Here’s everything you need to know about making your automatic transmission last longer when off-roading and towing.
Automatic transmission servicing is often overlooked these days, especially in modern motoring. Indeed, most manufacturers have deemed the automatic transmission to be a non-serviceable or not necessary item to be serviced under ‘normal’ driving conditions.
But what are normal driving conditions? Well, the problem is that most of ‘our’ driving off-road and in the outback is well outside the boundaries of normal driving. Indeed, where we drive our vehicles, if you run off the Owner’s Handbook definition, is generally referred to by car makers as severe operating conditions – operating your vehicle in rough, sandy, or muddy and snow-melted roads, beach driving and driving on dusty roads.
What will really surprise you is that yet another definition of severe driving conditions is stop-start city driving. So, a short trip running the kids to school and back and daily shopping trolley duties would be classified as severe driving conditions. Temperature is another component of severe driving condition. Extreme freezing temps and extreme heat can have a huge impact on how long the fluid in your automatic transmission will last. Towing is considered another severe operating condition, as towing a trailer generates more heat and strain on your transmission and its fluid.
But by having your automatic transmission serviced regularly and tweaking how you’re using it will ensure a long service life, so how often do you need to service the auto in your vehicle? That really depends on the manufacturer, but we’d recommend cutting the service schedule in half for those of us who spend a lot of time touring or towing. So, if your handbook suggests the transmission will be looked at at, say, 40,000km, you’re better off getting it checked at 20,000km.
Indeed, most mechanics and automatic transmission specialists recommend you have your automatic serviced every six months or 20,000kms. The reason for the date in months is because most oils will begin to lose their additive protection after six months; this means the additives the oil companies mix in the oil to make that type of automatic transmission fluid will start to lose its ability to do its job. This means the oil/fluids lose their ability to cope with heat and start to lose their lubricity leading to wear and tear. A tell-tale sign your transmission fluid has gone bad is when it turns from a pretty pink colour to a dark red burnt or just black colour. If your transmission has a dip stick it’s easy to check the colour of your automatic transmission fluid, make a habit of checking it once a month.
The servicing of automatic transmissions and automatic repairs are nearly always performed by automatic specialists. Even new car warranty rebuilds are nearly always carried out by an automatic specialist, because of the tools needed and ongoing training that is necessary to keep up with all of the latest models and their idiosyncrasies.
Don’t want to use a specialist? Well, you’ll need to check with your own mechanic, if servicing outside the dealer network, whether they’re able to perform a full pan-off and filter service of your transmission. The reason we mention pan-off service is because when all the fluid is drained, and the pan is removed it allows an inspection to be done on the filter and bottom of the pan. What your mechanic will be looking for is any traces of metal fillings. If there is any they will be stuck to the magnets in the bottom of the pan and in the filter inside the transmission. Metal fillings will be an indication of something going wrong in the transmission and if your mechanic’s not sure what it is, get a transmission specialist to check it out ASAP. The last thing you want is to be stuck out the back of beyond with a buggered transmission when an automatic specialist could have diagnosed and repaired the problem before you embarked on your adventure.
What else can you do to improve the life of your automatic? Most automatics will have one fitted as standard, but if you do a lot of towing it will worth looking into an aftermarket transmission oil cooler as either a replacement or to work in tandem. These things are essentially a small radiator for your automatic transmission and are generally located in front of the radiator and behind the grille where it can get maximum air flow over its core.
Some factory fitted auto coolers are very small in their size and were just fitted to keep the oil cooled under normal light load conditions. These small coolers are not suitable for heavy towing conditions or even just heavy touring loads. So, in this case fitting another auto cooler in line with the standard one will double the cooling. Testing has found that when oil coolers are used the oil temperature can drop by up to 13 degrees. The cooler the oil stays the longer it lasts and the longer the service life you will get out of your transmission.
It’s worth noting that, on the whole, vehicle makers designed their vehicles for time-to-time touring and towing. They prioritised building transmissions to have smooth gear changes for a more comfortable on-road experience. However, when you tow or carry heavy weight the strain on the transmission increases and the gear shifts can end up feeling a little slurred. The strain of towing generates incredible heat build-up in the transmission, not to mention the excessive wear that is caused internally from the slipping between gear changes.
So, what can you do to beef up your transmission for towing and touring off-road? Well, you can talk to a transmission specialist about modifying the transmission’s valve body. Not only will it potentially increase the life of your transmission by 150,000 – 300,000kms, it will also make for clean, quick and crisp gear changes. That means no more flaring between gear changes. The cost of a valve body upgrade is around $500-$1000 plus a service of around $250 including oil gaskets and labour.
The valve body is the brain of the transmission. It controls all the vital functions. It’s also the most complex component in the auto transmission. It directs hydraulic pressure to the clutches and bands at the correct time to initiate up shifts, down shifts, selects reverse, talk convertor clutch lock up, controls shift timing and quality of shifts. It also controls correct hydraulic pressure to the auto transmission oil cooler, as well as the lubrication circuit. So, when your auto transmission specialist modifies your valve body to compliment your increase in extra weight of towing, or for carrying a heavy load, it will involve increasing the line pressure and increased “clamp” on the clutches.
In a manual transmission, it’s the same as fitting a heavy-duty clutch with a heavier pressure plate spring to stop the clutch slipping under extra loads. This increased line pressure will raise the clamping pressure under load and at full throttle by up to 40 per cent. Because of the higher line pressure, auto fluid is moved more quickly through the oil cooler and lube circuit, keeping the oil cooler, which in turn keeps your transmission lubricated and the oil lasting longer. This also results in quicker, crisper shifts at higher engine RPMs and still nice clean low RPM shifts. This mod is a must for anyone doing a lot of hard work with their automatic transmission.
Last but not least, make sure you’ve got the ‘correct’ transmission fluid and oil for your transmission. There are many different types of automatic transmission fluids to suit different models of transmissions and using the wrong one will cause transmission failure. Oh, and you’ll only ever need to top up transmission fluid if you have a leak…and your transmission should never have a leak, okay.
So, there you go, hopefully these tips will help you get a little more life out of the transmission in your 4X4.