Wheel Bearing Pre-load

Topic: Wheel Bearing Pre-load (Read 2971 times) previous topic - next topic

Wheel Bearing Pre-load

July 18, 2019, 09:59:59 pm

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...

Re: Wheel Bearing Pre-load

Reply #1 – July 18, 2019, 10:40:17 pm

I'm sure Calflashbob will chime in on what to do and how to do it.

Re: Wheel Bearing Pre-load

Reply #2 – July 18, 2019, 10:48:24 pm

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

Re: Wheel Bearing Pre-load

Reply #3 – July 18, 2019, 10:50:26 pm

You need a old time commercial mechanic to "adjust" your front wheel bearing when you are not in the room.

Re: Wheel Bearing Pre-load

Reply #4 – July 19, 2019, 02:38:51 pm

Re pack bearings tighten down to 200 foot lbs while spinning tire.
Back off nut one full turn,re-torque to 50 foot lbs.

Re: Wheel Bearing Pre-load

Reply #5 – July 19, 2019, 02:43:59 pm

Sounds correct I check my hubs repeatedly with a heat gun and no different heating was there either way

Re: Wheel Bearing Pre-load

Reply #6 – July 19, 2019, 05:57:21 pm

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?

Re: Wheel Bearing Pre-load

Reply #7 – July 19, 2019, 06:51:02 pm

Call and talk to James T.

Re: Wheel Bearing Pre-load

Reply #8 – July 19, 2019, 07:11:04 pm

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.

Re: Wheel Bearing Pre-load

Reply #9 – July 19, 2019, 07:41:15 pm

Tapered wheel bearing have been around since the beginning of the modern automobile.
Here is some information from the Chevrolet P-30 manual:

Re: Wheel Bearing Pre-load

Reply #10 – July 19, 2019, 07:43:39 pm

Great idea Chuck. I'll call Meritor and James T. on Monday and report back.

Re: Wheel Bearing Pre-load

Reply #11 – July 19, 2019, 08:02:34 pm

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.

Re: Wheel Bearing Pre-load

Reply #12 – July 20, 2019, 12:36:10 am

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

Re: Wheel Bearing Pre-load

Reply #13 – July 20, 2019, 01:19:48 am

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.

Re: Wheel Bearing Pre-load

Reply #14 – July 20, 2019, 03:26:39 am

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.

Re: Wheel Bearing Pre-load

Reply #15 – July 20, 2019, 03:36:02 am

Does an 07 nimbus have independent front suspension?

Re: Wheel Bearing Pre-load

Reply #16 – July 20, 2019, 08:53:25 am

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

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

Re: Wheel Bearing Pre-load

Reply #17 – July 21, 2019, 10:54:27 am

The 2009 has IFS.

Re: Wheel Bearing Pre-load

Reply #18 – July 21, 2019, 11:59:19 am

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.

Re: Wheel Bearing Pre-load

Reply #19 – July 21, 2019, 12:11:11 pm

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.

Re: Wheel Bearing Pre-load

Reply #20 – July 21, 2019, 06:26:20 pm

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.

Re: Wheel Bearing Pre-load

Reply #21 – July 25, 2019, 12:53:34 am

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.

Re: Wheel Bearing Pre-load

Reply #22 – July 25, 2019, 01:15:26 am

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

Re: Wheel Bearing Pre-load

Reply #23 – July 25, 2019, 09:05:26 am

Quote from: Don Hays – July 25, 2019, 12:53:34 am

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.

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.

Re: Wheel Bearing Pre-load

Reply #24 – July 25, 2019, 09:23:33 am

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.

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