Chevy Astro and GMC Safari Forum banner
1 - 5 of 5 Posts

·
Registered
2000 Lifted 4x4 Astro 92 V8-350 Shorty
Joined
·
5,253 Posts
Discussion Starter · #1 ·
Just INSTALLED my NEW REAR KYB MONOMAX SHOCKS this past weekend!
(slow day today... so here are a bunch of photos and info, mostly for my own "future reference")

Mmusicman said:
(from previous post)
If you search the forums.. you'll probably find one of the MOST popular shock is monotube KYB.
Two basic monotube models:
* Gas-A-Just - 25% more firm than stock (standard upgrade)
* MonoMax - 40% more firm than stock and larger piston (heavy duty)
They both utilize 200 lbs nitrogen gas and valve sensing.
This prevents fade (aeration/bubbles) under heavy use, while valve sensing "adapts" to driving conditions.
The Gas-A-Just is firm (no bounce) but not harsh.

* Gas-A-Just is what I've happily used (on numerous vehicles) for decades... I love them!
Anyone here who has installed them always have same rave "great ride" reviews.

* MonoMax is considered more heavy duty for vans/trucks lifted, big tires, carry loads, and/or tow... and is often compared to Bilsteins, but at a fraction of the price. Coincidentally, I just ordered my first MonoMax set today to replace my "Tough Country" extended shocks that came on my lifted van years ago (the bushings blew out and the stamped part number is so old, they're no longer listed). I want to maintain the same ride I have now.
- OLD SHOCKS -

So my old shocks started noticeably clunking constantly while driving any normal roads lately.
I guess it had to get pretty bad to finally get my attention (bushing completely shot on one side):

20210911_140853.jpg

My first order of business was to find out what I had... and what I will need to replace it. My van sits about 8" higher than stock, and the rear shocks will need to be much longer (than stock) to accommodate my rear suspension lift.

The part number stamped on my old shock #751534 is no longer in production (or listed anywhere) but I found reference to it (in a Tough Country 6" Lift Kit ad for sale) on an old 4x4 Truck forum post.

20210826_180900.jpg

I took numerous additional measurements to determine nominal ride length, as well as compressed and extended lengths, in an attempt to find something similar.

My old stock shock appears to ride at roughly 22" nominal length:

20210826_175808.jpg

It also appeared that the old shock was compressing (from rest) no more than about 2"
(under normal use) with some room to spare before bottoming (which has NEVER happened)

20210826_175908.jpg

The old shock (once removed) measured about 18" compressed..

20210911_140916.jpg

and 30.5" fully expanded
(for a full 12.5" of travel.. more than needed)...

20210911_141022.jpg

This shock appears to slightly longer than what I need (riding more compressed than expanded)... but has worked fine. Knowing this, I think I have some "wiggle room" on expanded lengths.

I found similar to what I needed with "Rough Country" #23153-D (30" extended length for Silverado 4x4).. but for some reason kept shopping (I think initially it was because wrong eyelet size). I briefly looked at "Rancho 9000 Series" shocks, but saw a lot of poor reviews, along with an almost double price-tag.

Then I decided I'd go back and give KYB a try.. since I have ALWAYS loved their shocks! I researched the KYB website "specifications chart" to find the LONGEST shock they made that might meet my lifted van needs. Nothing close enough in stock 1/2" eyelet size, so I decided to look at a much more common and available 9/16" eyelet size. I found a "Gas-A-Just" in 27.5" (for Dodge Ram 2500)... and a "MonoMax" #565077 in 28.5" (extended).
https://www.kyb.com/resources/technical ... imensions/

I custom made these eyelet "sleeves" (from stainless steel strap) for the upper bolts, to convert the 1/2" stock bolts to 9/16" eyelets...

20210911_125310.jpg

For the bottom eyelets I purchased 9/16" x 3" Grade 8 hardware (see product photo below),
and drilled out the axle mounts to accommodate.

Much of these length specs will be irrelevant to most, unless you have similar lift.

- NEW SHOCKS -

Here's my "work area"...
(doing this job on the anniversary of 9/11)
I didn't even need to jack the van up to do the job!

20210911_103107.jpg

I really wrestled with whether I wanted an "extra-firm" ride, or would prefer a "normal-firm" ride. I liked what I had, but no way of knowing whether the old "Tough Country" shock I was running was considered "extra firm" or not. So I assumed my old shocks were likely extra-firm, and ordered my first set of MonoMax shocks to replace them. Additionally it was the longest shock they make with 9/16" eyelets (both ends)

20210911_101908.jpg

20210911_101920.jpg

Product description: "Tough conditions demand tough truck shocks. The large bore KYB MonoMax provides the additional stability that heavier, more powerful or high center of gravity vehicles demand. The KYB MonoMax is a heavy duty monotube shock absorber that provides the most handling, control and durability of any KYB shock; and it's just for trucks. The MonoMax's tough design automatically adjusts to driving conditions with fade-free performance. The KYB MonoMax has an outstanding reputation for vehicles that do real work, go off-road, tow a trailer or haul heavy loads. It uses a work-ready, zinc-coated steel piston ring and includes an off-road dust boot."

Specs MonoMax #565077:
* 18" compressed (same as what I had),
* 28.5" expanded (which would put my 22" nominal ride centered)
* 10.6" travel (more than I need)
* 9/16" eyelets (same both ends)

For stock reference: the "stock" KYB shock is
* 14.5 compressed,
* 23" extended,
* 8.5" travel
* 12x42 metric eyelets (equivalent of roughly 1/2" eyelets)

I purchased on Amazon for $57/ea (with free shipping)
https://www.amazon.com/gp/product/B000C ... UTF8&psc=1

For anyone who had never dealt with KYB monotube shocks, they come charged with 200-300lbs Nitrogen, and are strapped to keep them from expanding during packaging and shipment. Coincidentally, it was strapped mid-way at 22" (exactly where I needed it).

20210911_121355.jpg

The "trick" with these shocks is to cut the strap AFTER you hang it from top bolt, but keep bottle jack handy to position it exactly where you need it (for bolts to slide though). If you un-band them first, then you'll have to jack the vehicle (not axle) to fit them... which would also work fine.

20210911_122444.jpg

Finally.. the NEW MonoMax shocks are installed!

20210911_154237a.jpg

They are certainly the "prettiest & brightest" thing visible under the rear of the van! lol

--------------------------------------

SO... HOW WAS THE RIDE??

Honestly (first impression) is that I'm a little shocked! (no pun intended)

They were barely "noticeable"!
In other words, I really didn't notice they were there!
Just a transparent smooth controlled ride!
They were not "harsh" like I was expecting... just firm like I already had (more like a performance firm)

I could "feel" the road nice and firm (as I had before)... but actually smoother over bumps (it was more like a dull thud). No bounce or sway whatsoever. I suspect the nitrogen and "valve sensing" is FAR superior to what I previously had... being more firm on dampening but LESS harsh on bumps. This is their magic!

I've only driven 5 miles (on normal roads).. so that is my first impression.
I haven't had a chance to give them a REAL workout yet.
Locally I tote tools around, and of course I have needs of a lifted 4x4 vehicle with larger heavier tires.
I have a trip coming up (towing a trailer) so that's where I expect I'll get to see them really shine.

I'd really continue to recommend the KYB Gas-A-Just (25% more dampening power) as I have used on most of my vehicles over the decades. But for my lifted 4x4 application, I figured I'd give the MonoMax (40% more dampening) a try.. and I can tell you I am delighted! I think they are going to be PERFECT for me!

Hope you enjoyed all the silly photos and long story about my performance-shocks installation!
There's not much more I could add... if I tried! lol

The saga continues...... :D
 

·
Registered
01 Astro Cargo RWD, 97 Astro Mark III AWD
Joined
·
1,770 Posts
Added to the list of great info from hurricane central :D

Just 1 question. Why not just replace the upper bolt also?
It is a through bolt and would easily upgrade to 9/16.

And to offer another option for keeping the shock from over extending. A ratchet strap can be used to hold/compress the shock if needed.
 

·
Registered
2000 Lifted 4x4 Astro 92 V8-350 Shorty
Joined
·
5,253 Posts
Discussion Starter · #5 ·
I purchased new shocks and new lower hardware before pulling the old shocks.
I didn't know the length of the top bolts... the sleeves were simple enough to make.
It worked out perfectly.

Yes, more than one way to install these.. ratchet straps might work as well.
I just happen to have a bottle jack handy... :D
 
1 - 5 of 5 Posts
Top