41 replies to this topic

[iain1967s]

Sorry to bring it back up, did you get this working any photos of the frame work you attached to the subframe?

The one I built for towing my mini is exactly the same as this:
http://restorationmi...p?page=page3689


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Edited by iain1967s, 31 July 2019 - 12:56 AM.

[Rorf]

How so? It's in the oil bath the whole time....what's the difference between it being towed and driving?

 

When driving in fourth gear both shafts are turning at the same speed, and on the open road doing long distances you would usually be cruising in fourth gear most of the time. When in neutral and being towed the first motion shaft is stationary and the main shaft driven by the diff is spinning merrily away.Get the picture

Edited by Rorf, 31 July 2019 - 05:22 AM.

[Spider]

 

How so? It's in the oil bath the whole time....what's the difference between it being towed and driving?

 

When driving in fourth gear both shafts are turning at the same speed, and on the open road doing long distances you would usually be cruising in fourth gear most of the time. When in neutral and being towed the first motion shaft is stationary and the main shaft driven by the diff is spinning merrily away.Get the picture

 

 

Rolf is correct here with his advice.

 

Although the shafts and bearings are in an Oil Bath, the Oil is stone cold and has no way of heating up.

 

Also, when flat towed in Neutral, the 3rd motion shaft spins over quite fast, while the 1st motion shaft is stationary, between there two shafts is a small bearing, which is not rated for continuous duty like this, the end result usually being this bearing and the shafts being damaged.

 

This is a 3rd Motion Shaft I took from a Gearbox that was damaged from being flat towed;-

 

[Rorf]

Thanks for the pic Chris, picture tells a thousand words

[DeadSquare]

 

 

How so? It's in the oil bath the whole time....what's the difference between it being towed and driving?

 

When driving in fourth gear both shafts are turning at the same speed, and on the open road doing long distances you would usually be cruising in fourth gear most of the time. When in neutral and being towed the first motion shaft is stationary and the main shaft driven by the diff is spinning merrily away.Get the picture

 

 

Rolf is correct here with his advice.

 

Although the shafts and bearings are in an Oil Bath, the Oil is stone cold and has no way of heating up.

 

Also, when flat towed in Neutral, the 3rd motion shaft spins over quite fast, while the 1st motion shaft is stationary, between there two shafts is a small bearing, which is not rated for continuous duty like this, the end result usually being this bearing and the shafts being damaged.

 

This is a 3rd Motion Shaft I took from a Gearbox that was damaged from being flat towed;-

 

 

 

 

Hmmm,  how many miles had that been towed ?

 

KAD make a 'Pinion support' that replaces the speedo take-off,  Guess what they use as a bearing.

 

To be fair, they intend it to be used in hot oil under a full race engine which is a season of about 50 miles for each practice and race, and it is much closer to the support of the pinion bearings than on the end of the gear cluster at the 1st motion shaft.

[Magneto]

I'm curious how you determined that was from flat towing and not improper lubrication due to long change intervals or the wrong oil being used or  something?

 

I think most Minis spend more time in 1-3rd gear, at least those used in town, and the the spin rate difference in those gears is plenty high. As there's no load on that bearing when it's being towed, I don't see how RPM by itself would damage it.

 

Not disputing your word in any way, but I've flat towed my car well over 5K miles at 70-75 mph with no noise or other issues so far. I use a good high zinc oil and change every 3K or less.

Edited by Magneto, 04 August 2019 - 12:29 AM.

[imack]

[quote name="DeadSquare" post="3609709" timestamp="1564814979"][quote
 

[
 
KAD make a 'Pinion support' that replaces the speedo take-off,  Guess what they use as a bearing.[/quote]

I'm running a KAD pinion support housing, the bearing in there definitely isn't a 1st motion shaft needle roller. The KAD bearing inner race ID is 17mm.

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[DeadSquare]

[quote
 

[
 
KAD make a 'Pinion support' that replaces the speedo take-off,  Guess what they use as a bearing.

I'm running a KAD pinion support housing, the bearing in there definitely isn't a 1st motion shaft needle roller. The KAD bearing inner race ID is 17mm.

 

That is not what the KAD man said in his video.

 

Glad to see that it is more substantial.

[imack]

[quote name="DeadSquare" post="3609823" timestamp="1564901305"][quote name="imack" post="3609821" timestamp="1564900990"][quote name="DeadSquare" post="3609709" timestamp="1564814979"][quote
 

[
 
KAD make a 'Pinion support' that replaces the speedo take-off,  Guess what they use as a bearing.[/quote]
I'm running a KAD pinion support housing, the bearing in there definitely isn't a 1st motion shaft needle roller. The KAD bearing inner race ID is 17mm.[/quote] That is not what the KAD man said in his video. Glad to see that it is more substantial.[/quote]

I've not seen the KAD video, I think the MED pinion support bearing is a smaller id than KAD's but I don't think that a 1st motion shaft bearing either.

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[Spider]

The Pinion support is getting a little off topic, but while they can add some support, they are not a Primary Bearing, that being the (double row) Main Shaft Bearing and this is a supplementary support taking some load.

 

While the idea of these is OK, I've had two in my workshop that cases the end of the Mainshaft to break off. Where they fit to is only small and not really rated for carrying any or much load.

[Magneto]

The setup that Iain1967s uses above is very similar to mine - the only difference I can see is that I use a very heavy  angle iron between the subframe bolts, to which I welded some 1/2" ID tubing.....I pass the 1/2" grade 8 bolts thru this tubing and into the subframe holes. This system is very rigid and takes all the bending moments away from the subframe. My car just follows me along the road like a puppy.

 

I understand the point Nick makes with his pics and description of the small bearing in the first motion shaft, but I don't think that bearing is RPM limited. I know a lot of people who flat tow their Minis here in the states, and most are over pretty long distances. I've not heard of anyone having transmission failure, but we're all pretty careful about oil change intervals and using the right oil.

 

I don't know of any rules regarding brakes on the towed vehicle this light in the US, but as I wrote before I can see where this would be useful as I had a woman turn right in front of me and even tho I was only going 35 mph it was hard to get the car slowed quickly enough. You need to make sure the brakes on the towing vehicle are in top shape.....fortunately the brakes on a MINI are excellent - thank you BMW for that. 

[nicklouse]

 

I don't know of any rules regarding brakes on the towed vehicle this light in the US, but as I wrote before I can see where this would be useful as I had a woman turn right in front of me and even tho I was only going 35 mph it was hard to get the car slowed quickly enough. You need to make sure the brakes on the towing vehicle are in top shape.....fortunately the brakes on a MINI are excellent - thank you BMW for that. 

in the UK if the trailer has brakes fitted they must be operated by the tow hitch the same as a normal braked trailer. even though the mass of the Mini is less that requires brakes to be fitted to a trailer as it has them they must be operational and be operated by the hitch.