After reading the discussion regarding "wheel play" I want to explore front wheel bearing pre-load. I bought the coach in March of 16 and have never been happy with the play in the steering especially at speeds above 55 when its windy. While at FOT a year ago for a renovation, I had them check the front end. They put it on the rack and said everything is in spec. They recommended I run a lower tire pressure. Said the IFS works better so I lowered to 100 PSI. That made a small improvement but it is still not as good as I think it should be.
Questions;
1. What is Foretravel's position regarding this method and is it an adjustment that their service department is willing to make?
2. Does anyone know of a good truck shop in the Houston area that does this type of work?
3. Is there anything more I should know about this before doing it?
I know that getting it wrong can be catastrophic so I want to draw on the experience of those in the know.
Thanks a ton...
I'm sure Calflashbob will chime in on what to do and how to do it.
Take a look at this Meritor propaganda. Possibly makes precision adjustment more achievable by mere mortal mechanics. Semi kidding here, not many mechanics have the time and patience to assemble and adjust the multiple times it takes to get it to the gnat's patookus.
https://meritorcya.com/PDFs/MERITORWHEELBEARINGADJUSTMENTSYSTEMBrochure.pdf
You need a old time commercial mechanic to "adjust" your front wheel bearing when you are not in the room.
Re pack bearings tighten down to 200 foot lbs while spinning tire.
Back off nut one full turn,re-torque to 50 foot lbs.
Sounds correct I check my hubs repeatedly with a heat gun and no different heating was there either way
This is exactly the procedure that is described in several U tube videos. Some of those guys seemed a bit hackish to me so I don't have allot of confidence in what I saw. The procedure they describe is the method for achieving the standard spec, not for preload spec. The Meritor system that Chuck Person referred to seems like the most accurate method for achieving the right preload. There is a graph in that link that illustrates the preload spec to the standard spec. So, another question is where to find a shop that uses the Meritor system near Spring, Texas?
Back to the original question, has anyone heard what Foretravel has to say about the preload practice?
Call and talk to James T.
This preload system is dependent on using a "Temper Lock" wheel nut. These things are precisely machined locking nuts. Unknown if there is a temper lock nut for our application. Cross reference to Stemco is on the last page of the document.
A call to Meritor might serve to locate a shop that uses the system. Someone needs to try it out and then we'll do a group buy on the tool if it's the magic bullet.
Tapered wheel bearing have been around since the beginning of the modern automobile.
Here is some information from the Chevrolet P-30 manual:
Great idea Chuck. I'll call Meritor and James T. on Monday and report back.
Nice for Chevy to cover themselves. Their Salisbury steering box was so poor the coach wandered a lot. So much that an aftermarket guy made up replacement steering boxes for them.
Every Unihome I sold had preloaded wheel bearings from the Factory. Ask JamesT. See if he owns up.
All tapered bearings require a preload. BUT having made that statement, the bearings must also have a small amount of clearance for expansion. In our part of the world, trucking is a major industry.
The procedure is to tighten the wheel while spinning the wheel. . A firm pressure on the wrench, then back the nut off , till the cotter pin fits.
Using this procedure I have never seen a wheel bearing fail. Most wheel bearing failures occur when a seal leaks and there is an oil loss.
Safe Travels
Dave
Safe to say everyone is somewhat familiar with the old school method of bearing adjustment. That's how they were set when they rolled out of the factory.
What this new setup does is allow the application of an exact, measurable preload on the bearings for zero end play. This SAE specified preload can not be accurately and repeatably set by torquing a nut. Once this is set the nut is locked at that setting.....not backed off to align a cotter pin....by a microadjustable locking ring.
Apparently the ability to accurately and quickly preload wheel bearings to exact spec yields some performance advantages for fleet owners.
If you watch the stemco seal installation video the instructor mentions several times the DOT legally defensive-able .001-.005 end play. The same as the Chevy p30 link to the manual shows.
Read between the lines. This method is legally defensible. A "feel" is not in court.
Dave has the method my Foretravel dealer long term line mechanic did on mine while I watched.
I asked him how many he had done. "Hundreds" any issues? "No"
He was the guy who serviced Barry beams coach here in so cal.
Does an 07 nimbus have independent front suspension?
It's interesting how GM in a classic CYA move forbid bearing pre-load. SKF in Torrington, CT is a precision bearing manufacturer, once upon a time I re-purposed a surplus to SKF Lidkoping centerless grinder for a Chrysler project.
SKF Tapered Roller Bearings - Mounting and dismounting - YouTube (https://youtu.be/JugU6NHgqVY)
Timken was the original manufacturer of tapered roller bearings in this country and was supplier to Ford.
That being said, and I run my wheel bearings with no play, here's what the manufacturer has to say on the subject.
Brett tells me that he can't open my .pdf file, I'd like to know of others also having a problem. Here is a link to one of the Timken engineering manuals for tapered roller bearing fit. You may want to skip ahead to page 28.
https://www.timken.com/wp-content/uploads/2018/10/Timken-Tapered-Roller-Bearing-Catalog_10481-1.pdf
The 2009 has IFS.
Some of the original IFS coaches I have driven had an inherent wander to them.
Country coach went to Toyo tires back then to help. Still wandered. Drove all the demo coaches at the Pomona FMCA rally and all exhibited some wander.
Newer coaches and prevost use a 20k ZF front end if memory serves me,
Being as changing the front end is not possible if the coach were mine I would preload the bearing from .001 to .005 negative like the Timkin chart shows and add two new Michelin energy tires with the directional sipes on them.
Probably as much "fix" as available
Seems the preload is quantifiable.
The changes in the bearing movement based on the thread pitch can be carried on to the negative side.
The IFS is manufactured by Reyco Granning. I have two new Michelin Energy tires w/ 2K miles on the front so the preload is the next step. The preload should include inspection of the existing bearings for wear and replacement if necessary, so I'm half way there. I'll be calling Meritor and James T tomorrow.
I like the links posted.
The Timkin chart shows the bearing life the best at minus .001-.005 preload and the skf video states some applications may require preload.
I spoke with James T today. He had some knowledge of the pre-load concept. He stated that Foretravel strictly complies with the manufactures specs when adjusting wheel bearings. No consideration is given by Foretravel to a pre-load setup as we've discussed. He even described the procedure for the standard spec setup. I'll reach out to Meritor about their tools and local shops that use their system and report back.
Try both positive and negative preload like I did. Took it apart twice just to compare.
James gave the politically correct answer.
Not a single new Unihome I drove out of a hundred had any wander.
My Foretravel factory stores shop line mechanic preloaded every wheel bearing he worked on. I watched him do it.
I watched him preload mine years later.
Next shop went positive preload and induced a slight wander
Lawyers looking for income and owner's who don't want to take responsibility for their actions are ruining this world.
That being said, if the wander bothers you that much, and if you're willing to take a slight risk, then choose the method you prefer and go for it. I spin the wheel and use a torque wrench. Then I go for a ride. I developed this technique trying to eliminate front end shimmy in king pin steering systems.
Just my observation every tapered roller bearing I ever messed with ( hd transmission, differentials, etc.) have a preload on them.
As far as all the lawyer/liability talk, I would like to see one documented case based on wheel bearing installation. JMHO, by the time there is a wheel off incident there is hardly a way to prove preload or not.
I used to re-build drilling spindles with tapered roller bearings, and if you don't correctly pre-load the tapered roller stem bearings on a motorcycle you will have an interesting riding experience.
I spoke to a rep from Meritor today who referred me to a rep at Truck-Pro who is a retailer for the "Pre-load Dr." tool. I learned that each tool is made specific to each spindle manufacturer and their catalog has a long list of them listed by part number. I have IFS and calculate a high probability that mine is not like any of yours and would require a different tool. So Chuck's idea of purchase sharing a tool is a great idea but won't work in this instance. I was again referred to the service manager at Truck-Pro who is out till Tuesday of next week. I hope to learn that they can precision adjust the front wheel bearings to the desired spec. Their shop is less than 25 miles from me so it should be an easy trip and hopefully not too costly.
More as I learn it...
I doubt they will preload it.
Spin the tire by hand, snug the nut by hand, add 2-4 degrees of additional nut turn preload, or less than 20#.
Thats what I use on these spindles as does the HD truck shop across the street. Q
I mark the nut as run before adjustment.
The square tube thing is my wrench .
That's how mine where done. I like this method since the bearing tells you how tight they want to be. :)
see ya
ken
I'm supremely confident that I can make this adjustment. I've replaced bearings on boat and utility trailers with no problem. This is a much bigger deal and I Just don't want to get 1000 miles from home to find out I got it wrong. Thanks for all of the comments and advise.
Light duty trailers are greased and require some end play.
The oil bath HD tapered bearings run with zero end play minus a little .
Not the same.
All TAPERED bearings require preload, the load is carried by the whole brearing. The older ball bearings ie older Chev cars just need to be snug, they are ball bearings and roll . Torrenting bearings are a different breed of cat.
Safe Travels
Dave
Yes preload can be difficult to accurately attain. Probly the main reason the manufacture stays away from preload is that your at .001" preload your at the best possible state.
At .002" preload you have dropped to 60% of rated life down from the peak of rated life.
At a loose end play of zero you have dropped gone to 115% rated life.
At a loose end play of .001" you have dropped 110% rated life
At a loose end play of .002" you have dropped down to 97% rated life
At a loose end play of .008 you finally drop down to 50% rated life
From peak life one thousandth tight drops you to 60% rated life
From peak life nine thousandth loose to reach 50% rated life
Loose is critically better than too tight by one thousandth.
Also no one has mentioned the fact that your adjustment is made with two nuts. There IS free play between the nut and the axle threads and once the first nut is installed, the locking washer is placed and the second nut is torqued against it pushing it to a unknown preload value.
This is resolved with the single axle nut and lock ring . That being said every day I change wheels with a preload torque of 150 foot pounds, difference is there not being used to drive too there destination, just a little use at the start and end of every trip.
Scott
It will be interesting if after all this effort to nail down the proper setup for get the wheel bearings right. Will this fix the slight wander at speed?
Bill
dsd your info matches my experience. Mine are set at .001 and .003 and a very slight dead spot is present.
No wander.
Caflashbob. The point I was trying to make is a little too tight is critical and a little loose is no big deal. I've always tried for the -.001 but am always aware too much is unacceptable. Truly reduces wander IMO. I've always keep in mind preload run up from the locking nut and adjusted to offset for it.
Scott
Fact of the matter is, it is VERY difficult to achieve a dead nuts accurate to+or- .001-3 tolerance in something like a large tapered wheel bearing. Especially the -.001-3 which is called preload with the equipment most shops have on hand. Example of preload when doing things like pinion bearings and carrier bearings the preload is measured in inch/ foot lbs of torque to make it turn, as specified in the appropriate service manual .It's not rocket science any good truck shop can do it. Don't stress over it. Just my 2 cents s worth.
My Cummins dealer will only adjust the wheel bearings to the legally defensible.001-.005 loose setting.
I preload. The bearings will last longer, in theory, with some preload. And the allowable preload is actually more than the posts in this thread make it out to be. It's not super duper sensitive that 0.001" preload is all that is allowed....even from the chart shown in previous posts it's more like 0.003 or more. Here's two posts I made in the past with actual engineering information from bearing manufacturers. Preload will increase reliability. I also use the "pro-torque" nuts.
Wheel seal--Stemco (https://www.foreforums.com/index.php?topic=33605.msg333052#msg333052)
front wheel bearing preload? (https://www.foreforums.com/index.php?topic=21982.msg165441#msg165441)
I always preload bearings. When I was taking my apprenticeship as a heavy duty mechanic I was working on a off highway logging
truck doing the preload and the boss said to tighten it as tight as you can with 6 ft of pipe. I said isn't that too tight. His answer
was we don't have wheel bearing failures. I don't do it as tight as I can but I do have preload. I always use a Molly Grease.
Old guy, off highway slow turning wheel bearings are not the same as truck ( MH ) bearings turning at 50 to 70 or more MPH . You over tighten a MH wheel bearing you will be lucky to get 1000 miles out of it
Just my 2cents
Chris
WOW.
If you only weight 150 pounds and just hang (no muscle) at end of 6' pipe, that is 900 ft-lbs.
Even a 100 pound weakling= 600 ft- lbs.
Not on my watch.
Yes I know it sounds crazy but that's what they did and the only time I had to replace a wheel bearing was when the cage wore out
which meant it had been used for a long time. I don't do wheel bearings like that any more.
Yes heavy Equipment traveling slow speeds require higher preload. Daily I install wheels rated at 40k lbs each at final preload of 150+ foot pounds. Have for years. Difference is they only spin the wheels for ten minutes at a time. IE; were not driving there. They do see 120+ mph, but only for seconds. Very little excessive preload on a continuous duty wheel bearings will cause failure. Lots of play will too. Sweet spot is difficult to duplicate, and prove in court. And yes 150+ is way excess for road applications. IMO
Scott