BUSHES REDUX or WHY DO SO MANY NEW AND REBUILT FRONT ENDS SEIZE??!!!!
by GoMoG

A properly-installed Morgan front end is not only a smooth pleasure to drive and steer, it is also easy to get it that way.

Secondly, there is nothing complicated about the Morgan sliding pillar front suspension. The kingpins are held between the upper and lower bars of the crosshead and the springed stub axles slide up and down them. (duh!) The steering system pulls and pushes the stub axles and that pivots them around the kingpin.  

Thirdly, the most common reason for a seized front end is the improper installation of the bushes creating by an insufficient clearance between the bushes/kingpin and/or an inexact alignment of the two bushes.  A seized kingpin will be unable to move up or down negating/prejudicing the front suspension AND the steering will become stiff and often refuse to ssmoothly self-center. 

This problem is compounded as many owners, and even Factory staff, do not always sense that a front end happens to be seized.  

WATCHPOINT: Testing for a seized front end is also easy. Place a jack in the front below the middle of the crosshead. Raise the jack until it makes contact with the bar. Now smoothly jack up watching the right stub axle. The springs should compress smoothly, without any hesitation before wheel rises at all. Lower the car and do the same procedure again watching the left stub axle.  I suggest this test regularly. When you receive a new car, a rebuilt car, after long storage and every time you grease the car. Morgans can also have their front ends seize with accumulated grit , a hard knock and/or rust, aside from sloppy installlation workmanship.   If these symptoms appear with a new car or one that has a newly rebuilt front, you must remove the front axles and increase the bush/kingpin clearance to .004-005". The deceiving element about these cars is that if you jack them and remove the weight from the front stub axles, they will most often seem perfect with no detectable problem in steering or up-and-down movement! The reason for this is simple. You have removed the effect of the weight and the chassis flex.

WHY DO NEWLY INSTALLED FRONT ENDS SEIZE?

The answer. Insufficient kingpin/bush clearance or inexact bush alignment on one side or both.  Why is this so common, especially when the job has been done by the Factory or professionals?  

The Factory and professionals have their own set of front end installation mistakes they make. Owners, when they do the job are prone to a different set of mistakes  unless they listen to the wrong advice on clearance or alignment. Amateurs are inherently too cautious to err on something as simple as kingpin/bush clearance. They will very carefully measure clearance. For insufficient clearance from new, you need someone who ignores a two second detail like measuring.

Let me start off by correcting a recent article on this very subject. It was placed in one of the Morgan newsletters that are sent to me, gleaned from one of the UK Morgan forums. The writer made a number of mistakes.

1. On the minor side, he incorrectly maintained that the Factory "reams" its bushes. That ended some time ago.

Some years ago the Factory finally purchased a Sunnen honer, a machine made Morgan-popular on eMog well over a decade ago. News of this purchase appeared in a trade journal at the time with details. Sunnen had designed and made a line boring tool specific for Morgan to make their life easier with suspension bushes. Neat and simple and fast. One would suppose that it could only produce both a perfect alignment of the bushes and a perfect clearance.... or would it?  

Tools wear. Over time, cutting edges cut less and maintenance or adjustment is necessary. This doesn't happen if the users never measure their results. Over time, the ever-wearing tools will create a clearance that incrementally diminishes.  With the non-adjustable honer owned by the Factory, this is even easier to miss. If the machine is not regular checked and maintained, the amount it hones will get less no matter how it was originally set. When the individual Morgan stub axles, weight, chassis flex or tiny component differences are factored in, new front ends will begin to seize.  

Many pros will tell you they are so practiced with the job that they are beyond the need to spend a few seconds to measure anything as mundane as clearance. They maintain they can "feel the proper clearance". After all they note that kingpin slips through the stub axle bushes before it is re-installed on the car..nver thinking that this is before hundreds of pounds of weight, various component anomalies and varying forces are applied!   I can assure you, from sitting from sitting in this seat, receiving thousands of sad Morgan emails over 20 years, very few of these fellas are actually correct. For confirmation, simply read the report of new Morgans, seized directly fron the Factory!


2. More seriously, the same writer went on to recommend a .002 inch clearance for all cars.  A clearance this small is an illogical risk. It is akin to the clearance the professionals and machinists are mistakenly creating regularly. (see above)  This attitude and the .002. clearance ignore the following:

WITH ALL CARS

1. the effect of a flexing frame on the clearance

2. the effect of the weight, static and dynamic, on the crossframe, the kingpin, the stub axle tube and alignment.

WITH OLDER CARS ADD

3. the effect of a mildly bent crosshead

4. The effect of wear on other parts,
 
I do not mean to suggest that a .002" clearance will not be enough for some cars. But the only way to dynamically test that is with the stub axles installed and the car used for a period in real conditions! So if the clearance is insufficient, it will require the entire job to be redone. Why risk a clearance that is going to be wrong even some of the time?

Risking a minimal clearance no longer makes any sense for other reasons. Bushes, of any type, no longer wear at the speed they used to because of the use of non-rusting kingpins in the last decade. Mileages over 100,000 are common. So why risk a seized front end and redoing a tedious job in hope of gaining a bit extra mileage? Incidentally, all oldtimers will confirm that a bit more clearance is a better steering and feeling front end. In fact, here is the guru consensus even before the advent of non-rusting pins! THE EXPERTS PANEL

Proper bush clearance should be .005"

As noted above, the present plague of Factory seized front ends mirrors the samer plague of 10 years ago with the resultant-fit DEVOL bushes, which made the front end job easy for owners in their garage and lasted longer than bronze when used with non-rusting pins. At that time, the Factory gave out confidentially, that these bushes would "swell", something the multi-national supplier denied was possible.  As these bushes were designed to be a resultant fit (press them in and nothing more), there was seemingly no need to measure them. Yet some seized. Then eMog had the factory DEVOL bushes measured, (at that time Morgan still made their own bushes, now they simply install them) we found that they were imprecisely machined and had different dimensions from one to the other.

Bronze has nothing in common with DEVOL. Bronze does not "swell". Yet both seize new from the Factory. The only thing these bushes have in common, then and now, they are used on the same car and installed/machined by the same Factory.  

DIFFERENT MORGAN BUSH DIMENSIONS!!! (July 2016)

I would be happy to end here..but the same article IS correct in one area, there are now two different stock bushes being sold on Pickersleigh Road. (I am not counting the over-size bushes made for the DEVOL stub axle cars. And yes, the one you buy can make a big difference! One is currently made to and sold by the Factory and the other is supplied to and retailed by another division, Aero Racing  Ltd. They have different dimensions.

BUSH 1 Aero Racing (the .98s)

The originally dimensioned bronze bushes are more similiar these being supplied by Aero Racing. These have a smaller ID (.98 inch) and  a .003 to .004 inch press (aka interference) fit for the outside diameter. This is wise. There are too many stub axle tubes that start (warped  in the welding) or become slightly out of alignment with usage. Additionally, the tubes stretch and become wider with bush changes and that will also effect the key installed internal diameter. The extra bronze stock gives the installer a better chance of properly  boring/reaming/honing/cleaning up the inside of the bush for a proper alignment and clearance.

BUSH 2 Morgan Factory (the 1.00s)

It appears that the Morgan Factory now have their bush ID made to a new 1.000" bore. This leaves them less to clean out on their installation into the stub axles on new cars. However, it also means that there is less bronze for a later installer to achieve a proper alignment and clearance. If the stub axle tube has stretched, that often leads to bushes where there is not enough 

left internally to clean up entirely. Only part of the bush, sometimes as little as half, gets cut and the remander of the bush passage is untouched and unhelpful! The smaller bush id (the 98s)

they clean up fully. I applaud the writer for noticing that and reporting it. Every cloud has a silver lining. 

COMMENT ON REAMING VERSUS HONING At one point in time, there was a debate over which was more better, hand reaming or machine honing. The goal was to create a grease holding surface and to obtain a prescion alignment and a, hopefully minimal clearance to allow for the longest possible front end life.. However, now, hardchrome kingpins prevent wear and annular grease grooves are cut into the bush inner surface.  So who cares which method is used unless you are into mass production? You no longer need to balance off a minimal clearance against the risk of a seized front end and there is no need to be concered about grease adhesion.

WATCHPOINT: BEWARE YOUR NIPPLES! I have received many emails on the difficulties owners are having pumping grease into the stub axles in front. At first I thought it was the grease gun they chose, but I soon found the problem was even more basic. Many owners change the stub axle grease nipple (zirk) for angled ones which allow an easier time fitting their grease gun onto it. Sadly, they do not notice that the threaded portion of the Morgan grease nipples are very short..shorter than nipple normals. When they fit the new nipples they often thread them until they are forced into the kingpin. This blocks the flow of grease despite the use of eye-popping pressure. The front gets little of its needed grease feed and the kingpin can be damaged and movement prejudiced, even seized.