25-05-2023, 11:37 PM
MDJT25 bearing was only fitted to the "Heavy" axle, introduced in mid 1938 (same as the Ruby types). Earlier axles used the ordinary AC bearings, back-to-back.
I have the "Heavy" axle but fortunately, the bearings were all perfect, no marks at all. However, my Lathe broke down, half way through making a new spacer, so I had to resort to shimming the original by 0.045" to regain the factory length of 1.125". The spacer appears to be made of ordinary mild steel, not HT steel, which is probably why it wears out.
The real problems came when trying to get the torque tube back into the axle, it just wouldn't go in! Gravity was having an effect on the rollers of the rear bearing and jamming them. I had to resort to removing the axle from the car, whereupon the torque tube fairly fell in. Just as well I did this as the rear spring pins were jammed with old grease. They're different to ordinary Seven pins, with an ACME thread in the bush/pin area and internal greaseways. This makes them easy to wind out if unworn but they need frequent greasing, which couldn't happen in my case as the greaseways were blocked. Replacement parts are of course, unobtainable.
Car was back on the road today and has covered nearly 70 miles. The axle is much quieter, not quite silent but better than expected, given the state of the pinion.
We should be at Beaulieu for the Rally in July as there will be a number of Big 7s there this year.
I have the "Heavy" axle but fortunately, the bearings were all perfect, no marks at all. However, my Lathe broke down, half way through making a new spacer, so I had to resort to shimming the original by 0.045" to regain the factory length of 1.125". The spacer appears to be made of ordinary mild steel, not HT steel, which is probably why it wears out.
The real problems came when trying to get the torque tube back into the axle, it just wouldn't go in! Gravity was having an effect on the rollers of the rear bearing and jamming them. I had to resort to removing the axle from the car, whereupon the torque tube fairly fell in. Just as well I did this as the rear spring pins were jammed with old grease. They're different to ordinary Seven pins, with an ACME thread in the bush/pin area and internal greaseways. This makes them easy to wind out if unworn but they need frequent greasing, which couldn't happen in my case as the greaseways were blocked. Replacement parts are of course, unobtainable.
Car was back on the road today and has covered nearly 70 miles. The axle is much quieter, not quite silent but better than expected, given the state of the pinion.
We should be at Beaulieu for the Rally in July as there will be a number of Big 7s there this year.