Spent the last few days to replace the air bag and shock for my 91 GV U300. I know it has been posted numerous time here. I benefit tremendously from those posts about changing the air bag and shock. I just want to share my experience to maybe help others.
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Air Bag
AS9448 by CONTITECH from FintItParts (https://www.finditparts.com/products/7889630/)
About $90/EA delivered. TAKE10 should give another 10% off.
No need to discuss this model. It has been used by many many people here. Cheaper than the Firestone bag with decent quality.
I am not sure if the proper term is called Air bag or air spring. I see people using both term here. People are confused with the car air bag deployed during accident. I think most people here call it air bag.
Shock
Gabriel 89407 GasSLX Heavy Duty Adjustable Shock (https://www.amazon.com/Gabriel-89407-GasSLX-Adjustable-Absorber/dp/B004K838YI)
About $75/EA. If you are patient enough, you can buy them at $40/EA.
Not as good as the original Koni FSD shock, but it is about 1/4 of the price. And I think it is a well established brand in Trucking business.
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Tools I used
- Milwaukee Mid Torque Wrench 600ftlb
- 1 1/8 Shallow Impact socket
- 10 inch and 5 inch extension bar
- 1 inch 2 ft pipe as break bar
- G32104-0604 Air fitting just case the air fitting is damaged.
Setps
First step is safety. Block rear wheels from both side to make sure the coach will not accidentally move.
Raise the coach to maximum then put for 12 inch standard receiver tube (https://www.harborfreight.com/class-iii-12-in-x-2-in-standard-receiver-tube-69879.html) between the frame and the house. My 91 GV has the three lever manual level system. Just pull all of them backward, when the air pressure reach to 120PSI, there is enough space between the frame and the house to put in the 12inch tube without issue.
I used 4 tubes. Two before the rear wheel two after the front wheel.
After tube in place, release the valve so that coach firmly seat on the tube. This gives enough space to work on the air bag and shock.
Many post talked about replacing the air bag without removing the skirt. But to replace the shock I don't see any other way. The skirt has to be removed to gain access to the shock. It just make things so much easier. And it is pretty easy to be removed.
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Rear
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Front
As you can see, once the skirt is removed, the air bag is right in front of you.
Use 3/4 wrench or socket to remove the 3 bolts. Use 1 1/18 inch to remove the nut holding the air fitting.
Use 5/8 to remove the air hose compression fitting. Use 5/8 wrench to remove the 90 degree air fitting. I have two seized air fitting that I have to cut using a saw. So it is a good idea to have few of the fittings ready just in case.
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Once the air bag is removed, the access to shock are much easier. Using the socket and extension bar, I am able to use the Milwaukee mid torque to take them off. The mid torque is struggling to take off the 1 1/8 bolts with over 30 years of corrosion. I think his high torque big brother should handle the bolts with easy.
For this coach, I think the previous owner replaced the shock once. 6 shocks are already Gabriel 89407 GasSLX. Only 2 are original Red Koni Shock. The shocks looks like still in decent condition. Didn't see any sign of oil leak.
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(https://www.foreforums.com/MGalleryItem.php?id=4793)
(https://www.foreforums.com/MGalleryItem.php?id=4794)
(https://www.foreforums.com/MGalleryItem.php?id=4795)
It took me about two days to finish the work. Most of the time spent on fighting with the 1 1/8 bolts and nuts. The mid torque wrench is struggling so I have to use one inch pipe break bar which slows down the process. With proper tools, I think the process can be greatly improved. It is definitely doable within a day to change just all 8 air bag only.
Thanks for you reading, hope you find this helpful.
Outstanding photos and description. +++
It really helps to have a little special tool made to remove the brass air fitting at the top of the bag.
Pierce
"DSD" Scot has a whole set...worked for me
Also changed the engine air filter.
It must have been a while since it was changed last time. There was some mud wasp nest inside the air filter housing. I don't know how they get in >:( .
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Old filter is NAPA Gold 2960 (https://www.napaonline.com/en/p/FIL2960) at $150
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I replaced with WIX 46726 (https://www.amazon.com/WIX-Filters-46726-Heavy-Filter/dp/B0014BIIU8) at $70. Much cheaper.
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NAPA Gold is usually made by WIX. I use a lot of NAPA Gold secondary fuel filters and if in a hurry, buy from a local truck supplier that has NAPA product about 40% cheaper than a NAPA store. If you shop online, you can find all these filters much cheaper than at the store.
As far as air filters go, the Donaldson Blue air filter I installed last year or so was far better constructed than the WIX that partially collapsed. Did you see the photos of the comparison? Very easy to see the difference. I was lucky not to have dusted the engine.
Just like the members who drive South for paint, you never have to pay list price.
Pierce
I remember the picture you posted about both filters. Unfortunately, for this 91 GV U300, the filter on manual is Donaldson XLP 18 2099. I could not find the exact same one from Donaldson any more.
Ordered a Fleetguard Air Filter AF871M from simply filter. But after 3 weeks, the order is cancelled.
So I decide to go with WIX 46726 from Amazon. Not the best filter there, but cheap enough to replace more often. And it is Amazon prime eligible so I know I can receive the item in two days.