4. Jack Knight and Quaife
5. The Centre Gaiter
6. Steering Play
7. Centre Plate to Rack
8. Tierods to Centre Plate
9. Bolts Through the Securing Blocks
10. Bump Steer Comment
In 1983, the Morgan Motor Company approached Jack Knight Ltd., a noted British aftermarket steering specialist, to design a rack and pinion steering system for the Plus 8, the heaviest of the model line-up and accordingly the most in need of a steering improvement. The resultant rack was a great step forward and was first offered in 1984 as an optional extra at £250. It became standard on all Plus 8s by 1986, unless a customer was crazy enough to ask for the older system. By 1991, it became a free option for Plus 4s and by the mid-1990s it was standard on all Morgans.
Though the design falls far short of an ideal in areas, it is a vast improvement on previous Morgan steering systems and has three great virtues; it is simple, it is solid and it fits on the Morgan front end. There is little that go wrong with it outside of the most basic human errors in fitting and checking it. On very rare occasion it can require adjustment, which is dealt with by David Poole in his eMog posting, and after much mileage the rack channel and spacers may require redressing, and easy job for any machine shop. I have had a full refurbishing done in the UK for 75£.
The Morgan Motor Company had the stock rack's turns-to-lock changed a number of times during its history. The Jack Knight rack can be had with 2.3, 2.7, 3.0 or 3.5 turns to lock and the choice will be one major determinant, of the compromise between steering reactiveness or ease of steering.
In 2007, the original Jack Knight company fell into bankruptcy and the MMC asked Quaife Engineering to supply the rack. For all intents and purposes, the Quaife Morgan racks are the same and can be retrofitted to Jack Knight cars. The Quaife racks can be distinguished only by their different centre gaiters, a big improvement over the Jack Knight gaiter. However, Jack Knight has been reborn under the management of its former employees and an upgraded gaiter, as good as the Quaife gaiter, can be had from them.
The old style JK gaiter is flimsy and expensive. Once the are torn (a MOT issue), the wisest course is to replace them with the new JK gaiter. (The Quaife gaiter will not fit a Jack Knight rack.) Quaife parts can only be order through the MMC, Jack Knight parts can be ordered from Jack Knight directly.
time the tie rods are removed from the steering rack center plate, the
stering alignment should be verified. This is made more important if the
plate itself is removed and even doubled again if both clamps holding the
rack to the crossframe are removed, (Though this is not strictly necessary
to change the gaiter, many take both clamps off to remove the whole assembly.)
All or most of this must be done simply to change the center gaiter. The
play at each junction is suffient to through your steering out of alignment.
Trust ME on this and not your local non-Morgan mechanic. Many owners have
found the steering canting off one way or another after a gaiter change.
Every vehicle has the same three component systems that form the first line of safety for the occupants. They are tyres, brakes and steering. There can be no compromises entertained with any of them. Happily, Morgan trads are very wondrously simple in these areas and the task to keep these areas safe is not difficult or cumbersome. However, I cannot over-emphasize the need for vigilance or the dangers of getting the wrong advice (I have seen some horrid examples of the latter! If you have any doubts whatsoever, consult an experienced Morgan dealer. Happily, the key safety watchpoints are SO simple that common sense should warn you away from any advice you cannot immediately judge as correct at a glance, whether you are mechanically enabled or not.
WATCHPOINT - PLAY AT THE STEERING WHEEL
Morgan rack and pinion steering systems should have NO play at the steering wheel. None. There are a number of causes for play, but the most dangerous ones relate to the fitting of the rack and its tie-rods. Be aware that the length of the steering column will exaggerate any rack anomaly at the steering wheel. making the steering wheel your best early warning system. A soon as play is noticed, three areas MUST be checked before driving further.
1. the two bolts holding the centre plate to the steering rack itself.
2. the two bolts holding the tie-rods (those rods which connect the steering rack to the front stub axles and therefore the wheels) to the steering rack centre plate.
3. the four bolts (2 each side) running through the two blocks that hold the rack to the car frame.
(Consult the diagrams).
Between 1-3 the rack is held to the car and the wheels to the rack. If they are compromised so is your steering and your safety. At one time or another, I have seen each of these areas with loose bolts. Care can prevent this.
Many times a visual test will locate the problem. To test,
have someone at the steering wheel and have them turn the wheel while you
look at the three areas, #2 will be difficult as the bolts are obscured
by the #1 bolts. To it with the front tyres on the ground and then again
with them off. The rack should NOT move on the frame and the only movement
of the rods should be from side to side.
|WATCHPOINT - CENTRE PLATE
These two bolts go through a lock tab, the centre plate, often a small washer and then through the important rack spacers (that keep the assembly guided within the parameters of the channel in the rack) and then thread into the pinion. Obviously, if these bolts come loose, the rack is no longer fully secures the centre plate and therefore the tierods. Effectively, the steering wheel is losing its connection with the front wheels. There are supposed to be secured by the lock tab..but this can be left off by forgetfulness, or the tabs can be forgotten (not closed), or have a insufficient contact with the bolts.)
It is hard to perfectly ascertain the state as the tierods cover these bolts. The centre plate tierod bolts, must be removed and the tierods moved away top allow these inner bolts to be examined. Once this is done, pull back the tabs and try to tighten the two bolts. Once tightened, carefully bend back the tabs.
|N.B. Use a white paint marker to draw a reference line from a point on each bolt to places on the plate of your choosing. This reference line will make future examinations easy as you will know in an instant if the bolt has moved if the line on the bolt and the plate are no longer aligned.|
|N.B. If you remove the bolts entirely, you will have to reposition them through the gaiter and then the spacers (by fiddling with the spacers) and then find the correct hole in the pinion.|
|N.B. With the older style Jack Knight gaiters (approximately 6000 Morgans from 1984 to 2007), close examination will show that the spacer has a round raised area or that there is a small washer between the centre plate and the gaiter. This was done to match the holes in the gaiter for the bolts. Without the raised area or CORRECT sized washer, the plate will clamp the silicone gaiter and the gaiter will split.|
WATCHPOINT - TIERODS TO CENTRE PLATE
If you have properly dealt with the Centre Plate to Rack bolts, you have removed the tierods from the centre plate. Simply reassemble these, tighten and lock them with the tabs. Use the paint market system on these bolts as well.
WATCHPOINT - BOLTS THROUGH THE SECURING BLOCKS
Simple. There are two sets of 2 half blocks that secure the rack to two L brackets on the car's crossframe. (See the diagram above indicating "rack holder" & cross frame".) Each half block has a half round centre that together match the rack and two high grade long bolts going though the two halves into the L brackets. When assembled the blocks clamp the rack onto the brackets and the frame. If the bolts loosen, the rack loosens and moves askew with steering and road anomalies. If the bolts fall out...
Check whether they are tight. In the normal course,
these bolts should not loosen as they are held with nylocs. However, negligence
is always possible and the re-use of nylocs leads to their losing their
ability to lock. One can use new nylocs, or a bit of loctite blue or ultimately,
stover nuts instead of nylocs. If there is concern, use the same white
line reference discussed above.
|There is sufficent play in these bolt holes to warrant verifiying the wheel alignment if any looseness has been detected and cured.|
I will not dwell on this issue. There have been many who have written expertly on whether tie-rods should be affixed below or above the stub axle arm. (The Works have used both positions.) The truth of the matter is that the unique sliding pillar suspension makes bump steer impossible to eradicate and the short R&P tie-rods exaggerate it.