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.
Lifting the Trailblazer
- Thread starter daydriver
- Start date
jham
Member
- Nov 20, 2011
- 1,334
daydriver said:
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
I agree with what JHam has already stated, if you understand what he is saying.daydriver said:
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.
What a thinly-disguised thread hijack this is.Cable810 said:
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. 
) 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?"
Short Bus
Member
- Dec 2, 2011
- 1,906
daydriver said:Don't mind the thread hack haha. just answer the part about the shocks on back!
You can use the stock or BDS shocks. You only need longer shocks if you plan on needing more articulation for off-roading.
Here's the best lifts for the money.
Chevy/GMC Leveling Suspension Lift Kit :: THE LIFT MEISTER
djthumper
Administrator
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.
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
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.Short Bus said:
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 dunesnavigator said:shock absorbers do not add height.
They can limit lift and create a harsher ride if they are too short.
The better the shocks then in all likelihood the better the ride.
I keep hearing this so often over the years it must be true.daydriver said:
NOT.
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
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
daydriver said:
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.
jbones
Member
- Dec 5, 2011
- 658
daydriver said:
Sure will, I order mime from here, Bilstein - KYB - Rancho - Monroe - Edelbrock Automotive Truck Shocks and Struts - Shockwarehouse.com
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:
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
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.
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:
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:
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?
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
jham 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 onHARDTRAILZ said:
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
daydriver said:
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.
OEM springs use Airlift #60779
Avalanche/Tahoe/Escalade Z71 springs use Airlift1000 rear coil bags #60769
Avalanche/Tahoe/Escalade Z71 springs use Airlift1000 rear coil bags #60769
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?HARDTRAILZ 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.daydriver said:
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.
Ooops. The end is nigh. 87's and 88's are already gone. Get your 89's while you can.jham said:
I talked to a couple of vendors at the SEMA show who might be persuaded to enter the market.