Thanks for sending the pix of the viscous coupler. It definitely didn't look like what I had imagined. I was imagining the VC was similar to the torque converter VC that they use inside automatic transmissions, which is basically an impeller-propeller assembly. This thing is nothing at all like a torque converter, and now I have a better picture in my head about it.
Yousuf Khan
I have got exactly these symptoms on my 2005 Forester 2.0 XT after only 20k miles. The dealer says it needs a new rear axle for 3k pounds but it feels more central to me so I will have to get a second opinion. I like the reversing idea, I only tried figure 8s forwards on grass.
Changing the oil/fluid etc, shuffling/inflating the tyres makes absolutely no dirfference. Carrying a heavy load makes it much worse, presumably because the wheels cannot slip on the tarmac so easily.
Actually, the thought crossed my mind. The fluid viscosity is the obvious variable affecting VC performance, at least over the near term, with shear resistance governing it's long term outlook.
Funky weather over the weekend prevented me from swapping transmissions (Sat, Sun, never got above 22F, with a little snow and freezing mist mixed in; hello . . . still October . . .), but as soon as the weather co-operates I'm going to do so. Gonna need that AWD soon by all indications.
At some point I will pull and clean the bad CD again, and then see if I can some of our Mechanical Engineering/SAE types involved. (They owe me anyway :-)
Well beyond what little I remember from Classical Mechanics in college (been a long time; we were still using slide rules), but probable that a sharp ME can calculate viscosity requirements based upon the VC design, and engine HP.
If this leads anywhere, you guys 'll be the first to know.
ByeBye! S.
Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101
Here's an update on my problem. Finally got it over to the dealership the other day, and we found out what the problem is. The power steering fluid is leaking out, and it's because the rubber seals have cracked on the assembly. The dealer is suggesting that I totally replace the entire steering rack assembly. He is saying that there is no fix for just the seals alone, the whole rack has to be replaced!
Is this true, or is he just blowing smoke up my ...? Replacing the steering rack will cost $1100 including labour, he says.
I was thinking of just topping up the power steering fluid as a temporary fix.
Yousuf Khan
Replacing the rack yourself is not that hard, and would save you hundreds of dollars. If weather won't allow this, then just keep topping it off until spring rolls around. I did mine in about four hours without really knowing what I was doing prior to getting the rack. I think knowing now what I knew then, and being more familiar with the area, I could do it in two or so hours. I used a haynes manual and this site:
FWIW, you can almost always loosen tie rod ends using the following procedure, and it doesn't disturb the alignment settings.
1) Remove the cotter pin, and loosen the nut. Thread the nut back on with the crenelations down, such that the bottom of the nut is flush with the top of the threaded part of the tie rod. 2) Place the flat head of a ball pean hammer against the nut/tie rod, and give it (the hammer head) a sharp wack with a second hammer. Usually, the taper will pop right out.The heavier the second hammer is, the better this works. You don't really need the first hammer, if you have good aim, but if you fail to hit the nut squarely, you may damage the nut/threads.
I don't recall there being any thing else particularly difficult in removing/replacing the steering rack, except that they are usually pretty greasy/dirty (hit the area with some Gunk before hand), and there may have been a couple of the fasteners that were challenging to access. An air impact with swivel sockets is your friend.
Another thing, if you _do_ have to disturb the alignment, either thru removal of a tie rod or whatever, you can put it back pretty close by taking careful measurements from the center of the back of the tie rod to where the threads enter the link, and also center to center across the rack. Duplicate these numbers when you reassemble.
ByeBye! S.
Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101
Looks like that's going to be my solution for now. In another thread I have now mentioned that it looks like the shudder had absolutely nothing to do with my steering mechanism, it was caused by a loose cracked exhaust pipe. Once that pipe was replaced, the shuddering just stopped. So even though the power steering fluid is leaking out, it doesn't look like it was as bad as I thought.
Yousuf Khan
Hi Yousuf!
Yea, I wouldn't tackle the rack job unless/until:
1) The leaking fluid was making an intolerable mess, getting on the exhaust and causing a stink, whatever, or 2) It was leaking to the point where you couldn't keep up with it by topping off the reservoir when you do a fuel fill-up more or less. Power steering fluid is cheap; manual labor isn't :-)ByeBye! S.
On Tue, 27 Oct 2009 22:13:38 -0700 (PDT), YKhan wrote:with
Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101
Any chance you were heating up the center diff with the exhaust leak ? This low speed turn shudder is typical of the viscous coupling getting tight.
My 05 XT shudders at parking lot speed while turning, doesnt seem to do it at all in reverse and its an automatic transmission so it may be a separate issue than what yousef has been having but its similar.
the tire pressure theory sounds preposterous as racers use different air pressures on tracks all the time.
Well, this is a nearly 7 year old thread, and I don't have this vehicle anymore. However, as I recall, the problem turned out be a leaking power steering fluid pump.
It's a little different on 4 wheel drive vehicles, especially full-time
4WD like Subarus. Racers are by and large, 2WD vehicles. Since there are at least 3 differentials and stuff in Subarus, that tire pressure differentials between front and back will get noticed.However, this was not the problem in my previous vehicle's case, it was the power steering failing that caused it.
Yousuf Khan
I had this problem in my 04. Its called torque bind. The clutch valve springs that normally open to let the inner and outer rotations differ during turns are stiff and causing the valves to bind. I fixed mine and there's 2 solutions. You can get a kit which replaces the springs with lighter ones ($$$$$) OR, here's the best one, get some Seafoam transmission oil treatment and change the oil in the differentials. The whole service cost me about $150 and it worked like a charm. That was over 6 yearrs ago and I've had no issues since. Cheap and VERY effective.
If you do some research online you will find others who did the same thing with the same results. I still have my 04 - its a little tank.
Not sure of drive train in the vehicle but had similar problem in RWD Mitsubishi that was fixed by adding a few ounces of an extra slippery additive in a tube from NAPA to the differential case.
I googled this problem which kept getting worse (winter time). A month ago I had checked my air pressure and one back and one front were about 22 lbs . So when I saw this guy's post on air pressure, I felt like a fool, check ed my air again and one front tire was at 11 pounds. I drove away after ai ring up and bingo, all is perfect again. Thanks to this guy that posted, G oogle, and smart phones. I was about to spend hundreds or possibly thousan ds to have it repaired. Jim
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