Front suspension overhaul

Brian Diehl · February 08, 2009, 05:30:47 PM

I'm doing a reconditioning of my 96A3 front suspension. I'm replacing the following parts:
- Air bags
- Radius rod bushings
- Air brake diaphrams
- Air lines to brake cans (the rubber part)
- over pressure protection valve on the air system (just rebuilding if I can get it apart)
- Front leveling valve
- Suspension air supply filter (type E)
- shock absorbers

I have the suspension almost all tore apart now. I have the two air bags on the passenger side left to remove. I only had one HARD nut to break loose on the radius rods. Everything else has come apart very easily with just hand tools.

Now comes the question: Is there any trick to getting the old radius rod bushings out of the radius rods? I'm planning to just use my sawsall and cut them in half in order to pop them out. Any other ideas? I remember struggling with removing them from the radius rods on the rear axle when I did them a number of years back.

Thanks in advance guys!

johns4104 · February 08, 2009, 06:53:19 PM

Brian,
I just sprayed mine with pb blaster and they pushed out by hand.
I had the pb blaster out while getting bolts loose.
It worked great on my 4104, front and back

John

johns4104s · February 08, 2009, 07:14:30 PM

Yes I used a good penetrating oil. While your in there have you checked the king pins? I changed mine out on the 4104. not to bad a job saved a bunch,got the parts and advice from Luke.Changed the bags front and rear, bearings front and rear,all bearings,all brake shoes,shocks Total cost $2000 ( not including king pins).

John

Airbag · February 08, 2009, 07:15:42 PM

Brian

Howsa about some pictures? My radius rod bushings could use some new ones, I have a bunch on the shelf, it's getting the nerve to tackle it. The manual shows a very fancy tool for installation, I wonder if there is an alternative?

Brian Diehl · February 08, 2009, 07:51:54 PM

Thanks for the PB penetrating oil idea. I have some of that on hand and will give it a try.

Airbag, I'll try and get some pictures in the next couple of days. Really, the job is easy once the radius rod bushing bolts are loose. I purchased the polyurethane two piece bushings from Internation Bus Parts about 4 years back. I put them on the drive axle and have had no problems with them. The two part bushings really are easy since you don't need the special tool to put them in like you do with the one piece rubber bushings. I've heard reports some people think the polyurethane is too harsh, but I've had no problems with mine.

Good luck on your bushing replacement project!

My king pins? Well, the driver's side was just replaced about 3 years ago by C&J bus. The passenger side is in great condition. So, I think I good there! Thanks for the idea though.

Airbag · February 08, 2009, 08:04:18 PM

Quote from: Brian Diehl on February 08, 2009, 07:51:54 PM
Thanks for the PB penetrating oil idea. I have some of that on hand and will give it a try.

Airbag, I'll try and get some pictures in the next couple of days. Really, the job is easy once the radius rod bushing bolts are loose. I purchased the polyurethane two piece bushings from Internation Bus Parts about 4 years back. I put them on the drive axle and have had no problems with them. The two part bushings really are easy since you don't need the special tool to put them in like you do with the one piece rubber bushings. I've heard reports some people think the polyurethane is too harsh, but I've had no problems with mine.

Good luck on your bushing replacement project!

My king pins? Well, the driver's side was just replaced about 3 years ago by C&J bus. The passenger side is in great condition. So, I think I good there! Thanks for the idea though.

I did not know about the urethane replacements, that's a great alternative. I am the original cheap screw so I will probably fab the tool or hunt for one used. I will look forward to your pictures that's a real meat and potatoes job.

JohnEd · February 08, 2009, 08:16:33 PM

Brian,

In the auto world, the urethane bushings were a bad idea. Only the hard core young racers installed those. It is true that they give a much harsher ride. That isn't the major drawback, though. The frame stuff that the bushing attaches to wasn't designed for this and the mounting points crack after time. At 60 mph down the freeway in rush hour, there is precious little in the way of major front end components that you can do without even briefly. I think control arms are on that list. I could tell that those things were breaking my little Z car and I removed them even before I heard about the frame mounting bracket failures.

I am sure the MCI is tougher that a Datsun but the theory holds.The way I have seen them do it is to heat the bushing/rod up with a torch till the rubber falls out....on fire of course. They then use the cutting torch to remove the bushing shell without damaging the rod. Waiting for the rod to cool took the longest.

HTH,

john

belfert · February 09, 2009, 06:32:46 AM

Brian, you must be a lot tougher than I am. I couldn't imagine doing heavy work on my bus in the winter even though it has been in the 30s the past few days.

The only thing I have done on my bus since October is to make sure the batteries are charged. Well I have also started the generator a time or two to exercise it.

Brian Diehl · February 09, 2009, 09:45:35 AM

Thanks for the info John. IBP has been selling these for years. I'm pretty confident with the resiliency of the suspension on my bus. I'm going to continue with the Polyurethane bushings.

JackConrad · February 09, 2009, 10:41:46 AM

Brian,
We have had the IBP polyurethane busings in our bus for about 8 years and 40,000 miles, no problems so far. We may feel road noise a tad more, but there is also a smidgeon less play in them. Overall, we are very pleased with them. Jack

JohnEd · February 10, 2009, 03:19:22 PM

Brian,

With Jack's testimonial and your confidence I would use them myself, at this point. They were a popular upgrade in cars because they made the steering more precise and responsive. Harsh ride and frame stress excluded, they were a serious plus. Most of the bus steering problems are associated with excess play and wander so anything you can do to reduce play is a serious move in the right direction. Thanks for the info.

John

Brian Diehl · February 10, 2009, 05:01:18 PM

Thanks Jack and John.

I am doing this now because I've been having problems with a pull to the passenger side getting worse and worse over time. I'm hoping this will get rid of the pull altogether. If not, I'll be bringing it to truck a-line in Blaine and see if they can help me get it back to neutral handling.

Jack, I thought I heard some time in the past that IBP changed their recommendations for putting grease on only the one side of the bushing to putting it on both sides of the bushing. Do you know or remember anything about this?

Brian Diehl · February 10, 2009, 05:37:45 PM

Just went out and used the PB blaster technique to remove the bushings. I actually just used my WD-40. I am amazed at how easily they came out of the rods. NICE! Sure beats the struggling I did over the rear bushings. I don't know why I didn't think to use WD-40 then.

Anyway, I also reread the instructions and it pointed out the drive axle should only have grease on the ID of the bushing. However, the front axle needs grease on both the ID and OD of the bushing and on the machined metal surfaces. So, that is what I'll do unless others have good reason to believe I shouldn't.

NJT5047 · February 10, 2009, 06:58:53 PM

Urethane bushings are used on most MCIs. Mine has all urethane. Howeve, I have no idea whether the ride quality is compromised?
Brian, I know you have the bushings out...but I've read somewhere that if the radius rods have wear marks or are knicked, that they should be tossed? Anyone?
Did you replace your kingpins? I don't have any obvious kingpin looseness, but my bus doesn't exactly drive like a slot car. Always thought it could be improved...if I throw enough bucks at it.
Shocks, airbags, draglink, and bushings are all new or only a few years old. Kingpins and steering box are all that's left. I'd like to improve the steering. I got to pay attention or it'll move around in the road quite a bit. It's a sorta on-the-wheel-experience. Not too bad on interstates. But the backroads are tedious. I spend a lot of time on little roads doing bluegrass festivals.
Like Airbag says, pictures would be appreciated. Also like to know if the bushings improve your handling? Have you replaced your steering box?
One last question? What repair made the most improvement in your steering quality?
Thanks, JR

Brian Diehl · February 14, 2009, 05:33:59 PM

Well, today was a very productive day.

I have all the radius rods back on the bus. I had to jack the axle around in order to get the rods all lined up correctly again. So, I think I'm on the right track to getting the alignment issue solved. I forgot to put the axle at the correct ride height before tightening down the inside radius rods. So, when I remember to put the axle at the correct ride height I had to loosen and then re-tighten the bolts. At least I remembered before having them ALL tightened down!

I got the rebuilt pressure relief valve on and the front leveling valve on as well.

I was able to remove the last of the air bags and only need to cut off two nuts in total! I'm really happy with how easily they all came apart. I have one new air bag back on and ready to go.

I got the brake diaphrams replaced as well. Boy, the passenger side one hanging together by a thread (or two!) only. The brake lines were not much better either. Those will be replaced before it all goes back together.

I'm hoping to have time to get another bag or two on tomorrow afternoon. Hopefully one more weekend of work and I'll have it on the road again!