Revert back to OEM Z55 suspension, good or bad idea?

[chutkin]

Hello all,

First, brief introduction. I live in Bulgaria, Europe and we do not have much experience with such cars. Last year I bought 2007 GMC Yukon XL and discover it was originally equipped with Z55 suspension. I have driven the car for less then 1k miles. I cannot tell if suspension is OK or not.

My plan is to use this car in a long term as a family car, so currently I am "refurbishing" it. I need to replace leaking steering rack. During the process I discovered that front shocks were replaced and electronics bypassed. Right shock is very smeary, I guess it is damaged and in any case I need to replace front shocks.

I do not know how working Z55 suspension will feel. Is it worth reverting back with OEM parts?

Also, my only reliable part source is Rockauto. Others may not ship overseas or other complications.

I will appreciate your thoughts and advises.

Thanks,
Ivo

 

[SpareParts]

Z55, Some love it, Some hate it. Personally i like and nothing will ride better than the stock Z55 suspension.
It is all repairable but will cost ya if you need all 4 shocks/struts/compressor/module + programming the new module. Maybe you don't need all that tho. You have to figure that out.
If i was going to get rid of the Z55 i would use Belstein shocks and Z71 rear springs.

 

[LSCALADE]

Adash!

Yes the oem suspension is quite nice and it is nice to have as it makes the ride very smooth but having said that I am impressed by the set of Bilstein shocks I put on mine and the ride is quite amazing, very soft but very quickly controlled.

One way to tell if the shocks are still good is if you go over a speed bump and you get a little bit of float, up down up down before it settles then the shocks are busted.

If you go with the OEM suspension pay attention the magneride shocks have springs with 8 coils and most others you see in the aftermarket world are 6 or 7 coils. So you may have to find a set of springs along with shocks.

My advice go with bilstein shocks, raise the front a little with a spacer and enjoy it. '

PS, Born and Raised in Bulgaria been in the USA for 25 years.

 

[chutkin]

Hi guys,

As I said, I have not driven the car and cannot judge if the suspension was OK. Now it is on jack stands and I work on it whenever I have time :-(

I found that there are heat shrink tubes on front struts connectors, I guess these are the resistors or something... See the pics.

When I turn on the ignition, I hear compressor starts and in a minute or so it stops. I have not checked rear struts if inflated. They are not OEM I guess, there is SACHS sticker on them.

Leveling sensors are all there.

I want to believe, I will be good if I replace front end with OEM parts.

I checked Rockauto, and it looks they have all the OEM parts except the springs for around $1200 shipped to Bulgaria. Does anyone knows what springs could be used?

@LSCALADE Здравей!

 

[SpareParts]

You will not find a pair of springs listed for your truck as it was equipped with Z55 You want to look for non Z55 springs.
You would be pretty much converting to a non Z55 suspension. Non Z55 without auto level would need these rear springs i believe.

More Information for MOOG 81069

Are you wanting to keep rear auto level? If so you will want a pair of air shocks. I believe these are what you would want.

More Information for MONROE MA830

 

[LSCALADE]

All magneride suspensions have softer springs, aka more coils such as the photo below.

All regular suspension systems have about 6 coils even the silverados etc, so stiffer springs.

If you want to get the magneride back on there you can go with ARNOTT they make excelent OEM replacements. OEM is always an option but the cost is sky high, but if you are going to keep the truck for a long time its worth it.


A nice walk around that is to keep your current suspension and install some Bilstein 4600 or 5100 shocks on all 4 corners and that is probably one of the nicest riding set ups with good wheel control and quite comfortable for rough roads.

I have the 4600 on the rear and I will soon have that on the front as well and I love how they ride.

Any time you can, try to go for Monotube shocks, they have large internal pisonts and generate much higher resistance forces so they can control the wheel movement better than any twin tube suspensions out there.

 

[Joseph Garcia]

Hello all,

First, brief introduction. I live in Bulgaria, Europe and we do not have much experience with such cars. Last year I bought 2007 GMC Yukon XL and discover it was originally equipped with Z55 suspension. I have driven the car for less then 1k miles. I cannot tell if suspension is OK or not.

My plan is to use this car in a long term as a family car, so currently I am "refurbishing" it. I need to replace leaking steering rack. During the process I discovered that front shocks were replaced and electronics bypassed. Right shock is very smeary, I guess it is damaged and in any case I need to replace front shocks.

I do not know how working Z55 suspension will feel. Is it worth reverting back with OEM parts?

Also, my only reliable part source is Rockauto. Others may not ship overseas or other complications.

I will appreciate your thoughts and advises.

Thanks,
Ivo

I have a 2007 Yukon XL Denali, and I've had both passive and Z55 active systems on it. For me, the Z55 active suspension is far superior.

The comments regarding rear springs are correct. If you go with a passive system, then you'll need to change the rear springs to stronger/stiffer springs.

Full transparency, however, there are lots of folks who prefer a passive aftermarket conversion.

 

[chutkin]

Hi guys,

Thanks for the info. I am going to revert back front end for now. Rear looks good, no leaks, compressor starts and stops, and for little driving I have it does not start/stop constantly.

I use this picture from petethepug post as reference:

Everything OEM matching RPO codes is available from Rockauto except coil springs, trust washer and spacer.

In Rockauto I see two options with "Front; Electronic Dampening Control Suspension" note:

More Information for MOOG 81250

More Information for TRW JCS153T

Can anyone confirm if these springs will work with Z55 OEM parts?

For reference, at the time of this post, Sep 2025, other parts cost $1183.00 shipped to Bulgaria:

Thanks for your help,
Ivo

 

[Joseph Garcia]

Hi guys,

Thanks for the info. I am going to revert back front end for now. Rear looks good, no leaks, compressor starts and stops, and for little driving I have it does not start/stop constantly.

I use this picture from petethepug post as reference:

View attachment 467773

Everything OEM matching RPO codes is available from Rockauto except coil springs, trust washer and spacer.

In Rockauto I see two options with "Front; Electronic Dampening Control Suspension" note:

More Information for MOOG 81250

More Information for TRW JCS153T

Can anyone confirm if these springs will work with Z55 OEM parts?

For reference, at the time of this post, Sep 2025, other parts cost $1183.00 shipped to Bulgaria:

View attachment 467774

Thanks for your help,
Ivo

I used the Moog 81250 front spring when I rebuilt my Z55 suspension 4+ years ago, after I found out that the OEM spring was discontinued. The Moog springs have worked well for me.

 

[chutkin]

Hi guys,

I managed to collect all missing parts except coil springs:

Part Number	Part Name	Price	Quantity	Total
15815517	Multi-Purpose Nut	$11.60	2	$23.20
15815519	Front Suspension Strut Nut	$9.93	2	$19.86
11548570	Multi-Purpose Collar Washer	$6.30	2	$12.60

Subtotal: $55.66​

Estimated Shipping to 34249 via Economy Shipping: $7.04​

Total: $62.70​

I ordered washers and nuts from this guys:

revolutionparts.com​

Shipping is to forwarder, so I will know exact shipping cost to me later.

I will post next update soon

 

[chutkin]

Hi guys,

Finally I got all the parts for front struts.

What I see from the firs look is that springs are much taller then the shocks they must be mounted on.

Uncompressed springs are about 37,5 cm (~15,3 inches) and I guess, they must fit in 27 cm (~10,8 inches) space when assembled.

Does it look right or shocks must be expanded somehow?

Can I use DIY spring compressors or I have to look for some professional equipment/shop?

I have this spring compressor:

Thanks a lot for your help!

Ivo

 

[Joseph Garcia]

Hi guys,

Finally I got all the parts for front struts.

What I see from the firs look is that springs are much taller then the shocks they must be mounted on.

Uncompressed springs are about 37,5 cm (~15,3 inches) and I guess, they must fit in 27 cm (~10,8 inches) space when assembled.

View attachment 471046

Does it look right or shocks must be expanded somehow?

Can I use DIY spring compressors or I have to look for some professional equipment/shop?

I have this spring compressor:

View attachment 471047

Thanks a lot for your help!

Ivo

Yes, the springs have to be compressed, in order to complete the assembly of the strut assembly.

The spring compressor equipment that you have looks like it could do the job for you, but you need to be VERY careful, and do the work EXACTLY like the instructions say. The forces that you will be applying to compress those springs will be LARGE, and if you make a mistake, and the spring compressor fails, you have a very dangerous situation, which could result is serious injury to you.

 

[chutkin]

Hi Joseph,

It was my point, I know springs are dangerous. I find useful video and the guy there uses four spring compressors.

I might buy another pair just to be on the safe side.

Here is the video:

I will report my progress
Ivo

 

[Joseph Garcia]

Hi Joseph,

It was my point, I know springs are dangerous. I find useful video and the guy there uses four spring compressors.

I might buy another pair just to be on the safe side.

Here is the video:

I will report my progress
Ivo

I took the new parts to a local repair shop, where they have a press and spring compressor attachments, and I had them put together the strut assemblies. The job was performed 10 times faster that I could have done it myself, everybody was safe, and the cost to have the shop perform this work was small.

 

[SpareParts]

I have a set of spring compressors like shown above.
I really like them. For a DIY person they are fantastic and are WAY safer then the cheap rod style.

 

[chutkin]

Hi Joseph,

I am not looking to save on this. I am in Europe, and whenever I go to some shop usual answer is... American car? Go away...

That is why I become DYI "mechanic"

 

[Joseph Garcia]

Hi Joseph,

I am not looking to save on this. I am in Europe, and whenever I go to some shop usual answer is... American car? Go away...

That is why I become DYI "mechanic"

LOLOL

I became a DYI Mechanic, because I could not afford to have somebody else fix it, and without it, I had to walk.

 

[chutkin]

For me, being DIY mechanic is also stress relieve from my main job

How much will be labor cost on conversion like this in USA?

Parts cost is clear, except I have to pay shipping and import duties, sometimes doubling parts cost.

BR,
Ivo

 

[chutkin]

Hi guys,

I am slowly progressing on this.

I bought another pair of spring compressors like above and I can confirm, it could be done with four compressors.

I discover another "issue". The springs that are currently installed, and on pictures I have seen, upper spring end is facing outward in the center.

On the parts I got, (I bought GM OEM), upper shock mount and plastic spring seat/insulator, when assembled, spring end will be facing off center, forward on the left side, may be backwards on right side (have not reached right side yet).

See on the pictures what I mean.

Plastic insulator cannot be mounted any other way. There are tabs that match only one position on shock mount.

Any info and help will be appreciated,
Ivo