Making the a-arms "wider"...besides camber issues,, what other "gotchas" will I hit?? Options

[groot]

And... when I made my camber plates I actually had to use them to reduce camber... like you're suggesting.

[Mueller]

QUOTE (groot @ Mar 28 2006, 11:43 AM)

You can lengthen the tie rods to accomodate... why would you mess with the rack?

I was under the impression from another thread that the tie rods cannot be adjusted more than 1/2" or so....I personally have not looked at mine to see how far out they can go.....

I'd like to go at a minimum 1" per side to make the front and rear track equal....at a maximum 2" per side if I decide on 1" flares front and back...

[groot]

You have a welder, right?

They can be lengthened more than 1"... you just need that 1" for toe adjustment.

[Mueller]

QUOTE (groot @ Mar 28 2006, 11:49 AM)

You have a welder, right? They can be lengthened more than 1"... you just need that 1" for toe adjustment.

I guess so....just something about mod'ing certain components makes me nervous (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[groot]

Do it!!!! It'll make you feel good (IMG:http://www.914world.com/bbs2/html/emoticons/drooley.gif)

Seriously, put a nice chamfer on both sides and build the weld carefully and it will be plenty strong.

[Mueller]

QUOTE (groot @ Mar 28 2006, 12:55 PM)

Do it!!!! It'll make you feel good (IMG:http://www.914world.com/bbs2/html/emoticons/drooley.gif) Seriously, put a nice chamfer on both sides and build the weld carefully and it will be plenty strong.

watch out, Muellers going to be playing with power tools (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

[Mueller]

QUOTE (turbo914v8 @ Mar 28 2006, 11:39 AM)

How wide do you want to go? = How deep is your pocket? Adjustable width 935 front end

true story....I sold a set of the needle bearings to a 3.8 911 owner that had that 935 setup on his car and couldn't get any of the local Porsche/Go fast track shops to make it work half-way decent, he went back to stock a-arms w/needle bearings and loves the car even more....


that is a big chunk of change...I don't see going down that path anytime soon (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

[Porcharu]

QUOTE (Mueller @ Mar 28 2006, 10:35 AM)

the second modification to the steering rack will be just as "fun" to perform (IMG:http://www.914world.com/bbs2/html/emoticons/smash.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/welder.gif) you'd need a "sacrificial" rack so that the ends can be cut off, machined and installed to a good rack....this will cure the problem of the turbo tie rods being too short....

If you do that your changing the inner pivit point and will be causing bump steer. Just make the tie rods longer.

[J P Stein]

I've stared at this till I'm blue in the face and can't come up with any way to allow a larger backspace wheel/tire to be used......short of throwing the whole works away & starting over. I guess I gotta look at a late model Porsche's front suspenders & see how they do it & if it can be adapted to the front of a 914. I hear that increasing the front track is gud, but I ain't going for someone's say so for a nut buster like that....unless they got a room fulla trophys. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

All I want is to run a wide W/T set up without gawd awful scrub radius problems. Pushing out the top mount & the ball joint gain you nothing here.....as I see it. If you move out the bottom an inch or 2 & not the top, you can (or will) 10 deg negative camber (or so) unless you change the angle of incidence twixt the strut & axle.....and even that would gain you a bit more that half your movement of the lower arm.
The strut housing would be at a greater angle(to the earth) & side load the hell out of it. I gots those problems now.

Now,.... a guy could sneak in a sub frame & double A- arm
set up..... (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif)

[Mueller]

QUOTE (J P Stein @ Mar 28 2006, 05:56 PM)

I've stared at this till I'm blue in the face and can't come up with any way to allow a larger backspace wheel/tire to be used......short of throwing the whole works away & starting over. I guess I gotta look at a late model Porsche's front suspenders & see how they do it & if it can be adapted to the front of a 914.

now that I think of it, I'd still have to run a spacer (not as large) to make room between my wheels and the strut (I have 47mm offset 7" wide rims or almost 6" backspacing)

all this would really do is increase the track which would not be a bad thing for those running flares and spacers "just to fill up the wheel wells"

if I get motivated, I'll pop a wheel off my 911 and snap some pictures this weekend....the 964 series and newer have the "FWD" offset suspension

[andys]

QUOTE (Mueller @ Mar 28 2006, 01:25 PM)

QUOTE (groot @ Mar 28 2006, 12:55 PM) Do it!!!! It'll make you feel good  :drooley: Seriously, put a nice chamfer on both sides and build the weld carefully and it will be plenty strong. watch out, Muellers going to be playing with power tools (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

Mueller,

If you're going to put a sleeve over the outside, then cut each end on an angle to both increase the weld area, and avoid having a circumferencial weld on a plane that intersects the axis at 90 degrees. Hot rodder have been doing this for years.

Andys

[Mueller]

QUOTE (andys @ Mar 28 2006, 08:01 PM)

QUOTE (Mueller @ Mar 28 2006, 01:25 PM) QUOTE (groot @ Mar 28 2006, 12:55 PM) Do it!!!! It'll make you feel good  :drooley: Seriously, put a nice chamfer on both sides and build the weld carefully and it will be plenty strong. watch out, Muellers going to be playing with power tools (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif) Mueller, If you're going to put a sleeve over the outside, then cut each end on an angle to both increase the weld area, and avoid having a circumferencial weld on a plane that intersects the axis at 90 degrees. Hot rodder have been doing this for years. Andys

the angle cut crossed my mind, I was too lazy to draw it, easier to do a rotational cut (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Porcharu]

QUOTE (J P Stein @ Mar 28 2006, 04:56 PM)

If you move out the bottom an inch or 2 & not the top, you can (or will) 10 deg negative camber (or so) unless you change the angle of incidence twixt the strut & axle.....and even that would gain you a bit more that half your movement of the lower arm. The strut housing would be at a greater angle(to the earth) & side load the hell out of it. I gots those problems now.

That would be BAD. Ever drive a late model Mustang? - those cars use a strut with about 20 degrees of kingpin angle. That is the main reason those cars handle like pigs, if you "adjust" the spindle back to 10 degrees or so the car handles very well even with the horrible front weight bias.

[McMark]

What about extending the spindle outwards? That would move the wheel outwards, while increasing the clearance with the shock. (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif)

[McMark]

Notice the extra bit moving the spindle out.

[alpha434]

QUOTE (McMark @ Mar 28 2006, 11:48 PM)

Notice the extra bit moving the spindle out.

RSRs had this done... I even have a picture somewhere. But the shocks had to be custom welded if you changed them out.

[groot]

As I understand scrub radius, it increases the moment about the knuckle during braking. I agree that's a bad thing if you have compliant bushings (because you get serious toe changes), but what if you have spherical bearings... or needle bearings?

[Brett W]

Scrub radius is bad. This is one of the major problems with the strut suspension. When you increase the tire width you have to increase the scrub radius. The more scrub radius you have the harder the car will be to drive and the more effort the driver willl have to put in. Many race cars are going to a zero scrub radius design, but that has its draw backs as well.

Cutting the spindles and extending them is not a good idea. One thing you could do is change the angle of the strut in relation to the spindle. Right now there is 10deg of KPI in the stock strut. You could lay the strut back to 15deg and lessen you scrub radius with wide tires, but then you would run into other issues.

The rules in many classes say you have to keep the strut inside the spring, but you could do something like the sliding strut on jim blakewell's car.

[Bigbohr]

This is what a 964/993 front looks like: the strut is more inclined towards the middle of the car, plus the strut center at hub level is way inward from where the balljoint is. Both of these features allow you to run higher offset rims and larger tires, plus this reduces scrub radius. I think a 993 actually has a slightly negative scrub rad. If you look at a front hub, you may be surprised to see where the strut is connected to the hub, it's behind the hub center. It looks like Porsche did that to allow passage for the front axles on a Carrera 4. The steering arm is also at a different elevation. Anyways, the geometry is very different.

[J P Stein]

Positive scrub radius doesn't seem to be a huge problem with a track....other than the steering effort.....at least from my experience with wider corners.
On an AX car where you're cranking in a lot of steering lock, it will make the car push like a bitch. At 5 mph in the pits and a lot of lock, I can feel the front tires skipping sideways over shittage laying there. I *think* this translates into push in tight corners....bad push. In larger radius corners
and slaloms, we gots oversteer....a bunch of that also. I'm looking for more balance twixt the 2......it's tough for an old guy to keep track of what to expect. (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)