Rear Bump Stops

for those with Series MM sidevalve cars produced between September 1948 and February 1953
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alanworland
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Rear Bump Stops

Post by alanworland »

I have had a measure of the rear bump stop rubbers and they are 2 1/2 inches high above the top of the axle tube, I dont think I have the correct rubbers. Are the rears the same shape as the front? mine have a pronounced 'flat' on the top where they would contact the body (unlike the front)
Also I have measured from the top of the bump stops to the body, which measures virtually 3 1/2 inches, which makes the top of the axle tube to the body 6 inches - does this sound anywhere near correct?
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mike.perry
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Post by mike.perry »

Some diagrams of MM bump stops. Are these any use?<br>Image<br>
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alanworland
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Post by alanworland »

Thanks Mike, they appear to be like the fronts, are they a similar size rubber section? If so I shall cut a bit off to bring them down to the correct dimension. Is it the same rubber used across the range (saloons)
I have a feeling that mine might be from a Marina? I can remember sticking them onto the original tube section! but they look huge compared to these.
Have you any dimensions from axle tube to body bump pad?
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mike.perry
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Post by mike.perry »

I will have a look at the Traveller tomorrow.
The bump stops on my MM are Marina rubbers which I cut the tops off. They are square section tapering towards the top.
The rear rubbers are larger than the front ones but I don't have any dimensions.
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alanworland
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Post by alanworland »

Sounds like we have the same bump stops as mine are square section also! - forgot to mention that before! I am trying to establish if my rear end is sitting at the correct height! I believe it to be high.
I have found some figures for the height of the rear end in the workshop manual - from ground level to the front eyebolt centre and the rear shackle top fixing, I shall have a measure tomorrow.
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mike.perry
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Post by mike.perry »

The Traveller bump stops are tapered square section but not as big as the Marina bump stops. There looks to be about 2 - 2 1/2 in clearance between the top of the bump stop and the "stop plate".
Possibly the wide wheels affect the clearances with the MM wheel arches.
Have you got a pair of standard wheels you can fit to check the measurements?
Are you sure that you have the correct 7 leaf springs 7/32". Total thickness 38.9mm
The Traveller springs total thickness is 44.4mm I have just measured my spare spring.
The M1000 5 leaf total thickness is 31.75mm.
I changed from the original 7 leaf springs because they had flattened. I fitted Traveller springs by mistake and the handling was terrible, I nearly lost the back end on a couple of roundabouts so I very quickly fitted 5 leaf springs and the handling has been quite accepable.
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alanworland
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Post by alanworland »

I had a measure today and the rear shackle (top) dimension from the workshop manual indicates a figure of 15 7/16 inches, I had a masure of mine and found 16 1/4 inches!
I don't think my wheels have anything to do with this as they are of the correct section, I believe. Measuring from ground to tyre top I have 24 1/2 inches - I have no standard wheels to try, but the front torsion bar dimension is spot on.
I then removed the bottom leaf and found it made NO difference!
I then removed another leaf and found the dimension dropped to 16 1/16 inches (plenty of jiggling to make it settle)
The leaves I took out were covered in what looked like dried waxoyl and therefore very 'tacky' which I decided wouldn't let them slide over each other very well.
So, I then removed both springs (well, what was left of them!) washed all the leaves and when dry wiped them over with an oiled rag then re fitted - the dimension would now settle at 15 15/16!
Still more than the manual, but a bit closer.
I measured the leaves that were now on the bench and they are 1/4 thick! I was always under the impression that they were the correct spring (specified when ordering - but 20 yrs ago!)
Have I now turned my Traveller springs into Saloons by removing as above?
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mike.perry
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Post by mike.perry »

If the total thickness of the springs is 44.45 mm then you have indeed got Traveller springs.
The trouble with ordering things is that the supplier either doesn't know the difference or sells you whatever is in stock and hopes that you don't notice.
Are the remaining springs the same length as the saloon springs and have you got enough thread on the U bolts?
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alanworland
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Post by alanworland »

Not sure what length the individual leaves should be - can measure.
I did have a search for a suitable die should there not be enough thread, but it did all do up - with a bit to spare!
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linearaudio

Post by linearaudio »

So.. your bumpstop clearance is way above the 2" oft bandied about, mine is struggling to reach 2", perhaps we should mix and match spring leaves between us :lol:
All sounds to be down to indifferent manufacturing, but we are lumbered with sorting the mess out :cry:
Oh, yes my second brand new flasher unit in six months has just failed! Get fed up keep sending things back, and it adds to the "unreliable old banger" image!
Keith
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Post by Keith »

If it helps the length of the rubber on the original (right in picture) is 2.5 inches. regards Keith<br>Image<br>
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