Vauxhall Cavalier/Opel
Vauxhall Cavalier 4x4 - Do's & Definitely Don'ts
Open a printer friendly .pdf file for 'TXB do's and dont's'
  • The advice given here is derived from the author's own experience of a failed transfer box which was stripped and rebuilt. This is how the author defines looking after what is not the strongest transfer box in the market.
  • No responsibility is implied or accepted for this advice, but it does continue to serve the author well.
Definite Don'ts
Reasoning
   
  • Never apply the handbrake while driving the car.
  • Under normal driving conditions the transfer box is engaged, except while and only when the brakes are applied over 16 mph.
  • If the handbrake is applied, without the foot brake, the stress applied to the viscous coupling and txb clutch is anything up to enormous.
  • In an emergency situation, try to have the presence of mind to apply the foot brake as well as the handbrake (disengages the txb), failing that pray you get out of the emergency with or without a working txb.
  • Don't start & drive the car immediately
  • If the accumulator has lost any of it's pressure, either by operation of the brake pedal with the ignition on or, the car has been standing for more than a day, starting the engine and immediately driving off can cause TXB clutch slippage, with resultant wear. It is always good practise to start the engine and wait 3-5 seconds on every occasion and then drive off. If the accumulator is below pressure it is possible to detect a slight increase in the tick over revs when the recharging is complete. Then it is OK to go.
  • Don't drive the car like a maniac.
  • The txb will get you in the end.
  • Don't run a lowered car without adjusting the camber & toe angles
  • Lowering the car without adjusting the camber angles, effectively reduces the diameter of the rear wheels. This is the same as running with more than 2mm tread depth difference between the front & rear wheels. The result will be a damaged txb (overheating) quite apart from the accelerated wear of the tyres (inside edges). Camber bush kits are available and the camber should be restored to GM's stated values.
  • Don't fit the spare wheel without pulling fuse 19
  • If you fit the spare wheel, as a roadside emergency, you must remove fuse 19 to disable the transfer box. In addition, the handbook tells you to not drive faster than 50 MPH. Fitting a wheel that is not part of the set should only be considered as an emergency measure. The wear pattern will almost certainly be different, which is the same as running the car with more than 2mm tread difference between the front and rear wheels. Failure to comply will almost certainly damage the txb. (See 'Tyres' below)
Do's
Reasoning
   
TYRES  
  • Always fit tyres as a set of four
  • It is essential to keep all four tyres very close to the same diameter (within 2mm tread depth or 15mm running circumference front to back) and with the same characteristics. This means you change the whole set. If one tyre becomes defective e.g. a blow out or damage, then the set of four must be changed - (see the vehicle handbook). They must also be of the same make and rating.
  • Failure to keep all four tyres the same will strain the mechanics of the txb, The txb clutch is put under additional strain to slip and wear the lining material or, in extreme cases, to cause the lining material to break up. (It's glued to the metal plates). At the same time the viscous coupling is also under additional strain, having to continuously respond to differences in diameter, front to back. This will be a constant force causing the build up of heat, which when hot enough will cause the txb to go over temperature, and in extreme cases it all happens too quickly and the box can go into 'meltdown'.
  • A good indicator that all is far from well is mysterious 'thumps' at certain times when driving.
  • Txb £2500 off the shelf - set of 'Z' rated tyres £300 - £500. QED
  • Change wheels front to back every 1500 miles.
  • It is quite reasonable to expect the front and rear wheel sets to wear at different rates and in different ways. The rear tyres tend to wear on the inside edge, easily missed when conducting 'kick and look at what you can see' approach.
  • The higher rated tyres are also directional. (Arrow on the casing). Change the wheels front to back to maintain the rotational requirements.
  • BE RELIGIOUS about the wheel changing, it is essential to maintain similar wear front to back (within 2mm). Failure to achieve this will cause the txb to overheat with sometimes disastrous consequences.
  • It is also reasonable to change the directional tyres on the rims to even out the wear from the driven nearside tyres. ie. Have the nearside tyres swopped out to the offside rims thus maintaining directional requirements.
  • If the tyres do not have a directional arrow then complete wheels can be changed from the nearside to offside.
  • Regularly check tyre pressures
  • Driving round on unevenly inflated tyres has the same effect and accelerates wear.
TRANSFER BOX OIL
  • Change the txb oil annually
  • GM recommend, for those vehicles using the synthetic oil, that it is only necessary to top up the oil as required.
  • The author says a new txb costs £2500 off the shelf, £800 rebuilt (with second hand parts) or up to £500 off the shelf second hand.
  • 600 ml of synthetic oil costs about £7 - QED.
  • In addition, it gives the user a chance to check what's in the old oil. E.g. dirt, bits of txb clutch lining, metal swarf etc.
  • The early boxes apparently used DEXTRON II ATF fluid. - Its principally the same box - always use the synthetic oil.
  • The author always uses the GM oil just in case something goes wrong and GM became involved. (Good Luck!)
  • If the box seizes in service, it will usually be because of bearing failure or a gear tooth breaking. Either way a not too big a piece of steel entering the gear train will, in extreme cases, literally split the txb casing. Another good reason for changing the oil regularly and closely inspecting what comes out, if only to spot early signs of potential failure.
BASIC FUNCTIONAL CHECK
  • This is quite a good test, the difficulty is that you do not necessarily know what a good box should sound like when it is forced to disengage - 'the thump'. If you follow the guidance in the workshop manual, and are only lightly accelerating out of the corner the thump is heavy.
  • The first time this happened to the author, because the temperature sensor was intermittent, he thought he had dropped a rear wheel into a manhole type hole with the lid say, 3" - 5" below the surface, but without the body lurch.
ACCUMULATOR  
  • Change the ACCUMULATOR at 54k miles or 6 years
  • If the accumulator bulb does not have a white ring, clearly visible, then change the bulb immediately, unless it is a Cav16 bulb with a plastic label attached. Original accumulators without the markings are faulty and were a recall item, which has now time expired. Accumulators with white dots preceded the white ring model and are very likely time expired and should also be changed.
  • The accumulator bulb must be changed every 54k miles or six years, which ever comes first. If you do not know the history of your vehicle then follow the procedure in the workshop manual for 'bleeding the hydraulic system' and check how many 'whooshes' its takes to empty the accumulator. GM calls it a pressure vessel and it costs £99+vat. The instructions say the brake pedal should be applied at least 25 times to empty the accumulator, much less and the author recommends a change. It is still £116 against a potential £2500, or £800 etc etc etc. QED
  • Experience with a new Accumulator has shown that a cold engine run for a few minutes should achieve 25 whooshes but the same accumulator after a run, and with a hot engine, will return in excess of 30 whooshes.
  • The Accumulator' change procedure is available from the main menu above.
POWER STEERING OIL
  • Periodically and regularly check the Power Steering Oil reservoir level
  • This is a service requirement and must not be overlooked. The oil is required to operate the transfer box, as well as the steering. If the level falls too low air can enter the system, requiring it to be bled, and/or the txb ceases to function properly. The procedure for checking is in the workshop manual.
  • If the Power Steering Oil level suddenly drops, investigate immediately.
  • If the steering reservoir oil level drops the power steering pump may start to whine and gurgle with the engine running. Using the workshop manual procedure, check the oil level in the reservoir. If it has dropped, say out of sight, then follow the procedure to bleed and fill/top up the system.
  • At the same time withdraw the txb mounting bolt, used for oil level checking in the txb and check for the box being over filled. If it is over filled, probably by the amount you have used to top up the system then you have almost certainly got terminal 'pressure plate (or ram) seal' failure. It is now a case of removing fuse 19 to disable the system. The car can still be driven, but it will be without 4WD and NO fluid pressure is applied to the txb pressure plate resulting in further loss of steering oil. (This should be considered an emergency procedure because over a period of time the wrong type of tyre wear will develop).
  • Do carry a bottle of DEXTRON II in the boot for such a failure away from base.
  • The total and immediate failure of the seal will result in a dashboard 4x4 tell tale and the loss of fluid. Oil will be expelled from the txb breather/filler, behind the water header tank. The roadside cure is the same, as above, but without the txb oil level check, you know it is overfilled. (Fuse 19 must be removed to maintain power steering and the level replenished).
   
   
January 15, 2004