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H3-45 IFS Alignment
Okay, as some of you must now be aware I’m having Prevost Nashville convert my steer axel to 365s. My coach is pulling to the left, as in I have to turn the steering wheel about 15 to 20 degrees to go straight. I’ve been told aligning is irrelevant as very little is adjustable, is that the case? Secondly I know I have at least one bushing failing could that be causing it, and will it cause my new tire to ware oddly? Thanks again for the help!
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12 Replies
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Alignment is adjustable and has a profound impact on handling and tire wear. On our coaches the three axles should be aligned at once. A fraction of an inch or a degree or two out of spec changes the handling. When all is correct most coaches will drive down the highway with little input from the driver. A misaligned or bad handling coach will wear you out even on short trips.
Are your tires experiencing and unusual wear? If you run your hand across the tread do you detect any indication the tires are wearing unevenly?
Bad bushings will have an impact on steering and alignment, but unless you have something else going on A arm bushings should last a long time. It is not unusual for them to have 500,000 miles on them before they need attention. I do not know however if age is a factor on the bushings.
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I check my tires before every trip, weekly, and have not noticed any uneven wear on any tire, except for my inside drives. Though they are the oldest on the coach and I plan to put my year old 315s in place of them. The reason they are wearing oddly; I have to believe is they are becoming close to racing slicks. Haven’t tried a burn out… Yet.
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Is it just your steering wheel that’s off or do you actually have to apply pressure on the wheel to go straight? If it’s just the wheel off they can pull it and rotate it.
When we bought our bus, it pulled hard to one side and the wheel was off about 15 degrees. It was supposedly fixed and we drove it north. By the time we got north the new tire on the front was gone. Took it to our truck place and asked them to align it. The owner has an XL and knows Prevosts. He said he’d need to check it out before he simply aligned it. He found to bad bushings in the A frame. He had to mill them over size and put in new bushings. Other things were found. He then lined it up and pulled the wheel and put it on straight. It runs like a sports car now.
The bus and about 60,000 on it when we bought it. The bearings can get crushed when you hit a big pot hole or 4×4 in the road.
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My 01 Liberty had to have A Arms at 105K.
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I’m now wondering if it is not an age related issue. High mileage buses are easily reaching 450,000 plus before the A arms need bushings. But they are doing those miles in 5 or 6 years.
Tires age so it is not too unrealistic to expect bushings in A arms will do the same.
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Never, never let anyone pull the steering wheel and rotate it to correct an off-center condition. Anytime an alignment tech suggests that run as fast as you can from there.Here’s why (briefly): the gears in the steering box have a center position. When on the center position there is no play (space) between the teeth. When they go off-center there is free play between the teeth. The free play is not noticeable because there is pressure on one side of the teeth in the direction you are turning. If the gears are off-center when the vehicle is traveling in a straight line there will be ‘play’ in the wheel because the gear design.
The correct way and only acceptable way to center the steering wheel is through toe adjustment. That goes for cars and trucks too.
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Even Though you say, never never never , that doesn’t mean someone hasn’t in the past. Is there a way to tell if my steering wheel has been altered ?
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Matt
You are correct in that someone may have indexed the steering wheel. Here’s how you can tell if that’s the case. Remove the cover from the steering wheel so that the nut and shaft end are visible.
The steering shaft will have a top dead center mark on it, (if it can be installed in any way but properly). The steering wheel may or may not have a matching mark, but it’s pretty obvious when it is perfectly straight. Match the straight steering wheel with the mark on the shaft in the 12 o’oclock position. Then get the vehicle alignment done properly at a factory Prevost service facility.
When the steering wheel has been incorrectly indexed on the shaft (usually because the technician is too lazy to properly set the toe adjustment) the vehicle will not drive at its best and there will be ‘play’, felt by lose sloppy steering.
I’ve had some of the so called best tire and alignment facility owners tell me they we’re going to index my steering wheel. Needless to say, my comments to them about their suggestion we’re not sugar coated as I departed.
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This past January, while at Jeff Rowe’s in Tennessee, I mentioned to Peter Campbell that it seemed I had to “chase” the steering wheel on our 16 year old, 70000 mile, new to us Prevost. Mentioned that Jeff had put new tires on the previous may. Peter said to get a three axle, laser alignment at a Prevost facility. We were headed to Florida so I made an appointment at Prevost Jacksonville for the alignment on our way back home.
Peter (and I think Jeff too) tried explained to me why the three axle alignment was important, but until the Prevost tech had the coach up on the alignment platform with the laser things hooked up and could actually explain to me what was going on did it finally sink in what was important. It was just like “stringing” a race car. Prevost (and me with the race car) start by establishing the parallel frame rails (Prevost uses center of the chassis). Then Prevost uses the laser (me strings on jackstands) to ensure that the wheels and tires are perfectly parallel to the center line of the chassis and hence that the axles are exactly perpendicular to the center line of the chassis (me the frame rails). If they aren’t, then shims are put in or taken out until axles are perpendicular/tires and wheels are parallel to that centerline.
In our case the tech first checked for any “play” in the front end and found one or more tie rod ends to be loose, so those had to be replaced first. The Prevost tech told me that is not uncommon, infact they had a whole set of them laying out before the coach was pulled into the bay and he was able to show me the play.
In our case, the drive axle was way out of alignment. The passenger side wheel tire was ahead of the driver side which would “push” the coach to one side, for which I tried to correct for, over correct, relax, and hence I was spending all my time “chasing” the coach with the steering wheel. The Prevost tech told me he has aligned many brand new coaches and while the new ones are “close”, they aren’t perfect. I asked if mine was “close” like a new one could be and he said “not by a long shot”, he took a stack of shims out of one side of the drive axle to get it perfectly alignment. I surmised that someone had “aligned” the coach at some point along the way. We never got service records with the coach so we didn’t know.
We also had new shocks put on all around; Koni’s on the front and regular Prevost (Monroe?) in back. I don’t think the shocks should impact steering on the straight and level.
I did notice immediately upon driving the coach on the road that I wasn’t chasing the steering wheel from one side of the road to the other, so the alignment must have solved that problem.
The Prevost tech told me that if you don’t get a quality laser alignment done by someone who knows what they are doing, the odds are good it won’t be a good alignment and you end up with what we had … badly out of alignment. Apparently if the alignment is done on a Hunter machine (not sure what that is although I’ve heard of Hunter machines) it tough to get it “right and precise”. The tech said if the alignment is done “by a truck shop that doesn’t know how to do a Prevost coach right”, you could end up with a bad alignment. I presume there are probably some truck shops with techs who know how do it right.
The tech did set the toe; with just a touch that would help the coach running in the far right lane with the pitch of the road to the right (i.e. a touch to the left to get it even). As I recall they started in back and worked to the front.
I wish I had the above great explanation by Grizz of the positioning and indexing of the steering wheel. That makes lots of sense to me. I would have asked the Prevost tech about that.
I probably shouldn’t even suggest this, but given the size of the tires and wheel base of the coach and not knowing if the axles were properly aligned I might try to check the alignment using string and jackstands just like on the race car. I suspect it might be a useful exercise to determine if axles weren’t square. The bigger the tires and the longer the wheelbase, the easier it should be so even small misalignments. If the rears axles aren’t perfect squarely to each other and the centerline of the coach, then something is wrong. That is as far as i would take it as I’m not about to start playing with the shims, even if Jon explained to me how to find them.
After leaving Prevost Jacksonville I realized I had forgotten to ask for and get a printout of the alignment both before and after the alignment job. Quite frankly this is what creates value for an alignment job. Whether its a $99.95 alignment at the Chevy dealer (which I recently had done on the HHR) or the $650 Prevost alignment, it all in the numbers. What did you find? Was it far off? How close were you able to get it to perfect. I had to ask the Chevy shop for the numbers, they didn’t offer it.
Reminds me of the time I took the drive shaft from the race car to an ancient drive line shop on Milwaukee’s north side across the street from the old A.O. Smith factory for balancing. When I picked it up there was a simple bill taped to it. I asked the guy at the counter how far off it was. He said “let me get Leo up here, he did the work”. A few minutes later scruffy, toothless Leo appeared and in great, articulate detail explained to me how he first had to straighten the driveshaft as it wasn’t perfectly straight, how he ground off the existing weights, and then balanced it. He asked what kind of a race car I was using it on and I told him a Cup car and would turn the engine up to 9200rpm. He said any vibration I sensed in the drive train was no longer attributed to the driveshaft. Leo created value by telling me what he did. The same thing goes for an alignment. Make sure you ask for the pre- and post-alignment numbers to see the value.
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FYI
JOSAM in Orlando is very qualified to do a complete alignment on a Prevost. I’ve been very happy with their work for over 15 years.
IMHO Josam alignment system is the best in the world and if I remember correctly it’s what Prevost has in their shops.
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Jon,
Prevost-Ft. Worth told me that the A arm bushings do age like tires. The more you use them by driving a lot, the more miles they will last. The bushings release a compound that protects them as they are used. The worst thing you can do to shorten their life is to let the coach sit and not drive very often.
Mine were replaced around 200,000 miles.
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Just like our tires. Good to know.
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