Philostang

Ok, so I just measured the mounting points of my LCAs, and I'm confused. I apologize if this has been addressed already, but I can't get the search function to work (for days now).

Measured from eye to eye (center of bolt), I get a 7/8" vertical difference between the front and rear pointing DOWN. That is, the front mounting point is lower than the rear by 7/8". What gets me is that this is mostly a stock suspension set up. No lowering, different tires, but almost identical diameter. Shouldn't they be almost dead even, or even favor an uphill orientation a bit?

I'm going out on the sketchy limb of my suspension geometry knowledge here, but I thought that a lower rear point favored launch traction and that even front/rear points favored handling (less axle movement through the full range of movement). [:@] I cringe at my ignorance, but wouldn't a downhill orientation just suck for all parties envolved?

I'll be lowering my car soon, and this has me all wigged out, as the fronts will plummet even further. Did Ford really set us up from the factory with the worst angle for launching?

Can someone explain this to me?

Best,
-j

Sleeper_08

Here is a useful link

http://www.cherod.com/mustang/HowTo/LCA%20_adj.htm

Norm Peterson

Stick axle suspension geometry is a 3-D problem, and also involves rear axle steer effects. An OE is likely more interested in making rear axle steer easier for some lowest-common-denominator driver to handle than in giving him even more launch traction to get himself into trouble with. From the axle steer perspective, it is entirely possible for lowers to be intentionally run "downhill" toward the chassis if they also converge in plan view (and depending on PHB height). A little less launch traction can also reduce warranty costs by acting sort of like a fuse to limit stresses in the drivetrain.


Norm

BMRFabricationSales

Hello, norm is correct, forddoesn't always have the optimum performance in mind when they release a car to the public. I have seen numerous instances where the control arm are going downhill from the rear to the bodyon a stock car. The only way to get that corrected is with the relocation brackets, also when you decide to lower the car you will also need an adjustable panhard bar as well. Keep us in mind whenever you decide to upgrade.

http://www.bmrfabrication.com/2005Mustang.htm

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F1Fan

Hi Philostang,

It depends on whether you are tuning the rear suspension for drag strip use or cornering use. For drag strip use LCA's pointing up hill towards the axleare not ideal. For cornering use level or slightly uphill is prefered due to the rear axle steering issues and stability this gives when cornering. As you can see the optimum setting for both are at odds withone another. BMR makes some simple LCA relocationbrackets thatare geared towards drag racers. For road racers anddrag racer the better choice IMO is the Steeda LCA relocation brackets for the two additionalLCA adjustment points they have over the simplified BMR brackets. The BMR brackets are easy to install but donot offer the addtional adjustment holes the Steeda LCA brackets havewhich give you a much better chance of finding that perfect adjustment. I have the weld-in BMR brakets and if I could I would replace them with theSteeda weld-in brackets for the additional adjustment options as I cannot get the LCA's in that perfect spot because the BMR's lack enough adjustment holes.

HTH!

Import_Slaya

So here's a question for everyone. What is the best way to minimize the roll understeer associated with a slight suspension drop (0.75" - 1.5") and the stock LCA mounting points? Is it possible to minimize the effect with spring rates and roll bars, without sacrificing overall cornering grip?

I ask because for NASA time trial classing, changing the mounting points is worth 6 points, which is huge. I just removed my CHE LCA brackets to see if I can deal with the stock locations...

F1Fan

Hi Slaya,

Just leave them off. The negative effects of roll understeer when the LCA's are pointing uphill to the axle are fairly small with only a moderate drop in ride height. You can't drop the hammer as soon on corner exit but rolling the throttle on works well and the car will be more stable at high speeds when the LCA's are in the stock location and the ride height is lowered only an inch. This problem is more of an issue when the car has roll oversteer as with the LCA's pointing downhill to the axle. You should be O.K. with them as the effect is more of inducing stability then instability.

HTH!

Philostang

Thanks Norm and F1 Fan,

I should have responded sooner, but I went back to some old notes and realized I was just confused about what was happening with the rear axle steering under different control arm configurations. I thought level control arms were optimal for handling around corners, but I see that this is not the case and that our OEM configuration is actually more stable around corners (even though it gives up some launch grip at the strip). So, mostly I get it now (wow, scary stuff usually happens when I say that).

I'm not interested in drag strip performance, so I'm less wigged out about the whole thing. Besides, with such advice as we've gotten from the suspension gang here, I opted some time ago for the Steeda relocation brackets and they're going on this Friday.

Since F1Fan brought it up, I've found that I'm doing quite a bit of "rolling the throttle" through corners, especially on long sweepers where I almost seem to be throttle steering my way around the entire second half of the corner. This is with an OEM configuration/shocks/springs. The whole trip feels very linear and controlled, but I can feel the rear very sensitive to my throttle inputs. It is almost as if I'm drifting just after the apex and through to the straight.

So I suppose I was wondering if this was ok or if I am doing something wrong? Again, I don't feel out of control, and I'm able to ease on to full throttle pretty much were I want to upon straightening out. So I keep doing it. But I'm such a noob to real high-performance driving (as opposed to the stupid stuff we did as teenagers) that I don't know if I'm doing the best thing or if I should be letting the car take a set longer before easing onto the throttle.

Any thoughts?

Best,
-j

Import_Slaya

Yeah, I'm leaning towards leaving them off to keep those points available for other upgrades if needed. I can also toss on a splitter to helpcancel out some of the understeer in high speed turns (although that will cost a few points...). It's the low speed tight turns and transitions that I'm worried will bug me. Time to hit a parking lot this weekend!