MYSTERY SOLVED

kylant · January 13, 2003

2500HD and 3500 torsion key lift mystery solved. GM has 4 different torsion keys. they all have the same casting number:

15530030

each of the keys is indexed differently, have their own part number, and a color code (small paint mark on the bottom of the key). the mark can be seen by looking under the truck, it is on the bottom of the key.

part numbers are:

15592573 GREEN

15592574 WHITE

15603963 ORANGE

15045171 PURPLE

I have a 2500HD with the PURPLE 15045171 keys. Today I looked at a 1500 and it had the GREEN mark. I talked to the part guy and he had one in stock. GREEN mark, part number 15592573.

I had my stock key with me and compared it to the GREEN key.

Guess What!!

The green key was indexed more than the purple, there for if it was installed on a 2500HD, it would provide a lift just like the Hill and Victoria keys. I knew the Victoria key was a GM product with the numbers ground off. The GREEN 1500 key was indexed exactly the same as the Victoria key I had.

Therefore:

Stock 1500 GREEN keys=torsion lift keys for 2500HD and 3500

There might be others that work for the the 1500's so people don't have to buy the fords anymore

:thumb: :thumb:

good luck

Texas1836 · January 13, 2003

:thumb: Good Job! Very nice detective work.

Thomas from TEXAS

kshuart · January 14, 2003

I know there has been a lot of posts about this lately, but what does an indexed key give you that turning the TB bolts won't?? There has to be a point in which a key or turning the bolt won't do you any good. You run out of front end travel. My 2500HD has the snow plow prep package, so it may be a little different than others, but my truck sits pretty close to level after 3-4 turns of the torsion bar bolt. Another turn or 2 and it would be level, and I still have bolt threads left.

Please help me understand what it would get me. Better ride? or nothing that I don't already have? ???

Firetiger(MN) · January 14, 2003

Any idea what the orange and purple keys are for?

Shaners · January 14, 2003

Please help me understand what it would get me. Better ride? or nothing that I don't already have? ???

If I understand him correctly (and I'm not sure that I do), the indexed key (green ones) have the cam lobe in a different location from the "standard starting point". Therefore, the bars sit higher on the lobe with the green key as opposed to the stock key. So I'm guessing that as you crank the bolts, you can get more lift before you run out of travel. Your ride is proportionate to the amount of tension or preload that is on the front torsion bars. I'm also guessing you can get a little more lift with a little less preload on the bars if you use the green keys and that should result in a little better ride.

Someone please correct me if I have this all flubbed up...

Firetiger(MN) · January 14, 2003

You are correct.

DanaliHD · January 14, 2003

As far as I can tell by the GM repair manual I have, 15592573 is the right torsion bar arm, 15592574 is the left. Also, they don't distiguish between 2wd, 4wd, 1500 or 2500. Kinda confusing, just make sure you get one for the left and one for the right.

hdmax · January 14, 2003

As far as I can tell by the GM repair manual I have, 15592573 is the right torsion bar arm, 15592574 is the left. Also, they don't distiguish between 2wd, 4wd, 1500 or 2500. Kinda confusing, just make sure you get one for the left and one for the right.

The only 2 wheel drive trucks that have the torsion bar suspension is the 2500Hd and 3500 trucks. And they are the same as the 4 wheel drive version of the 2 wheel drive.

kshuart · January 14, 2003

OK, so if you have no more travel left in your adjusting bolts, the keys will give you more lift. I'm not sure about the better ride part though. To hold the truck up to a certain position, the torsion bar has to have so much tension on it. More tension = higher lift. Less tension = lower lift. No matter where it is indexed, the same tension has to be on the torsion bar. The only way I see to change ride quality, is to change to a different torsion bar rate (kind of like spring rates).

I haven't really looked at the end of the adjusting bolt closely, but could you just get a longer bolt and do basically the same thing as a different key (to a certain point)??

kylant · January 14, 2003

to clarify some things i did some more research:

victoria sells key for both the 1500 (the ford keys) and the 2500, 2500HD, 3500. they keys they sell for the 2500, 2500HD, and 3500 are the gm 1500 keys with the green mark.

I have a 2500HD my keys have the purple mark on them.

I don't know which keys are indexed the most. i was only able to compare the purple keys to the green keys. the green key was the only one the dealer had.

both of my keys are purple. i looked at a 1500 z71 it had green keys both sides. i looked at a 1500 4x4 it had green keys on both sides. i also looked at a new tahoe, it had green keys on both sides.

i am willing to bet the orange and white keys are for the 88-99 old body style 1500 and 2500 trucks.

i hope this clarifies some things

Shaners · January 14, 2003

To hold the truck up to a certain position, the torsion bar has to have so much tension on it. More tension = higher lift. Less tension = lower lift. No matter where it is indexed, the same tension has to be on the torsion bar. The only way I see to change ride quality, is to change to a different torsion bar rate (kind of like spring rates).

I agree that your ride quality is based on the preload on the bars. The only thing I'm not sure of (and I'm not willing to crawl under the truck to look and see because the weather is crappy here) is if you replace the keys, will you start at the same ride height as the stock keys and the same preload settings? A key with a different cam lobe may allow for more lift with less preload... yes or no??? (help me out here...)

I think with the "hill leveling kit" (which is basically ford keys), they advertise more lift and better ride than just cranking the torsion bars on the stock keys... So I'm still in the "grey" area a little.

jelisfc · January 14, 2003

On torsion bar systems the lift is generated by the amount of twist placed on the torsion bar. No matter what key you use X amount of torque will generate Y amount of lift. Think of it this way. If you twist someone's hand it doesn't matter where around the hand you grab, if you twist with the same force the same amount of pain is generated. The difference with the keys is the location of the hex, ie position you grab the bar. All this does is allow a different preload on the bar without maxing out adjusting bolt travel or running the cam into the cross member or other immovable object.

As far as I know all of the cams have the same profile. If they were to have a different profile the preload would happen faster or slower. One turn of the bolt on one cam would have the same effect as 2 turns of the same bolt on a less agressive cam profile.

Mortgage Paul · January 16, 2003

which keys come stock on the 02 and 03 2500 HD' 4 WDs??

Ive crawled under a few and seen no paint/color on them.

kylant · January 16, 2003

my '02 2500HD 4x4 has purple keys stock. the mark is on the bottom of the key. it is visible by just looking at them from under the truck. it is just a mark, looks like a crayon mark, but it is paint

good luck

mmayo · January 17, 2003

Has anyone installed these "keys" on a tahoe? My wife is driving an 01 4x4 with 285 BFGs AT on stock rims. It looks great but im wondering if with these torsion keys and some new 16x8 wheels if i could fit 295s??? Anyone out there seen or tried this?? ???