New to lifting

[CarbEnvoy]

I am new to lifting vehicles.

I started a thread on GMTNation http://gmtnation.com/f76/replacing-air-springs-coil-springs-add-bit-lift-10273/ about replacing my air springs and doing a lift at the same time.

At this point, I am planning to go with the BDS kit, including the shocks http://www.bds-suspension.ca/chevrolet-gmc/trailblazer-envoy/2002-2009/2-front-2-rear-kit/, and NAPA, Avalanche HD coil springs. They have the same specs as these Raybestos springs http://www.rockauto.com/catalog/moreinfo.php?pk=2665844&cc=1440255. They say design load is 1300, and the spring rate is 229. That's a big jump over the OE replacements which have a design load of 815 and a rate of 159. I'm a little worried that the GMT truck would just be too light for those, but I just don't know. Maybe a good compromise would be XL/EXT springs?

I don't want the ride to be too harsh, and I'm not 100% sure that the NAPA springs are variable rate, although the Raybestos seem to be. Are the Avalanche Z71 springs variable rate? My concern is that the NAPA springs will be too stiff for the Envoy. I do tow a 3300lb (dry) travel trailer a couple times a year. The other option I was considering are Envoy XL springs in the back.

The off-roading I do is mainly limited to potholed logging roads, and river banks with large cobbles. Last year I just scraped the oil drain plug on the river bank.

I am running LT245/70/R17 Firestone Transforce A/T tires. More highway tread than A/T, but they work for the stuff I do.

EDIT: I can't seem to figure out what my front springs are. RPO codes appear to be 6SP and 7SN. I replaced my struts a few years ago, and I think I removed the tags, I'll have to look more closely next time I have the tires off.

[Cable810]

Welcome!! Sound like you got a good plan together.

[CarbEnvoy]

Thanks. I'm looking forward to doing it!

I'm really interested to know what people think of the HD Avalanche springs from Raybestos/NAPA. Will they be too stiff for the envoy? I'm ok with stiff, but my concern is that they will be so stiff that the empty weight of the vehicle will sit really high on the springs, and not have much up-travel left.

[navigator]

Welcome, I don't recall anyone running those HD Avalanche springs on here.

[The Roadie]

GM Z71 Tahoe/Avalanche springs of the two part numbers we list in the Accessories thread, are progressive. Some report that the first coil or two is collapsed almost all the time if they don't have Airlift1000 bags inside like I run.

I think even progressive springs aren't going to be to your liking unless you're heavily loaded down with spares, recovery equipment, and camping gear, and a spare hanging behind your rear bumper that increases the leverage. That, along with ground clearance, are why many of us are running the stiffer springs.

If you're getting by now without oil pan armor on a bit less than AT tread, without ever airing down, I'd recommend sticking with GMT305 (long wheelbase EXT/XL) replacement springs and BDS or Markmc spacers, and skip the upgrade to Tahoe/Avalanche.

But I see no comfort in running without an oil pan skid plate.

[CarbEnvoy]

Thank you Bill. That is a very helpful assessment.

You've helped me make up my mind to go with the slightly heavier duty XL springs. The BDS kit comes with spacers like you said, and shocks. So that's perfect. If the trailer proves to be too much, I'll add the Airlift bags in the future.

Any idea why the XL springs are listed at about 1/2" shorter free height? At least from NAPA or Raybestos.

I hear ya on the "under" armor. I'll have to figure out where I can source one up here.

[navigator]

the SWB have a decent amount of rake.
Do the LWB have that same rake?

[CarbEnvoy]

I don't know about the rake on the LWB.

Still, the EXT/XL spring has a higher load 970 vs 815, and higher rate, 210 vs 159 than the regular spring. It also has a thicker wire diameter. Both say load height is 12".

The XL free height is 16.62 while the SWB spring is 17.13.

I think with the BDS 2" lift kit, I should be good with the XL springs, and have a bit more load capacity for towing.

[87chevy]

Welcome

[HARDTRAILZ]

I hear ya on the "under" armor. I'll have to figure out where I can source one up here.

Paging Dr. Barton....Dr. Barton Please present your goods

[CarbEnvoy]

I found his Vendor thread. That would be great. Have to find out about shipping to Canada.

[djthumper]

Road Trip!

[CarbEnvoy]

While switching from winter to summer tires yesterday, I checked out my front springs. It looks to me like I have a dark green (82) spring on the FR, and a pink spring (84) on the FL. The only RPO codes that look like spring codes are 6SP and 7SN. Does this make sense to anyone?

Maybe I should post this on the spring thread?

[DirtyBacon04]

http://forums.offroadtb.com/viewtopic.php?f=15&t=158

The link will take you to the full thread. Could you post a pic of your RPO sticker so we can see all of it to better help you?

The table below works by looking up your stock front spring part number or tag color on the top line first. This can be found by looking at your stock spring tag, or by looking for the associated RPO code in the glove box (see below for RPO > Spring # conversion).

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

[CarbEnvoy]

Yes I've read that thread. My codes just don't match anything listed. I will post my RPO sticker over there.

[CarbEnvoy]

My new rear springs arrived, along with insulators, and front sway bar bushings. The springs are the Raybestos EXT/XL springs. The label on the box is dated the day I placed my order. This just adds to my belief that springs from Raybestos, Moog, NAPA, and maybe others, are all the same, just labelled differently.

Springs, insulators, swaybar bushings

Springs and parts.

Label for the springs. Plain white box, with a sticker dated the day I ordered them. I'm guessing they have these boxes sitting there, and depending on what you order, Moog, Raybestos, etc. they slap that sticker on the box.

Spring label

EDIT: added the photos.

[Trail X]

Any idea why the XL springs are listed at about 1/2" shorter free height? At least from NAPA or Raybestos.

The information in your earlier post really paints the whole picture, but it should be the same deal with the front springs. The higher spring rate springs are slightly shorter so that the resting height of the vehicles are basically unaffected by the spring rate change. Thats why a stronger GM spring for these vehicles generally comes with a shorter unloaded spring length.

[CarbEnvoy]

The information in your earlier post really paints the whole picture, but it should be the same deal with the front springs. The higher spring rate springs are slightly shorter so that the resting height of the vehicles are basically unaffected by the spring rate change. Thats why a stronger GM spring for these vehicles generally comes with a shorter unloaded spring length.

Makes sense. I read that same explanation in another topic, maybe the springs part number thread.

This site has become a new online addiction reading all the info!

[navigator]

....
This site has become a new online addiction reading all the info!

it gets worse...you read, you buy, you install, you play.... after a while you get withdrawals, you read more, you buy more, you install, you play more... the withdrawals get worse....

[CarbEnvoy]

....
This site has become a new online addiction reading all the info!

it gets worse...you read, you buy, you install, you play.... after a while you get withdrawals, you read more, you buy more, you install, you play more... the withdrawals get worse....

There are a lot worse addictions that one can have on the internet