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MG MGA - Driveline spline wear
|steering wheel the Pacific NW,|
Besides chasing pin-hole leaks in my rust bucket of a gas tank (epoxy is slowly getting the upper hand), I am trying to sort out a shimmy that shows up at about 5,000+ RPM. I cannot tell you what the exact speed is since the speedo is in the shop. The shimmy is most likely in the front end or an out of balance wheel
|The seals can be replace without removing the trans or dif. A good drive shaft shop should be able to replace both sides of the spline joint for you.|
If I understand you correctly you have the sliding joint at the rear - on the diff. end of the shaft? I thought that the spline joint should always on the transmission side of the shaft. The spline joint was obviously built into the tranny in the early cars. I assume they would keep the spline on the same end of the driveshaft when they changed to the later style.
|One of the first things other MGA owners comment about driving my car is how taught it is - the result of a front end that is in tip-top condition and all aligned and balanced. If your front end is worn out, then the shimmy could well come from anywhere in there. The rebuild can be done in a few hours (and it's usually VERY dirty work), so should be the first step. Only then can you be sure that you have a wheel balance problem or not. It will be a revelation when you have replaced all the tired and perished seals and bushings, and had the wheel alignement checked out.|
The propshaft should be switched so the spline is at the front end, though it may be hard or impossible to get it out with the gearbox in the car. It can be done by removing the hadbrake support brackets at the tunnel, but that is also a pig of a job. Last time I just moved removd the axle U bolts and slid the axle back along the springs (but I have a 1500 propshaft without the centre spline, so you may have a chance with yours).
While you do that, change the seals in the rear of the gbx and the front of the diff - as Mr Heisenfeldt says, this is easy enough if you can get under the car (make sure it is properly suported when you are tugging the old seals out.), just get a stout screwdriver under them and butcher away till it comes out, you won't break anything else in the process. Use a large socket as a drift to install the new ones, making sure they are square.
|I would not bother changing the spline from the rear to the front, unless you need to take the driveshaft out for another reason.|
There is no operational difference with the spline at the front or rear. The MG factory put the spline at the front, but the Triumph factory put it at the rear.
I do not believe that play in the spline would cause your "shimmy". Wear in the U joints certainly could. Also, spline wear would not damage the seals.
The probable culprits are the wheel balance, wheel alignment, and general front suspension condition.
|Worn splines can cause quite a vibration as the drive shaft can start to swing like a jump rope, quite common on pickup trucks. It would not however be related to engine RPM, only the speed of the car.|
John Backman writes:
> BTW – Had a chance to meet David Breneman at the PNW All British car show this past weekend, always nice to put a face to a regular contributor.
But I'm sure you could have picked a better face. :-)
Still, it was very nice talking to you, John. Hope we meet up again!
This thread was discussed between 29/07/2008 and 31/07/2008
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