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Koni shock absorbers

What is the service life of our Koni shock absorbers? We have 122,000 miles on our '99 U320 36' (built date 6 '98) and they seem to have deteriorated.  No oil leaking that we can detect.
Replacing the front 4 air bags next week, did the rears last summer, and I'm thinking about replacing all 8 shocks with new Koni. The originals do not appear to be adjustable. 

Any one have a good source/price to purchase the shocks?
Dick & Sue
'99 U320, 36'
2015 F150 4x4 Supercrew
M & G with brakeaway system
Blue Ox Avail 10,000# tow bar
Grosse Ile, Mi.

Re: Koni shock absorbers

Reply #1 –
Was thinking just that. I replaced my shocks about 80k miles ago. I feel and have a bit of porpoising again.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Koni shock absorbers

Reply #2 –
Dick,
Are your shocks red?
Should be adjustable.
Take the bottom bolt out, push the shock together and feel for the detent.
Turn it in about 1 1/2 turns. That should help a lot.
You will feel quite a difference when you pull the it back down.
John Duld
1995 U320C SE 40'

Re: Koni shock absorbers

Reply #3 –
No mine are gold and not adjustable. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Koni shock absorbers

Reply #4 –
                       JOHN ;  How much air do you run in your tag tires.?    Brad Metzger
Brad Metzger
2010 Phenix 45'

Re: Koni shock absorbers

Reply #5 –
Dick,

I was in your situation 2 years ago.  I had increased porpoising.  I thought about stiffening up the red Koni's, but thought it was so much work I went ahead and had FSD's installed.  The ride has been much improved, at the same 85psi tag air pressure.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Koni shock absorbers

Reply #6 –
85psi.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Koni shock absorbers

Reply #7 –
                   The reason for the PSI question is , when we had the 2003 320 , I had to reduce tag PSI to 75  to stop the porposing  bit . Felt that might be not enough PSI for the tires , so called FOT and was told that was just fine .        Brad Metzger
Brad Metzger
2010 Phenix 45'

Re: Koni shock absorbers

Reply #8 –
Interesting.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Koni shock absorbers

Reply #9 –
Quote from: Brad Metzger –
                  The reason for the PSI question is , when we had the 2003 320 , I had to reduce tag PSI to 75  to stop the porposing  bit . Felt that might be not enough PSI for the tires , so called FOT and was told that was just fine .        Brad Metzger

Interesting point to ponder - the tag axles on our 2003 are rated at 9000 lbs capacity.  Michelin's inflation for that 9000 lb max for the 275/80R22.5 LRH XZA3 tire is 75 psi (actually, that equates to 2 x 4915 lbs or 9830 lbs; greater than the capacity of the tag axle). 

I wouldn't think there would be any benefit to inflate beyond the axle capacity (especially since FTs generally aren't even marginal on weights).
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Koni shock absorbers

Reply #10 –
We put on eight Koni FSD's many years ago and on the first drive with new shocks it was extremely obvious that we did one of the best changes for our coach as the ride was MUCH improved. Easy to see the change because we could remember how we rode before we put new FSD's on. But the old ride was soon forgotten and we did not have the ability to compare anymore. Koni FSD are great shocks and were worth it to us. We were surprised how poor our original shocks were, even though none had leaked.

Re: Koni shock absorbers

Reply #11 –
Is PSI in tag axle air bags (i.e amount of weight on tag axle which also affects weight carried by front and drive axles) or tires being discussed???
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Koni shock absorbers

Reply #12 –
At 140k miles our original Koni (adj) shocks were pretty far gone. Replaced all 6 (have ifs) and it made a huge difference. The shocks for our coach are red (adj) in the front set at medium and FSDs in the rear. Along with new tie rod and drag link ends and a great alignment at JOSAM it drives like a big SUV - pretty good for such a big rig!!
Jeff & Patricia
Rescue dog Molly
Previous Foretravel owner

Re: Koni shock absorbers

Reply #13 –
I think the Tire rep sain not to go lower than 85psi on their tires.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Koni shock absorbers

Reply #14 –
Quote from: John S –
I think the Tire rep sain not to go lower than 85psi on their tires.
I just checked charts for Michelin RV tires. Lowest pressure listed on the chart depends on the tire. Many of the recommendations for 22.5" RV tires show values down to 70 psi. Some of the charts only go down to 85 psi. I infer that the values listed in the chart indicate the lowest recommended pressure for a specific tire.

We replaced the Bilstein shock with Koni FSD about two years ago. I did not notice a dramatic difference in ride and handling. It seems to be a bit better. I generally try to run tires near minimum recommended cold pressure rather than maximum recommended pressure. I think the ride is a bit better and porpoising not quite so annoying at the lower pressures. (Your experiences and choices are likely to be different from mine. ;)  )
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Koni shock absorbers

Reply #15 –
Update, we do have the red adjustable Koni shocks and far as I know, they haven't be adjusted.
We purchased her at 85k miles and we haven't touched them.

So now the question is, with a 122k mile, how much "useful" life is left in the shocks?

My plan at this point is to have all the Koni adjusted while replacing the front air bags. If that doesn't improve the ride then we'll look into new FSD's. They run about $1400 for 8.

Dick & Sue
'99 U320, 36'
2015 F150 4x4 Supercrew
M & G with brakeaway system
Blue Ox Avail 10,000# tow bar
Grosse Ile, Mi.

Re: Koni shock absorbers

Reply #16 –
Dick,

Three things to judge useful life (actually you are checking present condition) of the shocks:

Check top and bottom bushings-- should be no play.

Look for leakage (not just dampness, but fluid leak)-- should be none.

As far as adjustment, it really depends on current setting.  If at or near softest setting, you have quite a bit of dampening increase available.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Koni shock absorbers

Reply #17 –
Question: Is the porposing a bucking like feel, front to rear, OR is it more of a tire hop ?

I had the expereince with the MCI tag bouncing the tag tires, Had no idea what was going on, so asked my MCI guru, he laughed and told me I had too little air pressure in the tag axle air bags, has set the psi at 25, laughing again, said minimum is 33-34 psi.  So I cranked it up to the 34-35psi, all was fine.

This issue could be confused as thinking a need for new shocks

With too little weight on the tag axle, the wheels will hop.  I do not have a Foretravel Tag model, so have no idea how the weight is adjusted.  Would have to be a method of setting the pressure, would look if I owned one.  ;D
 

Re: Koni shock absorbers

Reply #18 –
The porpoising I referenced is exaggerated front to back motion that made the motorcycle on the lift REALLY sway.  Cured with FSD's, which control large motion well, but I think transmit more small highway defects to the occupants.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R