Lowering blocks

[Skittler]

Happy New Year to everyone.

Like so many other members I am busy on other projects but it is my intention to lower my Roadster before re-taxing in the spring.

It has the Marina 1.55 diff rear axle.

Does anyone know where I can purchase a set of lowering blocks along with requisite U bolts?

Alternatively, and perhaps preferred, has anyone the dimensions (including tech drawings) of the blocks so that I could machine a set. To this end it may be possible to make more than one set if other members should require!! (I am in the early stages of chatting with a 'fabricator'.)

Thanks in advance

[stevejgreen]

Re: Lowering blocks

When I swapped to a Dolomite sprint axle, one of my standard Marlin U bolts sheared off so I needed some new ones. I struggled to find some that were the right length but more importantly diameter, as I did not want to drill out all the holes in the leaf spring clamps etc (24) the right diameter. Eventually I tracked some down that were UNF threaded. I think I have a spare set in my garage. The length of any new u bolts you can source, may determine the thickness of the lowering block. Of course new u bolts can be made, but off the shelf will be way more convenient if multiple quantities are required.

Not being sure of the van axle, does it have the same size locating hole in its axle pad as a standard Marina? Off the shelf blocks will not have the same spigot diameter

There are some pictures at http://www.fastmarinamagazine.com/in...hp&f=13&t=2860



I take the opportunity to ask why the lowering blocks are tapered? Does anyone know the mathematics? In a Marlin with a very short prop, under normal service the prop shaft is nearly horizontal, but constantly moving, mine does go over centre, perhaps due to my size, the prop sloping upwards from gearbox to diff, with a passenger I am sure all will. Personally I can see no technical reason for the taper. Discuss.

[Tony Stott]

Re: Lowering blocks

source some round bar the correct diam, work out where the 1/2 round(?) should be, hot up the bar to cherry colour use a jig and bend, check on axle, thread the spigots to the correct length + a bit, get an enamel or similar bowl which will accept the bolt in entirety, fill bowl with old engine oil, hot up bolt to cherry and plunge in the oil bath, the carbon im the oil acts as a hardening agent, used this method on a trailer axle with a carrying cap of 1 ton without probs over a long time, a chum used this method to produce a chain wheel for an old Morgan 3 wheeler and its still going strong(he initiated the method after an apprenticeship in Longbridge)

[stevejgreen]

Re: Lowering blocks

source some round bar the correct diam, work out where the 1/2 round(?) should be, hot up the bar to cherry colour use a jig and bend, check on axle, thread the spigots to the correct length + a bit, get an enamel or similar bowl which will accept the bolt in entirety, fill bowl with old engine oil, hot up bolt to cherry and plunge in the oil bath, the carbon im the oil acts as a hardening agent, used this method on a trailer axle with a carrying cap of 1 ton without probs over a long time, a chum used this method to produce a chain wheel for an old Morgan 3 wheeler and its still going strong(he initiated the method after an apprenticeship in Longbridge)

I agree its possible to make your own but, thread the rod first as it's difficult to swing a diestock past the other leg whilst keeping the thread straight. But for the convenience......

I have just tracked down my old purchase details when I bought mine from a 'trade only' source http://www.a-r-b.co.uk/ in Sept '09 they were £12+Carriage+vat = £20.
You could expect to pay around £10+P&P for the raw steel alone, so for the time and trouble, buy ready made especially if you plan to make more than one set.


48/22

[Tony Stott]

Re: Lowering blocks

Used a die nut and ring spanner! accept your point though!

[b_caswell]

Re: Lowering blocks

Google "Grayston" they make lowering block kits but most are for Fords and one for the Morris Minor so not sure if any will do the job on a Marina axle. Needs someone to do a measure up!!

[stevejgreen]

Re: Lowering blocks

The size of the hole in the standard Marina leaf spring pad is 1"dia. Ford blocks are much nearer 1/2"

None of the commercial blocks are tapered so I again take the opportunity to ask why the Marlin/Marina lowering blocks are tapered? Does anyone know the mathematics? In a Marlin with a very short prop, under normal service the prop shaft is nearly horizontal, but constantly moving, mine does go over centre, perhaps due to my size, the prop sloping upwards from gearbox to diff, with a passenger I am sure all will. Personally I can see no technical reason for the taper. Discuss.

[b_caswell]

Re: Lowering blocks

Depending on the axle some Marina Axles needed a 3 degree wedge to tip the nose of the diff up to stop the u/j running out of range. My lowering blocks from Marlin were parallel and the wedge was an Austin/Rover part number FAM 1387 Tapered shim.£2.80 each. Without the shim and the car unloaded the u/j was beyond its range and when you moved the car you could see the u/j jumping over itself......Earlpart list the wedge on their Marina parts as SUR 222.

[Skittler]

Re: Lowering blocks

Hi
Thanks for the discussion ...

I had read many(all) the forum posts and realised that the off-the-shelf (Ford) blocks and bolts were not compatible and that Marina ones were difficult to source. Hence fabricating a set.

Not sure as to the difference, if any, of the locating hole, etc. I have a feeling there is no difference!
I have though sent an email to a-r-b (thanks Steve) who are not a million miles from me. I'll keep you informed.
The email address from their website is 'old' but an automatic reply gave their new email contacts:

sales = [email protected]
technical = [email protected]

I haven't looked at / calculated the degree of 'slope' in my propshaft nor therefore the amount of 'work' the UJs are doing. I would suspect tough that with a shorter prop than standard Marina the angles are increased and the wedge would be desirable!

[stevejgreen]

Re: Lowering blocks

A quick memory jolt, it was Peter I dealt with at ARB. I do not have a commercial account with ARB but I know a man who might!

Ben's statement that 'some' Marina axles needed a wedge is confusing. I wonder if its perhaps related to different spring rates and the angles they sit at, either way it will remain a conundrum until an accurate set of parts books can be looked at and mine are miles away.

Finally, if a lowering block is fitted it will automatically reduce the angle of the prop, over 700mm 3 degrees equates to a block of 36mm so it may not be necessary but, petter safe than sorry.

[ruby131]

Re: Lowering blocks

Hi Brian, my MK2 roadster has original blocks fitted when the car was built in 86. Sadly due to incapacity I cannot for some time get under and take any measurements or images for you, but if you or any friend is anywhere near me in Exmouth Devon you are welcome to come and have a look. Cheers Chris

[neiltechspec]

Re: Lowering blocks

Some years ago, I changed the rear axle on my hybrid for one with a better condition casing (less rusty), kept the same diff though - 3.63:1.

I forgot the lowering blocks had a 3 degree taper and ended up putting them back on with the tapers opposite each other (early senior moment !).

Made a horrendous noise with the propshaft UJ angle being too extreme at the diff end.

So if you fit tapered, then make sure to put them the right way round to tilt the diff flange upwards.

Neil.

[Skittler]

Re: Lowering blocks

Thanks Chris,
If my 'senior moment' memory is not playing up didn't we chat in the summer at Exeter? If so you offered the same then! I'll certainly bear you in mind. Would be good to get measurements for I could then fabricate at leisure!

[b_caswell]

Re: Lowering blocks

Quote "Ben's statement that 'some' Marina axles needed a wedge is confusing. I wonder if its perhaps related to different spring rates and the angles they sit at, either way it will remain a conundrum until an accurate set of parts books can be looked at and mine are miles away.".................Well it was strange as I used the complete set of axle and springs etc all from one donor car with no wedges. but I had to fit them when I built the Marlin to stop the binding of the rear U/J.

[h_m_cumming]

Re: Lowering blocks

Perhaps this clarifies it, from the build manual.