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thunderbolt
United Kingdom
11 Posts |
 Posted - 15/11/2008 : 01:09:19
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 Have just returned my PA to the road and the smile to my face'
A familiar but slightly alarming trait which it has always had (but I have never been in a position to fix) is now annoying me enough to ask advice.
When being driven in reverse it clanks and jumps as if running on a square cog, even on mild throttle and gentle clutch. Best guess is that it is wear /play in the drive train, which has been used to going forwards and reversing exposes the wear. The back of the car leaps and it is not a pleasant or encouraging experience.
Any suggetions of cause, remedy, or potential for self distruction if not resolved
Progress can be good, but I think yesterday was better.
1935 PA 4 seater |
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Terry Andrews
United Kingdom
546 Posts |
Posted - 15/11/2008 : 12:08:27
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Before you pull your gear box apart I would want to check out the back end.
30 years ago, I built my P type on a shoe string with the best of the second hand parts that were available. It is far easer to restore a Triple-M car now than it was 30 years ago. There are far more new spares around thanks to Mike Dowley and others. I had something along your lines some while back. It could well be a combination of things at are easily checked before you pull your gearbox apart.
Jack the back of the car up and have both rear wheels of the ground supported by axel stands. Chock the front wheels and make certain the car is safe.
1 Turn each wheel and then put the and brake FULLY ON. Now see if with your full strength à. can you revolve your rear wheels fore and aft? If you can, you have worn wheel splines and possibly hubs as well.  You could try different wheels on the same hub to reduce the fore and aft movement. Knocking up the knock on spinner will NOT help and WILL make the situation worse. Do not run worn wheel splines on new hubs or vice versa. They should be changed together. New hubs and wheels make amazing differenceà. But cost úúúúúú!
1.1 Now check from side to side. This should be solid. If not à.. wheel bearing and carrier problems and possible half shaft issues.
2 With the hand brake off à.. hold the diff nose piece and see if you have play between the crown wheel and the rear wheels. If you do have play, then it could be a number of things.
2.1 Diff not set up correctly.
2.2 The tab washer has been bent back because you MOT was carried out on rollers (I had this, so going forward the diff was set correctly. In reverse the planet wheel adjustment would go slack.)
2.3 Half shaft splines worn at diff end or on the hub.
3 Check if you have any slack in the prop shaft couplings. Rock the prop shaft back and forwards.
4 Check the gearbox output shaft for play again by rocking the flange drive in all the different gearsàà this would tend to indicate a gear box fault.
5 The clutch may not be running true and you may need to adjust the fingers. With the car now back on the ground. Start the engine in neutral with the bonnet open. Gently push the clutch pedal with your hand. If you can feel the pedal ôflutteringöàà then the clutch is not operating squarely with the flywheel. You would notice is more in reverse than when on the move.
Finally, if to need to check or replace the rear hubs check that the rear hub bearing has not fretted on the axel tube. With the bearing tab washer removed is it difficult to remove the bearing carrier? If it wobbles or is easily extracted of the axel tube you will need to get this fixed.
The above would be my starting point before taking the gear box out.
Hope this helpsà.Terry
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George Eagle
United Kingdom
3240 Posts |
Posted - 15/11/2008 : 21:01:53
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I friend of mine had much the same trouble except the reverse gear would at time also disengage with a loud bang. It was all down to the reverse gear and pinion and having the spacer in the wrong place!
George |
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thunderbolt
United Kingdom
11 Posts |
Posted - 16/11/2008 : 09:33:31
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Thanks you all especially Terry, I am just about to move house but now have a plan of works for when I arrive and tools are unpacked.
Who needs a manual when you have access to such timely advice?
Progress can be good, but I think yesterday was better.
1935 PA 4 seater |
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