MGB Tips – Steering:
MGB Steering “weight”
I recently bought a “quick ratio” rack and pinion for my MGB. The standard ratio for a chrome bumper MGB is already reasonably quick at 2.93 turns lock-to-lock. The heavier, rubber bumper MGBs have 3.57 turns lock-to-lock, which results in slightly more elbow action in tight bends but it reduces the exertion needed to turn the steering wheel. This is despite the additional weight of their heavier bumper bar ahead of the front wheels, combined with the smaller, factory fitted 15.5” then the later 15” diameter steering wheel which also has the effect of increasing the effort required to turn the steering wheel.
The quick ratio rack and pinion that I purchased is listed at 2.6 turns lock-to-lock, which provides a slightly more go-kart feel of turn-in at corners, while not significantly increasing the effort required to turn the steering wheel. I can report that I’m very pleased with this latest modification if anyone else has considered it. The steering action is more “sudden” but you soon get used to it and enjoy it.
By comparison, the earlier Mazda MX-5 has 3.12 turns lock-to-lock for the manual steering but when power assisted it uses a quicker 2.8 turns rack and pinion, showing how Power Assisted Steering (PAS) can sometimes be beneficial.
Steering “weight” is a common complaint of MGBs today, especially for people who climb out of their Modern, “power-assisted everything” car and get straight into a Classic.
This is a result of five things that I can identify;
1) Radial instead of Cross-ply tyres.
Of course, I’m not suggesting that MGB owners should make a retrograde step and revert to cross-ply tyres, if you can even find them in this size, but Cross-ply tyres were what the MGB steering and suspension was designed to use.
The evolution of tyre technology over the past 50 years has without doubt been one of the greatest improvements for the automobile.
If it was possible (and if they’d allow me) I’d love to fit MGB 14”x4” wheels and original cross-ply tyres to the very fast SA – MGCC members’ Lotus Exige and Mitsubishi Evo to learn how their circuit laps times compare against the modern tyres that they use now.
For all of the benefits of modern tyres, their larger contact patch with the road surface and their higher “slip angles” both act to increase the effort required to make them change direction.
This is exacerbated when larger, soft-compound, semi-slick tyres are fitted, like the ones I use at the track on my MGB.
2) Under-inflated tyres.
Tyre pressures should be checked on a frequent basis anyway, so I wouldn’t expect the MGB of any car club member to have incorrect or uneven tyre pressures.
In my opinion, the pressures in the owner’s manual are too low. My own preference is to have my tyres inflated slightly higher than the factory setting. Remember also that early cars had stiff side-walls on cross-ply tyres which is why for early MGBs the factory recommends just 21psi in the front tyres and 24psi for the rears. Later model MGBs were fitted with those new, fangled Radial tyres which needed more air in the tyre to stiffen the sidewall a little, until the tyre manufacturers were able to increase the sidewall stiffness as tyre technology improved. Tyre pressures are subjective and each driver has their own preference, especially as altering front to rear tyre pressures can have an understeer or oversteer effect, but my choice for the road is to use 28-30psi Front / 30-32psi Rear. This allows reduced steering effort while not detracting too much from the ride comfort of the car.
3) The large castor angle incorporated into the MGB suspension geometry.
A car’s front suspension Castor Angle is the angle, off vertical, between the top and bottom suspension joint, which is the top and bottom of the Kingpin on MGBs. Think of a castor wheel on an office chair. More Castor improves the vehicle’s straight-line stability and it quickens the rate that the steering wheel returns to the straight ahead position, reducing the need to manually unwind steering lock after a tight turn.
Many modern cars have a castor angle of 7° or more, but they have power assisted steering to overcome the manual effort required to turn the steering wheel. It’s not clear why the MGB was designed with such a large castor angle of 7° but it certainly helps with the self-centring action. The steering wheel of an MGB snaps back into the straight ahead position very quickly if the driver’s grip on the wheel is released when exiting a corner. This attribute is great for spirited driving or motorkhanas but it’s just another thing to make winding in more steering lock even more heavy in an MGB.
There are a couple of devices sold by MG specialists to reduce the castor angle to just 4°, the same angle as it is in an MGA. It takes plenty of effort to fit these devices and they need the steering rack housing to be shimmed correctly to allow the correct angle at the steering column universal joint and to have car’s wheels re-aligned after it’s been fitted. I’m possibly going to use the Frontline brand device on my car, to help reduce the force to turn the steering wheel, at parking speeds, particularly after fitting the quick ratio steering. I’ve bought a kit but I’m not quite sure yet if I’ll use it.
4) Smaller diameter steering wheels.
OK, so the 16.5” steering wheel is the factory fitment on early MGBs but in my personal opinion it makes you feel like you’re changing course on the “City of Adelaide” clipper ship, and that’s after you’ve managed to slide your legs underneath the rim of this rather large steering wheel. Later MGBs had 15” diameter steering wheels which were more user-friendly, especially with the altered rack & pinion ratio to reduce the steering effort. This is all about preference; even the factory acknowledged that a reduced diameter steering wheel was an improvement but I’ve taken this even further on my Yellow B with a 12½” steering wheel. This wouldn’t be recommended for most MGB owners but it suits my driving style and I accept the trade-off in increased effort to turn the car from left to right at parking speeds, especially with wider tyres and this will be worse still when I transfer the quick-ratio steering assembly to this car.
5) Lack of maintenance.
The steering rack must be checked to make sure that there are no splits in the rubber gaiters at either end of the rack assembly. Damaged gaiters allow the oil (yes oil, not grease) to leak out and for rain, dirt and debris to get inside which exacerbates the wear on internal parts even more than losing the lubricating oil. Also, the kingpins must be in good working order and greased every 3,000 miles. Worn kingpin bushes will dramatically increase the effort needed to steer an MGB, as will kingpins with dried out grease that hasn’t been refreshed.
MGB Tip – Steering Assembly Lubrication:
A little while ago I bought in some used MGB steering assemblies from overseas because apparently every 2nd hand MGB rack & pinion in the country has been used to convert all of the many MGBs imported from the USA to RHD. You can purchase new, Argentinian-made MGB steering assemblies but I’ve read mixed reports about them, although I’m sure they’re a good option for many MGB owners who aren’t concerned about originality. It should be noted that the Argentinian units use grease for lubrication which I don’t like, particularly for rack and pinion steering.
It’s important to acknowledge that the factory specified ⅓ pint (190ml) of SAE90EP hypoid gear oil (Diff. oil) to lubricate the steering rack assembly. The beauty of this is that during use, the oil is washed over the entire inside of the steering mechanism. When turning in one direction the bellows action of the rubber gaiters forces the oil across the rack to the other side until the steering is turned in the opposite direction. Apart from protecting the entire steering assembly, the movement of the oil transports any particles of foreign debris or metal particles worn away during contact of the moving parts, to settle between the ridges of the rubber gaiters, away from the internal mechanism. It’s important to replace the gaiters as soon as any splits occur and to top up any lost oil. The correct clamps should be used to secure the gaiters and not cable ties. Obviously; they’re not cables, so using cable ties instead of the correct clamps means that they are less likely to grip with sufficient force to stop oil from leaking out, even though cable ties will probably suffice if grease has incorrectly been used.
I’m sure that many well-meaning MGB owners have used a grease gun on the “grease” nipple fitted to early MGB steering housings. In fact, this is not a grease nipple, its purpose was to allow the correct dose of OIL to quickly be injected into the new steering assemblies at the factory. This feature was soon dropped from production, probably due to it being used for grease instead of oil by owners and even Dealers.
Wheel bearings occasionally need to be repacked with grease, Kingpins and Universal Joints have grease applied under pressure with a grease gun to expel the old, contaminated grease. So how would you remove metallic wear particles from a Steering Assembly if it was packed with grease? If a blob of grease is dropped in when removing the top cover from the housing, how does that grease get to the areas where it’s needed?
If necessary, oil from the steering assembly can be drained by releasing the larger clamp and pulling the gaiter away, then work the steering wheel from lock-to-lock with an oil drip tray underneath. Fresh oil can then be poured in with the top cover of the housing removed and the Yoke inside hooked out.
Having now fully dismantled and rebuilt several used MGB steering assemblies, I have first-hand experience of how ineffective grease is to lubricate MGB steering. Apart from needing so much more time to clean out old grease from the rack housing and components, the racks that had oil in them were in much better condition.
Oil was coating the entire surface of all internal components, there was much less wear from friction, there was no corrosion and I could clean the parts with one 15-minute session in my ultrasonic cleaning tank.
The racks that had grease on them were a sticky mess. After no doubt a very short period of use, the grease that had been used in them was pushed away by the steering action, leaving the parts that need lubrication mostly dry. The dried out grease needed to be wiped out with rags and an engine cleaning brush before giving them 3-4 ultrasonic sessions to get the last of the gunk out from inside the housing. The greased assemblies showed significantly more wear of all internal contact surfaces, probably because grease captures microscopic wear particles instead of washing them out of harm’s way like oil does. This exercise has provided enough proof for me about which is the correct type of lubrication to use in MGB steering. Oil; the same lubricant that the factory specified.
Curiously, many of the “wear” components that should be replaced when rebuilding an MGB steering assembly are no longer available as new parts. This is frustrating for me but at least it shows how well designed and manufactured this item is that it can survive for so long, while usually neglected, and still not experience mechanical failures, just some inevitable wear. The rack and pinion gears from my used assemblies were all in excellent condition, not even any visible wear in the straight-ahead position as might be expected when this is where the teeth are meshed for most of their lives.
One point to anyone contemplating replacing/rebuilding their own MGB steering assembly, the prices that I paid for all of the available parts (excluding the “quick ratio” rack that I used) totalled well over $400, from Track Rod End to End. It took about an hour to completely strip the assembly, another hour to clean it, a further couple of hours to shot blast the exterior of the housing and repaint it in Chassis Black and a fifth hour to reassemble the unit. Admittedly, I used more new parts than I strictly needed to, just because I already had them, but consider these costs and hours of labour when deciding to purchase an off-the-shelf new or “reconditioned” steering assembly for your MGB. There are several overseas MG suppliers offering so called reconditioned rack assemblies for much less money than just the cost of new parts that I used. I’d also bet they fill them with grease instead of oil so they can save a few dollars by using cable ties on the gaiters instead of the correct steel clips.
I hope my research and experience on this subject has been helpful to others.
Remember; once it gets contaminated with wear particles, or with dirt entering through torn gaiters, using grease in an original MGB steering assembly is almost like using valve grinding paste. The photo above of a dismantled MGB steering assembly show what a disgusting mess grease causes inside them.