I am putting together a 1929 M type and logic would tell me that the fabric joints either end of the propshaft should not be unduly distorted in "rest" position. Thus there should be more or less a straight line, both horizontally and vertically from the Engine/gearbox to the back axle.
To achieve this one would need the engine/gearbox, propshaft and rear axle being in a near as possible straight line. The engine/gearbox with new (S&V) mounts fitted, points slightly upwards and the rear axle which one also cannot alter, points downwards, and as the engine/gearbox is higher than the back axle this means the flexible joints are extremely distorted.
Also the propshaft appears to be too long by about 1/4 inch adding to the distortion. Were I to fit 'hardy-Spicer' universal joints this would not matter, but as I want to use it in VSCC LC&ES events basic originality is needed.
Are my assumptions correct and how can I overcome the problem? I don't want to 'butcher' the engine mounts just yet! Or is this how it should be?
Fabric Joints
Moderators: Ian Grace, Will Grace
Re: Fabric Joints
Hi John,
This is a common issue with these fabric couplings. As the gearbox spider and diff spider are both nominally vertical, but the gearbox is higher than the back axle (specially with new rear engine mountings), then the flex of the coupling has to take up the angles in the drive train.
Compounding the problem is the prop shaft lengths which vary depending on various gearboxes, being shorter for the 4-speed boxes, of which there were several variants.
When I bought my first Minor, the owner told me that it ran well. When I winched it onto the trailer, there was a loud 'click, click, click' from the rear end. Investigation when I got the car home revealed that the spiders at the diff end were bolted directly together with NO coupling!
No problem, I thought,I just ordered up a pair of new couplings from Sports & Vinatege. But of course, when I came to fit the rear one, there was no gap for it - they are a good half inch thick (and probably thicker than the original leather ones, which also does not help).
I ended up cutting and shutting the prop shaft and that solved the problem. I took off a tad more out than necessary to aid fitting the couplings. New ones are very stiff, but, as you indicate, they have to be distorted when in position, so, working under the car on ramps or jacks, this is one of the jobs I never look forward to. It is a slight help to have the rear wheels of the ground (i.e. jacking the rear chassis).
Hope this helps,
Ian
This is a common issue with these fabric couplings. As the gearbox spider and diff spider are both nominally vertical, but the gearbox is higher than the back axle (specially with new rear engine mountings), then the flex of the coupling has to take up the angles in the drive train.
Compounding the problem is the prop shaft lengths which vary depending on various gearboxes, being shorter for the 4-speed boxes, of which there were several variants.
When I bought my first Minor, the owner told me that it ran well. When I winched it onto the trailer, there was a loud 'click, click, click' from the rear end. Investigation when I got the car home revealed that the spiders at the diff end were bolted directly together with NO coupling!
No problem, I thought,I just ordered up a pair of new couplings from Sports & Vinatege. But of course, when I came to fit the rear one, there was no gap for it - they are a good half inch thick (and probably thicker than the original leather ones, which also does not help).
I ended up cutting and shutting the prop shaft and that solved the problem. I took off a tad more out than necessary to aid fitting the couplings. New ones are very stiff, but, as you indicate, they have to be distorted when in position, so, working under the car on ramps or jacks, this is one of the jobs I never look forward to. It is a slight help to have the rear wheels of the ground (i.e. jacking the rear chassis).
Hope this helps,
Ian
Re: Fabric Joints
Thanks for your reply Ian. The car has been apart since about 1962, but the back axle, engine/gearbox (including the unused handbrake drum) and prop shaft all came with the car, so I assume that they should all fit. But, and there is a big but, they don't grrrr. It is only about 1/8 to 1/4 of an inch but enough to be a b****r. Thinking about it the only thing that might be different is that I have had the springs re-set, so that might be where the problem arises. Don't know how I can check that, but I'll keep pondering.
Re: Fabric Joints
I don't seem to be be able to get a satisfactory result, so I may have to go down the U/J route, has anyone done this and how? If so can you use M.G. J type couplings and prop shaft, does anyone do these as S&V don't?
Re: Fabric Joints
Talk to Clive Hamilton-Gould who had several conversion sets made. I'll send you his contact details.
Re: Fabric Joints
Thanks Ian - info received
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PeterWHills
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Re: Fabric Joints
I pay considerable attention to the prop shaft alignment and Fabric Coupling discs. Do not assume that the Fabric Disc is there to take up any alignment errors unless you never travel faster than 25mph. At 40mph+ (down hill) if you get increased vibration then the Prop Shaft Assembly is the most likely cause and apart from lost power, the miss-aligned discs will have a reduced life.
There are several issues to attend to: First all the Spiders' bolt holes should be at right angle to the centre line and be in the same plane (often bent and distorted). Those fixed to the Prop Shaft must be in line with the central axis of the shaft. This can be checked on a long bed lathe, in my case I have made a rig with 'Vee" blocks to check the Spiders radial plane. With slight pressure you can bend the spiders back to position but make sure their contact face with the Fabric Disc is in the same plane.
I stopped using the original machine bolts with Castellated Nuts and split pins as I found that after use with a new Fabric Disc, the nuts needed tightening but then the split pins may not be in the locking position. I have switched to Aero Lock Nuts.
I have also found that the New Fabric Discs bolt hole metal plates (either side) are easily deformed so fit more robust washers but with corners ground out to settle between the plate rivets. This increased contact surface area has reduced any distortion of the Disc's riveted plates.
It is best to replace both Fabric Discs at the same time for optimum results. Once installed, do not tighten up the Spider Bolts but jack up the rear wheels onto stands, then run the engine and engage gear. Assuming you have removed the front floor boards you will be able to determine if the Prop-Shaft is running true. If not, taking a stout plank of wood, applying slight pressure to the Prop Shaft (in motion) this will aid its alignment. Once acceptable, tighten the Spider Bolts but not too much that would overly compress the Fabric Disc.
There are several issues to attend to: First all the Spiders' bolt holes should be at right angle to the centre line and be in the same plane (often bent and distorted). Those fixed to the Prop Shaft must be in line with the central axis of the shaft. This can be checked on a long bed lathe, in my case I have made a rig with 'Vee" blocks to check the Spiders radial plane. With slight pressure you can bend the spiders back to position but make sure their contact face with the Fabric Disc is in the same plane.
I stopped using the original machine bolts with Castellated Nuts and split pins as I found that after use with a new Fabric Disc, the nuts needed tightening but then the split pins may not be in the locking position. I have switched to Aero Lock Nuts.
I have also found that the New Fabric Discs bolt hole metal plates (either side) are easily deformed so fit more robust washers but with corners ground out to settle between the plate rivets. This increased contact surface area has reduced any distortion of the Disc's riveted plates.
It is best to replace both Fabric Discs at the same time for optimum results. Once installed, do not tighten up the Spider Bolts but jack up the rear wheels onto stands, then run the engine and engage gear. Assuming you have removed the front floor boards you will be able to determine if the Prop-Shaft is running true. If not, taking a stout plank of wood, applying slight pressure to the Prop Shaft (in motion) this will aid its alignment. Once acceptable, tighten the Spider Bolts but not too much that would overly compress the Fabric Disc.