[We have received so many requests for an article on the preparation of Ford Ten Specials for competition work, such as the races under the new 1,172 Formula, that we asked CDF Buckler, manufacturer of Buckler Special chassis frames and components, to contribute something under this heading. His remarks apply specifically to post 1937 Girling-braked Ford Tens. Naturally, controversy exists as to the best methods of obtaining the required performance from the popular and durable Ford components, especially where engine modifications are concerned, but Mr. Buckler describes well tried methods, which may be satisfactorily followed.—Ed)
Part 1.—Preperation of chassis components
What follows applies specifically to Ford components, but the methods generally are applicable to other makes.
Axles and Suspension.—The aim is to reduce to a minimum the fore and aft movement and lateral movement of the axles. The spring clips (U-bolts) should be checked for tightness. If any spring leaves have been removed, packing pieces of steel (not aluminium) should be inserted to ensure that the spring-clip bars are not bottoming on the front and rear chassis cross-members. The spring centre bolts, which play an important part in lateral location, should be inspected and replaced if worn. The springs should be replaced if they have reached a stage where the ends of the leaves are “digging” into the leaves below. Genuine Ford spring leaves are beautifully tapered, reducing “digging-in” tendencies. The shackle bushes should be inspected, as any play here will give undesirable lateral movement. Tighten the bolts holding the axle beam to the radius-rod. Looseness here is usually accompanied by rusty “drip marks” at the joints—a quick visual check. If the bolt is a tight fit in the axle beam and Ford conical-faced nuts are used, tightening the latter is all that is required. No other type of nut should be used.
As the axle is located positively in a fore and aft direction by the radius rod, its rear mounting is equally important. If necessary, replace the spherical rubber bearing, which is a push-fit over the steel ball. The king-pins, which should be a tight fit in the axle beam eyes, are held in place by cotter-pins, the special nuts of which act as lock-stops. Here again, use no other form of nut. A thick spring-washer is used under these nuts.
The standard lock is ample but may be increased if desired by facing down the mushroom head of these nuts, followed by a check that, on full-lock and from full bounce to full rebound, tyre and wheel do not come closer than in. to any other part of the car. Check both wheels, on both locks. Excessive lock is to be deprecated, except possibly for trials cars.
If necessary, replace the king-pin bushes but do not ream these unless proper equipment is available. It is not possible to attain correct alignment if each bush is reamered separately. The pin may appear a good fit but in use very rapid wear will occur. Heavy steering can sometimes be traced to burrs on the working faces of the axle eyes, stub axles and/or the thrust washer. The washer should, of course, be between the bottom of the axle eye and the stub. Remove any such burrs but do not reduce the thicknesses of the pans. The inner tracks of the front wheel bearings should be a press fit on their stub-axles. If loose, either the races or stub-axle, or both, should be replaced. Centre-popping or knurling should not be employed. The stub-axle nuts should be tightened and turned back until the brake drum revolves freely but without side shake. At this point, check the drum for true-running. A fairly accurate check consists of using a scribing block with pointer against the circular flange near the wheel studs. For a more accurate check mount drum on a stub with back-plate removed and scribing block or clock gauge bearing on both circular flange and brake-lining contact face.
To return to wheel-bearing adjustment, with no play and a truly revolving wheel, any failure of the castellations on the nut not lining-up with the split-pin hole can be overcome by removing a few thou from the back face of the nut. These nuts are hardened, but coarse emery wrapped round a large file will do the job, finishing with fine emery. Inspection of the rear-wheel bearings is by removal of the brake drum. A hub-puller is necessary and, being inexpensive, is worth acquiring. Providing the race appears to be in good condition and the rollers show no signs of damage, the bearing may safely be retained. Its outer surface, in the drum, should be thoroughly cleaned and inspected. A new oil seal must be fitted. This is retained by a circlip. Wear will usually be restricted to the lower half of the axle casing-end, which forms the inner-race bearing surface. Any lip or pitting of the surface indicates wear, probably due to inadequate lubrication. There is no alternative but to replace the axle casing. When reassembling, repack the race with grease. Subsequently lubricate via the grease nipples behind the brake back-plate, giving two or three shots every 500 miles. When replacing drums, check tapers, keyways and keys. If the car has been run with the half-shaft nuts loose, the tapers may be worn to a point where the hubs go too far on their shafts and the brake drums foul the back-plates. Renew worn parts if possible, but if drum is well clear of sides of brake shoes, up to 1/16 in could be machined from offending face of drum. However, worn tapers usually result in the drum running out of true, and loose hubs or worn axle casing ends can be detected by listening for drum rubbing on back-plate when cornering. An oil-sealing fabric gasket is fitted under the hub nut steel washer. It is essential that the slightly chamfered end of the key must face towards the differential and towards the half-shaft. The hub nut must be really tight, and split-pinned. Split-pins should be of correct size. The Ford Motor Co. is making increasing use of self-locking nuts, which can be fully tightened. Use specified types; discard those which can be turned by finger pressure.
(1) Operating tappets and expanding plungers free in their housings.
(2) Rubber dust and water-excluding covers unbroken.
(3) Linings firmly attached to shoes and free from oil and grease.
(4) Rivets at least 1/16 in. below lining faces.
(5) Drums true (see above) and free from score marks.
(6) Shoe return-springs free of rust.
(7) Clevis pins unworn and split-pins sound.
(8) No elongation of holes in clevis eyes.
(9) All bell-cranks and levers approaching but not over tdc with brakes applied.
(10) One-sixteenth to one-eighth inch gap between end of compression tube and shoulder of plunger in “off” position.
(11) Brake rods straight. Bent rods can be dangerous.
(12) No broken strands on cables.
(13) Equal clearance both sides of balance lever in “off” position.
(14) Link (brake pedal balance swivel) with stop lug facing downwards. Dangerous to use in inverted position.
Scored drums are sometimes lightly skimmed (up to 0.030 in) to true up, but slight loss of stiffness is inadvisable for high-speed cars. Special felt bushes, which should be covered with a film of grease, are fitted to the two brake-shoe support pins attached to the back-plate. Their omission will result in squeaky brake operation. After assembly, the pair of bolts holding the adjuster housing to back-plate should be loosened, the expander housing checked for freedom to float in its slotted mounting holes, and the square-headed adjuster fully tightened. Then lock the two adjuster housing bolts. The two nuts holding the expander housing must, after locking, be slackened back half a turn. A double-coil washer is essential under these nuts, which must be self-locking or split-pinned! The floating action thereby given to the expander housings ensures maximum lining contact and assists towards the smooth and powerful braking for which the Ford is renowned.
Final adjustment is by anti-clockwise rotation of square-headed adjusters, which, having been fully adjusted, should now be slackened back two “clicks.” Check for free running. If linings rub, slacken back not more than four “clicks” and readjust after a few road miles. If shoes are not Ford-factory lined, sides of lining may foul drums and need cleaning up with a coarse file. Two or three “clicks” to the adjusters at 5,000 miles is all that should be required to maintain minimum pedal travel.
Steering.—Steering-box and column must be rigidly mounted, nuts split-pinned. Box adjustment is used on the latest steering units to take up play between ball-peg and steering-nut. This is readily visible as a square-headed set-screw with lock-nut. Removal of steering-wheel exposes two large nuts (one a lock-nut) which adjust the column race. Adjust to remove all end float of the inner column. If worn, rebush sector shaft housing. After each adjustment and before the next, check for completely free movement lock to lock, axle jacked-up or drag-link removed. It is advisable to replace steering-nut and inner column if square threads on either are worn, and, if cylindrical bore of box is worn, to replace entire column. For some years now the drop-arm has been fixed to the sector shaft by tapered splines and so long as the retaining nut is tight no play can obtain. Remember to split-pin !
Inspect all ball-joints for wear, replacing as necessary, and fit rubber dust and water-excluding shields. Only previous running in a loose state will have damaged the tapered holes in the steering-arms. Without question, bent or damaged steering-arms (integral with stub-axles) should be replaced and all ball-pin nuts split-pinned if self-locking nuts are not used.
Shock-absorbers.—The mounting of the shock-absorbers should be checked, preferably by removing the “shockers” to ensure no ovality in bolt holes. No play is permissible here or in any linkages. Refill with recommended fluid and if any dead-spot is apparent send for reconditioning.
For soft suspension with large wheel movements, an essential for good roadholding, damper characteristics are important. Small wheel movements require gentle damping, with stiffer effect for large wheel movements, and resistance should be greater on the downward movement of the wheel. Hydraulic dampers are, therefore, a sine qua non. The Ford-Armstrong dampers are entirely adequate.
Chassis.—The first essential is correct chassis alignment. A rough but fairly accurate check can be made by following the car over a very smooth, straight, uncambered road, when it will be visibly apparent whether or not the rear wheel tracks are following in line with those of the front wheels. There should be no pull on the steering under these conditions and car should steer “hands-off” at 15-20 mph. All rivets and bolts should be checked for tightness. Loose rivets should be hammered tight with correctly shaped drifts, not heated, as most of them are in sheer and must fill their holes, which hot rivetling cannot accomplish. A whippy frame will destroy most of the benefits incurred in correctly locating the axles. Ford centre-point spring attachment permits fairly large wheel movements, which, with a stiff frame, is most desirable. The standard frame was not intended to be used for high-speed work when bereft of the stiffening effect of its saloon body. A stiffer frame was, indeed, made for the pre-war Ford Ten open tourer.
All wheels, including the spare, should be balanced and checked for true running with tyres fitted. Tyre pressures have an important effect on roadholding. They should be sufficiently high to obviate tyre squeal on corners but may differ as between front and back tyres. Larger-section rear tyres than front will, of course, reduce early rear-end breakaway tendencies and conversely, larger front tyres will reduce early front-end breakaway when this occurs much in advance of rear-end breakaway.
Before concentrating on engine tuning and gear ratios, cheek performance in standard trim. Speedometer and rev-counter should be checked for accuracy, and stop-watch and Tapley meter will be found indispensable. Note that the time in seconds taken to accelerate over any given. 20 mph-range almost exactly equals the gradient that can he climbed at the average of this speed, ie, 40-60 mph in 6 sec indicates car could climb a 1-in-6 hill at 50 mph.
The correct solution of last month’s Quiz Picture was Semmence Special. The car is the Frazer-Nash base car powered by a rather special AC Six engine with which Whitfield Semmence did so well in sprint events before the war, at Lewes and elsewhere. Incidentally, Mr. Semmence watched his first motor racing since the war when he attended the recent. meeting at Ibsley.
The “Chain Chatter” feature will appear again next month.
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