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Bushmaster

Negative Aspects Of Lowering?

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My newly purchased '09 GT500 will be here next week and I have a set of FRPP springs I can install. However, my friend took them off of a customer's car at his shop - apparently the customer wanted the car back at stock ride height as he was "tired of hitting the splitter all the time".

 

That's making me wonder - how serious a problem is this? On my SGT I learned the first day that I had to be very careful pulling in my driveway. If I hit it square it would hit the valance - I had to leave and enter the driveway at a 45-degree angle or more, and slowly, to keep from grinding on the pavement.

 

I love the lowered look but I don't want to be hitting the splitter and tearing it up. Is this something to be concerned with, or will the same caution I used on the SGT keep me out of trouble?

Edited by Bushmaster

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i dont think its that serious if you're reasonably careful. the appearance is worth it, in my opinion. the OEM splitter is a buck seventy-five from the dealer. not cheap, but not crazy expensive.

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Thanks - you know, I was already thinking about buying another one just to have a mint one on hand. At that price, it only makes sense and they aren't gonna get cheaper over time so the time to do it would be now.

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Mine is stock height and no matter how careful I try and be, I'm always scrapping it on something. I had the same problems with my former 2011 but could come up at an angle and not scrape on my driveway ..... usually. My 2014 is a little lower and I have yet to find an angle it won't scrap pulling into my driveway. After about two weeks I ordered another lower spoiler and still have it in the garage in the box. I've considered taking off the lower portion but now that I have the spare in a box I don't worry about it. However I do "shave it's whiskers" occasionally.

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It's inevitable. Eventually the splitter will find a curb no matter how careful you are so go ahead and get the car lowered to the proper ride height.

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Thanks, guys - I will proceed with the lowering when the car arrives. Bill, it sounds like your driveway must be worse than mine - I don't think mine's really that bad, though I sure chewed it up with the tongue of my racecar trailer whenever I'd try and back the trailer up the driveway. I'll just have to use the same technique I did with the SGT but more carefully and slowly.

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Thanks, guys - I will proceed with the lowering when the car arrives. Bill, it sounds like your driveway must be worse than mine - I don't think mine's really that bad, though I sure chewed it up with the tongue of my racecar trailer whenever I'd try and back the trailer up the driveway. I'll just have to use the same technique I did with the SGT but more carefully and slowly.

After you lowered it did you check pinion angle?

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After you lowered it did you check pinion angle?

 

Good question. After doing some searching there seems to be little consensus on this. Is it something to worry about when lowering the car 1.5 inches or less? Does the change to a one-piece driveshaft change the necessity to check the pinion angle? In my case, we're talking about an occasional driver that won't be raced.

 

I didn't check it on my '01 GT or my '05 GT and never had any problems, and I drag raced the '01 pretty regularly.

Edited by Bushmaster

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I scrape mine at my kids school no matter how I hit the angle. They actually will take quite a beating. I thought for sure mine was a gunner a while ago. Got caught in some construction, long story short I basically used it as a shovel. I would buy a replacement for later on in life

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After you lowered it did you check pinion angle?

 

^^^Check axle center also.

 

The oem non-adj. panhard bar is a specific length from the right body mount (upper) to the left axle mount (lower) for the oem ride height, when you lower the body, that distance will change and the body to axle relationship will be different, pushing the body one way and the axle the other. This difference will show up with the axle no longer being centered under the car. <<And the need for an adj. panhard bar to pull the axle (or body) which ever way you want to look at it back to center.

 

OP - I would install the lowering springs, make sure the car is settled on those new springs and then check for axle center before I would do any other adjustments/changes. Once the car is settled and the axle centered then I would check pinion angle using something as simple as a magnetic mount degree indicator which can be purchased at Home Depot.

 

"If" your pinion angle does need to be adjusted, then you are going down another path of installing an adjustable UCA (Upper Control Arm) and UCM (Upper Control Mount). <<This is another project all by itself.

 

FYI - The much beefier 2011-2014 UCA/UCM fits in the 2007-2010 nicely. <<If it comes to that point.

 

 

 

R

Edited by Robert M

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^^^Check axle center also.

 

The oem non-adj. panhard bar is a specific length from the right body mount (upper) to the left axle mount (lower) for the oem ride height, when you lower the body, that distance will change and the body to axle relationship will be different, pushing the body one way and the axle the other. This difference will show up with the axle no longer being centered under the car. <<And the need for an adj. panhard bar to pull the axle (or body) which ever way you want to look at it back to center.

 

OP - I would install the lowering springs, make sure the car is settled on those new springs and then check for axle center before I would do any other adjustments/changes. Once the car is settled and the axle centered then I would check pinion angle using something as simple as a magnetic mount degree indicator which can be purchased at Home Depot.

 

"If" your pinion angle does need to be adjusted, then you are going down another path of installing an adjustable UCA (Upper Control Arm) and UCM (Upper Control Mount). <<This is another project all by itself.

 

FYI - The much beefier 2011-2014 UCA/UCM fits in the 2007-2010 nicely. <<If it comes to that point.

 

 

 

R

 

So you are saying you definitely should go with a adjustable panhard bar in order to centre the rear .

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So you are saying you definitely should go with a adjustable panhard bar in order to centre the rear .

 

If the axle needs to be centered, that is the only way to do it after the car has been lowered. The body attachment point and the axle attachment point of the panhard bar will not be the same distance apart once the body is lowered. There is a little bit of lowering that can be done without a panhard bar change, but most lowering springs go beyond that point and the body/axle has to be re-centered. if I remember correctly, the adj. panhard would have to be shorter than the oem panhard bar length to get the body and axle re-aligned.

 

In a picture form, think of the body on its oem springs, it sits pretty high and there is a specific distance from that body panhard mounting point (upper right) to the axle mounting point (lower left). If you lower the body with springs, that distance between the body and the axle will become less because the body is moving down. If the panhard bar is not adjustable to compensate, the body "as originally attached" will move to one side when the lower springs are installed.

 

The amount of panhard bar adjustment will depend upon how much the car is lowered.

 

 

 

R

Edited by Robert M

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One thing to keep in mind with axle centering is that there seems to have been a good bit of variation from the factory. My friend has had a couple of cars in his shop that were off-center from the factory and lowering them centered the axle. My SGT was off-center by about 3/8" but it was almost unnoticeable - in fact, I pointed it out to a couple of people who still couldn't see what I had verified by measurement.

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One thing to keep in mind with axle centering is that there seems to have been a good bit of variation from the factory. My friend has had a couple of cars in his shop that were off-center from the factory and lowering them centered the axle. My SGT was off-center by about 3/8" but it was almost unnoticeable - in fact, I pointed it out to a couple of people who still couldn't see what I had verified by measurement.

 

You are right, the amount can be different from car to car.

 

The main thing I wanted to verify with my 2008 was that the drive line is straight, or as close as possible. Since the engine and transmission are directly connected to the body via engine mounts and transmission mount/crossmember and the rear of the drive shaft is connected to the axle (which could be offset), I wanted to have it adjusted as straight as possible for the driveshaft. 3/8" body offset may not be much at the rear (tire to fender well), but it may be quite a bit by the time you get up toward the transmission driveshaft flange.

 

Does it matter how much the pinion flange and transmission flange are offset from each other, making the driveshaft at an angle? I guess it would matter at some point? At what point it becomes an issue, IDK.

 

 

 

R

Edited by Robert M

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Another variable...............is the car a 1pc. driveshaft or a 2pc.? It may be more important for a factory 2007-2012 GT500 2pc. shaft to be more in line than a car with one long shaft?

 

 

 

R

Edited by Robert M

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If the axle needs to be centered, that is the only way to do it after the car has been lowered. The body attachment point and the axle attachment point of the panhard bar will not be the same distance apart once the body is lowered. There is a little bit of lowering that can be done without a panhard bar change, but most lowering springs go beyond that point and the body/axle has to be re-centered. if I remember correctly, the adj. panhard would have to be shorter than the oem panhard bar length to get the body and axle re-aligned.

 

In a picture form, think of the body on its oem springs, it sits pretty high and there is a specific distance from that body panhard mounting point (upper right) to the axle mounting point (lower left). If you lower the body with springs, that distance between the body and the axle will become less because the body is moving down. If the panhard bar is not adjustable to compensate, the body "as originally attached" will move to one side when the lower springs are installed.

 

The amount of panhard bar adjustment will depend upon how much the car is lowered.

 

 

 

R

Thanks Makes sense for sure

 

Another variable...............is the car a 1pc. driveshaft or a 2pc.? It may be more important for a factory 2007-2012 GT500 2pc. shaft to be more in line than a car with one long shaft?

 

 

 

R

two piece . Is the correct pinion set at 0 or -1

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From the online research I've done, the prevailing opinion seems to be that pinion angle is more critical when changing to a one-piece driveshaft.

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Thanks Makes sense for sure

 

two piece . Is the correct pinion set at 0 or -1

 

I think (but am not positive) that when Kelly from BMR came on one of my suspension posts he said -1 to-2, but I don't remember for sure, and Bushmaster may be right about it being more critical on the 1pc. The BMR site may have some info. in their tech section.

 

I also did a LCA relocation bracket thread with some good pictures including angle changes. <<This mod is to get the lower control arms back in the correct angle (as they were from the factory) after a car has been lowered. Having correct angle on the LCA's helps much with traction and correct I.C. (Instant Center).

 

Above in this thread we were discussing centering of the axle and Bushmaster mentioned his SGT being 3/8" off to one side. If I remember correctly the SGT got FRPP springs as one of its mods at the Mod Shop before it went to it's original selling Ford dealership. If I also remember correctly the article I read in one of the Shelby magazines (about 2008) showed SGT's being built in the Mod Shop but no mention of a panhard bar change. <<This would be the reason the axle is offset, the car was lowered, but no panhard length change. Now, think of something else...............the oem panhard bar has rubber bushings at each end, the axle is already 3/8" to one side offset...............what happens when this car is pressed into a turn toward the 3/8" offset? The rubber bushing are going to "give" (deflection) and the 3/8" is now closer to 3/4" while the car is in the turn. When the car is turning the opposite way, the axle is moving back to a more center position (where it should be normally) because of rubber bushing deflection.

 

Having the axle as centered as possible from the start is best from a performance standpoint, and getting some of those rubber bushings out and replacing with poly will also get rid of rubber deflection. <<But I will also mention that "some" suspension points may sacrifice a smooth ride with a poly change. <<Not the panhard, but other points.

 

 

 

R

Edited by Robert M

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I never really noticed any significant difference in ride quality but those polyurethane bushings sure do make a racket in cold weather. All that squeaking took a little getting used to.

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I never really noticed any significant difference in ride quality but those polyurethane bushings sure do make a racket in cold weather. All that squeaking took a little getting used to.

 

Here in Florida I don't experience much cold weather, but I have had to add additional poly grease to the joints to get it quiet. The correct/recommended grease for the poly bushing is also critical to keep the noise minimal. I am currently fully poly on my rear suspension except the bushing at the top of the differential housing. I don't notice a harsh ride, but I do notice that mine is considerably stiffer when I go over a bump, or cross a RxR crossing.

 

 

R

Edited by Robert M

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