Community Forums

Shutterbug57 · 10-11-2020, 07:23 AM

We have a 2011 Tiffin Phaeton 36QSH (32,000 GVWR). It has 83K miles on the clock. How many miles are other folks with similar rigs getting out of their shocks. How do you know when it is tone to replace them?

Gary RVRoamer · 10-11-2020, 11:45 AM

It's probably time, but shock service life varies widely depending on the terrain you travel on, exposure to road chemicals, etc.

There is no good way to determine if a heavy duty shock like yours is still functional or not. You can't use any of the shade tree mechanic tricks on a rig that size. If there are no signs of leaking hydraulic fluid and the coach doesn't porpoise over major bumps, your shocks are still OK, but at 10 years and 83k miles you might consider preventive maintenance. The other approach is to simply wait until a problem shows up, and that too is a valid philosophy for big rig shocks.

jcussen · 10-11-2020, 01:10 PM

I went 16 years and 100000 miles, did not realize they were bad until I put on Koni FSD's, big improvement

Shutterbug57 · 10-11-2020, 07:45 PM

Thanks guys. We bought the rig this year and have put on a little over 3K miles. We are taking it in for its annual in a couple of weeks. I don’t really have a benchmark on what they should handle like, but I might have them replaced. I am zeroing out the maintenance on up the engine, tranny and generator and doing a cassis lube and overall checkup. Zeroing out the shocks may be a good idea.

FIRE UP · 10-11-2020, 07:57 PM

Quote:

Originally Posted by jcussen

I went 16 years and 100000 miles, did not realize they were bad until I put on Koni FSD's, big improvement

Yeah,
Our coach, an '04 Itasca Horizon 36GD with the CAT C-7 330HP, is also 16 years old and, at present, has 94K miles on the clock. It still has the original shocks. While I don't hot rod that coach (not sure what diesel pilot would) I'm not all that sure my shocks are still working as designed. I'm always one of those skeptical types that, I'd hate to spend a whole bunch of dollars for some FSD's or any other good quality shock, only to find out, ZERO improvement was reached. I don't get a bunch of porpoising, no ill fated wandering, no side-to-side leaning (other than when I hit a drive way at an angle, then it goes nuts). So, at present, I'm not sure mine are causing any issues.
Scott

Shutterbug57 · 10-11-2020, 08:07 PM

Quote:

Originally Posted by FIRE UP

I don't get a bunch of porpoising, no ill fated wandering, no side-to-side leaning

I don’t get porpoising, but the body roll is insane. I am talking taking turns onto a particular on ramp at 10-15 mph or you feel like you are going to flip the rig. This same turn is perfectly comfortable in our Expedition Max, which is not exactly a sports car, at 40 mph.

Ray,IN · 10-11-2020, 08:08 PM

Todays shocks are gas-charged in addition to having oil in them. They can go bad from age as well as road work.
If your coach rebounds( some call it porpoising) more than 2X after traversing a road sudden dip or hump, the shocks are bad.
My shocks were bad even though the chassis only had 23,000 miles on the odometer @ 13 yrs old. New Bilsteins made a world of difference.

Shutterbug57 · 10-11-2020, 08:11 PM

Ok, I am hearing Bilsteins and Koni’s here. Both brands generally have great reputations. For a 16 ton Solid front axel rig, what is the best choice and why?

jcussen · 10-11-2020, 09:58 PM

Quote:

Originally Posted by Shutterbug57

Ok, I am hearing Bilsteins and Koni’s here. Both brands generally have great reputations. For a 16 ton Solid front axel rig, what is the best choice and why?

General consensus for the Foretravel bunch, is that the Koni FSD's are the best improvement, no matter what the weight of the coach is. I know mine made a major improvement. FSD's damp in both directions, think that is why they are better.

Sonic · 10-11-2020, 11:20 PM

All shocks damp in both directions (compression and rebound). That’s what a shock does. The amount of damping and balance between compression and rebound damping determines the ride characteristics. Koni FSD technology dynamically adjusts damping based on the frequency of the vibration.

FIRE UP · 10-11-2020, 11:51 PM

Quote:

Originally Posted by Shutterbug57

Ok, I am hearing Bilsteins and Koni’s here. Both brands generally have great reputations. For a 16 ton Solid front axel rig, what is the best choice and why?

Well,
This is a preference thing for sure. But, I've had Bilsteins on motorhomes before and it rode like a rock. I'm not the only one that feels that way about Bilsteins. But, to each his own for sure. If and when I decide my rig is due, which could be tomorrow or, next year, it won't be Bilsteins. It might even be SACH's (I think that's what came on it and that's the appropriate name). I don't even know if they're still made or not. I might spring for some Koni's but, not sure. We'll see at that time.

Quote:

Originally Posted by Sonic

All shocks damp in both directions (compression and rebound). That’s what a shock does. The amount of damping and balance between compression and rebound damping determines the ride characteristics. Koni FSD technology dynamically adjusts damping based on the frequency of the vibration.

"All shocks damp in both directions". Well, there's some validity to that statement but, not entirely true. There are shocks that have almost ZERO compression dampening. They're made that way because, they let the vehicles springs take care of that action where as, on the opposite action, they do most of their dampening. This is all in an attempt to keep the tire on the road and not let it bounce and loose traction.

Then, there's racing shocks. Those are all in a class of their own. Those are completely adjustable in all facets of travel. But, if you had a shock that is 50/50 in dampening, both in compression and rebound, that is gonna be one seriously rough riding vehicle because, you're not letting the tire and suspension suck up larger bumps due to the shock attempting to stop the upwards travel. I'm certainly no expert on shocks. Just messed with a few in my life.
Scott

dcfleetwood · 10-12-2020, 06:45 AM

Like Fire up said it's a preference thing. I was debating on what to do with our rig as we were experiencing back and forth rocking as we went in and out of driveways and I would notice a lean while turning. I finally decided to replace the shocks which were Sachs on or rig which is standard. I went between Billsteins and Konis and chose Billsteins which IMO was the way to go. I only replaced the fronts as I'm on the road and OMG what a difference! I have now ordered the rears so I can have new all the way around. Also, I couldn't find the Koni's in stock anywhere and they were way more expensive so that helped to make the decision. I think you can't go wrong with either shock.

jcussen · 10-12-2020, 09:47 AM

Agree with Fire up, have changed two coaches from Bilsteins to Koni FSD's. The Bilsteins had almost no compression damping, you could compress them with little effort. Believe the airbags take care of that.
FSD's were equally hard to compress or expand.

paul65k · 10-12-2020, 11:36 AM

When we bought our coach a couple of years ago it was 17 years old with 88K miles and the PO had actually changed them one peviously.

I decided to change the front shocks which were easier to access and OH MY what a difference. The leaning and side to side rocking when going into a driveway is very much controlled now and the porpoising that we noticed slightly was all but eliminated.

I plan to do the rears this year when we do pull the rear wheels to service the brakes.

We went with the Koni 99's in the front and plan to use the appropriate Konis in the rear as well.