Lifting the Trailblazer

daydriver

Original poster
Member
Mar 4, 2012
10
I have a 2007 2wd Trailblazer and I was just wondering if I could use those z71 89 springs and the bds shocks on the rear as well as the 2" suspension lift on the front? I'm new to this and was just wondering. Want to fit bigger tires.
 

jham

Member
Nov 20, 2011
1,334
daydriver said:
I have a 2007 2wd Trailblazer and I was just wondering if I could use those z71 89 springs and the bds shocks on the rear as well as the 2" suspension lift on the front? I'm new to this and was just wondering. Want to fit bigger tires.

With 89 springs you will need the extra weight of a bumper and skids or it will be a harsh ride same with Z71 springs in the rear harsh ride. If you want larger tires you will need spacers to clear the upper ball joint with any tire taller than 30.5 inches. For a lift just check out MarkMC his lift is great. I have his 3 inch suspension and with 83 springs up front it was a little rough with being 2wd and the less weight up there. Adding a steel bumper and skid from Barton MD made it sag about half a inch but improved the harshness of it with a 2wd I would go over 85's but this is my opinion from my experiences
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
daydriver said:
I have a 2007 2wd Trailblazer and I was just wondering if I could use those z71 89 springs and the bds shocks on the rear as well as the 2" suspension lift on the front? I'm new to this and was just wondering. Want to fit bigger tires.
I agree with what JHam has already stated, if you understand what he is saying.

Your comment on z71 89 springs makes me believe that you think they are the same springs. 89 springs are the front springs that you can get to handle heavier weight up front. The Z71 springs Are take offs from Tahoes and Avalanches. You don't need either spring for bigger tires. You only need a lift and spacers to fit bigger tires and the spacers are only needed if you want to go bigger than 30.6" as JHam has stated.
 

Short Bus

Member
Dec 2, 2011
1,906
djthumper said:
I agree with what JHam has already stated, if you understand what he is saying.

Your comment on z71 89 springs makes me believe that you think they are the same springs. 89 springs are the front springs that you can get to handle heavier weight up front. The Z71 springs Are take offs from Tahoes and Avalanches. You don't need either spring for bigger tires. You only need a lift and spacers to fit bigger tires and the spacers are only needed if you want to go bigger than 30.6" as JHam has stated.

and you don't need a lift or spacers for 3.6 or less. YMMV so have the fronts test fitted. I had 265/65/17s without a lift or spacer, but I've heard some aggressive tires can rub the upper ball joint (you may be able to fix this with a grinder).
 

Cable810

Member
Dec 5, 2011
690
Lets say he dosn't put the 89s upfront just leaves the stock springs. He adds the MDB Skid Plates, the stock springs can handle it?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Cable810 said:
Lets say he dosn't put the 89s upfront just leaves the stock springs. He adds the MDB Skid Plates, the stock springs can handle it?
What a thinly-disguised thread hijack this is. :wink: We don't know what the stock spring rate is, because there's a dozen the factory could have chosen from, but for a SWB 2WD, they're probably 81 or 82's with a spring rate of under 300 pounds per inch. Adding 100 pounds of oil pan and radiator skid plates might cause 3/8"-1/2" of sag. You could do the same experiment (because I'm SURE you're asking the question for your situation, not his. :raspberry: ) by getting 100 pounds of stuff and hanging it from the front bumper. Measure the sag. The phrase "handle it" is imprecise, and you would be better off asking "what do you think the sag will be?"
 

Cable810

Member
Dec 5, 2011
690
Is there anything on the vehicle that would tell me what springs I have? THREADHIJACK!!!!!!!!
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
This all really is determined by your mission. As the roadie says to almost every newbie that starts to ask so many questions, "Define your mission as that will determine how your vehicle is built." Determine what you are wanting to do with your vehicle then we can start help guide you on your build.
 

daydriver

Original poster
Member
Mar 4, 2012
10
Well I heard those shocks add a little height. so thats what I want to do. lift it...
 

navigator

Member
Dec 3, 2011
504
shock absorbers do not add height.
They absorb "shock" which makes better ride quality.
They can limit lift and create a harshe ride if they are too short.
The better the shocks then in all likelihood the better the ride.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Short Bus said:
You can use the stock or BDS shocks. You only need longer shocks if you plan on needing more articulation for off-roading.
Not exactly. You need longer shocks if you drive on road, but add much lift in the back. Seems the 1.5 inch spacer or z71 springs being used in the rear is ok with stock shock lengths, but using anything or combination of things to get over 2 inches of rear lift demands longer shocks or driving, on or off road, with thumps and such from the shocks topping out on bumps.


navigator said:
shock absorbers do not add height. :thumbsup::thumbsup::thumbsup:

They can limit lift and create a harsher ride if they are too short. :thumbsup:Yep, topping out will kill ride and a short shock that is fully extended could definitely keep you lift from being to its full height potential
The better the shocks then in all likelihood the better the ride.
Proabably true, but most cheap shocks can handle what 99% of people do with this platform on-road or offroad. Unless you are hitting washboards at speed like Roadie or bombing down fire roads or sand dunes:biggrin:
 

The_Roadie

Lifetime VIP Donor
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Nov 19, 2011
9,957
Portland, OR
daydriver said:
Well I heard those shocks add a little height.
I keep hearing this so often over the years it must be true.

NOT. :no:

Gas pressurized shocks usually get shipped compressed with a strap because they tend to extend automatically if they're not compressed for shipping. But 5-10 pounds pressure is enough to get them shorter for installation. So think about it. If you pulled UP on your bumper with 5-10 pounds force, how much higher would you sit? 1/10" maybe.

On a related note: In the old days, there were air shocks that COMBINED a shock absorber with an air bag, and those you could add air to to get adjustable lift. They still make them, but think about those as well. The force of the coil spring on our rear axle acts on the spring perch, a strong disk welded to the TOP of the axle tube. Stronger springs will transmit their force to the strongest place to receive the force. Air shocks (or coilover rear shock/strut units) are sending their force to the shock mount, a much weaker sheet metal bracket welded elsewhere, not on top of the axle tube.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I had a 3 inch air shock lift on an 85 Camaro. Rode like crap but was pretty entertaining.
 

jbones

Member
Dec 5, 2011
658
daydriver said:
So as far as bds rear shocks. 5500 series? or whats preferred?

My rear spacer is 1", and although the rear shocks are worn and will be replacing them with BDS late spring, the stocks are barely, if any, bottoming out any more than before the lift.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
daydriver said:
I was looking at bliestin HD front shocks. would that work on my year? 2007 2wd.

Our front has struts....

Bilstein HD struts seem to be the best replacements and many people have good feedback after running them for extended periods.
 

daydriver

Original poster
Member
Mar 4, 2012
10
Thanks guys. So If i'm thinking of adding some weight to the front. Maybe a new bumper, roof rack and lighting. Would like 88's or what would be best spring up front? Not just for riding the roads, but I go down a lot of rocky sometimes a tad muddy terrain to go hunting.
 

jham

Member
Nov 20, 2011
1,334
daydriver said:
Thanks guys. So If i'm thinking of adding some weight to the front. Maybe a new bumper, roof rack and lighting. Would like 88's or what would be best spring up front? Not just for riding the roads, but I go down a lot of rocky sometimes a tad muddy terrain to go hunting.

as I said earlier in this thread 85 or 86 at the most with your truck and mine being 2wd so there's less weight than the 4wd's have I have 83's right now and I am going to go to 85's to get the half inch I lost with the bumper and skid if you need to see how the truck rides come on down and you can drive mine
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Spring#,Rate(N/mm),Check Load(N),Free Length(mm),Label Color
81, 50, 6820, 418.8, Lavender
82, 53, 7240, 417.0, Dark Green
83, 56, 7578, 415.7, Gray
84, 60, 7934, 412.6, Pink
85, 63, 8307, 412.2, Light Blue
86, 67, 8646, 409.6, Orange
87, 70, 8988, 408.3, Dark Blue
88, 74, 9331, 406.8, Light Green

89, 77, 9674, 405.5, Tan

No longer available new from GM sources. So all you can get is 81-86 or 89's. I can't believe 89's will be available forever, especially with offroaders targeting them for upgrades.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
jham said:
as I said earlier in this thread 85 or 86 at the most with your truck and mine being 2wd so there's less weight than the 4wd's have I have 83's right now and I am going to go to 85's to get the half inch I lost with the bumper and skid if you need to see how the truck rides come on down and you can drive mine

The weight difference is what...a couple cv shafts and the front diff. So 100 lbs. Not much really.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
jham said:
a 100lbs is the weight of the bumper from Barton

Trust me...I know. Lifted a few of them in my day. But it still is not enough to really change what springs since the weight of a bumper is up and out and has more effect on the ride. The 4x4 weight is low and inline w springs so it would have less effect on ride.

Have you driven any w heavier springs than your 83s?
 

jham

Member
Nov 20, 2011
1,334
HARDTRAILZ said:
Trust me...I know. Lifted a few of them in my day. But it still is not enough to really change what springs since the weight of a bumper is up and out and has more effect on the ride. The 4x4 weight is low and inline w springs so it would have less effect on ride.

Have you driven any w heavier springs than your 83s?

yes I have driven others with heavier springs. I wasn't implying that you didn't know I was just comparing the weights and if anyone would know it would be you. I was just speaking of my experiences and from what i have done to mine
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
jham said:
yes I have driven others with heavier springs. I wasn't implying that you didn't know I was just comparing the weights and if anyone would know it would be you. I was just speaking of my experiences and from what i have done to mine

Ok. I add and subtract 100 to 200 lbs off the front of my truck fairly often and don't see much difference in ride, so I can't really see the minimal, well located weight of 4x4 vs 2wd affecting ride but it could. I can't tell if my 100+ lb winch setup is on the front or not. It rides the same.
 

jham

Member
Nov 20, 2011
1,334
HARDTRAILZ said:
Ok. I add and subtract 100 to 200 lbs off the front of my truck fairly often and don't see much difference in ride, so I can't really see the minimal, well located weight of 4x4 vs 2wd affecting ride but it could. I can't tell if my 1000+ lb winch setup is on the front or not.

ok maybe this is with the 83's I have I felt a big difference adding the bumper and rad skid to mine. It sagged close to half an inch but feels like it soaks up the pot holes and such with way less harshness.
 

daydriver

Original poster
Member
Mar 4, 2012
10
HARDTRAILZ said:
Ok. I add and subtract 100 to 200 lbs off the front of my truck fairly often and don't see much difference in ride, so I can't really see the minimal, well located weight of 4x4 vs 2wd affecting ride but it could. I can't tell if my 100+ lb winch setup is on the front or not. It rides the same.
So regardless of 4wd or 2wd, If I plan on packing a lot of stuff onto my TB then it wouldn't matter if I got say 88's, the ride wouldn't be crazy uncomfortable because i'd still have a bunch of weight added on
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
daydriver said:
So regardless of 4wd or 2wd, If I plan on packing a lot of stuff onto my TB then it wouldn't matter if I got say 88's, the ride wouldn't be crazy uncomfortable because i'd still have a bunch of weight added on

A big part is weight placement. When you say "packing a lot of stuff" that seems to indicate the rear of the truck so the front really would not be carrying much of the weight.

The 87s and 88 front are pretty well non-exsistent for purchase. If you think you will be adding skidplates or a bumper or a winch, you might consider 89's but they are reportly kinda harsh. My 88s are not bad even without much or any extra front weight, but the 89s seem to be enough stiffer to create some issues. I would go for 86s since they are the strongest you probably have available unless by some magic you have 85s factory. They would give you an extra bump in height and future load bearing ability if you do want some front protection...skidplates should be your first purchase IMHO.

Since you seem to plan on weight in the back, many people really like the extra carrying ability and bump in ride height of the z71 coils in the rear. You may also consider some air bags like Mr. Roadie has for handling the weight he carries.
 

daydriver

Original poster
Member
Mar 4, 2012
10
HARDTRAILZ said:
If you think you will be adding skidplates or a bumper or a winch, you might consider 89's but they are reportly kinda harsh. My 88s are not bad even without much or any extra front weight, but the 89s seem to be enough stiffer to create some issues. I would go for 86s since they are the strongest you probably have available unless by some magic you have 85s factory. They would give you an extra bump in height and future load bearing ability if you do want some front protection...skidplates should be your first purchase IMHO.

Since you seem to plan on weight in the back, many people really like the extra carrying ability and bump in ride height of the z71 coils in the rear. You may also consider some air bags like Mr. Roadie has for handling the weight he carries.
Yeah I'm thinking about a roof rack for my spare tire with lighting, also a new metal front bumper. So there will be weight on the front as well. Do you know the service code for factory springs?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
daydriver said:
Do you know the service code for factory springs?
The master list is kept up on our sister site, offroadtb.com (also known as ORTB). Check your glove box sticker for RPO codes starting with 6 or 7.

6## = Left front spring
7## = Right front spring

## = the letters below:

15125881 - FH, HM, HU, FZ, JC, CC
15125882 - HN, HW
15125883 - HP, HX, CB
15125884 - FL, HY, JL, HC
15125885 - FM, HD
15125886 - HT, JA, JR, JT, HF, JC
15125887 - RL, RX
15125888 - RM
15125889 - HK, HL

For more reading:
OffRoad TB - View topic - Factory Spring Part Numbers & Associated Lift

There is also a color code for painted splats on the springs. Some people even find the factory part number sticker still on the spring! There are also three letter codes on the springs, such as "YUX" and "YHM" but its easier to look them up this way.

Anybody finding new entries for the chart, please let me know! This took a long time to collect.
 

jham

Member
Nov 20, 2011
1,334
the roadie said:
The master list is kept up on our sister site, offroadtb.com (also known as ORTB). Check your glove box sticker for RPO codes starting with 6 or 7.

6## = Left front spring
7## = Right front spring

## = the letters below:

15125881 - FH, HM, HU, FZ, JC, CC
15125882 - HN, HW
15125883 - HP, HX, CB
15125884 - FL, HY, JL, HC
15125885 - FM, HD
15125886 - HT, JA, JR, JT, HF, JC
15125887 - RL, RX
15125888 - RM
15125889 - HK, HL

For more reading:
OffRoad TB - View topic - Factory Spring Part Numbers & Associated Lift

There is also a color code for painted splats on the springs. Some people even find the factory part number sticker still on the spring! There are also three letter codes on the springs, such as "YUX" and "YHM" but its easier to look them up this way.

Anybody finding new entries for the chart, please let me know! This took a long time to collect.

I was looking to order new springs today I found that 85 and 86 springs are on back order there is one dealer in Florida that has 1 85 and no 86's available and there is less than 10 89's in stock just FYI
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
jham said:
I was looking to order new springs today I found that 85 and 86 springs are on back order there is one dealer in Florida that has 1 85 and no 86's available and there is less than 10 89's in stock just FYI
Ooops. The end is nigh. 87's and 88's are already gone. Get your 89's while you can.

I talked to a couple of vendors at the SEMA show who might be persuaded to enter the market.
 

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