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MG TD TF 1500 - Vibration mostly in third and fourth
|My newly acquired 51 TD has a lot of vibration at medium to high RPM in 3rd & 4th. I feel it mostly in the gear shift lever but of course it could be the whole engine. I also have a bit of judder when engaging the clutch in 1st gear but I think they are unrelated. It shifts smoothly in all gears.|
BTW I want to thank all of you in this community for the helpful suggestions on my previous questions.
One comment. I have seen several mentions of the workshop manual being wrong with respect to the diagram of the orientation of the front brake cylinders. The error is one of omission. They do not mention that it is a diagram of the RIGHT front brake not the left. I guess in England with RHD that would be a natural view. Here we all assume it is a left wheel and that is what makes it wrong.
|I would check the drive shaft first. Make sure someone hasn't taken it apart and miss aligned the front and rear U joints. They should be in line with one another. Make sure the U joints are good. Make sure it isn't bent or a balance weight has fallen off. Drive shaft vibrations usually are only noticeable at speed, like in 3rd or 4th gears. Just a thought, but a strong possibility. PJ|
|P S Jennings|
|Actually, there is a typo in the brake section of the WSM, on M.12 (Issue 2 (E) 8/52) it states:|
The front brake wheel cylinders are interchangeable but the link pipe banjo unions must be fitted to them so that the flexible hose is connected to the FORWARD cylinder and the bleed screw to the REAR cylinder." (caps are mine)
The opposite is the case. It contribrutes to the pictures in Section M.3 (Fig. M.5 and M.6) to be assumed to be the LHS of the car. It should be noted however that the figure of the Hydraulic System and Components on [age M.2) everything is shown correctly, albeit small.
|Dave, which of the diagrams are confusing people as to being the wrong side - Fig M.6 or Fig M.10?|
Fiq M.6 appears to me to be the right side front.
|Check the front motor mount, the rear tranny mount, and the stabilizer bar/bushings at the front right of the engine. The rear tranny mount steel box that retains the rubber blocks often breaks off at the ears bolted to the chassis. I would also check the rear axle spring mounting pads. Check the archives for many write-ups on those. If one of the above is bad, that could also cause the judder. Let us know what you find. George|
Fig. M.6 is the RHS but if you read the paragraph that I cited above, and note the flexible hose, you could easily surmise that it is the LHS.
|Thank you all again. I will report progress when it happens.|
|You may also want to check the timeing, off time can cause the shift lever to vibrate. Had this happen to me long ago. Adjusted the timeing and the rattle/vibration went away. Just a thought.|
|Tom Maine (TD8105)|
|I found that the rear transmision mounts were rotted and the metal trouph was broken. Replaced them and vibration on take off was smooth. We did the same on 2 cars in our gathering tech sessions. It worked|
Just to make absolutly sure that the vibration is in fact comming from the drive train, and not for the (possibly bent) wheels, Have you brought it up to the speed to get the vibration, and then taken it out of gear???
|You could still be getting the vibration from the drive shaft if out of gear. I have a vibration at 50. It's definately vehicle speed dependent, not engine speed. |
It's not the wheels for sure, I can just tell. It's something else. I think the drive shaft but I put a dial indicator on it and could not decern much run out. Not sure what is acceptable. Does anyone know?
|Vibrations at 50 or thereabouts can be harmonic. Most TD's that I know of have some sort of vibration at or around those speeds. Mine is there about 50 and goes away about 53 or soI think it has to do with the way the car is designed with that scuttle and bracing. A lot of us in our club have discussed this at length and no one yet has the total answer. If you find it let me know...|
|Tom Maine (TD8105)|
|Thats reassuring. I've always been kind of leary of trying to punch through that zone but maybe I'll give it a go this weekend.|
|I have the same thing at 55 or so...keeps me at 52 unless I want to go 60 or higher... |
I have always assumed it was the wheels/drums.....at least wheel associated. When I tried to have my wheels balanced on the car, the chap pointed out bent rims .... I would tend to think vibration and shimmy might be related?
|Vibration can be related to the placement of a wheel at a corner. My current rotation (I have about 13,000 miles on my tires) produces a very slight vibration at about 55 mph. It is so slight that I haven't bothered trying to figure out which combination is causing it. Prior to this I had zero vibration. As Larry says, I just 'punch' through it... I typically cruise at somewhere just under 70 mph.|
Try putting your best wheels/tire combinations together and mounting them on the front.
With respect to prop shaft runnout, the flanges of the shaft need to be in the same plane. This is adjusted by pulling the splined end off and reorienting it. The shaft can be quite out of balance and have zero runout, the best bet is to have a drive line shop spin balance it.
|My wheels got perfectly balanced by 'indexing' the wheels. Have the tires turned to 180 degres on the wheels and then balanced . Made a perfect difference. Mine would vibrate at 50 to 60 mph. Not now Try it|
|Just got a chance to look around underneath. The front mount looks fine. The rear mount is not distorted and would function much better if it was attached to the gearbox. The clevis pin has come loose and is trapped between the gearbox and the mounting. The fork is protruding through the bracket and has the nut and cotter pin attached, but it is coming through the hole at an angle. The cupped washer is there but not the rubber washer.|
My questions are;
What is the best way to remedy this situation?
Is it safe to jack up the gear box to create a space to recover the hardware and reset them?
Can I support the gear box with a jack and remove the mounting?
Right now the car is up on 4 jack stands.
|Mort TD 1851|
This thread was discussed between 26/10/2010 and 03/11/2010
MG TD TF 1500 index
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