Need help lowering my 2004 GMC Yukon XL Denali

[Chip18]

here you go
http://www.tbssowners.com/store/index.php?act=viewProd&productId=86

Aww that looks like the kit I will need! Two questions at the moment ... do I need a "Camber Kit' to dial in 1 degree of negative camber and is the adjustable rear panhard bar "required" with that kit???

 

[TheAutumnWind]

Im very sorry for being a rookie and all but what does "Jounce" mean?

Jounce stops are the progressive front bump stops on torsion bar sprung vehicles. Torsion bars have a completely linear spring rate. They sit on the jounce bumpers at stock ride height. The jounce stops then give you a progressive ride (stiffer the further up the wheels travel) which makes it less jarring once the wheel has reached its maximum upward travel.

Normal "bump" stops are in the rear. Since you have springs in the rear which have a progressive spring rate, they are not as integral to the function of the rear suspension. They simply stop upward travel before the springs bottom out so you don't have metal on metal contact. Most people completely cut the brackets off when lowering in the rear, and then run much shorter bump stops that allow for way more travel.

 

[TheAutumnWind]

It's a situation you want to "avoid" the rear axle bangs off the rear bump stop. Shocks and springs work together by absorbing the upward energy from bumps, if you hit a bump and you don't have enough suspension travel in the rear ... the process gets halted and the energy gets "transferred to the frame" through the unaltered bump stop location to the vehicle.

In the "Real World ..." that means "instant unanticipated" change of direction! My most spectacular example was back in the day with a full "Koni" Fiero!

80 mph sweeper with a mid corner bump ... I knew it was there (the bump) because, I'd hit it many times in my Merkur XR4Ti (Stock) at 100 or so. So 80 in the "modded" Fiero ... no big deal?? Yeah not so much it was late at night in Ca ... all the "nut balls" prowl the canyons late at night.

I hit that bump hard and the rear end lifts up and I'm in the other lane??? Still pointed in the intended direction since I never lifted but my eyes got pretty big!

But think "Unlimited Hydrofoil" and the boats skipping off the waves ... your "Vehicle" will do the same thing if you don't have enough rear suspension travel!

In San Jose Ca we have a popular stretch of road with some really bumps! And it often takes out high dollar, modded cars with full coilover suspensions! Super stiff springs and limited suspension travel ... the unknowing hit those bumps on full kill and they don't make it to the bottom of the hill!!

Happens all the time out there. Most stock cars with full suspension travel were actually faster down that hill than the full kill turbo charged, coilover equipped monsters!!

I actually shattered a headlight one night going up there in my "Modded Mini Truck" Toyota. A Mustang though ... he was going to pass me up the hill??? Yeah ... I don't think so!! Good Times Good Times ...

But yeah as I am want to say ... I give sound advice ... I don't often follow it so ... don't drive like that on "public roads!"

Pretty sure "Norcal SS" can tell you how much clearance you need to have with your vehicle at rest.

Fun story, but you didn't really answer the question.

Edit: sorry, that seems to come off a little rudely. I mean, you didn't directly answer the question, but you did give some insight. Cheers friend.

 

[TheAutumnWind]

It works properly but the warning is stuck on "i


It works properly but the warning is stuck on " Service Auto Ride". I replaced the compressor and went underneath and applied air to the shocks and they pump up all the way and didn't have any leak at all that heard and they stayed pumped up for 5 minutes on each one without a whisp. But That dumb warning wont go away.

You might have to clear the code for service autoride. Does your compressor now come on automatically? Do the bags fill on their own? Does adding weight to the rear cause the suspension to compensate automatically?

There is a ton of information on this site regarding that thankfully!

 

[TheAutumnWind]

Im very sorry for being a rookie and all but what does "Jounce" mean?

No worries man, we've all been there at some point

 

[NORCAL SS]

Don't do keys and spindles fir 3. A arms Wil ridea better and my rear kitvrides best by far. Proven for years

 

[Chip18]

Fun story, but you didn't really answer the question.

Edit: sorry, that seems to come off a little rudely. I mean, you didn't directly answer the question, but you did give some insight. Cheers friend.

No problem thanks for the insight ... to be brief ... Jounce for the front ... Torsion Bars and Bump Stops are in the rear?? Resting on either is bad news ... so I got that part right.

And ... what are these "Key" things for the front T-Bars??? My only experiance with T-Bars was when I swapped them out for stiffer ones on my Toy (Mini truck) and I cranked them down so much that the front cross member dragged on speed bumps!! Not good so I dialed them up to gain clearance.

 

[NORCAL SS]

If your doing more then 1 inch trust me dont do keys. The a arms ride way better and you get new bushings plus balljionts and mated with the belltech sp shocks smooth ride. I have that for 445 shipped and best of all adjusatble from 2-3 inches.

 

[Zigger21]

Thanks for the explanation. Sounds like you live the life I want to live with cars. Modding, customizing and just having the knowledge and fun with cars. I was born in the wrong life I guess. Thanks again. Take care and Drive safe.

 

[TheAutumnWind]

No problem thanks for the insight ... to be brief ... Jounce for the front ... Torsion Bars and Bump Stops are in the rear?? Resting on either is bad news ... so I got that part right.

And ... what are these "Key" things for the front T-Bars??? My only experiance with T-Bars was when I swapped them out for stiffer ones on my Toy (Mini truck) and I cranked them down so much that the front cross member dragged on speed bumps!! Not good so I dialed them up to gain clearance.

SOunds like you have it a bit confused still.

Torsion bars in the front, with jounce stops. In the front you should be just barely resting on the jounce stops.

Coil springs in the rear with bump stops. In the rear you want to have as much clearance for the bump stop as possible (without causing tire contact with the body, or suspension binding) for a nice ride.

 

[Chip18]

SOunds like you have it a bit confused still.

Torsion bars in the front, with jounce stops. In the front you should be just barely resting on the jounce stops.

Coil springs in the rear with bump stops. In the rear you want to have as much clearance for the bump stop as possible (without causing tire contact with the body, or suspension binding) for a nice ride.

Awww Ok thanks, kinda "tricky" with the T Bars.

I looked again and I see the "OP" has 2004 so no need for a coil spring compressor in anycase.

Sooo "apparently???" With T-Bars ... they are allowed to be closer to the "Jounce Stops" then is the case with rear "Bump Stops??"

I'll have to crawl under there and take a closer look at that?? All I saw was T-Bars and yeah shocks with bags ,wires, sensors, rods and an Air Line ... lot of stuff.

I saw the threads on the lowered "Police Yukons" but the site on how GM lowered them, no longer work?? Wouldn't they have just dialed down the T bars and used shorter coil springs in the rear ... no "AutoRide" as I understand??

And most likely a "NORCAL SS" question but what exactly are the T-Bar "Key" things and what is the issue with using them???

I still don't understand what a NNBS or an OBS is?? I have seen those terms pop up a lot??? Inside stuff, kinda like in "Porsche" land when you say ... 951 S ... no one knows what that is.