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misterp

Collection of Lowering Notes and Best Practices

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I dredged through all the lowering-related threads, and here are some technical high points from 2-3 years of talk on the subject:

 

FRONT:

* changing the front suspension more than 1-inch up or down will create HUGE changes in suspension camber, the truck will "walk like a bull dog" until it is aligned so remember to budget for a good alignment as part of the project;

* Spindles are preferred over keys or nothing at all, nobody has ever posted that they wished they used torsion bar keys instead of spindles, nor has anyone said they regretted using spindles;

* correctly installed/adjusted spindle kits have a small improvement in handling by significantly lowering the truck's center of gravity, the torsion key swaps retain near-stock body roll, and torsion bar jobs have shown significant increases in body roll (due to loss of suspension travel) with several saying they seriously feared driving their freshly lowered truck;

* Early McGaughys (pronounced MA-goys) spindles caused an increase in turning radius - this design oversight was corrected in later spindles, and Belltech spindles never had this problem;

* Front lowering spindles will only fit a 17-inch or larger rim, and as the spare is a 16-inch rim this means that you cannot use the spare on the front any more however you can put the OEM spare on the rear and move a good rear tire up to the front;

* Torsion key swaps will require that you relieve spring pressure by using a special tool or 7-ton puller to uncompress/re-compress the torsion bars (rent from auto parts store), several have tried using hardware store c-clamps and the clamps failed (busted) in the process;

* a few enthusiasts who bought the torsion key kits (not all) changed over to, or later added, dropped spindles and reported that doing so finally made their efforts worthwhile;

* Lowering the suspension by cranking down on the torsion bars to excess has in cases caused loss of suspension travel, spongier ride, alignment issues, and darting under braking;

* many that cranked down their torsion bars (rather than use keys or spindles) later either regreted it, changed it, or admited that they were living with a compromise in handling but appreciated its cheap cost;

* Dropping the front of the AWD SS more than 2-inches (by any method) risks causing CV-joint binding and hence front-end vibration which is felt under acceleration at specific vehicle speeds in the steering column and firewall, and will momentarily disappear as you travel over a bump in the highway - it was discovered that this is corrected by cranking the torsion bars back up a quarter-turn at a time until the binding/vibration is relieved;

* vibration can also come from the truck riding on the bumpstops, and Mike McGaughy recommends improving ride quality by cutting 1/3rd off the factory bumpstop (one 'nub') - there are also shorter aftermarket bumpstops on the market (stylinconcepts) but they are harder than the OEM rubber ones;

* Spindle kits allow you to retain stock-length shocks, torsion key kits and adjusted torsion bar jobs will benefit from correspondingly shorter shocks as there is less suspension travel (the Ground Force and Belltech units come well recommended), but are not absolutely required as the suspension will bottom-out before the shock does;

* There have been fit-up problems with the McGaughy's spindles on '05+ trucks, as the OEM ball joint design was changed with introduction of larger OEM rotors; this requires an advanced installation workaround.

 

REAR:

* Installing aftermarket leaf spring hangers (secures front of the leaf to the frame) is an absolute biatch of a task as the OEM hangers are riveted and must be ground/torched/drilled out - you'll cry tears of pain in the process and tears of joy when it's done;

* If installing leaf spring front hangers you must remove the fuel tank for access, prepare beforehand by running the truck almost out of fuel as each gallon weighs 6.1 lbs;

* the best way to get the spring hanger rivets out is with a cutting torch, a skilled hand will have both hangers off in 15-minutes flat - the second way is to grind the heads of the rivets off with a 4.5" grinder (or air chisel) and pound them out with a 5/16" drift punch and 3 or 5-lb sledge hammer, this will take several hours; IF AT ALL POSSIBLE get a torch!

* I discovered it is easiest to remove the spring hangers if you cut/grind the outside head of the rivets, not the head on the inside of the frame rail (trust me on this, after grinding on the inside heads you will still not be able to hammer them out with a punch, grind/cut/torch the outside ones)

* step-by-step: first cut/grind down all six outside rivets (and don't worry about digging into the bracket), second use a 5/16" drift punch to punch out the bottom two rivets, third use a 3 or 5-lb sledge and *bash* the hanger off from the inboard side (3 or 4 solid hits on the bottom-inside edge of the hanger will have it free); after removing the hanger, it is an easy job to pound the rivet stubs inward through the frame rail until they're flush and then a final few hits with the drift punch will clear the holes;

* though not required a few have pulled the truck bed to make the job easier (8 bolts, a couple extra friends, 20-mins);

* On heavily lowered trucks with the large aluminum driveshafts (SS) it is highly recommended that the mid-bed frame crossmember be cut-out the as it adds no support to the frame (it's not much thicker than exhaust tubing) and will strike/damage the driveshaft if the truck *totally* bottoms-out;

* When using the recommended combination of front hangers and rear shackles it is still important that the installer uses the correct bracket configuration to maintain the critical pinion angle - this is a mistake a lot of McGaughys installers make and according to Mike McGaughy to set the correct pinion angle (assuming his 2"/3.5" drop kit) the leaf spring is to be attached to the front hanger using the 2-inch (lower) hole, and to the rear shackle using the 1-inch (lower) hole;

* using only rear leaf-spring shackles (without front hangers) will certainly alter pinion angle and introduce vibration that can be felt in the seat and/or floorboard, several have reported that this is corrected with installation of either a 2, 3, or 4-degree shim - the thick part of the shim is oriented to the rear of the spring;

* vibration can also come from the truck riding on the rear bumpstops, an improvement in ride quality can be gained by removing the mounting bracket from the rear bumpstops and remounting the bumpstops to the frame (an OEM mounting hole is already present for this), also Mike McGaughy has said that the rear bumpstop length can be cut down as short as 1/2-inch if desired;

* The McGaughy's deluxe kit (comes with both hangers and shackles) maintains stock-length shocks;

* Hard-core tech - according to Ground Force engineers, the OEM Silverado SS pinion angle is 3.8, driveline angle is 2.8, and trans angle is 5.7;

* If the truck is fitted with a rear sway bar, the links ("dog bones") will need to be shortened/modified so that the bar is level again in its resting/neutral position;

* towing with a lowered truck can get bumpy (as you are bottomed-out on the bumpstops) but does not present any problems, several have installed either an overload/helper spring (low-tech) or the Firestone rear airbag kit (high-tech) with great success - owners of the Firestone kits rave about them;

* it may still be necessary to have the driveline (U-joint) angles double-checked and corrected by an experienced driveline, 4x4 off-road, or chassis fab shop to eliminate driveline vibration, this could require shimming or shaving of engine mounts, transmission mount, or axle mounts to restore correct drivetrain geometry.

 

COSTS (GIVE OR TAKE):

* Several have reported real aerodynamic gains after lowering - both increased fuel economy (1-2 mpg) and top speeds;

* Complete drop kits featuring front spindles cost between $400 and $450, and require a moderate-to-professional degree of automotive skill (or talent) to install - these are not newbie friendly kits and will take 6-12 hours to completely install; professional shops typically charge $300-400 to install a complete lowering package, not including price of the kit, so if you elect to do this the final expense could be anywhere from $750 to $950;

* For those contemplating a front spindle kit DIY, rice750sxi was nice enough to document his McGaughy's front spindle install here;

* Complete torsion key kits cost anywhere between $265 and $385 (depending on whether they come with new shocks or not); the torsion key kits can be installed in a half-to-full day by most automotive novices right in the driveway with the help of jackstands, a rented key compressor, and a couple favorite beverages - since these kits cost less plus do not require professional labor they can be a decent bang-for-the-buck option;

* The low-budget lowering option is to crank on the torsion bar adjustment bolts 6 to 8 turns, install rear spring shackles and shims, hacksaw-off all four suspension bumpstops, and take the truck in for an alignment - total project is between $100 and $150, excluding shorter shocks; don't go more than 1-1/2 inch if you choose to do this.

 

FINDING PROFESSIONAL HELP:

* lowering a vehicle is an exact science, there just aren't very many qualified, experienced 'scientists'!

* If you are searching for a shop or installer first try major/well-established 4x4 off-road shops - these facilities mainly raise trucks all day everyday for a living so they are *very* comfortable working with aftermarket suspension and very intimate with the details of proper suspension and drivetrain alignment. Do not take the truck to just any local front-end alignment place, you want a shop that customizes suspension all day every day and the 4x4 crowd has already conquered many of the mentioned issues in their own projects;

* If you are having trouble finding a competent off-road or suspension shop, get opinions from several driveline balancing shops as they will be able to steer you to those that do have their 'black-belt' in both suspension installation and drivetrain alignment/phasing.

 

TESTING:

* I cannot stress enough, test on known good (balanced) tires. The wheels/tires have got to be as perfect as possible for later testing or else you will have a shake but not be able to decide if it is a tire (or multiple tires), or rim, or driveline, or CV joint, or bumpstops, or something else unrelated. Use wheels/tires that you KNOW are in balance so that any shaking discovered can confidently be traced to suspension modifications, not new (out of balance) tires or rims.

* I've found the easiest way to reveal vibration is to slowly gain speed at WOT, so imagine pulling the steepest grade you can think of while trying to put a lot of power through the drivelines; because the truck is speeding up slowly you will not blast right past a shaky-spot on the speedometer, plus you will be putting so much power through the drivetrain that any mis-alignment in the drivelines will be made obvious;

* Rear vibration - felt primarily in the kidneys, seat bottom, or the floorboard. There should be none! Evidence to this point on these trucks suggests that rear pinion angle mis-alignment will reveal itself as a strong 'humming' vibration at 67-73 mph (depending on tire size); you will know it is the rear driveline as the vibration will always be present but intensity increases with engine load - the more power you are putting through the driveline to the ground the stronger the shaking is - coasting, you can't feel it; pulling a grade at 70mph full throttle, it's pretty violent.

 

 

Mr. P. :)

Edited by misterp

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great tech article, i would go with the mcgaughy's bags though instead of firestone. they work great for towing, wouldn't even know the truck is lowered

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great tech article, i would go with the mcgaughy's bags though instead of firestone.  they work great for towing, wouldn't even know the truck is lowered

I don't get it though because I almost gaurantee that the McGaughys kit comes with firestone bags probably the 224's

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How much of this applies to a 2WD 06 Intimidator SS?

 

It looks like the How-tos are for the AWD SSs.

 

Diggs

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Who is selling Mcgaughy's now? I remember reading somewhere they weren't selling direct anymore. I'm putting my drop on in the next week or so, once it warms back up again. But I want to get helper bags and put them on at the same time so it doesn't ride like crap towing the boat.

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Who is selling Mcgaughy's now?  I remember reading somewhere they weren't selling direct anymore.  I'm putting my drop on in the next week or so, once it warms back up again.  But I want to get helper bags and put them on at the same time so it doesn't ride like crap towing the boat.

 

 

Call them, I did when I bought the drop for my '02 Silverado. They do NOT sell direct anymore but have a phone number for a place they recommend. (I think it was Pacific Customs, or California customs or something like that.. I cant remember the name or the number).

 

Good luck

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Who is selling Mcgaughy's now?  I remember reading somewhere they weren't selling direct anymore.  I'm putting my drop on in the next week or so, once it warms back up again.  But I want to get helper bags and put them on at the same time so it doesn't ride like crap towing the boat.

 

 

Call them, I did when I bought the drop for my '02 Silverado. They do NOT sell direct anymore but have a phone number for a place they recommend. (I think it was Pacific Customs, or California customs or something like that.. I cant remember the name or the number).

 

Good luck

thanks

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Ordered mine from Street Beat Customs; the total was $425, and the kit was actually drop-shipped from McGaughy's.

 

Also, installation is *very* similar for 2WD SS's as I am told they also have the torsion bar front-end; just omit the steps where you have to deal with the front hubs.

 

Mr. P. :)

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Wow, those notes were great, I talked to the shops that perform most of the installations in the Sacramento area and there were several things about your comments that even they were not aware of. At this point, I am leaning towards the Mc Gaughy's spindle kit with either air bags or an active suspension. Does any one have experience with either kit? In addition, the front and rear of my vehicle is about the same so if I went to a 2/3 drop the rear would be lower than the front. I've heard that once the kit was installed the torsion keys can be adjusted. If the keys were adjusted to lower the front end, would it cause any problems or reduce the handeling?those notes were great, I talked to the shops that perform most of the installations in the Sacramento area and there were several things about your comments that even they were not aware of. At this point, I am leaning towards the Mc Gaughy's spindle kit with either air bags or an active suspension. Does any one have experience with either kit? In addition, the front and rear of my vehicle is about the same so if I went to a 2/3 drop the rear would be lower than the front. I've heard that once the kit was installed the torsion keys can be adjusted. If the keys were adjusted to lower the front end, would it cause any problems or reduce the handeling? :ughdance:

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I dredged through all the lowering-related threads, and here are some technical high points from 2-3 years of talk on the subject:

 

FRONT:

* changing the front suspension more than 1-inch up or down will create HUGE changes in suspension camber, the truck will "walk like a bull dog" until it is aligned so remember to budget for a good alignment as part of the project;

* Spindles are preferred over keys or nothing at all, nobody has ever posted that they wished they used torsion bar keys instead of spindles, nor has anyone said they regretted using spindles;

* correctly installed/adjusted spindle kits have a small improvement in handling by significantly lowering the truck's center of gravity, the torsion key swaps retain near-stock body roll, and torsion bar jobs have shown significant increases in body roll (due to loss of suspension travel) with several saying they seriously feared driving their freshly lowered truck;

* Early McGaughys (pronounced MA-goys) spindles caused an increase in turning radius - this design oversight was corrected in later spindles, and Belltech spindles never had this problem;

* Front lowering spindles will only fit a 17-inch or larger rim, and as the spare is a 16-inch rim this means that you cannot use the spare on the front any more however you can put the OEM spare on the rear and move a good rear tire up to the front;

* Torsion key swaps will require that you relieve spring pressure by using a special tool or 7-ton puller to uncompress/re-compress the torsion bars (rent from auto parts store), several have tried using hardware store c-clamps and the clamps failed (busted) in the process;

* a few enthusiasts who bought the torsion key kits (not all) changed over to, or later added, dropped spindles and reported that doing so finally made their efforts worthwhile;

* Lowering the suspension by cranking down on the torsion bars to excess has in cases caused loss of suspension travel, spongier ride, alignment issues, and darting under braking;

* many that cranked down their torsion bars (rather than use keys or spindles) later either regreted it, changed it, or admited that they were living with a compromise in handling but appreciated its cheap cost;

* Dropping the front of the AWD SS more than 2-inches (by any method) risks causing CV-joint binding and hence front-end vibration which is felt under acceleration at specific vehicle speeds in the steering column and firewall, and will momentarily disappear as you travel over a bump in the highway - it was discovered that this is corrected by cranking the torsion bars back up a quarter-turn at a time until the binding/vibration is relieved;

* vibration can also come from the truck riding on the bumpstops, and Mike McGaughy recommends improving ride quality by cutting 1/3rd off the factory bumpstop (one 'nub') - there are also shorter aftermarket bumpstops on the market (stylinconcepts) but they are harder than the OEM rubber ones;

* Spindle kits allow you to retain stock-length shocks, torsion key kits and adjusted torsion bar jobs will benefit from correspondingly shorter shocks as there is less suspension travel (the Ground Force and Belltech units come well recommended), but are not absolutely required as the suspension will bottom-out before the shock does;

* There have been fit-up problems with the McGaughy's spindles on '05+ trucks, as the OEM ball joint design was changed with introduction of larger OEM rotors; this requires an advanced installation workaround.

 

REAR:

* Installing aftermarket leaf spring hangers (secures front of the leaf to the frame) is an absolute biatch of a task as the OEM hangers are riveted and must be ground/torched/drilled out - you'll cry tears of pain in the process and tears of joy when it's done;

* If installing leaf spring front hangers you must remove the fuel tank for access, prepare beforehand by running the truck almost out of fuel as each gallon weighs 6.1 lbs;

* the best way to get the spring hanger rivets out is with a cutting torch, a skilled hand will have both hangers off in 15-minutes flat - the second way is to grind the heads of the rivets off with a 4.5" grinder (or air chisel) and pound them out with a 5/16" drift punch and 3 or 5-lb sledge hammer, this will take several hours; IF AT ALL POSSIBLE get a torch!

* I discovered it is easiest to remove the spring hangers if you cut/grind the outside head of the rivets, not the head on the inside of the frame rail (trust me on this, after grinding on the inside heads you will still not be able to hammer them out with a punch, grind/cut/torch the outside ones)

* step-by-step: first cut/grind down all six outside rivets (and don't worry about digging into the bracket), second use a 5/16" drift punch to punch out the bottom two rivets, third use a 3 or 5-lb sledge and *bash* the hanger off from the inboard side (3 or 4 solid hits on the bottom-inside edge of the hanger will have it free); after removing the hanger, it is an easy job to pound the rivet stubs inward through the frame rail until they're flush and then a final few hits with the drift punch will clear the holes;

* though not required a few have pulled the truck bed to make the job easier (8 bolts, a couple extra friends, 20-mins);

* On heavily lowered trucks with the large aluminum driveshafts (SS) it is highly recommended that the mid-bed frame crossmember be cut-out the as it adds no support to the frame (it's not much thicker than exhaust tubing) and will strike/damage the driveshaft if the truck *totally* bottoms-out;

* When using the recommended combination of front hangers and rear shackles it is still important that the installer uses the correct bracket configuration to maintain the critical pinion angle - this is a mistake a lot of McGaughys installers make and according to Mike McGaughy to set the correct pinion angle (assuming his 2"/3.5" drop kit) the leaf spring is to be attached to the front hanger using the 2-inch (lower) hole, and to the rear shackle using the 1-inch (lower) hole;

* using only rear leaf-spring shackles (without front hangers) will certainly alter pinion angle and introduce vibration that can be felt in the seat and/or floorboard, several have reported that this is corrected with installation of either a 2, 3, or 4-degree shim - the thick part of the shim is oriented to the rear of the spring;

* vibration can also come from the truck riding on the rear bumpstops, an improvement in ride quality can be gained by removing the mounting bracket from the rear bumpstops and remounting the bumpstops to the frame (an OEM mounting hole is already present for this), also Mike McGaughy has said that the rear bumpstop length can be cut down as short as 1/2-inch if desired;

* The McGaughy's deluxe kit (comes with both hangers and shackles) maintains stock-length shocks;

* Hard-core tech - according to Ground Force engineers, the OEM Silverado SS pinion angle is 3.8, driveline angle is 2.8, and trans angle is 5.7;

* If the truck is fitted with a rear sway bar, the links ("dog bones") will need to be shortened/modified so that the bar is level again in its resting/neutral position;

* towing with a lowered truck can get bumpy (as you are bottomed-out on the bumpstops) but does not present any problems, several have installed either an overload/helper spring (low-tech) or the Firestone rear airbag kit (high-tech) with great success - owners of the Firestone kits rave about them;

* it may still be necessary to have the driveline (U-joint) angles double-checked and corrected by an experienced driveline, 4x4 off-road, or chassis fab shop to eliminate driveline vibration, this could require shimming or shaving of engine mounts, transmission mount, or axle mounts to restore correct drivetrain geometry.

 

COSTS (GIVE OR TAKE):

* Several have reported real aerodynamic gains after lowering - both increased fuel economy (1-2 mpg) and top speeds;

* Complete drop kits featuring front spindles cost between $400 and $450, and require a moderate-to-professional degree of automotive skill (or talent) to install - these are not newbie friendly kits and will take 6-12 hours to completely install; professional shops typically charge $300-400 to install a complete lowering package, not including price of the kit, so if you elect to do this the final expense could be anywhere from $750 to $950;

* For those contemplating a front spindle kit DIY, rice750sxi was nice enough to document his McGaughy's front spindle install here;

* Complete torsion key kits cost anywhere between $265 and $385 (depending on whether they come with new shocks or not); the torsion key kits can be installed in a half-to-full day by most automotive novices right in the driveway with the help of jackstands, a rented key compressor, and a couple favorite beverages - since these kits cost less plus do not require professional labor they can be a decent bang-for-the-buck option;

* The low-budget lowering option is to crank on the torsion bar adjustment bolts 6 to 8 turns, install rear spring shackles and shims, hacksaw-off all four suspension bumpstops, and take the truck in for an alignment - total project is between $100 and $150, excluding shorter shocks; don't go more than 1-1/2 inch if you choose to do this.

 

FINDING PROFESSIONAL HELP:

* lowering a vehicle is an exact science, there just aren't very many qualified, experienced 'scientists'!

* If you are searching for a shop or installer first try major/well-established 4x4 off-road shops - these facilities mainly raise trucks all day everyday for a living so they are *very* comfortable working with aftermarket suspension and very intimate with the details of proper suspension and drivetrain alignment. Do not take the truck to just any local front-end alignment place, you want a shop that customizes suspension all day every day and the 4x4 crowd has already conquered many of the mentioned issues in their own projects;

* If you are having trouble finding a competent off-road or suspension shop, get opinions from several driveline balancing shops as they will be able to steer you to those that do have their 'black-belt' in both suspension installation and drivetrain alignment/phasing.

 

TESTING:

* I cannot stress enough, test on known good (balanced) tires. The wheels/tires have got to be as perfect as possible for later testing or else you will have a shake but not be able to decide if it is a tire (or multiple tires), or rim, or driveline, or CV joint, or bumpstops, or something else unrelated. Use wheels/tires that you KNOW are in balance so that any shaking discovered can confidently be traced to suspension modifications, not new (out of balance) tires or rims.

* I've found the easiest way to reveal vibration is to slowly gain speed at WOT, so imagine pulling the steepest grade you can think of while trying to put a lot of power through the drivelines; because the truck is speeding up slowly you will not blast right past a shaky-spot on the speedometer, plus you will be putting so much power through the drivetrain that any mis-alignment in the drivelines will be made obvious;

* Rear vibration - felt primarily in the kidneys, seat bottom, or the floorboard. There should be none! Evidence to this point on these trucks suggests that rear pinion angle mis-alignment will reveal itself as a strong 'humming' vibration at 67-73 mph (depending on tire size); you will know it is the rear driveline as the vibration will always be present but intensity increases with engine load - the more power you are putting through the driveline to the ground the stronger the shaking is - coasting, you can't feel it; pulling a grade at 70mph full throttle, it's pretty violent.

Mr. P. :)

 

Can you tell me what the pinion angle is on a stock All Wheel Drive 05 SS?

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