365 Front Tire Upgrade/Koni shocks/Airbags

I have just left the Jacksonville Prevost service center this morning for San Antonio Fl where I left my coach at the Marathon shop for some repairs.

I am now in the Tampa Airport waiting on my flight so i thought I would report on a few upgrades that I had done at Prevost.

1. I have a 1999 Marathon/1998 Prevost XL 45 shell. I have a slideout that is rather heavy and of course the Marathon genset in the C/S bay 1. I was not happy with the way my front end felt and decided to make some upgrades. Here is what I ended up with.

1. Michelin 365 R70/22.5 upgrade kit on the front, along with Koni shocks and new airbags and new A-ARMS on the top front, a new A-arm that has a grease fitting. My A-arms were badly worn, no good reason for the worn a-arms.

2. Changed Drive and tag tires to 315 80/22.5 XZA 2 Energy plus koni's and new bags. had all Koni's placed on medium.

3. had a 3 axle alignment. I was out of align by a little.

4. had the ride height set at factory specs, was out by a little.

5. Met with Prevost regional rep and tried to get them to find me some Studs for my tags that will allow for the 365 tire upgrade on the Tags as well. I have the Rockwell Disc brakes on the tags and there are no studs available for this retro fit. they are looking into it with rockwell.

I drove out of jacksonville this morning at 6:30 am and drove back roads mostly for about 100 miles at 60ish and I-75 for another 75 miles at about 75mph. The ride and handling are markedly different. Greatly improved in the steer, the side to side, almost no wind buffeting from trucks, none when following them, an amazing improvement overall, and I would recommend them to anyone who wants to change the way their coach runs over the road. It turned my coach from a 2 hands on the wheel to two fingers on the wheel operation.

Really nice people at Jacksonville Prevost, learned a lot about the coach and John the Branch Manager is a great guy.

Regards,

Bruce

Bruce, that's good news. What I wish you had been able to report was the relative benefits of each improvement. For example we know a bad alignment can make steering a real task. Even a little correction may have been felt.

Good shocks as others have reported in the past make a big difference and I am sure your new size tires also contribute. Do you have any opinion as to how much the different things you did actually made and can you break down the cost of each?

If you don't mind me asking, can you give me a ballpark figure for the 365 upgrade for the front? My coach is front heavy, and if I can't get the weight down, I'm considering getting the 365's up front to allow a lower pressure.

Ray

Bruce,I agree with how much the 365 tires change how the coach drives.It is unfortunate that Prevost only used them on 2004 and later shells which have the EGR motors(POOR FUEL MILEAGE) I understand that the modification with wheel,tire,and studs change is quite expensive,but if a coach is on the edge weight wise at least the tire and wheel meet the weight requirement.I have seen several pre 04 coaches with the 365 tires on the steers but I don't recall seeing any on the tags

Quote:

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Originally Posted by Jon Wehrenberg

Bruce, that's good news. What I wish you had been able to report was the relative benefits of each improvement. For example we know a bad alignment can make steering a real task. Even a little correction may have been felt.

Good shocks as others have reported in the past make a big difference and I am sure your new size tires also contribute. Do you have any opinion as to how much the different things you did actually made and can you break down the cost of each?

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Good morning Jon,

I finally weighed my front end yesterday. It is 16,080 lbs. I thought you might want to have this # as part of this report.

Anyway I agree it would have been nice to do each one of these items separately, but I felt that the sum total of each of these upgrades would provide the very best result that one could expect to achieve from this vintage of coach. My hope was, and I do believe it has been proven to be the case, was to make an older independent front suspension Prevost perform more closely to the fully independent Prevosts with the newer 356 setups etc. I truly feel this has been achieved, and I am a nut about this stuff. My final wish is that Prevost will get back and tell me they have a solution for the Tag axle (Rockwell Disc Brake Stud issue) The studs need to be about 3/4 of an inch longer to span the distance on the disc. This should not be difficult to achieve and the end result will provide both a wider profile (13 inches) tire, a higher profile and a tire set that can rotate to the steers when needed like the newer coaches.

Here are the costs. I do not have my paperwork, it is in the coach but here are the round numbers for each upgrade and service.


1. Michelin 365 R70/22.5 upgrade kit on the front. This includes tires, wheels, studs, all parts necessary to change over including labor at Prevost $3750. per axle. Tires alone mounted are about $1650 of that total, this includes Alcoa wheels, really nice looking with the larger profile.

2. Koni shocks and new airbags. This includes all shocks, bags, coach ride leveling, testing the air system. I had the Koni's set at Medium ride stiffness. About $4000.


Steer A-ARMS on the top front, (1998 XL45 shell) The new A-arms have a grease fitting in the center top connection, the old ones were sealed units. My A-arms were badly worn, where the arms connect at either end at the top right and left, the rubber was torn up badly. Total cost $2000. Most Prevost shops will need to order these in.

2. Changed Drive and tag tires to 315 80/22.5 XZA 2 Energy plus koni's and new bags. These are the tires that are used on the newer units. $4800

3. had a 3 axle alignment. I was out of align by a little. $695 It was out by a very small amount.

4. had the ride height set at factory specs, was out by a fraction in the front, 1/4 inch. This was part of the bags and shocks replacement costs.

All prices included sales taxes and did not include any trade in amounts for old wheels and tires.

Some important notes, the ride height was not out by much, and the alignment was not out much either. My assumption from this is that the upgrades including bags, shocks, front wheels and tires and the A-Arm make the difference. My bags and shocks had only 35,000 miles on them over 10 years, doesn't sound like much, but time is the killer, sitting, my other thought is the 365 upgrade makes for a much better front end profile stance , and the side to side control, handling is much improved, and I have experienced no slow speed turning problems at all, I actually felt like it turned more easily, more smoothly if that is possible.

Thats my final thoughts, will keep you abreast of the Tag axle 365 upgrades if they become available. I think that JON should have the studs machined to Prevost specs and sell them to each of us who wants to upgrade, how about it Jon.

Quote:

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Originally Posted by 0533

Good morning Jon,

I finally weighed my front end yesterday. It is 16,080 lbs. I thought you might want to have this # as part of this report.

Anyway I agree it would have been nice to do each one of these items separately, but I felt that the sum total of each of these upgrades would provide the very best result that one could expect to achieve from this vintage of coach. My hope was, and I do believe it has been proven to be the case, was to make an older independent front suspension Prevost perform more closely to the fully independent Prevosts with the newer 356 setups etc. I truly feel this has been achieved, and I am a nut about this stuff. My final wish is that Prevost will get back and tell me they have a solution for the Tag axle (Rockwell Disc Brake Stud issue) The studs need to be about 3/4 of an inch longer to span the distance on the disc. This should not be difficult to achieve and the end result will provide both a wider profile (13 inches) tire, a higher profile and a tire set that can rotate to the steers when needed like the newer coaches.

Here are the costs. I do not have my paperwork, it is in the coach but here are the round numbers for each upgrade and service.


1. Michelin 365 R70/22.5 upgrade kit on the front. This includes tires, wheels, studs, all parts necessary to change over including labor at Prevost $3750. per axle. Tires alone mounted are about $1650 of that total, this includes Alcoa wheels, really nice looking with the larger profile.

2. Koni shocks and new airbags. This includes all shocks, bags, coach ride leveling, testing the air system. I had the Koni's set at Medium ride stiffness. About $4000.


Steer A-ARMS on the top front, (1998 XL45 shell) The new A-arms have a grease fitting in the center top connection, the old ones were sealed units. My A-arms were badly worn, where the arms connect at either end at the top right and left, the rubber was torn up badly. Total cost $2000. Most Prevost shops will need to order these in.

2. Changed Drive and tag tires to 315 80/22.5 XZA 2 Energy plus koni's and new bags. These are the tires that are used on the newer units. $4800

3. had a 3 axle alignment. I was out of align by a little. $695 It was out by a very small amount.

4. had the ride height set at factory specs, was out by a fraction in the front, 1/4 inch. This was part of the bags and shocks replacement costs.

All prices included sales taxes and did not include any trade in amounts for old wheels and tires.

Some important notes, the ride height was not out by much, and the alignment was not out much either. My assumption from this is that the upgrades including bags, shocks, front wheels and tires and the A-Arm make the difference. My bags and shocks had only 35,000 miles on them over 10 years, doesn't sound like much, but time is the killer, sitting, my other thought is the 365 upgrade makes for a much better front end profile stance , and the side to side control, handling is much improved, and I have experienced no slow speed turning problems at all, I actually felt like it turned more easily, more smoothly if that is possible.

Thats my final thoughts, will keep you abreast of the Tag axle 365 upgrades if they become available. I think that JON should have the studs machined to Prevost specs and sell them to each of us who wants to upgrade, how about it Jon.

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Good morning all,

Here is the post that I made yesterday for those of you who wanted a breakdown of the cost for each item.