a PM on sway bars.

[bobcowan]

Is this something new? or has it always been that way?

Sway bars won't help you.

The FFR front end is pretty simple. Nothing fancy or complicated about it. That's good, because it makes it easy to fix.

The first thing to check is everything. Pull the wheels off, check all the bolts, bearings, steering rack, etc. Make sure nothing is loose or worn out.

The second thing is alignment. This is a big issue, especially with the MI. If your alignment specs are not dead on, it's a handfull.

Finally, check bump steer.

[puppster]

The car has exhibited the behavoir since we aquired it.

When the car went in for an allingment, it was noted that a rod end was worn out, so it was replaced. I assume everythig else was checked, but it will be checked again. We do not have any documentation that calls out the allingment specs from FFR. The build manual is very light. I believe the tech. looked up a Fox body Mustang and used those specs. I don't recall what they were. Please pass along the specs if you have them.

If this is a bump steer issue would it happen on smoothe roads? On a nice flat surface it still has this issue.

[bobcowan]

During a turn, the outside suspension is compressed, if you have enough bump steer, you'll get erratic behavior.

For the street, I use these alignment specs:

Ride Height: 3.5" Front, 4.5" rear
.25 camber
2.5 Caster
1/32" toe in.

I have manual steering, with a FR rack. I use differant specs for the track.

[puppster]

If it is a bump steer issue a sway bar would (I think) help by keeping the suspension from compressing so much.

Are the ride height specs measured from top of tire to wheel opening? I think this will be a good place to start, as the car looks high in the front, however the rear is not set up with coil overs, and not adjustable. Once getting the ride set, we will get it realigned, possibly then go ahead and add a sway bar.

Thanks for all of the tips.

[bobcowan]

No, a sway bar will not change your bump steer. A sway bar is mostly used to fine tune the car in hard corners. Alignment and ride height settings are done with the sway bars disconnected.

Ride height is measured between the round tube frame and the ground, at the very front and very rear of the tube. It's important to set this correctly before doing anything else. Changes in ride height will affect the other measurements/adjustments.

[puppster]

Thanks for the advice. I think these details will make a difference. It's like tuning a carb... you can't skip these important steps, and you can't do things out of order. I'll report progress, but it may be a few weeks before we can get to it.

Jeff

[RACERAL]

If its a mk1 you may want to slap in a set of offset steering rack bushings.. you need to go to www.ffcars.com to ask this question.

[puppster]

Do these bushings offset the rack forward in the car? I have asked over at ffcobra before, and I did not get as much help as I have recieved here.

I am plannig to see the family next weekend, and hope to have time to crawl around on the ground. I'll post an update after the holiday.

ps. I just found the offset bushings at Jegs. I understand that they will move the rack up in the car, so my question is. Is there something that indexes the bushing to keep it from spinning? From looking at the picture, it seems that the movement of the rack would force them to rotate, leaving the rack lower in the car.

[bobcowan]

If you raise the rack but use standard tie rod ends, the angle of the steering rods will be pretty severe. You need to use a bump steer kit that moves the rod end to the top of the steering arm.

If you don't use a bump steer kit you can use the rack bushing to lower the rack in the frame; which improves the angle while using the stock tie rod ends.

http://www.breezeautomotive.com/deta...=139&cat_id=12

[puppster]

Finally had a chance to see my Dad and his car. We found that the car was sitting high in the front and low in the back. We adjusted the rear to 4.75 like the manual says, and the front to 4.5, all with a person in the front seat. We then checked to camber which seemed good, with a small amount of negative camber (between 1/2deg and zero, and we reset the toe to approximatly 1/16' toe in. I just noticed that you sugested .25 deg camber, I assume you did mean it as positive.

This has helped some, but the car still is overly responsive to steering input. Due to at large Canton oil pan hanging down below the scatter shield, we are not willing to lower the car to the suggested specs above. May need to change the pan in the future.

Not sure what to do next, we wanted to remove a front coil over, and measure the bump steer, but we ran out of time. Dad would like to install a slower rack. Does any one have a suggestion for a rack that will help with bumpsteer in a mark I by shortening or lengthening the inner tie rod positions?
I know he wouldn't mind the easier steering, and he's never going autocrossing. The unit in the car looks like it's right out of a loaner car.

[Don DePontee]

The camber should be around negative 1/2 to 1 deg.
Don

[bobcowan]

What you probably have is a Mustang rack, for power steering. That has a ratio of 15:1 , IIRC.

I use a Flaming River rack, 15:1; which is considered a quick ratio. I find it to be just about perfect for what I do. Steering is very responsive, but not in the least bit scary. FR also makes a rack that is a standard 20:1, which is probably more of what you want.

http://www.flamingriver.com/index.cf...prod/prd41.htm

But keep in mind this is a sports car. It's supposed to be very responsive. Not as much as you describes; I agree this is a problem. But even with a higher ratio rack, it will turn very sharply.

I would take a close look at these parts from Breeze automotive. Might be just what you need.

http://www.breezeautomotive.com/deta...=364&cat_id=12
http://www.breezeautomotive.com/deta...=485&cat_id=12
http://www.breezeautomotive.com/home.php?cat_id=12

[puppster]

This is a help, but I did notice that the complete kit from Breeze shows a tie rod end that looks like a stock Mustang part. This is not what we have....This is getting more interesting all the time, since the car was purchased complete from a private owner.
What we have is a rod end type joint mounted to the top of the steering knuckle. I assume this was done to improve a bump steer issue? Anyhow, I am now wondering if we could even bo back to a stock set up. Is the knuckle drilled out to allow the top mounting of the tie rod?
I think the allingment is pretty good at this point. Best we can do in the garage with few tools.

[snakeski]

I have a mkI and fought it for a while. All the above is good advice. I switched from a depowered mustang rack to a 20:1 to help with the twitchyness. Make sure your front air pressure is about 22 psi, get your ride hieght right and adjust your alignment right. I had to drive mine with a set of wrenches, constantly adjusting toe unit it drove right. a quarter turn on the tie rods made a big difference.

what do you have for rear end?? Got a third link that is disconnected!!!???

[bobcowan]

Originally Posted by puppster

This is a help, but I did notice that the complete kit from Breeze shows a tie rod end that looks like a stock Mustang part. This is not what we have....This is getting more interesting all the time, since the car was purchased complete from a private owner.
What we have is a rod end type joint mounted to the top of the steering knuckle. I assume this was done to improve a bump steer issue? Anyhow, I am now wondering if we could even bo back to a stock set up. Is the knuckle drilled out to allow the top mounting of the tie rod?
I think the allingment is pretty good at this point. Best we can do in the garage with few tools.

Ah Ha! The root of the problem (maybe).

What you have is a bump steer kit. I have the same thing, and this may be the root of your problem. That type of bump steer kit (obviously) moves the tie rod to the top of the spindle. To go along with that, you have to use an offset bushing that will move the rack higher to match it. Otherwise the tie rods point upwards.

Some kits like that use a tapered bolt to match the stock tapered hole. And some use a straight bolt and require you to drill out the spindle - which is not an easy task. If you have a straight bolt, then you can't return it to stock parts without replacing the spindle.

You can do a good alignment in the garage, but you muct have an alignemtn tool. There's no substitute for that special tool. You either have to buy the right tools, or take it to a shop.

[puppster]

My old man got around to putting the offset bushings in, and I drove the car yesterday. It has made a noticable improvement, and he is very happy. His plans include going to a set of 15" Halibrand wheels which I think will make the car a little less responsive, and possibly a slower rack and pinion. I want to thank everyone who helped us get to this point. I guess this is what it's all about.... learning something as you have fun working on these cars.

Jeff

[TButtrick]

You might consider the SAI mod. Your problems will be solved.

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