4x4 Mag - Technical Tips

Technical Tips - July 1999

by John Deaville and Graham Scott

Free-Wheeling Hubs

My Suzuki SJ413 has free wheeling hubs fitted. Can they be left in the unlocked position all the time or should I lock them occasionally.

All free wheeling hubs that are manually operated should be locked occasionally to help prevent them from seizing up. Land Rover's especially as the rotation of the front hub assembly splash feeds the top Realco bush, thus preventing excessive wear.

Wading

What precautions do I need to take when wading in water ? My vehicle is a Lada Niva which I have fitted a Fiat twin cam engine.

First of all look at June's Technical Tips, we explained a little about water proofing the electrics there, so here we'll look at snorkels.. Most 4x4s have the air filter at the front of the vehicle adjacent to the radiator, which is OK if you can generate an effective "bow wave". However, problems occur when the water reaches the air filter. With a petrol engine it should just cut out, however, with a diesel it could do a lot of damage. We would advise that you fit a snorkel, either purchased from a firm specialising in them, or construct your own. This can be achieved using propriety household rain water goods, not the neatest method but it certainly can be effective. Make sure all the joints are sealed so that water cannot be sucked in during the induction process. The section from the air filter to the piping should be of a flexible ducting type securely mounted by hose clips for easy removal. Providing all the seals are tight water will not be able to enter and you can enjoy your wading.

Tyre Choice

I wish to do little bit of off-roading with my Suzuki SJ413 but do not think the tyres are up to this kind of work. Can you help?

First of all it depends on what kind of budget you have set yourself and if you want "serious" off-road tyres or something that will do both on and off-road work. If you want a good all round tyre then go for an All Terrain style, these will last longer on the road and will be quieter than a Mud Terrain pattern. But make sure you shop around, there are plenty on the market including wheel and tyre combinations.

Normal tread pattern fitted to standard showroom specification vehicles are of a mud and snow or "off-road" style such as that in the photograph on the right, which generally are a compromise tyre.

These tyres are suitable for a variety of conditions but when the going is really sticky they will not peform to the same extent as a mud tyre, and you may end up as in the photograph below, completely stranded due to the tyre tread clogging up with the mud and not clearing form the face of the tyre, thereby resulting in a "slick"! The mud-biased tyre has a more open and aggressive tread which cleans away the mud more efficiently thus still presenting a treaded grip to the elements and achieving you more effective traction.

Changing to a mud-biased tyre can increase fuel consumption and road noise, there can also be a deterioration in on-road handling, however, the benefits off-road are significant. Standard 4x4 vehicles fitted with mud biased tyres are completely transformed, they are easier to control over rough terrain. The tyre below is such an example.

Over Size Brakes

I have a Series III SWB Land Rover and I have fitted a V8 engine. Now I would like to fit 11 inch brakes on the front instead of the 10 inch. Is this a job I can do myself ?

Providing you have a little bit of mechanical knowledge this is a conversion you can do yourself. Fitting all new parts, that is back plates, wheel cylinders, brake shoes and drums can be an expensive way of doing it. The cheapest and easiest way is to buy two 109 swivel housings and hubs complete. these can normally be sourced from a supplier of used MOD equipment, changing the complete units is a lot cheaper and quicker. Of course replace any parts which need replacing in the process. Once you have the replacement units its a matter of getting the Land Rover up on axle stands, removing the road wheels, drag link assembly, steering rod and brake pipes. Remove the swivel housings from the axle and refit fitting a new gasket. Refit the brake pipes, bleed the front brakes and away you go ! You'll find an improvement in braking efficiency.

Under heating ?

The heater on my 1989 Trooper does not blow hot air anymore like it used to do, and the temperature gauge only just moves off the cold position unless the engine is really worked hard as when towing. I have been told it could be a blocked heater matrix. Can you help ?

Before embarking on the time consuming (and expensive) operation of renewing the heater matrix let's look at a more obvious and simpler point. Would suggest that you inspect the thermostat, if it is partially stuck open only allow a reduced flow of coolant you would get these symptoms. Inspect and replace the thermostat first.

Overdrive benefits ...

I have just bought a Series III 1979 Land Rover and some where along its life some one has put an overdrive unit on. Before I got hold of it is was taken off, serviced and replaced. Is there any harm in leaving it engaged all the time I am doing urban mileage ?

Overdrive units were only made to be used in 3rd and 4th gear. We cannot see any benefit to fuel consumption leaving the unit engaged all the time, since you will be pulling off in a higher gear each time from stationary.

Basic Off-Road Mods

Having been to a few pay-as-you-play sites I would like to ask for a few helpful hints or ideas of what I may need to do to improve my Lada Niva for off-roading.

As with everything off-road you've always got to be prepared for the unexpected, so take a look at the recovery points first. Make sure you have a good strong recovery point on the rear and one on the front of the vehicle. Most 4x4s will have a "tow hook", but this is not always strong enough to ensure safe recovery when the vehicle is up to the axles in mud ! Most 4x4s have a towing bracket on the rear which will suffice. However, to be 100% safe it's best to buy an aftermarket front and rear kit, or engage the services of a professional engineering firm to fabricate towing points for you. Don't forget you'll also need at least two 12 ton nylon tow ropes, recommend 25ft length.

Towing Points

Although this point has not been generated by a specific enquiry we have received a lot of query into this matter and it follows on from the point raised above by the Lada Niva owner. All vehicles have "towing eyes" as we call them, at least one front and one rear depending on the mnake and size of the machine. These are designed for use when the vehicle is carried on a transported for holding them onto the deck. They can also be used for general recovery by the various breakdown organisations for road side rescue. Take note, there is a vast difference between a tarmac road and a rutted muddy field with perhaps six to eight inches of mud ! These towing eyes are not designed for recovery of a bogged down vehicle, neither is the front bumper for that matter. The physical force needed to extract a vehicle which is snagged by its body and own weight in a mud-hole are considerable and for this reason a specially fabricated front tow assembly is recommended. The rear towing hitch on your 4x4 will suffice, having said that it will be necessary to check the security of all fittings. We will be covering aspects of recovery in the AUGUST issue, however, we must state here that only rope is suitable for vehicle recovery. Stay away from chains and steel rope, and NEVER MIX ROPE with anything else ! If you want specific advice on recovery equipment please send an e-mail to :richard@4x4mag.co.uk