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MG TD TF 1500 - Leaky front shock shimmy
|Hello I'm another new member been living around the edges here. 54 TF. Wish I had known about this site before I bought my car. I was lucky though.|
Did not want to hijack Richard Olson thread.
I have a right front shock that leaks fluid and I refill every couple months. If I don't I get a vibration shimmy around 55 MPH with a lateral kind of feeling. NO feed back in the steering wheel. I have installed new bushings, distance spacers, mounting bolts and tie rod ends. I have found that I need to carefully keep my tire pressure at 24/25 psi to reduce (but not eliminate) the problem. Tires are new Vredisteins (they go square over night). I have noticed a rear end "wiggle" at times that shifts me left a little when decelerating. I've been trying to think this through on my own but gave up and thought I'd throw myself onto the collective wisdom of the group.
|Wire or steel wheels?|
Very few wheels are perfectly straight after 50 years... two of mine are bent enough to create the shimmy no matter how well balanced the tires.
Drums that are not torqued enough and or have worn splines can give you your shimmy.
If you notice your car's direction changing (usually/always) from the rear end, your U bolts need tightening....(one side of your rear axle is moving)... after changing my diff to 4.3, I noticed I could almost change lanes by taking my foot off the gas quickly....little bolt tightening fixed that.
|Welcome aboard Peter. Send the front shock off to Peter at Worldwide Auto Parts in Madison, Wisconson for a rebuild. Warrenteed for life. The "rear steer" is most likely being caused by loose u bolts on the rear springs and is usuually magnified by worn or missing spring leaf rubber pads. Try tightning the u bolts and see if you get any improvement. Also check the condition of the spring hanger bushes.|
|There goes that time difference again Gordon|
|Hahaha.... I will call before posting....|
|Thank you for the welcome. |
They are wire wheels. Run-out is about 0.070. The tires are pretty round (except early morning). I will double check the drumms check the U bolts and probably replace the rubber bushings and rubber pads.
Hello. I too have a '54 TF with wire wheels. Good to see a new TF owner on the board. Your posting reads exactly like my car's issues. I have a similar shimmy at 55 mph. I too have a leaky front shock. I plan to send it off to world wide for rebuild, but will likely wait until fall.
I just haven't seemed to make the link between the shimmy (that feels like it is in the rear) and the shock. Time will tell. If you have yours rebuilt soon, I'll be interested to know if the shimmy resolves.
I but much effort this summer into that shimmy (a shimmy summer). I have replaced my rear spring pads and U bolts. I had my drive line balanced. I had the wheels trued and balanced. Rebuilt rear end even. Not one of these actions resolved the shimmy. It does keep be from driving over 55 which is not a bad thing.
I am puzzled about your new tires "going square at night". That doesn't sound right.
Keep us posted.
|If the u-bolts have been loose there is a good chance they have worn grooves in the top of the differential. Fitting buffer plates (Moss 267-560) is highly recommended. Tighten the u-bolts down very tightly.|
|Peter and Tom; I have a '53 TD with wire wheels and it also has a shmmy starting at 55mph. The tires are near new, but were put on by the previous owner. I have had the car since June. After reading this thread and watching the video, I decided to try adjusting the Spax shocks. They probably hadn't been reset since the eighties and were set on the weak end. I moved them to mid-scale for stiffness and took a test drive tonight. The ride is definitely stiffer, and I believe the shimmy is reduced. I don't do a lot of test driving at night, because the car has a lot of other modifications to pay attention to. My next move will be to check the rear suspension and possibly reset the Spax shocks on the rear axel to a stiffer level. I would appreciate any other suggestions, also.|
|B. F. Loughridge|
|Hi Bobby. Welcome.|
While a leaking front shock is not good, I would think that when it is full of oil, it would be close to optimum function. I have original Armstrongs, not Spax add-ons.
I am beginning to think it is all in the wire wheels. The art of balancing wires on splined hubs is vanishing from America. Here in Southwest Oregon, there is really no expert. I have a fellow at a tire shop who will "give it a try". He once owned a Jag XKE. I think that if I had all my wire wheels expertly balanced,"old school", all would be good, with no shimmy. I read about you guys having your wheels "balanced on the car". Here, they look at me like I am crazy when I ask about that.
I keep looking for that 70 year old wheel man.
|Here's where I take my wire wheels to be trued, balanced and also have my tires mounted. As they also do tires and wheels for a racing crowd, they have a tire shaving machine that balances and trues the tires. Our MGB had a vibration in it and after Hendrix worked over the wheels and tires, no matter what speed it's driven, it's as smooth as silk and vibration is totally gone. They balance wire wheels on machine with a splined hub, the same as on the car. Truly professionals! PJ|
Hendrix Wire Wheel
|P S Jennings|
|Paul, not quite the same as balancing on the car, as everything spinning (drums/hubs, etc.) come into play. Glenn at Glenn's MG Repair in St. Pete figured out some time ago that the front drums were often badly out of balance. He balance my TD front drums and that made a noticable improvement in smoothness. Even with new rotors, the only decent way to balance my 280Z is to spin-balance on the car- with the wheel covers on! Smooth as glass that way. But really hard to find a shop that can do it now. BTW, I don't think shimmy has much to do with a shock working or not. George|
|How does Glenn balance a drum, George? Grind off material/glue on weight after he spins it? Wouldn't one balance the whole package on the car?|
|i have never had a car with wires, but while the car is on its jack stands did you grab the tire and try to wiggle the tire 12 to 6 o'clock and 3 t 9 'clock? on standard TD steel wheels i would suggest looking at the bearings as well as the other items you checked. i have had bad shocks that did not give me a shimmy and i have had shimmy that was not related to the shocks...what got you focused on the shocks as being a cause of the shimmy? could shimmy combined with age have caused the shocks to develop the leak? i know...chicken or the egg...|
also how is the alignment? any unusual ire wear signs? regards, tom
|Tom, he used stick-on wheel weights embeded in epoxy on the outside. I never did ask how it was actually done as far as spinning it or what. George|
|Good morning and thanks for all the help. I will be fitting buffer plates and all the rest in a month or 2. |
The following is what gives me emotional/technical fits! This past weekend I was at about 55 mph, nice smooth highway, with my wife and an extra 40 or 50 lbs on the luggage rack. No shimmy at all. Smooth as could be. A few miles down the road the shimmy began to creep in then went away. I call it a shimmy but it's really feels like vibration at approx 20 Hz.
I've had the rear on jack stands and in 4th ran up the rpm's to about 55 mph and no vibration noted in the drive shaft. All the wires ping at roughly the same note so all are near equal. They were spin balanced. Also I've moved all the wheels around each corner.
Dave Braun had mentioned one time something about a vibration issue in the rack and "scuttle hoops". I don't think that's it. Motor mounts? I have grasped the wheels and shacken (violently at times) at all points of the clock and very solid.
I'm wondering if a bent frame? Car drives "straight ahead" under load (acceleration). Could be I'm a semi retired engineer with too much time on my hands and over analysing. I even wonder if the pistons in the shock don't have enough "push back" to dampen the driving forces of the road/tire input.
Lastly, square wheels. The Vredesteins develop a flat spot over night. I can't drink a cup of coffee for at least 2 miles. Could the tires be faulty. I dropped $500 bucks on'em.
|(I've also heard of turning drums on a lathe and or removing material to balance)?|
|Peter,you can check a couple of things for a bent frame. First, drop a plumb bob down from the center of a wheel and make a chalk mark on the floor. Repeat for each wheel. Move the car out of the way and measure between the chalk marks. The two line segments on each side shoud be the same lenght. Also the diagnols should be equal.|
|Thank you M Prince. Last year I crawled all over the garage floor with a couple long straight edges. Trying to find a reliable center point for reference. |
Your idea is eleganttly simple.
|Remember these cars have some degree of cowl shake. The chassis isn't totally rigid, same for the tub. Also TD's are as aerodynamic as a brick- I have always felt the general wind resistance/turbulance contributes to shake. My car still has some degree of shake/shimmy at highway speeds, that kind of randomly creeps in and comes and goes. before restoration it was really, really bad- improvement due to new tires/balancing everything, and replacing the rotten tub wood. George|
This thread was discussed between 01/09/2010 and 08/09/2010
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