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Recommendations for Replacement Rear Shocks on Z71

14K views 26 replies 11 participants last post by  SFLTruck 
#1 ·
Hi All,

I have a 2017 Z71 crewcab long bed Duramax. Found out my drivers rear shock is leaking after 23K miles. I’ve done some searching on here and on “Fans” and the recommendations seem to be for lifted trucks or off-road duty. I don’t go off-road with the truck, all on-road with some short distance towing (#5500 enclosed trailer). My hitch has leveling bars and anti-sway. I’ve read that people say the Z71’s ride is harsh, I don’t find that but that could be because of the blown shock or because I’m used to driving a 1999 K2500 diesel Suburban which is extremely rough. I don’t mind spending the money for good shocks but I definitely don’t want a stiff ride. I’ve used Bilstein’s before but always on cars where I wanted a stiffer ride. I’d like a comfortable ride but I don’t want something that feels like driving on marshmallows and will float all over the road.

I see Rock Auto has KYB GR-2/Excel-G’s and Monroe OE Spectrum for daily drivers as well as Rancho RS5000X’s for heavy duty. Don’t know if anyone has opinions on any replacement shocks. If people say the stock shocks are harsh then I assume the ACDelco’s are also going to be harsh.

Thanks,
Art.
 
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#2 ·
I've used Rancho RS5000s, RS9000s, and Biltsteins on several trucks. Can't go wrong with any of them. I personally prefer the Bilsteins. They seems to be better material and I've never had any issues with the ride being too harsh.
 
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#4 ·
FWIW
swapped out the rears at 1K miles because I didn't care for the way it handled with the factory shocks. It made a nice noticeable handling difference for the positive. Did the same thing on my last truck which was a Toyota with the same results although I used Rancho RS5000 on that vehicle. On the Colorado I used RS7000.

 
#5 ·
Go with Bilstein 5100s. They give you the flexibility to level your front end if you so desire. They are a little stiffer than factory and much stiffer than rancho shocks, but you get better body roll/ sway control as a trade off. If you are on road more than most days, I don’t think you can get a better riding shock for overall performance.
 
#9 ·
Dan, do you know the diff between the 5100's and the 5160's? I'm not a recreational off roader, but would like good support when going up and down on rutted gravel roads, while pulling my ~6000# (fully loaded) bed hitch travel trailer (~700# combined weight of hitch trailer hitch weight). Sometimes in 4H. The description wording is written by the Bilstein sales staff, but makes it sound like the 5160's are more manly. Both are suitable for never to be lifted Colorado's like mine.

And while only tread adjacent, any easy checks on when shock replacement times have arrived? We're at ~46K, half on a variety of roads, pulling/carrying ~5/6 of GCVW. Shocks seem ok to me, but I know that I can be dulled to gradual changes.
 
#6 ·
Same vehicle type as turbodiverart above. Discovered today (left rear leaking oil) but at 50k miles. Bilsteins enroute.
 
#10 ·
@bigoilbob I haven’t used the 5160’s but from my understanding, they are remote reservoir shocks designed for off-roading. The 5100s do not have a remote reservoir and are set from factory. In your situation, I would recommend standard 5100s and think about an add-a-leaf or airbags for towing. The add-a-leaf will make your unloaded ride much stiffer but you get an additional 750lbs of payload capacity, not to mention it serves as additional sway control when towing (that’s the route I went). IMHO, The addition of either AAL or bags will make a bigger difference than any set of shocks for your application. I certainly wouldn’t spend the additional money for remote reservoir shocks unless they were comparable in price.
 
#12 ·
Thanks RPB. Seems like sensible advice. I'm taking it.

And thank you DD as well, for your reply. I see your point, but since I don't ride that low even when fully loaded, and have never bottomed out, I'm sticking with my stock leafing. This is our only 4 wheel vehicle and my wife drives it all over without complaint.
 
#13 ·
Hey guys, on this topic, I've just installed the add-a-leaf, and 1.5" blocks in the rear, (already had 2" spacers up front), and my stock shocks (z71) are maxed out. Would like to replace them with Bilsteins, just wondering which model would be the right size. Any opinion on this? cheers
 
#16 ·
Try browsing the discussions here - so much good info for the Colorado. Sure there's a question about whether the kits are specific to the diesel's weight distribution (e.g. shock valving), but for general fitup / sizing topics, there shouldn't be any difference with the gasser Colorado. Search results for query: bilstein
 
#19 ·
Installed the 5160s Saturday. Loaded up my truck to work today and was surprised how stiff they were. Very planted just a lot less bouncy than stock.
Hey @PlopDuramax - how are you liking those Bilstein 5160s now that you’ve been on them for a bit? Although I’ve been running Fox remote reservoirs at all four corners, the rears are underdamped for my 400 pound topper (constant weight, always installed) and the rear end is constantly bouncing on local roads and highways. I’m also at +1.5” with custom Alcan leaf springs, and the 5160s are rated for the increased travel. Anyway, Bilstein says “they’ll work” but I figured I’d check someone’s experience here regarding how the shocks are under modest added load?

For anyone wondering, I enjoy rambling down long backcountry, FS, and desert unimproved roads and the constant washboards are a great application for 5160 remote reservoirs (to avoid fading).
 
#20 ·
so I haven't really taken my truck off-road at all aside from getting to customers properties but when I get the porpoise is when there's a dip in the road causing my suspension to drop out and then compress real fast.
I'm definitely carrying at minimum 400 lb in the back of my truck at all times and I don't feel the bilsteins helped much with the porpoise. matter of fact my mechanic buddy and I were talking about possibly using hydraulic bump stops to alleviate the issue but kind of an expensive Band-Aid to test out.
 
#21 ·
...when I get the porpoise is when there's a dip in the road causing my suspension to drop out and then compress real fast. I'm definitely carrying at minimum 400 lb in the back of my truck at all times and I don't feel the bilsteins helped much with the porpoise. matter of fact my mechanic buddy and I were talking about possibly using hydraulic bump stops to alleviate the issue but kind of an expensive Band-Aid to test out.
Interesting. Does it porpoise (back-to-front rocking) happen more than once, or just one dramatic motion and then done? Are you running a Z71 with stock rear leafs / are the Bilsteins the first mod you've done in the rear? I've read that some hydraulic bump stops have a long enough reach that they add to suspension (spring rate) well ahead of bottoming out. That said, it would seem to only try and slow down what your setup currently allows to begin happening. A lot of folks talk about how flat the stock leaf springs are - how fast they compress then rebound. You might consider a better leaf pack to support your heavier loads... I was interested in Deaver, but as it's been said they never returned my calls or emails. Instead I got a custom leaf pack from Alcan in Grand Junction, CO. Not a real HD/expedition upgrade, but a mild increase in spring rate. They curved, then slightly decurved my leafs and got me at about +1.5" higher than stock. Their default spring curve for our truck is more like +3". Anyway, shocks should control the spring action (from a single bump/dip) to no more than one excursion with minimal rebound... but they won't solve a spring rate undersized to load weight.

For anyone interested, I'm let down by Fox (2.5" remote reservoirs). Originally tuned nearly perfectly (by Accutune in CA) for my generally empty bed (yeah, I was 90% city commuting at the time). But now with 300-400# of topper, awning, etc, the Foxes are underdamped and the rear end loves to pogo. The tuner said I shoulda splurged on the fully adjustable Foxes (even more cash) - clearly a case of me misunderstanding it's a highly tuned performance product with a very narrow tuning range. They'll happily retune my shocks for the new load... After I uninstall them and run something else (e.g. Bilstein) while I ship them back to CA for the rework. Good grief.
 
#22 ·
Ok new development. loaded my truck past what i should have and the road master helper springs bottomed out on my frame. not happy.

so i picked up some Air Bags and im literally eating crow. my mechanic had been pitching them for 10+ years and i always had a different idea. should have listened to him.

ride height is back to normal, truck stops faster and I have gone from 19-20 mpg average around town to 21-22 mpg average.

seriously couldn't be happier. just need a better method of matching the height between the two sides.

new bags
Font Symbol Pattern Circle Automotive tire


before bags. loaded for a normal day
Wheel Automotive parking light Tire Automotive side marker light Sky


RoadMaster Spring before removal
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bags getting fitted.
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ill take a couple pictures of the truck how it sits now ASAP.
 
#23 ·
Ok new development. loaded my truck past what i should have and the road master helper springs bottomed out on my frame. not happy.

so i picked up some Air Bags and im literally eating crow. my mechanic had been pitching them for 10+ years and i always had a different idea. should have listened to him.

ride height is back to normal, truck stops faster and I have gone from 19-20 mpg average around town to 21-22 mpg average.

seriously couldn't be happier. just need a better method of matching the height between the two sides.

new bags
View attachment 9649

before bags. loaded for a normal day
View attachment 9650

RoadMaster Spring before removal
View attachment 9648

bags getting fitted.
View attachment 9647

ill take a couple pictures of the truck how it sits now ASAP.
The one this I did was to not use a tee fitting between the two sides. This does two positive things in my book, 1 is you can put more air in one side if needed. The second, and more importantly, is when you make a turn the body roll lifts one side of the truck and pushes down on the opposite side. When the bags are tied together this forces air pressure out from the side that's getting compressed during a turn and forcing it into the "lifted" side and forcing more body roll. I say plumb them separately and it solves the two situations.
 
#24 ·
I completely agree. I like having them separate because like you said sometimes the loads I cary are just a little bit different and I really like to have the truck leveled side to side.

Plus that whole cornering thing scares me if they were on a tee.

I installed the shraders on either side of my decked system. I was liking the idea of running it out the license plate holes however this keeps them a little more secure and definitely out of the way from me hitting them with anything.

Wheel Tire Automotive tire Motor vehicle Automotive design
 
#25 ·
I completely agree. I like having them separate because like you said sometimes the loads I cary are just a little bit different and I really like to have the truck leveled side to side.

Plus that whole cornering thing scares me if they were on a tee.

I installed the shraders on either side of my decked system. I was liking the idea of running it out the license plate holes however this keeps them a little more secure and definitely out of the way from me hitting them with anything.

View attachment 9651
I did the license plate thing and so for I haven't managed to hit them. I put them high almost even with the top of the plate.

So far so good, but time will tell.
 
#26 ·
here's a picture of the truck with the bags and loaded for work. please excuse the ladders I don't normally hang them off the back that far but I had conduit and other nonsense that was making it a biatch.
bags are sitting with right about 40 psi give or take to make the bed level.
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