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Replacing Oilite Bushes in ML7 Countershaft bracket

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William Ayerst04/02/2021 22:45:30
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259 forum posts

Hi all,

After posting about accidentally letting my ML7 run for 72 hours I've disassembled the countershaft and found heavy scoring on the shaft and bearing. I don't know if this was here beforehand, but now's a good a time as any to fix it:

https://i.imgur.com/6Dp1GjT.png

https://i.imgur.com/vaWKmBk.png

Is there a known-good method for replacing the bushes, without the aid of a lathe to make the tool?

My gut feeling is to use an appropriately sized piece of softwood to gently tap out the old bushes, then tap in the new ones from the outside in, the first one going all the way through to be flush with the inside face of the bearing, and the second one going in enough to be flush with the outside face - to leave the oil gap.

Is that going to work?

Lynne04/02/2021 22:54:57
101 forum posts
32 photos

Have a look at Steve Jordan on u tube. He did a project on replacing counter shaft bushes plus the home made

tooling you need to mfg. Lynne

William Ayerst04/02/2021 23:23:38
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259 forum posts

Yeah, he did make some cool things but the problem is my lathe is in bits, so I can't make them

IanT04/02/2021 23:50:21
1983 forum posts
211 photos

Having a range of 'antique' machinery William - I've replaced a few Oilite bearings and they tend to be a very snug fit.

You essentially need a 'pusher/puller' solid cylinder - just under the diameter of the bearing - tapped to take some screw rod - plus a slim walled 'pull against' cylinder - the inside diameter of which should be just over the diameter of the bush, such that the bush can be pulled through it - and a bar wide enough to bridge the 'pull against' cylinder, with a central clearance hole for the rod.

To remove the bush, place the 'pusher/puller behind it and the 'pull against' cylinder on the other side of the bush housing. Screw the rod into the p/p and place the bar over the top of the 'pull against' cylinder and just tighten a nut on the rodding up, such that the 'push/pull and bush are pulled out through the housing.

To replace it - essentially reverse the process - just pushing the bush back in.

Oilite bearings are designed to shrink to size once inserted into the housing, so are a very tight fit. You may get lucky and hammer one in with wood but more than often I think the bush will tilt and stick - and the more you bash it, the more it will get damaged. I speak from experience.

Having no lathe - you may be able to find alternatives - such as a stack of heavy 'penny' washers (pusher/puller) and a piece of pipe (pull against cylinder). Otherwise, measure everything, reassemble your lathe and turn what you need. The shaft may be scored but stone any protrusions down and hopefully it will last a good while longer with new bushes.

Remember to place your 'repair tools' in a bag with a note to remind you what they are - for the next time you might need them. I have quite a few 'bits' (tools/jigs/gauges) that I know I must have made for some purpose but I cannot remember now what it was....

Regards,

IanT

V8Eng05/02/2021 00:00:34
1696 forum posts
1 photos

This may be of interest.

Bush replacement

Lee Rogers05/02/2021 07:57:28
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166 forum posts

A socket with a through bore , threaded rod, long bolts ., lots of washers , plumbing fittings, you name it. In short have a rummage through the biscuit tin of hope and expectation, the tools you need are likely to be there.

IanT05/02/2021 08:29:35
1983 forum posts
211 photos

It was quite late last night when I first posted - I'd been crouched over a CAD screen for far too long, so was a bit tired from that too.

As I was climbing gratefully into bed, it occurred to me that I'd probably turned an inside lip on the 'push/puller' so that it was held centrally in the bush and not inclined to slip off sideways. The larger cylinder needs to be squared at each end too of course. The whole point being that the bush is pulled through squarely - they don't just slip in.

I have a feeling that I've also used another 'guiding' cylinder on one occasion (with a slight lead-in taper) - sandwiching the bush between the guide and the pusher with a second nut on the threaded rod holding the unit together. I think I was having problems getting things lined up and access was awkward.

Apologies for the long and windy description - a photo is always worth a thousand words and I'm sure I have some somewhere but if so, I couldn't find them.

Regards,

IanT

Edited By IanT on 05/02/2021 08:30:56

Howard Lewis05/02/2021 08:49:15
6004 forum posts
14 photos

With the lathe in pieces, it is probably a bit too late for this, unless you reassemble. (After all it has run for some time like this, and you are going to replace the parts anyway )

Obtain a short piece of studding and two nut (say M8 ) Tuurn up a large diameter washer and two cylinders,(with clearance holes through the centre ) one just smaller than the OD of the oilite bushes, and the other larger.

You now have the means to push the bushes out of the casting, and to pull the new bushes into place.

The new bushes had been soaked in oil for 24 hours before fitting.

My bushes were then too tight to admit the new shaft, so the an undamaged portion of the old shaft became a D bit to open up the bushes, to allow the new shaft to enter..

Howard

not done it yet05/02/2021 09:07:19
6716 forum posts
20 photos

One point to note is that the video linked by v8 shows brass bushes - hence the grease nipples. Oilite bushings would benefit from changing that fitting for occasional addition of oil to the bearing - although they are prelubed, they are longer lived with added oil of a suitable grade....

That shaft looks as though it would be serviceable with just a polish up?

Edited By not done it yet on 05/02/2021 09:08:08

Chris Evans 605/02/2021 09:50:56
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2050 forum posts

William, your profile does not give a location but there maybe one of us not to far away willing to make the extraction/fitting tool. I do this type of thing often when replacing little end bushes on old motorcycles. Covid safety applies to above.

William Ayerst05/02/2021 10:08:55
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259 forum posts

Thanks all - I started thinking about how to manage it with a push or pulling process after I posted. It took me all evening to get the original shaft disassembled and removed - but if it needs to go back together to get the parts done, so be it.

Just so I can repeat back to you so I make sure I understand, it looks like I need

- A new shaft, woodruff keys, bushes, fibre washer, (and probably belts as mine are knackered)

- Some threaded rod, nuts and washers

- A pusher (o/d less than bearing) with an inside lip (o/d less than bush i/d),

- A cylinder (i/d more than bearing)

- A plate (dia larger than cylinder) to fit over either the cylinder end or outside of he bracket.

- An adjustable reamer to open out the bushes to the right dia for the countershaft?

I have two more questions and then I'll get going - Will I need to turn down the oilite bushes to fit the bearings, or should they shrink in? If the bearings are scored rather than worn, could I get away with fitting a new countershaft now and then replacing the bushes at my leisure (i.e. when I'm not in the middle of a house move)

William Ayerst05/02/2021 10:16:35
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259 forum posts
Posted by Chris Evans 6 on 05/02/2021 09:50:56:

William, your profile does not give a location but there maybe one of us not to far away willing to make the extraction/fitting tool. I do this type of thing often when replacing little end bushes on old motorcycles. Covid safety applies to above.

Thank you Chris - I'm at the south end of the M25 and I would be incredibly grateful!

Michael Gilligan05/02/2021 10:25:57
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20052 forum posts
1040 photos

Posted by William Ayerst on 05/02/2021 10:08:55:

.

[…] could I get away with fitting a new countershaft now and then replacing the bushes at my leisure (i.e. when I'm not in the middle of a house move)

.

Frankly ... Given the circumstances, I would just put all the existing parts back together, after a general ‘clean-up and re-lubricate’ and do the job later. There seems little point in risking damage to a new countershaft by putting it into scored bushes.

MichaelG.

J Hancock05/02/2021 10:31:17
832 forum posts

What size Oilite bushes do you need ?

noel shelley05/02/2021 10:55:26
1275 forum posts
21 photos

Hello William, A few words of caution. Oilite is not a solid material as eg brass. It is a porous material and can easily be crumbled or broken so needs to treated with some care. If you have the right replacement parts then they will be tight to fit but should not need machining. DO NOT grease them, use oil. To remove them one method would be to grind up a small V shaped chisel and carefully cut a small V in the bush and the bush will fall out. Re fitting has been well documented by others ie threaded rod. Under the prevailing circumstances I cannot travel or this would be a simple job. The bushes will probably be imperial and tend to be to standard sizes. They are not expensive so I would get a spare or 2. Any good bearing supplier will be able to help you.     Good luck  Noel.

Edited By noel shelley on 05/02/2021 10:59:44

William Ayerst05/02/2021 11:39:51
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259 forum posts
Posted by J Hancock on 05/02/2021 10:31:17:

What size Oilite bushes do you need ?

The bushes are 1" long, 7/8" external diameter, 3/4" internal diameter - but it would appear they need to be reamed to precise size using an adjustable reamer on the specific countershaft?

Thanks for the tips on the bushes, Noel - my thoughts were to pick up a new set of belts since the machine is half dismantled anyway. Is it worth investigating the spindle bearings and spindle at the same time?

Dave Halford05/02/2021 12:11:38
2001 forum posts
23 photos

I confess that I have only changed one oilite bush and that was a blind one in the back of a Lucas dynamo.

The old one came out with a suitably sized bolt screwed into it (it was very oval)

The new one went in using the bench vice cushioned by a piece of wood with one calibrated finger driving it.

I would whittle a piece of wood to fit both and then tap it out with a tack hammer before resorting to the kind of parts list needed to remove the front bush out of a car leaf spring.

William Ayerst05/02/2021 13:02:31
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259 forum posts

Thanks Dave - the bushes are only 1/16" thick which I think might be a bit difficult for me to whittle a wood to within tolerance. I can 'rent' the gear from the Rita's Ears website listed above for £40, so may just do that to get it done.

I've removed the spindle and the bearings are fine there, so there is at least that good news. Order for the bushes, belts and shaft placed with Myford.

Richard S205/02/2021 13:44:37
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229 forum posts
134 photos

Another offer of help if required William. I've also made a replacement countershaft for my 1949 ML7, fitted new bushes and replaced the cone pulley. I'm local-ish (near Gatwick). As a visual example of fitting bushes, here is the method used for fitting a small end bushing to a 1922 Villiers MKV-

dsc01992.jpg

Howard Lewis05/02/2021 15:31:25
6004 forum posts
14 photos

Oilite bushes are sintered and porous, so that having been soaked in oil it is retained in the pores. Reaming can smear the metal and close up the pores, and therefore the oil supply.

Hence the need to soak the new bushes in oil for 24 hours before installation.

Followed by regular top ups when in service.

For the time that it takes, reassemble, and use the lathe to make the washer and dollies to press the bushes out and the new ones in.

As I said, rather than ream, and risk smearing, I used the unworn end of the old shaft as a D bit to skim the few tenths off the ID to allow the new countershaft to go into place. (Pulling the new bush into place will squeeze it and reduce the bore by gnats whisker )

By changing one bush at a time, the old bush can be used to ensure alignment whilst opening up the bore of the new bush, and then use the first new bush to hold alignment for opening up the second bus, ready for the new countershaft..

HTH

Howard

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