just a thought on geometry

[GM Muscle]

and it may have already been discussed.. but instead of the guldstrand mod, has anyone ever just used the howe tall upper balljoint, offset cross shaft and moved the control arm mounts back 7/8ths of and inch? im just exploring options and trying to save a penny.. im not trying to win any races.. just trying to rag on my car and maintain control id like to buy the spc arms and be done but i have other priorities in life all of the sudden and have to make due. life throws a few wrenches in right when you think youve got it all figured out!

i just wanted to explore this option and get some opinons.. i can see the pros being you dont have to redrill any holes, you dont have to do any notching, and it would save quite a bit of money. cons?- just plain wont work? haha

[Blake Foster]

if your using a stock subframe, and want to move the upper control arms back 7/8" then you have to cut the upper control arm off the sub any way so why not drop it down at the same time and the G mod is done, no need for special ball joints.

[GM Muscle]

i agree it would be easy but i was under the impression that the extra tall ball joints were superior to the g-mod? i dont like the idea of notching, it just seems like it would weaken an area. Im not oppossed to the g-mod at all. just exploring different routes. does pozzi still post on here? are the offset crossshafts even needed? i figured it would just allow for that extra bit of adjustability. for some reason on this computer i cant log in to protouring.com or teamcamaro.com i can only browse.

[Rick Dorion]

Mark, at SC&C, has posted alot about the benefits of tall UBJ vs Gmod, etc. Not sure if he did here but on pro-touring.com he has.

I have a tall (not tallest ) UBJ and his UCA's annd like it for the street. His arms allow caster/camber without shims. With max shims, I got a little over 3* caster and .5* negative camber. With his UCA's and no shims, I have 5* caster, same camber.

[GM Muscle]

Originally Posted by Rick Dorion

Mark, at SC&C, has posted alot about the benefits of tall UBJ vs Gmod, etc. Not sure if he did here but on pro-touring.com he has.

I have a tall (not tallest ) UBJ and his UCA's annd like it for the street. His arms allow caster/camber without shims. With max shims, I got a little over 3* caster and .5* negative camber. With his UCA's and no shims, I have 5* caster, same camber.

im pretty sure it was his post that i read about the x tall ball joints being more beneficial.

WHERE YOU AT MARK? lol

[David Pozzi]

I did what you are suggesting, cut off the mount, trimmed the bottom and welded it back on but to the rear. I only moved it 1/2" because I figured I would add tubular upper A arms.

I haven't run the tall balljoint version against the G mod, but a taller balljoint is only 1/2" longer, at least that's what my early Howe uppers are. The G mod lowers by a bit more than that, so I'd expect the G mod to be about as good or slightly better than 1/2" taller upper balljoints. The tall uppers could even be added to a car with G mod, or the G mod could be increased a bit lowering the upper mount even more.

Mark has some taller lower balljoints and for cars that are lowered a lot that would help bring the LBJ back more to level and increase neg camber gain even more.

There is a limit to all this neg camber gain increase stuff. The static roll center rises and increases jacking effects along with increased roll stiffness.
Excessive neg camber gain will hurt braking.

My car will have a G mod that is a bit lower position than usual, I will use stock upper balljoints, then swap in the 1/2" taller versions to compare.
David

[GM Muscle]

does anyone know how much taller the xtra tall ball joints are compared to the just tall ball joints? what if i moved the mount back 7/8 and down a 1/4 and used the extra tall ball joint? im really just trying to keep away from having to notch and clearence stuff. still no opinions on whether the offset cross shaft is even needed? id buy the uca's and be done but as far as the money goes i cant really justify it if i can get similar performance for a fraction of the cost!

[Marcus SC&C]

Okay, there are a number of different variations of the G Mod. Some are more aggressive and require more clearancing and modification some are less so and easier to do. The former generally cut the whole perch off,trim it and reweld it. The later simple move the mounting holes. On average they drop the cross shaft about 3/4" and back about 1/4". That`s enough to take a big step in the right direction but not enough to make the geometry "good" by todays standards.
The overall level of improvement goes something like this:
Howe/SC&C tall UBJ, G Mod, Howe/SC&C X-tall UBJ, Howe/SC&C tall ubj & G Mod.
Going beyong this to Howe/SC&C X-tall & G mod would go past the point of diminishing returns (as David pointed out) and aspects of the geometry such as the FVSA length would start going down hill rapidly. Bear in mind this is still better than some of the tall iron spindles on the market though.
Here`s the catch though. When you change one things,other things have to follow. Doing the G Mod moves the upper A arms closer to the top of the subframe reducing droop travel. Lowering the car reduced bump travel. So a lowered car with the G mod looses travel in both directions. Not a big deal on a race car with uber stiff springs but not ideal on a street car. The taller ball joints,or taller spindles or simply lowering with springs moves the upper A arms upwards and also outwards in their arcs due to the way they droop over the frame. This adds + camber. Since it`s about impossible to get a decent performance alignment with pure stock suspension this just makes things that much harder. Offset cross shafts will give you about 3/8" of extra adjustment. That`s probably not enough to make up for lowering, tall ball joints or a performance alignment let alone all 3. You need shorter arms and while you`re at it they should have the ball joints offset more toward the firewall to increase + caster. Lastly the stock ball joint mounting angle in the UCAs is optimized for stock geometry and ride height (ball joint stud angle roughly 0 at ride height and the same as the ball joint axis inclination ). Lowering (with springs or coil overs) combined with taller ball joints or spindles or some variations of the G mod with stock upper arms can put the upper ball joints dangerously close to binding in bump. Continual binding can lead to eventual component failure (usually the end of the arm) and that`s almost always bad so it`s best to avoid that. That means new upper A arms or a lot of time intensive custom fab work. The correct A arms will permit optimizing the geometry,travel and alignment at the same time. Short answer tall ball joints,G mod or tall spindles can make big gains in geometry but if you`ve done enough to really make a difference it`s usually necessary to change the upper A arms to get the most out of that geometry and do it safely. Mark SC&C

[GM Muscle]

you are one hell of a salesman.. haha.. i guess im going to just have to save up and get the stage 2 plus..