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Post by Chuck Berry on Jul 31, 2014 16:31:25 GMT
Some of you may recall that I thought I was suffering a faulty DG gearbox.... well I aint!
I took the plunge and towed my Cheltenham Caravan a few miles and what a racket! The car shook its nuts off! (not literally you understand), but the tell tale was that there was still a vibration on over-run.
The symptoms in the past were a very harsh change from intermediate to top gear. Thinking the Gearbox was on the way out I changed the oil and filters. A little improvement but the vibration was still there. Thankfully I didn’t take out the gearbox and have any work done to it at this stage. That would have been an expensive exercise, and still the vibration would be there.
Now with the extra weight of the caravan the vibration became critical, but it was also there on over-run; clearly not the gearbox. Up on the four poster lift it went and a running test carried out. The following was noted and blamed for the problems.
1) The final UJ on the prop shaft had been replaced but assembled backwards, preventing a grease gun reaching the grease nipple. Result? Dry Joint with high rough spots.
2) Dry running Spline no grease, and some play but not critical.
3) Springs are near inverted, forcing the drive train at rest, to be raised at the Differential Coupling. This meant that with a load the entire drive train at the axle was forced further upwards. Combine the acute and unnatural angle with the dry UJ, the issue was determined.
The rear and front leaf spring bush rubbers are near the end of their service life which exasperated the angles. So there is nothing left but to replace ALL UJ's Centre bearing rubbers and now the springs. I would say the same could be said for any gearbox combination.
As soon as some new springs are available they are going on tute sweet
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Post by Deleted on Jul 31, 2014 19:23:01 GMT
Some of you may recall that I thought I was suffering a faulty DG gearbox.... well I aint! I took the plunge and towed my Cheltenham Caravan a few miles and what a racket! The car shook its nuts off! (not literally you understand), but the tell tale was that there was still a vibration on over-run. The symptoms in the past were a very harsh change from intermediate to top gear. Thinking the Gearbox was on the way out I changed the oil and filters. A little improvement but the vibration was still there. Thankfully I didn’t take out the gearbox and have any work done to it at this stage. That would have been an expensive exercise, and still the vibration would be there. Now with the extra weight of the caravan the vibration became critical, but it was also there on over-run; clearly not the gearbox. Up on the four poster lift it went and a running test carried out. The following was noted and blamed for the problems. 1) The final UJ on the prop shaft had been replaced but assembled backwards, preventing a grease gun reaching the grease nipple. Result? Dry Joint with high rough spots. 2) Dry running Spline no grease, and some play but not critical. 3) Springs are near inverted, forcing the drive train at rest, to be raised at the Differential Coupling. This meant that with a load the entire drive train at the axle was forced further upwards. Combine the acute and unnatural angle with the dry UJ, the issue was determined. The rear and front leaf spring bush rubbers are near the end of their service life which exasperated the angles. So there is nothing left but to replace ALL UJ's Centre bearing rubbers and now the springs. I would say the same could be said for any gearbox combination. As soon as some new springs are available they are going on tute sweet
It's always very satisfying to identify a long-standing issue. Glad you got it sorted. I think you're right in that JRW is the only supplier of leaf springs but they are heavy duty and don't have the nylon inserts as per the originals. If you have your existing springs re-tempered (you might have to visit a heritage engineer to get that operation done) you might then be able to salvage the inserts....if they haven't disintegrated. At least springs with the proper camber will be easier on the re-manufactured "Y" bushes which don't have much shear resistance. |
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Post by Chuck Berry on Jul 31, 2014 21:10:46 GMT
Well at least that is reassuring Resurgam, I have the new pattern 'Y' bushes. Just need patience now to wait for JRW to resurface!
I would have thought that from 1963 and some 100,000 miles, that we think we know of, would have put paid to the spring inserts. Just hope the new ones do not sacrifice a smooth comforatble ride....
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Post by enigmas on Aug 1, 2014 6:44:57 GMT
The pinion angle is incorrect. It still may be incorrect after you re-temper the springs. You can correct it with a wedge(s) if you know how it's done. Try googling pinion angle or drive shaft angle for an explanation.
(Briefly, both the gearbox flange and the differential flange need to be parallel. This is complicated further on the P5 due to the split centre bearing tailshaft) Get the angle(s) correct and the vibration will magically disappear...the issue is one of physics. Under load the pinion will climb...increasing the vibration, especially if the angles are already incorrect)
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Post by johnwp5bcoupe on Aug 1, 2014 6:56:16 GMT
The pinion angle is incorrect. It still may be incorrect after you re-temper the springs. You can correct it with a wedge(s) if you know how it's done. Try googling pinion angle or drive shaft angle for an explanation. (Briefly, both the gearbox flange and the differential flange need to be parallel. This is complicated further on the P5 due to the split centre bearing tailshaft) Get the angle correct and the vibration will magically disappear...the issue is one of physics. Under load the pinion will climb...increasing the vibration, especially if the angles are already incorrect) As we know from experience Vince it's a very steep learning curve getting the angles correct  There will be a bit on this in the mag soon  the P5b set up is a compromise! |
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Post by enigmas on Aug 1, 2014 12:01:57 GMT
I agree John. I believe we've both experienced the frustration of out phase tailshaft angles with the individual modifications to our P5s.
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Post by Simon H on Aug 1, 2014 15:55:45 GMT
Reminds me of the time 'when I was a lad' back in the 80's and I treated my Series 2 Landy to a set of 4 new springs. I even replaced all the shackle bushes. At last the Landy stood tall and level. Then I went for a drive and found out that the propshaft U/Js were not very happy with the new angles they were working at...
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Post by djm16 on Aug 2, 2014 9:08:45 GMT
Aha! That might explain something with my P4.
There is a low frequency background rumble at around 30mph. At one point itt got worse and I became convinced it was the diff. Only when I got underneath did I realise that the four bolts securing the diff flange to the back UJ were loose. So I pulled out the diff anyway, reset the backlash, put it back. Rumble then back to usual levels.
How do you go about setting the gearbox flange and diff flange to be parralel? Is it guesstimates with a lead on a string? or is there a more subtle way of doing it?
Lastly do all three UJs have to be parallel?
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Post by Chuck Berry on Aug 2, 2014 10:59:46 GMT
Yes! All prop shaft journals should be in line.
I had terrible vibration that only manifest itself during changing gears from intermediate (2nd) to top; so I originally thought it was the DG gearbox. But when that same vibration (a little less but still there) was felt during over run then my attentions went to the drive train. Although all UJ journals felt tight at rest, it was a different matter when the bolts were removed and the UJ moved through all angles by hand.
Yesterday I did a wedding service with the car covering more than 200 miles during the day. The ride was more like it should be, just that annoying "jump" when it changes gears at low speeds, a traight I became used to in my earlier P5 saloon in the late 60's.
I am going to try shimming the axle mounting, having prepped them ready to fit, but I am hoping that when JRW come back from holiday's that they have new springs in stock then the entire back axle will get a full service, all suspension components will be renewed and the entire prop shaft and drive train including the centre bearing will have new bushes and end up like or as good as new. I only want to do this once!
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Post by enigmas on Aug 2, 2014 11:02:48 GMT
You do it with an angle finder. A small gauge with a magnetic base incorporating a dial marked in degrees. The pointer works by gravity. These tools are relatively inexpensive. You need to have the car at ride height on level ground or a hoist if you lucky. If you have a one piece tail shaft ensure both the gearbox flange and the differential flange are parallel. This doesn't mean in a straight line. If it's a split shaft (P5) prepare for a headache  Ideally have the gearbox flange, the centre bearing flange (with the sliding yoke) and the differential flange all parallel. The first half from the gearbox may be in a straight line whilst the second half from the centre bearing may angle downwards. (This depends upon whether the car is lowered at the rear or at normal ride height) Here's another factor to take into account. When you take off from rest the diff pinion rises (due to the load and torque applied) and this changes the working angle of the universal joint (Google 'hookes joint') putting the joints out of phase in relation to one another. This condition is more noticeable at low speeds under heavy load. So when you set it all up, allow for a small torque induced climb of the pinion under hard acceleration or take off. That is, the pinion should move into correct alignment as power is applied. Ever wonder what that low speed judder was when taking off or pulling a heavy load initially. Personally, I really dislike the factory centre bearing support (mine has been modified) as it's like an unconstrained bowl of jelly, allowing all sorts of uncontrolled movement which impacts on the drive line angles. However, it can be made to work without any discernable drive line judder, if you take the time get it right. Unfortunately, replacing every component in sight won't fix it, if you don't understand the operating principles. John, you may want to chime in and outline your views and experiences at some point. |
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Post by johnwp5bcoupe on Aug 2, 2014 15:12:30 GMT
The first thing to check is the driven yokes are correct they are shown incorrectly for the P5b in the WS manual it is shown as a parallel/parallel and it should be crossed parallel (all the driven yokes should be in line)The early P5's even had wedges between the spring and the axle to correct the pinion nose! after spending many hours calculating angles as I have said the Rover is a compromise and the center joint is out of spec for a good UJ set up! plus the pinion nose angle will vary a lot depending on the springs and spring loading Read more: roverp5.proboards.com/thread/7491/prop-shaft-poblem#ixzz39FLyZCJPMore Info Prop ShaftProp Shaft2 |
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Post by Deleted on Aug 2, 2014 16:35:34 GMT
The first thing to check is the driven yokes are correct they are shown incorrectly for the P5b in the WS manual it is shown as a parallel/parallel and it should be crossed parallel (all the driven yokes should be in line)The early P5's even had wedges between the spring and the axle to correct the pinion nose! after spending many hours calculating angles as I have said the Rover is a compromise and the center joint is out of spec for a good UJ set up! plus the pinion nose angle will vary a lot depending on the springs and spring loading Read more: roverp5.proboards.com/thread/7491/prop-shaft-poblem#ixzz39FLyZCJPMore Info Prop ShaftProp Shaft2This is a complex area. I didn't realise there was so much to it. I suppose some basic advice, on a car carrying its original set up, would be to replace any part of the drive train exactly as it stands carefully marking each component and remembering not to turn anything whilst a worn part is being replaced. |
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Post by enigmas on Aug 2, 2014 21:43:39 GMT
Yes that's the starting point, but some knowledge of how the joints work and what causes the out of phase vibrations in the system helps. Most hot rodders and custom car builders do and I'm certain, none are mathematicians. If you think about the P5 setup...if the first section of the tail shaft from the gearbox is in line with the crankshaft and main shaft (manual) or geartrain assembly ( automatic), that section really can't go out of phase because there'll be no angularity or changes of speed when the joints rotate. The second half from the centre bearing up to differential pinion flange is what needs to be parallel with regards to the flanges as this is what dictates the running angles of the universal joints. (Well, this is how I setup the driveline tailshaft on my P5)  If you're rebuilding this part of the driveline or fitting new springs etc, l'd recommend investing in an angle finder and being prepared to fabricate a set of wedges. This way you'll ensure a vibration free driveline.  Oh, one last thing, mark the splined yoke before disassembling the tail shaft assembly. |
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Post by johnwp5bcoupe on Aug 3, 2014 5:24:37 GMT
The rear sliding shaft has an arrow which lines up with a corresponding mark for correct assembly I would still make another mark of your own as it could have been move in the "distant past" to eliminate vibration! Yes a single shaft would have been easier Vince but the prop company said for the length and power involved the tube would have to be 3" in diameter! that wouldn't fit in the rear tunnel The Rover set up works within it's limits but it was for sure a compromise, if anyone wants a set of handmade wedges I have a pair free plus postage to members |
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Post by enigmas on Aug 3, 2014 9:09:31 GMT
Arrrow! What arrow.  Next time I'll take a closer look John. |
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Post by Chuck Berry on Aug 8, 2014 7:31:46 GMT
Must admit I never saw a mark when first changing the Axle UJ, made my own instead.
I have now the complete spring and bushes set up with new bolts so ready for the change. Although I thought I was....... after reading the above it all comes back to me. I fitted an overdrive to my 1982 Airstream Motorhome (32' of polished aluminum) some while ago. That involved fitting the o/D to the Thumping great Auto Box and shortening the first prop. Drive train line up was essential (3 drive shafts) and took some time but worth it. The old girl sings now!
So Yes I will apply the same sciences. Thankfully this time with much lighter gear!
If I am able to use next doors four poster I will take some photos of the progress - or lack of!
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the P5b set up is a compromise! 
Next time I'll take a closer look John.