Product Reviews
Custom
DoetschTech Shock Installation
Article and photos courtesy of Scott, AKA mrk5
What started as a 1-ton axle install turned into an entire new
suspension for the General, my 1984 Chevy K5 Blazer. My biggest concern
with the new suspension was the street performance. I need to drive the
truck to and from the trail and sometimes I just like driving the truck
around town. I decided it was time to explore some better shock options.
Now I'm not expert on shocks, but I am a thinking man. So everything that
follows is based on my own research and the conclusions I've drawn from
that research. I did a lot of searching on several Internet forums and
talked with several people I feel "know their stuff."
I think the first thing to look at is twin-tube versus mono-tube. Most of
us are familiar with twin-tube shocks like the Explorer Pro-Comp shocks I
was running in the past. Twin-tube shocks are less expensive to
manufacture hence their pricing and popularity. The difference between the
two types of shocks is evident in their design as illustrated in this
picture.
|
| Mono-Tube VS
Twin-Tube |
Basically the advantages and disadvantages of both styles are a result of
their basic design. Monotube shocks have a relatively larger piston,
subtle dampening adjustments are easier and they dissipate heat better all
because of the lack of a second chamber. However there is one obvious
disadvantage to the lack of the second chamber, a dent in the shock body
of a monotube shock may cause the piston to bind. The research and
development for monotube shocks is more expensive hence the higher retail
price.
For more detail on monotube vs. twin-tube designs I found these
sites informative:
I decided on monotube shocks for a couple of reasons. Primarily I
found through research and interviews that monotube shocks will
give me the best results for what I desired in handling
characteristics. I was also willing to pay the additional costs
involved with monotube shocks.
I narrowed my decision to 3 choices in my $100-110 price range:
- Bilstein 5150
- Polyperformance's BBCS-15
- Doetsch Tech's Monotube 2.0 smoothbody
I ultimately chose the Doetsch Tech (DT) Monotube 2.0 smoothbody.
The other two shocks are very good choices and come highly
recommended. I felt the DT shocks were just a better overall
value. Here's what they have over the other two options;
- Owner rebuildable
- Therefore owner revalveable
- Custom built to owner specifications
- Optional remote reservoir that can be added at any point.
The only reservation I had about the shocks is the lack of
information about them, or more accurately lack of reviews. I
wasn't able to find and other people using this shock. The closest
I came as a friend who has a similar but older style from DT. I
overlooked the lack of reviews because I know DT has been around a
long time and their other shocks are well received.
Below is the chart of shocks available as of March 2007. There
is also some sales information at the bottom:
|
| Shocks available
as of March 2007 |
Now don't get nervous about the custom valving choice because DT can take
care of that for you. I ordered the shocks direct from DT and I handled
almost the entire transaction via e-mail. I talked to them on the phone
twice and one of those was to pay for them by credit card. I gave them a
very detailed description of my truck, what I use it for, and what I
expected. They chose the valving options based on that.
The valving they set me up with was what they considered medium for my
truck.
Front
Compression: 8 8 8 8
Rebound: 10 10 10 10
Rear
Compression: 6 6 8 8
Rebound: 10 10 10 10
I'll bet you're thinking the same thing I was when I received the
information, "What the hell does that mean?" Well I sent a reply
asking that very question, albeit a little bit less vulgar. This is the
explanation I received:
2.0 monotube valving stacks are made up of 4 discs that control the
compression and rebound based on the thickness of each disc stacked on top
of each other. These discs flex upon the entry of oil through the piston
port. The ports in the pistons have 3 rebound ports and 6 compression
ports.
Below you will find the basic valve stacks and the dampening forces
produced using the stacks listed for both compression and rebound. The
valving that is installed in your new shock is the base line or
"medium" valving for that type of vehicle. Valving or dampening
forces are determined by personal preferences, i.e. soft, medium, firm
|
| Doetsch Tech Shock
Valving |
Other than oval track applications, valving's are very rarely #1 over
#1 "50/50 style", typically the rebound side is always greater
(thicker discs) than the compression side. Here is an example of a very
common medium valving and how it is described.
Medium valving: #2/#5, or 2 over 5, or 2/5 This means you use discs from
row #2 for compression and discs from row #5 rebound. Using these you
would have a valving of 180 lbs. of compression and 350 lbs. of rebound.
The other options I chose were rod end mounting and 15" travel.
In hindsight I would not choose rod ends again. They ended up being almost
as much of an adventure in research as the shocks themselves. They are
just like little heim joints on the ends of the shocks.
The first obstacle was the necessity for some sort of spacers in
conjunction with the rod ends. You can't just bolt them in because they
need to be able to pivot with the suspension travel. I found some spacers
through McMaster-Carr.com and they weren't cheap. You can also pay a
little more for some fancy ones from Polyperformance. Below is how they
look assembled with spacers:
|
| Assembled with
spacers |
The next problem with the rod ends became apparent once I received the
shocks. There is a big warning label specifically stating you cannot weld
on the truck with the shocks installed. The rod ends can allow electrical
current to flow through the shock and damage the internals. Now in some
conversations with guys running coil over shocks, they've been able to get
away with welding by putting the welding ground very close to the area
being welded. So if you have rod end style shocks be very careful!
My final issue with the rod ends is noise. The rear shocks enter the cargo
area of the K5 and at the time this is being written I don't have them
enclosed yet. Because they are basically rigid with no urethane isolation,
there is a constant "chatter" when going over rough terrain.
I don't know why I went with the rod ends. I guess it was a "cool
factor" decision gone horribly wrong. Buy poly bushings!
Back to my order options, let's address the choice of 15" travel.
Once I had the suspension installed, I built an RTI ramp so I could take
some measurements. I clamped a flat piece of metal to the top of the frame
rail and measured the total suspension travel at the factory shock mount.
It came out to 10". I thought pretty hard about the 13" travel
shock, but I ultimately decided on the 15" travel. It didn't cost any
more and I hope to use these shocks for a long time and I may need more
travel in the future.
I'm glad I went with the 15" travel now that I've finished the
installation. The reason is I had 5" to play with. Meaning I didn't
have to get the mounts to come out to an exact distance. This made the
bracket fabrication much easier.
Below are some pictures to illustrate the length of 15" travel
shocks:
|
|
| Shock length |
Shock length compared
to young Off-Roader |
The next step was to actually install the shocks which required
fabricating my own mounts. I had 2 goals with my mounts:
- Mount shocks as vertical as possible
- Keep the shocks as close to the wheels as possible.
I wanted to achieve those goals so that the shocks would have the
best operating advantage. And I'm sure this is how they build them
to operate.
This is what I ended up with:
|
|
|
| Front 1 |
Front 2 |
Front 3 |
 |
 |
 |
| Rear 1 |
Rear 2 |
Rear 3 |
So, how did I make them? It took a lot of drawing, math, measuring and
head scratching. I knew I had 10" of total shock travel, but you need
a little more specific information than that, primarily the difference
between up and down travels. The 10" travel broke out into 4" up
and 6" down from ride height.
Because I'd chosen the 15" travel shocks and had the extra 5", I
set the brackets so that there was 5" of up travel and the rest
remained for down travel. Plus I installed the bump stops at a height to
prevent the springs from excessively over-arching in the wrong direction
so I have plenty of room for up travel.
The other factor or measurement to consider was how far out to lean the
top of the shocks. The front driver side was the determining element on
the front brackets because of the steering shaft. I didn't think about
this when I started and the first bracket I made didn't clear the steering
shaft. In the rear I just leaned them out enough to keep the shock inside
the fender wells.
To make the brackets I used a piece of 4" square tube with 3/16"
wall. I cut the tube in half to make a C. Next, I notched the brackets and
bent them for the outward lean and then welded up the seam. I drew a
straight line from top to bottom through the seam and cut the excess off.
This made a nice smooth bracket. The final step was to add tabs for the
shocks to bolt in. Hopefully the drawing below helps explain what I did:
|
| Custom
shock bracket |
You may notice some extra bracing in the pictures above. The rear brackets
were so high off the frame I felt I needed to add a cross bar and it was
pretty simple to do it. In the front the engine would make a cross bar
very difficult, so I just settle for extra gussets and braces on the back
of the brackets.
Next I made the tabs for the axle mounting. The rears were pretty straight
forward but the fronts were a little goofy. The axle tabs landed right
next to the inner C on the axle end. I cut a piece of cardboard and used
that to trace and cut all of the tabs.
|
|
| Cardboard
template |
Front
axle shock tabs |
I did make one mistake when I welded them on in the last picture. I put
the 3 spacers in there to get the exact 1.5" spacing I needed to
install the shock and 2 spacers. It was a little too exact. I ended up
grinding some on my expensive spacers so they'd fit. On the rear tabs I
remembered to add a piece of .040" thick aluminum in there to give me
a little wiggle room.
Installing the shocks with spacers is a HUGE pain and another reason to
avoid rod ends.
Doetsch Tech recommends waxing the shafts periodically with
good car wax. This creates a protective barrier on them and helps
prevent dirt and debris from sticking to the shafts and creating
future problems. To remove mud and debris from the shafts they
recommend using WD40 (or similar product) to wipe it down and
rinse with water.
So, how do I like them? They work awesome! I feel no difference with
street performance compared to my old standard lift spring suspension with
no swaybar. I actually feel less body lean on the curves now with 52"
springs in front and 56" springs in the rear.
On the trail is where they really shine. The slow crawling stuff is not
much different, but now I can fly down the "smooth" sections of
the trail. Rough bumpy access roads are not nearly so horrible anymore.
The best way I can explain it is that the softer springs take the force
out of the initial impact and the shocks eliminate the rebound lurch in
the opposite direction. I'm no longer getting jarred back and forth over
the trail.
A buddy rode with me and immediately noticed the difference. My wife
confided that she initially thought the shocks were a bit extravagent but
after riding in and driving the General she feels they were worth the
money! Now there's an endorsement you can't beat!
|
| Testing
on RTI ramp |
|
