Bluedeviltorque

Ok, I'm not even sure of the correct term for the type of rim on my 92 D350. I've been told the rims are "Keyed" or "Coined" because they have a small hole which lines up with a small bump, lump, high spot or what ever the correct term is on the hub. (My rig is a 2x4.)

My question is, whats the reason for this and would there be any harm done if the the bump was ground off and a differnet set of rims put on. I have no plans of this, but I don't know the history or reasoning behind this type of hub/rim set up and as usual my curiosity has gotten the better of me.

Mike, the un-educated diesel lover.

92DuallyCTD

Aw, you ain't un-edu-ma-cated, you's just in-experienced-ed with diesels...but you WILL learn, right? ;-) Now on my 92 2wd, the front hubs do not have a flange for the wheel center to rest on to accurately center the wheel. So I always thought the purpose of the coined wheel was to positively align the wheel on the studs(and therefore the centers also). The coining also helps orient the duals together on the rear. There is a TSB concerning the centering of the wheels that describes using regular cone shaped lug nuts(5/8x18 threads) on 2 opposing studs first when mounting a wheel. Then running down the other 6 flanged nuts and removing the 2 cones. The TSB was in response to customer complaints of heavy wheel vibration after replacing a wheel and getting it on off-center. The TSB even suggests giving the customer the two 5/8 cone nuts to keep/use in the future. I have had good luck by first placing the 4 nuts on the studs with the coined side 'up'(the raised hump), then tightening them gradually till tight(FSM recommends 325ft lbs!). Then run the other 4 onto the coined 'down' studs. I'd think if you were to grind the coined surfaces off or replace with other style wheels, you'd not be able to true-center the wheels easily. I have thought about the front hubs and plan to upgrade to 94-newer 2wd hubs when/if they ever need replacing. They do have a centering flange and thereby do not rely upon the coining to center, but I don't know that the 94 wheel center is the same diameter(probably is)...anybody know fo sho?? :-)

BearKiller

There are two seperate methods of centering wheels on axles.

Lug-centric = the tapered nose of the nut guides the wheel to the axle centerpoint, usually by a matching taper in the lug-hole of the wheel.

Hub-centric = the outer surface of the hub is precision ground concentric to the axle centerline. The center-hole of the wheel is precision stamped/cut to the center-point of the wheels diameter. The lug-holes are usually slightly over-sized. The nuts, for this type of wheel, will usually be of the loose-washer-flanged type, and do no wheel centering. the center-hole of the wheel will be a precise TIGHT fit to the outside diameter of the hub, thus centering the wheel to the axle.

If you have "COINED" wheels, they are LUG-centric.

Now, the reason for the "COINS":

They perform two seperate functions.

You have two rear wheels.

Each one has a valve-stem.

The off-set coins, along with usually a PIN protuding from the hub, serve to align the valve-stems of both wheels, such that both are accessible from the outside, and that both are NOT located in the same hole, thus interferring with one another when being aired/checked.

Also, tire/rim manufactures use the location of the valve-stem as a point of reference for aligning slight out-of-roundness, between the wheel and tire, to sort of off-set one another, with the high spot of the rim being aligned with the low spot of the tire.

The PIN location, in the hub, along with the COINS on the wheel, serve to locate the high spots of the two wheels opposite each other.

I am not certain which year it started; but, Chrysler decided to further confuse the issue by using a SOLID flanged nut on COINED wheels, depending on the coins to do the wheel centering.

There is a host of problems with this set-up.

One being that, by themselves, the coins are a poor source of centering.

The other being that the large diameter of the solid flanged nut tends to bind with the wheel surface and sort of walk the wheel out of alignment, as it is being tightened, in much the same manner that a nut, being tightened against a slotted surface, will tend to pull that surface out of line.

SO, to clean up their mess, Chrysler says to use four CONICAL lug-nuts, at four opposite corners, to initially tighten/center the wheels.

Once the wheels are centered by the conical nuts, install, and torque, four of the flanged nuts on the remaining studs.

Then, one at a time, replace the conical nuts with flanged nuts.

The big dis-advantage of lug-centric wheels is the tendency of the lug-holes to develop stress cracks, due to the entire weight over the axle, and the driving/braking torque, being concentrated within the small area of the lug-hole, compounded by the necessary thinning created by forming the tapered seat.

On the other hand, the dis-advantage of hub-centric wheels is, if the nuts loosen ever so slightly, thus losing their "grip" on the wheel surface, the wheels will begin to "rock" back and forth, being stopped at each end of this rocking by the stud, thus cutting into the studs and "wallowing out" the holes in the wheels.

I see about as much of one problem, as I do the other; so, I can't really say which set-up is the most durable.

We get less im-balance complaints from the hub-centrics.

You can mix lug-centric wheels from one axle brand to another, providing you use proper fitting conical nuts.

Hub-centric wheels are AXLE-SPECIFIC, and cannot be moved from vehicle brand/model to another, UNLESS the machined surface of the hub is of the correct diameter.

I see people, all the time, that say "I put them on my truck and they are working fine"; then, a few months later, they come in with a wheel all chewed up, and the studs near eat in two, or they are driving along and lose a wheel.

I hope somebody gets something out of this.

BearKiller

I would sure appreciate a copy of that TSB to show the HARD-HEADS that I have to try to convince this to.

Thanks.

92DuallyCTD

http://dodgeram.info/tsb/1992/22-02-92.htm

Done!!

And here follows the text(source: Geno's Garage):

(QUOTE)
DodgeRam.info > TSB's > Other Models > 22-02-92

TSB 22-02-92
Wheel Vibration
Visit Geno's Garage
for Truck accessories.


--------------------------------------------------------------------------------

Date: Apr. 6, 1992

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 22-01-91 REV. A WHICH SHOULD BE REMOVED FROM YOUR FILES.

Models:

1989-1992 (AD) Ram Pickup/Ram Cab & Chassis
Power Ram Cab & Chassis

THIS BULLETIN APPLIES TO 350 SERIES AD MODELS WITH FLANGE TYPE LUG NUTS.

Symptoms:

A customer complaint of a wheel and tire vibration, at highway speeds, on smooth road surfaces. This condition may be caused by the wheels being off center on the wheel studs.

Diagnosis:

A properly centered wheel will have a balanced amount of space for each lug nut flange to the wheel center hole; an off center condition will show a variable amount of space. Perform a visual inspection and road test vehicle to verify condition.

Parts:

2 90° Cone Nuts 1273556

Repair Procedure:

This repair involves wheel centering procedure.

1. Raise the vehicle so that the tire(s) are off the ground. Do not remove the wheel(s) from the vehicle.

2. Loosen all lug nuts. Remove two (2) of the flange nuts 1800 apart (do not discard). Use the positions with the largest flare surface for cone nut contact.

3. Replace the two (2) flange nuts with the 900 cone nuts, PN 1273556, and torque to 68 N-m (50 ft. lbs.).

4. Some loosening and tightening of the cone nuts and repositioning of the wheel might be necessary to obtain a centered wheel.

5. When centered, tighten the six (6) flange nuts and torque to 68 N-m (50 ft. lbs.). Replace the two (2) cone nuts with the flange nuts that were previously removed and torque to 68 N-m (50 ft. lbs.).

6. Torque all the flange nuts to 407-475 N-m (300-350 ft. lbs.) in an alternating pattern, Figure 1.
Wheel Lug Nut Tightening Pattern

Figure 1 link:
http://dodgeram.info/tsb/1992/figures/22-02-92-f1.gif



7. Visually verify to see if the wheel is centered properly. Check tire air pressure to make sure it is properly inflated.

8. Repeat the procedure as necessary to assure all wheels are properly centered.

9. Road test vehicle to confirm your repair.

AS A COURTESY TO THE CUSTOMER, PLEASE PROVIDE THEM WITH THE CONE NUTS FOR FUTURE USE (EX. TIRE OR WHEEL REPLACEMENT).

NOTE: THE CONE NUTS SHOULD BE USED TO CENTER ALL WHEELS, FRONT OR REAR.

Notes:

POLICY: Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:
Labor Operation No. 22-40-01-93 . . . . . . . . . . . 0.3 Hrs.

FAILURE CODE: 51 - Improperly installed


--------------------------------------------------------------------------------

Thanks to Barry Dodge for supplying the TSB information

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This page was edited on: May 3, 2004
(END QUOTE)

BearKiller

Thank you very much.

That is just what I needed.

92DuallyCTD

Uh-yup uh-yup uh-huh, no problem Mr BK!!

Jim Lane

This will help explain what a Lug-centric rim is.

Of course I just happen to have a picture of our rims that were used on the stock 1990 D-350’s
Notice the hole for the guide pin that indexes the valve stems 180* apart.

Believe it or not I have had my duals installed with both stems in the same hand hole.
As you can imagine the wobbled like crazy.

BTW I did not do this, A tire shop did it.



This is a view showing the way the tapered conical ridges “COINED” and recesses alternate every other lug.

When I installed my alloy wheels I had to grind the protruding ridges flat with a die grinder so the rims would be flush with each other.
Now the inside rim is coined with the drum and the outside rim is centered by the tapered lugs.



The conical ridges fit into the recesses around each lug on both the front spindle.



And the rear drum. Notice the index pin.






These are the 5/8X18 Solid Flange Cap Nut that are used to secure the rim in place.






2500lbs. MAX. INFL at 90PSI COLD ONLY WHEN FLANGE CAP NUT IS USED

I am curious as to why this is stamped on the rim.
What would the weight rating be if a different kind of nut were used?
Was there an optional nut?

Do Not be alarmed by the cracked sidewall on this tire, it was my old spare tire.



I hope this was of some help.
Jim

wannadiesel

If you used cone nuts the wheel would not be attached as strongly. It probably would have been better to stamp it "Use flange nuts only".

Caver Dave

IIRC, 2500# is much less than the capacity of a single Load Range "E" tire?

And is my GVW sticker the only one that specifies Load Range "C" tires?

I picked up 4 Dorman 5/8" coned lugnuts last Thursday to center mine... since I'm sure they are all way off center

wannadiesel

Yes, but the 15,000 lb total capacity is still much higher than the GVW of the truck.

They did come with "C"'s, "D"'s were an upgrade.

BearKiller

I believe that stamping about the weights is just so much propaganda.

The older wheels, identicle between Ford and Dodge, among a handful of others, were rated for the same amount with the old conical nuts that were used for generations.

That is sort of like the warnings to "use only rims specified for radial tires" that is molded in the radial tire sidewalls.

The only difference in the wheels is the stamping.

If fact, rims get thinner every year.

They are almost thin enough to shave with now, especially on cars.

We install probably 30-40 sets of tires, each business day, and there is hardly a car that we see that doesn't have at least one badly warped wheel.

Back before the eighties, it was a rare thing to see a warped wheel that hadn't been in a wreck.

If you have a SRW truck, and want the best stoutest wheels that ever were made, find a set off of a late sixties to 1979 Ford 3/4-ton truck; they are five times as thick and heavy as the ones available today, and ten times as well made.

Ace

I'm sure those are some darn fine wheels, BK. But I'd still rather have Ricksons.

Now, If only I had an extra few thousand $$$ laying around...

Bluedeviltorque

Thanks for all the input guys. I know enough about our cummins engines to get by, but the reasoning for the wheels on my 1st gen had me befuddled.

Mike

G1625S

Cool thread Glad I checked it out.