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MG TD TF 1500 - front end shimmy at 25 mph
|i have a bit of a front end shimmy at about 25mph. it goes away once i go faster or slower. i can not rock the front wheels up and down when on a lift, like maybe loose wheel bearings or a bad ball joint. |
suggestions on where to start?
|Did you loose any wheel weights on the tires? Check that.|
|Unfortunately, our T's were seriously lacking in the front suspension adjustment, with the only adjustment being toe-in, toe-out. If you can't do it with that, you're scuppered.|
B&G do make a special adapter for the upper damper link, giving some caster-camber adjustment, but they are very expensive.
Also its possible to shim the kingpins, but that takes a degree of expertise way beyond me.
Your condition seems to indicate a harmonic balance problem. As Frank Cronin has suggested, start with the wheels and wheel balance, and if possible, eliminate that first. Only then, start playing with the toe-in, toe-out.
|Gordon A Clark|
|thanks. i had thought of that and is my next thing to do. |
the shimmy seems all in the steering wheel. it does not feel like it is coming from the seat.
|A lot of our cars have this scuttle shaking at certain RPM's Mine is around 2800 spins and goes away above that in fourth gear. Timing is one thing to check. Wheels balance is another.|
|It sounds like wheel balance to me; this can also be caused by out-of-round wheels or wheels with a lot of lateral run-out. These latter two are especially common on wire wheels.|
|At 25 MPH it looks like tyre squirm not a balance problem.Have you checked that the tread is running true.|
Ray TF 2884
|Mine used to shimmy at 50mph. New Verdinstein tires and it "went away"!|
|Try cranking one or both your tie rods injust a touch for toe-in, even though the workshop manual asks for zero.. It may disappear. Use a tape measure and measure your tire spacing in the front and back to achieve 1/8"-1/4" shorter dimension in front for toe-in. |
While you're adjusting your front end, you can center your steering wheel, too.
You might jack each front wheel/tire up and spin them to see how bent/out-of-round they are, especially if their wire wheels. Look for broken spokes, and tap each spoke to locate loose or overly tight ones. You can also evaluate balance with them off the ground by slowly nudging them at different positions to see if one heavy side always rolls to the bottom. A wheel badly out of true in the rear can also influence shimmy.
Are the tires old and cracked or new and subtle?
|It hasn't been mentioned, but I've had tires that created that problem also on our MGB. Bought a new duel axle car hauler and it would wander and wiggle with a load on it, replaced the new tires with decent ones and the problem went away! It was the tread design. Put them on a farm trailer, about all they were good for. Just a thought. PJ|
|Paul S Jennings|
|Rotate the tyres!|
|David Sheward 55 TF1500 # 7427|
|thanks i will try these things as soon as i get the TR off the lift. bigger problems there...|
i have steel wheels and also Cooper tires on them. that toe-in may help with the radials. never thought of that. tires are relatively new and do not appear to be worn funny. actually they do not look like they have any miles on them to speak of. i will get it up on the lift and spin them. then rotate them and see what that does. Next see about getting them balanced if no improvement. if all that looks good but still have the issue, i will try the toe in.
thanks for the ideas.
|Check the production date on the tires. You may have the beginning of tread seperation.|
Lift the front end and slowly rotate the wheels watching for out of roundness and wander in the tread pattern as it turns.
|Finally got the other car off the lift and did some checks as suggested. the tires look good. if i spin the front tires, there is a bit of lateral run out. but not real bad. (i do have the steel wheels) So that could be causing the shimy? i have not tried rotating the wheels or checking the balance yet. if i spin the back ones and they look better, i am going to rotate them.|
but here is one thing i noticed. on the right front wheel i have some free play. if i grab the tire at the 3 and 9 position, i can wiggle the wheel a little bit like the hub is loose on the spindle. but if i grab it at the 6 and 12 position, there does not seem to be any wiggle. SO now i am thinking tie rod or maybe something in the rack & pinion? the left front wheel has no play at all.
|You could be right on the tie rod thought. The ball might be worn where it fastens to the rack. That's not a fun job to work on. I don't think that can be repaired while the rack is on the car. PJ|
|Paul S Jennings|
|I'm with Dave on tire rotation. I fought "balance" issues for weeks including a rebuild of the front suspension until I found out that the wheels were out of round. I put the best two tire/wheel combinations on the front and most of the problem went away. I have a couple of wheels that seems to be okay that I'm going to work with next to see if I can improve the situation. Mark|
|Well I may have found my issue. The right front wheel's axle nut was stripped. I mean who puts a stripped nut on an axle of all places. It would hold a little bit but you could not tighten enough to seat the bearings. So headed to get a nut in the morning. Just hoping it is not some odd thread to match. I can not tell from the old nut. Does anyone know?|
While I am asking how do you all do these axle nuts? It seems every car is a bit different.
I assume on the back wheels the axle nuts are as tight as you can get them because they are direct to the axle that turns. I know the model A I have is that way. Sound right?
But is there any tricks to the front wheels? One car I had was torque to 15 ft/lb and back off one flat, another was to take it up to significant drag and back off one flat...
Thanks for the help so far
|Just read the thread by Dave saying the axle nuts need to be torqued to 50lbs. Wow. Different bearings. |
So hopefully the theads are not some odd spacing.
|99% sure it is a BSF thread, 5/8 or 3/4" depending on early or late car, so order from Moss or Abingdon. Tighten the nut very snuggly if no torque wrench), if the cotter pin does not align, file the nut face so it does. The backing off deal is for modern tapered bearings, not T-series ball bearings. If you back off from tight, the bearing/spacer stack will work back and forth and ruin the stub axle, etc. George|
I would definitely order this from Moss, As, or another trusted supplier.
In answer to the ?: "who puts a stripped nut on an axle of all places"...
Possibly someone that bought the nut they lost from local hardware store having no clue it was BSF thread and went with something "close".
Sincerely hoping your threads are ok so this does not turn into a bigger job.
|David Sheward 55 TF1500 # 7427|
|I worked on a TD with a nut so stripped that only the split pin held it on.That meant I had to check every safety related nut on the car.|
Ray TF 2884
|Ordered this morning. |
And checking everything is what I am doing now.
The nut looked just like the one on the left front. So not sure how they stripped it. But boy that is scary. The guy I bought this from had someone else working on it so I am sure he never knew. He just wants to turn the key and drive. He does not do wrenches. I know he spent a mess of money to get this car done. Just glad I caught it before I drove it very far.
|Could it be that someone forgot about left hand threads? Bud|
|This was the right side so RH threads. i got the new nut this morning. it was a bugger to get on. the threads at the end of the spindle were buggered up. clean them up and worked the nut on and off slowly until i could take it all the way up. then torqued it up as well as redoing the front left wheel. |
i still had a little play in the right front and sure enough you can trace it to the inside ball joint on the steering arm. my book does not give a lot of detail but it looks like i should be able to put a shim in there to take out that free play. any help or info on that would be appreciated.
i took the car for a ride and really virtually all the sterring shimy was gone. i did rotate the right side tires as well so maybe that also helped. right now it is not bad at all. in fact i would not have checked anything if it was no worse than this before.
but i know that ball joint has some play in it so i still feel like i should do something about that.
This thread was discussed between 30/06/2014 and 18/07/2014
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