Leaf spring shimming and setting

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stuartbell
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Leaf spring shimming and setting

Post by stuartbell » Sun Jan 15, 2017 12:04 am

Is there a guide available to the correct method by which the spring shackle-plates should be shimmed and packed (for the P2)?

During the recent strip and inspection of the rear leaf-springs on my 1939 '10, it was clear that excess lateral motion had been there for some time prior to the car coming off the road in 1972. What appears to be the correct order of build, looking at this forensically, is that the spring eye bushes should be located laterally by a Tufnell-type washer either side of the spring, and that the ground special washer (flat-ground on the faces; mine are both dished) should be nipped by the castle-nut directly against the end of the machined shoulder on each shackle-pin. In other words, I believe that the split-pin through the castle-nut is just to prevent rotation from the nipped-up condition, and NOT intended (as someone has fitted on "Lucy") to be used as a crude adjustment mechanism to control the lateral float on the shackle-pin.

The order of build, looking across the shackle-pin from the back face near the dumb-iron, appears to be a) Tufnell washer b) Spring/bushes c) Tufnell washer d) Possibly a third Tufnell washer or a shim? e) ground special washer against the machined face under the thread of the pin f) castle-nut & split-pin

I cannot find any guidance elsewhere on this forum or the P2 Workshop manual, but I'm sure the information is out there! My measurements suggest that the Tufnell washers are all approximately 60thou" (or 1.5mm) and that the "thinner ones" on Lucy are just worn-out.... Until I obtain some new parts, I will not be able to say whether the spring-eyes will shim adequately like the sequence I suggest above, however I am sure that the special ground washer must never be allowed to run loose over the shackle-pin, as this would cause the dishing I have seen on all the faces of the washers that I have inspected. It ought to be possible to set a reasonable "few-thou" running clearance for the springs (to avoid excess Bijur oil-loss and lateral play in the spring locations) without using the castle-nut as an adjuster?

Many thanks for any help that can be offered, Stuart
He with the most toys wins....

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luli
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Re: Leaf spring shimming and setting

Post by luli » Sun Jan 15, 2017 6:45 am

The following is taken from the Motor Trader, January 29, 1947:
"SPRINGS
Semi-elliptic front and rear. All centrebolts offset towards front. Master leaves marked "O.S." or "N.S." towards front.
All spring eyes and rear spring shackles bronze bushed, with fibre thrust washers. All shackle bolts and anchor bolts have nuts to outside, ex­cept front dumb iron anchor bolts, which have heads outside. Rear spring anchor bolts are retained in frame brackets by cotter bolts.
One of each pair of front -spring shackle plates, and one side of each rear spring shackle, drilled for oilfeed to spring eyes. Drilled side goes next to bolt head on inside, bolts being grooved near head and drilled for oil feed. Front spring shackles have plain distance washers between thrust washers and shackle plates on spring eye bolts. Tighten nuts on shackle and anchor bolts until thrust washers are just free, and pin."
The parts list, for 1939 10 says: " N26 - Plain washer (2) , shims - as required" - that's all.
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
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stuartbell
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Re: Leaf spring shimming and setting

Post by stuartbell » Sun Jan 15, 2017 11:53 pm

That's very interesting, Luli. Thank-you for the information.

I think I would have to take issue with The Motor Trader regarding the ground-faced-washers, as they appear to be suggesting that the washers are not clamped securely to the shackle pin shoulder by the castellated nut. To allow the washer on each pin to rotate, which is what will happen in normal road-service if the clamping-force over the spring bushes and shims is worn to zero, appears to contradict good engineering principles.

I tried to see what Rover had intended from the P2 1939- parts listing illustration, but this was not clear at-all. I had thought that they mentioned the presence of "shim" on each pin, but this did not clarify whether they meant the Tufnell-type washer/s, or indeed a further shim-steel washer. What is fairly clear is that the process of obtaining just the correct amount of clearance over the end of each spring would not be easy, without resorting to hand-fitting of the components by machining the washers to suit.
He with the most toys wins....

RobHomewood
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Re: Leaf spring shimming and setting

Post by RobHomewood » Mon Jan 16, 2017 4:07 pm

Fascinated by the discussion but a bit lost in the detail. Any chance of an illustration or 2 to show us what you mean? And does your reference to 'Tuffnel' washers equate to 'Tufnol' washers which seem to come either as a fibre fabric or cotton fabric (lubricated?) washer?

stuartbell
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Re: Leaf spring shimming and setting

Post by stuartbell » Mon Jan 16, 2017 10:19 pm

Rob,
Yes, I had misspelled the Tufnol trade name for the simple reason that my spell-checker does not recognise it, but does recognise Tufnell as a place-name! So apologies are due to all, especially those Brummies that have made this material for so long - hence the reason I assumed (being the Mother of all evil) that this was the material selected by Rover for their suspension washers.

I'll do what I can to get a sketch posted here, assuming I can find somewhere to store the image for linking.

Stuart
He with the most toys wins....

stuartbell
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Re: Leaf spring shimming and setting

Post by stuartbell » Wed Jan 25, 2017 9:47 pm

I've struggled with Photobucket for the last few days, but I hope the following link works -it should illustrate what I speak-of;

http://photobucket.com/user/stuart143/m ... j.jpg.html
He with the most toys wins....

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luli
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Re: Leaf spring shimming and setting

Post by luli » Thu Jan 26, 2017 2:24 pm

The picture you refer to shows the front pin of the rear spring (no shackle)
Image
Here is a photo of original, never touched shackle assembly:
Image
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
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stuartbell
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Joined: Sat Dec 13, 2014 8:49 pm
Location: Isle of Skye

Re: Leaf spring shimming and setting

Post by stuartbell » Thu Jan 26, 2017 6:49 pm

Luli,
I used that particular picture, as it gives the best view of the arrangement of the washers as-found, however I can confirm that this was also the same at the shackle-to-chassis pin arrangement to the rear of the rear spring.

When I measured the washers, it appeared that they had all started-off in life with approximately a 60"thou gauge, but some had worn to almost nothing (paper-thin) or disappeared altogether. This meant that I found the gap that is visible on your photo of the shackle-pin "as-found" - leading to a lateral play in the spring-eye location on the pins affected.

I can see the logic of using the castellated nut as an adjustment mechanism to achieve a close fit of the washers to the spring bushes within the spring-eye, without actually nipping the spring completely (and thus giving a high-friction clamped condition). This does, however, imply that that the ground-finished special washer will never clamp directly to the shoulder that is machined on the pin just beyond the runout of the thread, and that does not seem very "Rover" to me! Their Engineers have always struck me as being particular about such matters, and tend to have a good reason for all things!
He with the most toys wins....

RobHomewood
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Re: Leaf spring shimming and setting

Post by RobHomewood » Thu Jan 26, 2017 11:39 pm

I am gradually getting there with understanding the shackles I think. But if I am tempted to overhaul my springs I need to identify the parts. I have 3 pairs of shackle bolts it seems but should there should be 6 pairs total? The first one is easy as it has its part no (front of front spring) labelled '15' [img][IMG]http://i172.photobucket.com/albums/w27/RobHomewood/Rover%20P2/P1050327_zpsfxnz9kpt.jpg[/img][/img] .
On the Plate N in the parts book there is no lower pin on the shackle plate numbered for the front spring (upper pin '15A') whereas there is on the rear spring (labelled '26' upper and '27' lower). Is that an omission or am I misreading it?
The other 2 pairs of pins have lost their labels [img][IMG]http://i172.photobucket.com/albums/w27/RobHomewood/Rover%20P2/P1050336_zpsl5jzgjxx.jpg[/img][/img] [img][IMG]http://i172.photobucket.com/albums/w27/RobHomewood/Rover%20P2/P1050334_zps2yqwxwgc.jpg[/img][/img]- is there any way of identifying them?

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luli
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Re: Leaf spring shimming and setting

Post by luli » Fri Jan 27, 2017 8:51 am

You are right. The lower rear pin of the front spring is missing from Plate N and from the parts list. However, It must be identical to N15A (although it does not need a separate oil feed) . There are 6 pairs of pins: 3 for the front springs, and 3 for the rear springs. You can watch some pictures here :
http://wp.me/pXLKy-gE and here: http://wp.me/pXLKy-gn
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

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