Comments About the Cepek Shocks
Updated December 25, 2008
How Would I know if I Need Shocks?
This is hard to notice because the shocks deteriorate over time and the problem slowly worsens. It just doesn't happen all at once unless you out and out break one. Years ago my vacuum pump went bad. As you know the vacuum runs the turbo wastegate. Over time I didn't even notice I wasn't getting boost. Now I have a turbo boost gauge but things went bad so slowly I didn't notice what I was missing till I got it all back at once.
Because our trucks are so heavy and the springs are so heavy duty you usually can't just bounce a corner of the truck and see if the truck continues to bounce up and down like you can with a car. One way to test them is to drive into a dip at about 3 to 5 mph. When you come up and out of the dip the truck will shoot up, come down and compress a bit and should rest level. If your shocks are weak the truck will shoot way up high, come down fast then rise up a second time and depending on how bad the shocks are it could just bounce. The spring is what takes the energy from the hit. The shock is meant to damp the springs (keep the spring from 'twanging').
The other way to know if your shocks are worn is if your truck sways in the corners. This is another one of those 'I don't remember how it's suppose to be' things. In fact I'll bet that most of the owners never experienced how well their truck handled when it was new because they bought their trucks used. If you're going around a corner and the truck feels 'sloppy' and sways some it's a shock thing. All I can say is that if you ever felt like you could lose it getting off on a curved highway exit ramp then these shocks will go a long way to alleviate that fear.
What People are Saying about the Shocks
I'm running a 98 wagon with gsa's at 37psi cold. When I first installed them I didn't have the electronic Remote control (ERC) hooked up yet because I couldn't decide where I wanted to put the pump and display. I drove around with the shocks for about 2 weeks at their softest settings. The ride was soft and real smooth over bumps but a bit too mushy for my taste. The truck did sway in the curves, but not as much as my worn out AMG shocks. When I finally installed the erc and started playing around I found myself driving with the fronts at 4 or 5 and the rears one step lower. I was getting spoiled because whenever I would end up on a bumpy pot holed road I would lower the settings to 0 on the bumps and stiffen up the shocks when I got back to normal pavement.
Off the road is very different. I was running 15psi in my tires. I thought that the softest shock settings would be the best. What I found is when I was moving slowly through rough areas where the truck was constantly going through dips, over rocks and down into washes my front was heaving right, left and up and down. As I began to firm up the shocks I noticed that the truck started to settle down and wasn't being thrown around as much anymore. I was running as high as 8-7 on some of the stuff in Moab.
I thought I'd give the list my opinion of the Cepek adjustable shocks we installed last week on my 2000 wagon. First I'd like to thank Chuck Kopelson for selling the shocks at a great price and maintaining a website that made the install much easier ( I read pictures better than words) and Tom Cepek for all his trouble shooting help, answering the phone well after normal business hours and immediately caking care of a small problem that we had. It is very refreshing to deal with gentlemen who really care about what they make and/or sell. Both want to make certain that you have the knowledge of the system and how to get all the benefits from it. I had just over 40,000 miles on the set of stock shocks that we replaced, the immediate difference without playing too much with the 10 different settings that the control panel can be set for is amazing. With the shocks set at 5 in the front and 4 in the rear the wagon feels very tight and I no longer experience the body roll that I had when cornering with the old shocks. I've also noticed that most of the rocking is gone when braking on the steeper hills of San Francisco. My wife actually made mention that the ride is much smoother when we went out to dinner last night, I had the shocks aired down to 3 in the front and 2 in the back. I can't wait to go off road next weekend when I head up to the country to see what these shocks can do on the old logging roads in the Six Rivers Nat'l Forest and the gravel bars of the Klamath River. Gary Collings 2000 wagon 3/21/2004
A couple weeks ago I purchased a set of the Cepek Remote control shocks from Chuck Kopelson. The installation took a couple of days, mostly cause I was the only one tackling the task the first day. Anyway once installed, as with all newly installed toys needed to do a road test. Conferred with my wife, packed a carry-on bag and hit the road. Presently we started from Tennessee heading to see my son and family in Little Rock, Arkansas. As Chuck had indicated the first day had a bit of a leak, but by the afternoon the air was holding fine. During the first day had fun playing with adjusting the pressure from a soft setting of 1 to very hard 9. I run a '95 XLC2, an extended cab 2-door with a camper top. I found that in Tennessee a setting of 5 in front and 3 in back was good on the interstate until I got to Arkansas where I had to back down to 4 and 2 - the roads were a lot rougher. In between times the various settings provided different results from loping (1) to teeth-jarring (8). Visited my kids - impressed their neighbors with the Hummer, a real H1- not H2, which always earns points with the son.
I did the install on my new shocks yesterday. I went to a buddy's shop and we were able to install all four in about an hour and a half. Thanks to Chuck and his website for detailed instructions. Most of the bolts came out very easy, however we did have to heat a few of them up. I am very happy with the new shocks and have noticed a significant improvement in the handling and and ride of the truck.
Mark Weber May 8, 2003 I can’t believe the difference they make, and they are so simple to use compared to other systems I have worked with that adjusting them every time the pavement changes seems like it will be a habit.
Pat Mahan November 12, 2003 I just installed the shocks on my friend's 12,500 heavy Hummer. Now granted I do not drive the truck very often but when I drove it before it would scare me since it wondered around a lot. If you had to corner very hard the body roll was actually scary. When I test drove after doing the shocks, I pumped them all the way up and the truck felt like mine does when the shocks are set around 3 or 4. I really like the way they increased the performance on my truck and I think they made an even bigger improvement in the heavy truck.
There has been some commentary written about our beast's rough riding and adjustable shocks. I mounted a set of these shocks on my '95 XLC2 (Hummer extended 2 dr.) last October. It took a good day and then some to do the job myself with the help of a cousin and a couple six-packs of beer. Yeah a bit pricey, but I've spent money on many a' foolish doodads with a lot less results.
First of all, it is hard to believe how much road feedback shock absorbers pass back to the driver and passenger. With these shocks turned up to a high setting, every small expansion joint even on the interstate is felt - let's not even mention what it is like on a dirt road. On the soft setting of 1 or 2 you seem to float down the interstate and on the rough stuff much of the jarring disappears. Besides what fun to raise and lower the shock setting on the run, add to that continual tinkering with the CTIS - and you almost get an E ticket ride. I might mention that if you have a co-pilot along expect a reasonable amount of lecturing on keeping your eyes on the road.
After 4,000 miles of driving around 6 states and Canada, was it worth it? Maybe not from a pure benefit/cost ratio, but definitely big points when bellied up to the bar and the BS is waist-deep on who has what on their rig. You decide. Meanwhile, I can choose 9 programmed settings that automatically control front and rear shock settings, so there.
Myk
'95 XLC2
I rode them quite hard over some trails, with what could be described as Whoop-de-dos, and the only thing I can say is that I slowed down due to common sense before the suspension started to bottom out. We were almost airborne in some cases and the shocks did great. I was able to maintain a much higher speed in these conditions with the Cepek's than the stock shocks. I have run the same area for years, so the results are quite real.
On rough roads the truck has more control and stability, as well as the ability to run at much higher speeds comfortably. Stock shocks would get to a point of such incredible vibration on washboard roads that I had to slow down for fear of the truck coming apart. This was greatly reduced with the Cepek's.
On regular roads I was able to stiffen the ride so much that I felt I could corner like a sports car with almost zero body roll or instability. I continually left them on a setting of 7 as I liked the stiffer ride, but down to a 2 or 3 off road.
Of course everyone will have different experiences, but I can't say enough good things about the cost-to-benefit of the Cepek system. It's truly one of the best things you can do to your truck for the ride.
Common Questions Answered:
The shocks are basically the same length as the factory shock, with the exception that there are no built in hydraulic stops in the adjustable shocks. The factory shock during fairly fast internal piston speeds limit the stock shock travel to approximately 2 inches of travel, but in the adjustable you get full travel at any internal piston speed, which would provide twice the amount of usable shock travel, or a bit over 4".
Shock is Compressed.= 12.388" Extended. = 16.452" Travel = 4.064"
These measurements are pretty much cast in stone because of the suspension geometry of the Hummer. The A arm can only travel a given distance before the half shaft CV joint will start to bind. The shock actually limits the A arm travel to prevent this. Unless you were to modify the suspension you have to use a shock with the stock compressed and extended lengths.
That being said my shock provides more usable travel, since it's not restricted by hydraulic stops. The factory shock is setup to highly damp the piston at the beginning and end of it's travel to prevent the shock from slamming into it's end stops and destroying itself. Our shock uses an external bumper for compression which keeps the shock from bottoming out, and allows for a smooth transition for the final 1" of compression. Extended length is limited by the shock topping out, which rarely happens because of the damping properties of the shock. Sometimes if you are rock crawling at slow speeds you can get to the full extended travel of the shock. Our massive striker head prevents topping the shock causing no negative effect on the shock whatsoever.
We don't provide valving specs, since it will make little if any sense to the average user. If you are designing your own shocks where you have control over the internal construction, piston diameter, fluid viscosity etc valving specs would make sense. Because our shocks are designed for the Hummer and there are no options, valving specs in this case are a moot point. Added to this is the fact that our shocks are adjustable so the valving actually has 10 steps.
The Rod Hall shocks are excellent, but may not be what you need unless you are racing your truck, and as far as reservoirs are concerned, not necessary for the average user, since the shock never gets hot enough to require the extra fluid and cooling the reservoir provides. If you are going to drive your truck at 60 mph off road all day then I'd be looking at Hall shocks. Our shocks have a lifetime guarantee.
There is a huge difference between my shocks and the other types in that, the amount of damping of my shock can be changed on the fly, by the use of the ERC, (Electronic Remote Control) unit, from the cab, which allows you to have anywhere from a soft stock type ride to something that will ride very stiff, and reduce body roll to just about Zero. Nobody else has this for the Hummer.
