Hi, Does your transmission lever oscillate as you brake? Does your brake pedal pulse underfoot? These problems are commonly caused by a thickness variation in the front brake rotors especially if it worsens when the brakes are hot. Having the rotors machined, preferably on the car usually fixes it. You need to have enough thickness remaining on the rotors to do this otherwise you are a up for a another set. The usual reason this problem occurs is some rock ape did up the wheel nuts with an air gun and over torqued some of them. The correct torque is 103 Nm or 75 ft lbs, many tire shops routinely use much more than this 150 Nm being commonly used as a "universal torque" via various dodgy torque limiting attachments many of which are near useless. 150 Nm suits a Landcruiser fine but is much too high for a Soarer.
If you have one or two front wheel nuts done up more than 25 % over torque this distorts the brake rotor enough to cause uneven wear. This is especially a problem on standard V8 Soarers with the smaller rotors. Insist on the use of a torque wrench and if they won't, re-torque them yourself later (a torque wrench costs less than getting your rotors machined). I have measured wheel nuts 200% over torque along side nuts finger tight after wheels are fitted in a workshop. This will wreck the front rotors within a few thousand kilometers.
Transmission and engine mounts if worn will make the transmission lever oscillate more when braking. The thickness variation can be made worse by a sticking caliper or a brake hose that has gone soggy and is letting the pad drag excessively. I would try machining the rotors first. The engine and transmission mounts unless already changed will probably need doing as well but they will not fix the judder.
The only other cause I have ever seen for this is worn lower rear axle carrier bushes, but this is more common on LS400's than Soarers. The correct parts are available for the Supra and fit the Soarer perfectly. The identical Soarer bushes only come as part of a new complete axle carrier and you then need a new wheel bearing as well. Think about a thousand dollars and most of a day. Changing the axle carriers is a much much more expensive proposition and unless you already have a problem with rear wheel bearings, to be avoided.
The bushes PN: 48725-14070 are about $50 each plus 2-3 hours to change them at a competent suspension shop. Do not watch them do this job unless you enjoy distressing mechanical gore. Changing them is not a job for the faint hearted. The brake dust covers will need to be bent out of the way to press the old bushes out and the new in, there is no other practical way.
Replacing the transmission mount and engine mounts when you can afford it is worth doing anyway and don't worry about the lower rear axle carrier bushes unless they are shagged. There are about 22 other rubber bushes that usually age quicker on a UZZ30 Soarer, 25 on a UZZ31 and an unfathomable number on UZZ32's. I changed all of them on my car in one go using VFT bushes and Toyota parts where available and then did the rear axle carrier bushes some months later. The results of changing the lower rear axle carrier bushes felt like going from slightly under inflated tyres to the correct pressure. Only about 5% of the improvement changing everything else first had brought about. A Soarer with all new VFT suspension rubber and new struts is an absolute revelation. They handle and corner incredibly well without harshness or an unpleasant ride.
To sum up, rotors machined and check out sticking calipers and tired brake hoses is the fix more than 90% of the time. Correct wheel nut torque will usually stop it happening again.
Tuesday, July 26, 2005 - 04:09 pm, by: Don Bagnall
I've found ALL Roger's posts to be absolute gems both in depth of information, and presentation.
I STRONGLY suspect that when his previous posts are retrieved from the old ALSC server, they could be incorporated into the "Useful Info" department as permanent reference items.
Ian, I do as it happens. One Mike Abbot and although when we sang as a duo we could have been described as comically bad, he does not resemble Lou Costello and is Soarerless. I on the other hand do resemble in circumference the more substantial comedic gentleman star of monochromatic cinema you are thinking of and do own a Soarer.
The good news is I am no way related to a certain other Costello who stars on a different stage as a fiscally fixated feisty and frustrated pretender to the throne. I do however have the costello.com.au domain in Australia and hence get a certain amount of misdirected email. His popularity and that of his policies seem inestimable with the general public who on the whole feel he should keep his hands in his pockets more and out of theirs.
You I hope are not related to Iain of the hyper-complex multiphase computerized valve controlled twin turbo fantasy. If this makes no sense to you ask someone who was around during the great LSOC/TIF bust-up or who knows about the "you can't change the bushes you must change the whole lower control arm or you are all going to die" controversy (a religious argument about ball joints that encompasses neither logic or engineering)
Roger, such excellent posts on Soarers - many thanks. I might move or copy some of them to a Read Only area at some point to make them easier for people to find.
Wednesday, July 27, 2005 - 07:10 am, by: Ian Johnston
Roger, I am glad for you that your not related to the "polly" Costello. They say you can pick your friends, not your relations. I dont think I am related to the mentioned English gent, although my heritage dates back to 16th century Scotland,so anything is possible.
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