The Roller Bearing Conversion (The whys and wherefores)
by Lorne Goldman, John Sheally II, Peter Mulberry & Bill Button
June 2005

Watchpoint for earlier cars.

THE WHYS
LORNE  GOLDMAN As the spindle (stub axle) moves up the kingpin when the car goes over a bump, the large kingpin springs compress (obviously) and produce a twisting motion (not so obviously). All other things being equal, this twisting motion would be relayed to the spindle and would result in a slight turning of the wheel. When this occurs and a certain speed, it sets up a harmonic bounce which can express itself in a violent shimmy.

To avoid this, HFS Morgan placed a bronze plate between the spring and where its sits on the spindle. The bronze plate then is held steady (and untwisting) by being bolted to the damper blade which, in turn,
is held at the frame. With all this, the spring's motion is now transferred to the immobilized bronze plate rather than the spindle. Of course, since the spindle moves up and down the damper blade cannot be bolted to the frame as it must move in and out to follow to the spindle's movement up and down. Ergo the blades are "sandwiched" into a slot made of small metal plates and the damper blade shims.

This system has worked for almost 3/4 of a century. Its drawbacks are the maintenance it requires (as the blades get loose they allowing twisting to occur at the spindle unless the shims are readjusted and the blades and shims deteriorate. It handles the twisting movement in a less efficiently manner than other solutions. The roller bearings are one of these "other solutions" and a good one.

RESISTANCE

With the standard Morgan setup, the twisting action of the spring is the twisting action of the spring is dissipated on the bronze plate (attached to the damper blade). As the bronze plate is, in effect, fixed, there is some resultant resistance to the twisting on the plate.

In the roller bearing system, the twisting is on the collar and washer which are seated on the bearings and turn on these..ergo no resistance and lighter steering.

CLEANING

As the bearings are closed to the elements by the washers under them and the other washer atop them (with the collar and spring pressure to hold it all sandwiched, there is nothing that can get in and dirty those bearings. (Second) ergo, though the area would require normally cleaning, it would be not susceptible to road dust as it is fully enclosed in the stainless washers and I would find it hard to see how wear would be a factor.

I have attached a diagram the reflects my understanding. A 4-story sandwich. After removing the kingpin assembly and stub axles, the bronze plate that attaches to the damper blade is removed from its position around the stub axle tube (where the kingpins are placed). A washer is placed on then the thrust roller bearing is pressed fit. Another washer  is placed loose on the bearing ..diagram "C", then the top hat cover is placed on top of the assembly. The kingpin is re-installed and the large kingpin spring fits down over the kingpin and sits on the top hat. The top hat is used to properly position the spring and the sandwich and keep the grease in the bearing assembly and debris out. The top hat must turn freely. If it is too tight, use some sandpaper on the inner edge until it slides loosely.


JOHN H. SHEALLY II  Here is the "Sheally Setup". It is quite simple. The views included are of it on John's new Plus 8 Morgan Racer. If you look close under the bottom of the red main spring you will just see the stainless washers sandwich with bearing in between.

What you can not see is the machined collar pressed over the kingpin tube to center the bearing and washers. The collar or collet is drilled to match the grease fitting hole so that the existing fitting can be used to grease the bearing from inside to outside serving also to clean  it each time it is greased via gun.

The bearing is a FEDERAL MOGUL/NTA 2840 and the stainless washers are FEDERAL MOGUL/ TRA 2840 (total of approximately $30US collars extra). Toss the damper blades and bronze thrust plate and enjoy quick smooth steering at a small cost with my applied "KISS PRINCIPAL" I have found that the setup is too simple for a lot of folks to comprehend.

You have to make your own from round steel stock or good quality steel pipe. It is very simple, you are making a steel "ring" to press fit over your spindle bushing tube. make the ID tight to press fit over the tube and press fit all the way down to where your bronze plate would sit. make the OD to be a snug fit to the ID of your thrust roller bearing. put the stainless washer over the tube and slide down over the ring "collar" followed by the bearing and the second washer (lube the bearing well on both sides) and make sure your grease will feed to the bearing from your existing (grease nipple/zerk) by drilling a small hole in the ring and line it up with the oil hole on the spindle. Place your main spring in place and assemble spindle and kingpin, etc. and enjoy your Morgan. Sincerely, John H. Sheally II
 
 


top hat right side up
Kits of the Sheally set up were machined and assembled through the efforts of Roger Shawyer. Roger had the collar produced and used a grease ring to spread the grease evenly about the bearing. Care should taken to ensure that the collar freely turns about the tube. These assemblies, made as an eMog Pub initiative, are no longer available from Roger. However, they can be reproduced by a machine shop to order along with the other parts are listed above.. 

top hat upside down

PETER MULBERRY

Peter extends the thrust roller bearing principle ..using different ball bearings within a housing as can be seen by the picture. As well, the main spring is changed. For racers, there is an interesting adaptation (shown in the picture) of a treaded collar at the top with an adjuster. This allows the ride height to be changed quickly and conveniently.

Peter adds a worthwhile note on the reasons for vibration AFTER this mod.

"Probably the most likely cause of wheel wobble when fitting roller bearings is removing the damper blade. Strange to believe but every Morgan is different, some will 'wobble', some not at all.  Why could that be? What use is fitting rollers when the Mog is going to shake her head along the road?

The advantages have been commented several times, lighter steering, smoother action, disadvantages as far as I believe are capital outlay to buy the bits and getting your hands dirty to fit said parts. So this still does not answer the problem of wheel wobble. So why take away the damper blade?

Trying not to get too technical, the blade fulfills two functions. Without the bronze thrust pad the road spring would sit directly upon the stub axle. When the steering was turned the spring would turn as well, but the top of the spring is hard against the top of the crosshead which does not want to turn so the end result is akin to winding up a large spring in one direction and unwinding in the other. Very strange. So we have the bronze thrust pad between the spring and stub axle which stops the spring winding up. The second function is a friction damper to give it its correct name. Two key words here, first was friction, hard work and effort,  roller bearings take all that away, second word was damper. It is damping the oscillation that is wheel wobble.

If you still have the dreaded wheel wobble after the bearing installation, look to your castor.  A few will be conversant with the term, but basically it is the angle that the kingpin leans backward as you look at your car from the side. It is what gives your steering its self-centering effect. Too little and no self-center, too much and grossly heavy steering.

Everybody must have pushed a shopping cart sometime. Ever had one that the wheels do their own war dance?  The factory measurement for castor is 4 degrees, give or take a bit for allowance. If yours is a bit less you have lost the self-centering ability and gained wheel wobble, if you have a bit more than 4 degrees you have one of those delightful drivers that track straight and true with hands off the wheel. I always set mine up at six degrees and have no problems at all. Unfortunately the factory have made it all non adjustable. But it can be tweaked if you know what to do. If you are not sure where yours is visit an auto align center and they will give you a read out of your front suspension. Then you know.

IMPORTANT NOTE

Within the eMog community, many have performed the conversion. Overwhelmingly, they were successful and without issue. However,  success assumes, of course, that the front end dynamics are in proper order and condition. This was found to be more important with earlier cars with their thinner tyres and less castor (the modern era began with 4 degrees). The bearing systems do make the cars much easier to steer but also more likely to vibrate and wobble if all is not as it should be. When anomalies (ie.vibration) were experienced with older Morgans (pre-1968) we were forced to examine more closely and found and corrected other problems, after which all was well. Be aware. BILL BUTTON  If wobble/vibration is experienced by later cars (post 1980), it normally indicates a damaged, very poorly set up or poorly maintained front end which should be brought to the attention of your mechanic. In such cases, if this seems too much of a hassle, you can rebuild your front again with the damper blades, with or without the bearings. We do not recommend you increasing your castor without resort to an expert who has done so before. When all else fails you can try the Mercedes damper.

THE MORGAN MOTOR COMPANY (PostScript in 2009)

After this writing, the Morgan Motor Company copied the system designed by Peter Mulberry. Like the Mulberry system, the height of the bearing assembly requires the use of shorter main springs. (Be careful which spring rate you get!). After a period without, the Company began using drilled kingpins with grease nipples. This is NOT the one shot oiler system that was happily removed some years ago. The new passage is not for oil, but rather made larger for grease and is drilled further down to feed the steering bearing assembly which, unlike the other systems described above,  apparently gets an insufficient amount of grease and loses what it has. For these reasons, we cannot recommend a retrofit of their system.

WATCHPOINT FOR POST 2002 CARS From the eMog Pub in January 2004 and updated January 2011

All these bearing assemblies need grease. This is provided, in pre-2002 cars, by the little grease exit hole the MMC used to drill at the junction of the stub axle shelf and the stub axle tube.  (see image)  For these bearing assemblies, this exit was perfect as it comes up under the housing at a place where it flows easily into the whole assembly and the bearings.
 
However, in 2002, the MMC tried a different solution to ease steering and greasing. They cut an annular groove into  that shelf to spread the grease under the damper plate, which they retained at the time with the damper blades etc. To better feed that annular groove, the noted grease exit hole was moved outboard from the tube to the center of the groove as we show in the second image.

Here is the punchline. As noted above, in 2008 the Morgan company began using a bearing system copied from those above. People have continued to retro-fit bearing systems. The problem with the post-2002 (annular grooved stub axle) cars is that their owners may be unaware that THEIR grease exit hole is covered and blocked by the bearing. The proper method on these axles is to either cut a passage in the shelf to the tube or drill a hole at the junction of the shelf and tube. If you have omitted this, the solution is to disassemble the front and take the corrective action.
 
UPDATE March 10, 2011 SPECIAL NOTE: Recently, a new Morganeer and first timer published a bearing installation how-to methods. The subject car was made between 2002 and 2008. The method missed the dynamics of this era of Morgan front end assemblies and the noted feed hole was covered. The queries to GoMoG about it is the reason for this update. Because of the blockage he caused, the only way to feed grease to the bearing assembly without damage to the bearing casing is to redo the entire job correctly. This is the problem the MMC encountered when they first adopted this bearing idea from the commuunity sources above. 

BACK