Pictures & diagrams ...
Front suspension TEMS damper control pin. (John Corfield)
Front suspension TEMS dampers. (John Corfield)
Front suspension, 2WD strut
PAS pump. (Oblsud)
PAS system. (Oblsud)
Steering column. (Oblsud)
Steering rack
Steering. Track rods. (Oblsud)
Steering wheel. (Oblsud)
Suspension parts, bushes. (Oblsud)
TEMS Toyota Electronic Modulated Suspension (Obls)
Wishbones, bushes. (Oblsud)
During the warmer weather I was driving around Bristol with the windows open and noticed a bit of a clattering coming from the front suspension when hitting bumps. This noise turned out to be the lower part of the upper damper tube, which had rusted completely away and had dropped to the base - imagine a pair of knickers around someone ankles and you have a perfect picture of my front dampers! So off to Toyota I trotted and paid out £235 for a new pair of dampers that arrived in a couple of days. I took a quick look at the top mounting tube to satisfy myself that they were TEMS compatible and, although I didn’t know what to look for, I was happy to see a small flat-sided pin inside the hollow top tube (which also had two parallel flats on its outside).
Fitting them was easy but I had been worried about how the TEMS actuator located and worked - particularly whether the pin had to be preset in any way. I removed the first damper very carefully so as to note exactly how things had been fitted, and this was a must for the top fittings, which were rusty, needed to be prised off and must be refitted correctly (the actuator itself bolts to a guide plate that locates on the top tube flats to line it all up). I also found that the bottom rubber mounting bush on both dampers had worn such that they were rattling on the steel inner tubes. Having satisfied myself that replacing the dampers was well overdue purely for curing my rattles alone (!) I then proceeded to experiment with the old and the new ones.
The first thing I was pleased to find was that the TEMS pin didn’t screw in or out, it just rotated around and around so the setting up was purely to decide the direction in which the flats on the pin should point. I then tried to compress the dampers and found that I could do it fairly easily by leaning on them when vertical. I timed how long it took for the damper to return from fully compressed to fully extended and came up with a surprising (but very logical result). With the flats on the pin parallel to the flats on the top tube (it’s obvious when you’re looking at them) the old damper took 30 seconds and the new one took 40! Giving the pin a quarter turn, so the flats on the pin were at right angles to the flats on the top tube gave 8 seconds for the old damper and 11 for the new. Giving the pin another quarter turn got me 30 and 40 again and, finally, a last quarter turn gave 8 and 11 again. I therefore had to conclude that having the pin parallel to the top tube flats is the “soft” setting and at right angles is the “hard setting”. I also concluded that my old dampers were very definitely past it!
During the refitting I did discover one more useful tip, which came about because the alignment of the top tube seemed peculiarly slightly different on each side (I reasoned that this was because the pin alignment does not have to be precise, but this is just an educated guess). I was concerned that one actuator may not be working so I carefully put a screwdriver into the driving pin slot (again, obvious if you look at it) and found that it turned a quarter of a turn and no more. I then realised that when you switch the ignition on the TEMS suspension is set to “soft” so (the drivers side is the easiest to do this on) I watched the actuator driving pin whilst I switched on the ignition and I was pleased to see it move back a quarter turn. The tip therefore is to turn the actuator pin either way, switch on the ignition and see if it moves. If it does then all is well, if it doesn’t then repeat with the pin turned the other way - if it still doesn’t move then all is not well. In addition, and if the actuators are working, by switching on the ignition you will have reset the actuator and you can then work out where the flats on the damper TEMS pin should be set to engage properly (easy with a small mirror). As far as I could see, and bearing in mind that the pin in the damper top tube moves very freely, the pin and actuator slip into engagement very easily so you do not need to worry about being too exact.
The proof of the pudding was then to test drive it and I can say without doubt that my Townie has been transformed when dealing with the awful Bristol roads. The banging and rattling have all gone, as has a good bit of the bouncing up and down. The Townie now sounds and feels ‘secure’ and I can’t wait to try it on my 45-minute country road and motorway drive to work. The one last thing I aim to do for the dampers is to buy new top mounting parts; rubbers were supplied but not the metal brackets/plates and as they were badly rusted I don’t feel good about leaving the old ones on. Fortunately you don’t have to remove the dampers - you just undo two small bolts to remove the TEMS actuator and one top nut to release the bracket/plates.
I would add one final word in general about the Townie suspension, especially as I have driven it with all the interior trim out - and anyone who has lifted out a middle (swivel type) Royal Lounge seat knows just how much weight has been removed! Everything is a compromise and if you bear in mind that the Townie suspension has to cope with a weight varying from just the driver up to 8 passengers plus luggage then it is hardly surprising that the suspension seems ‘hard’ or ‘harsh’ when empty. Try driving a commercial vehicle when empty and when fully loaded and you’ll appreciate how well the Townie suspension deals with the range.
Having satisfied myself that my TEMS is working I will also add, as a final bit of information, that my TEMS switches from soft to hard when I apply the brakes (except at VERY low speeds) and also when it does what I call ‘lurching’ - for example it will switch to hard when I enter a corner during the initial roll but will return to soft once the body roll has settled, even though I’m still cornering. If I come out of a corner and straighten up sharply (as an experiment) the suspension again goes hard during the ‘lurch’. I’ve noticed that a few people have criticised not being able to differentiate between soft and hard and I also do not notice a change - but I put that down to some pretty smart engineering and congratulate Toyota on applying a bit of their magic. After all, the way we recognise good motor vehicle engineering is to say “You don’t even know it’s happening - the car does it all itself!” QED I believe folks!
John Corfield, 21 July 2002
Footnote:
When I replaced my front dampers I had to use the old (badly rusted) top mounting plates (2 per side) that line up the damper and the TEMS actuator. I bought new ones last week (all of £6) and fitted them today in about 15 minutes a side start to finish. I hadn't realised how bad the old ones were and the actuator alignment was much better after fitting them. I would strongly recommend to anyone who replaces their front dampers to spend the extra few pounds and get these plates - they don't come with the dampers!
John Corfield, 22 September 2002