04-07-2020, 04:43 PM
I know the topic of rear hubs on A7’s has been aired on numerous occasions on this forum but in my short time on here I have not seen any mention of a couple of problems I have recently encountered.
The rear axle on my Ruby was originally rebuilt in 1988 complete with new half shafts purchased from A7 Services, Kirby Wiske, but maintaining the original hubs. The car was never completed at that time and never ran on the road with this set up, and was only ever driven in and out of the garage and up and down the drive.
In 2017 the rear hubs were stripped down again and checked. The hubs were not tight and there had been movement as witnessed by the markings on the taper and woodruff key. New outer hubs were purchased along with new keys, bearings, brakes, springs etc. The hubs were lapped onto the shafts and all made good.
Refer Pic 1 attached
However, the location of the split pin hole on the half shaft was located too far towards the end of the threaded portion to engage with any of the slots on the castellated nut.
Refer Pic 2 attached
After a period of time and miles I checked the tightness of the nuts and found the offside was still tight and ok whilst the nearside came away without any need for a hub removal tool at all. Needless to say the hub taper had suffered showing signs of chattering and the key was pretty distressed. I have carried out dye penetrant testing of the hubs and shafts and all sound.
However, examining the hub I note that on the inside of the new outer hub, there is scoring around the hub which I believe indicates that the outer hub, when fully tightened onto the bearing, is actually making contact with the end of the fixed axle. So I have dug out the old hubs and find that both the old outer hubs are badly scored on the inside too, which to me indicates the hubs, old and new were and are coming into contact with the end of the thread which the large nut goes on to lock the inner hub and bearing in place see below, old and new:
Refer pics 3 & 4
So before I do anything else can anyone please offer any words of wisdom and comfort on the following:
Is it considered acceptable to add a washer behind the castellated nut on the half shaft end so as to move the nut to a position where the split pins can lock the nut?
If not any other suggestions......?
And
If the outer portion of the hub is in contact with the fixed axle shaft can the end of the fixed axle be fettled down the minimum required to clear the hub?
FYI, I have checked the depths of the original and new hubs and they are within a few thou of each other.
The length of thread on the half shafts including the runoff is 0.8”
The distance from the end of the taper to the split pin hole is 0.685”
The runoff between the taper and start of the thread is 0.112”
Thanks for taking the time to read this and any comments welcomed.
Best Regards
Denis S
The rear axle on my Ruby was originally rebuilt in 1988 complete with new half shafts purchased from A7 Services, Kirby Wiske, but maintaining the original hubs. The car was never completed at that time and never ran on the road with this set up, and was only ever driven in and out of the garage and up and down the drive.
In 2017 the rear hubs were stripped down again and checked. The hubs were not tight and there had been movement as witnessed by the markings on the taper and woodruff key. New outer hubs were purchased along with new keys, bearings, brakes, springs etc. The hubs were lapped onto the shafts and all made good.
Refer Pic 1 attached
However, the location of the split pin hole on the half shaft was located too far towards the end of the threaded portion to engage with any of the slots on the castellated nut.
Refer Pic 2 attached
After a period of time and miles I checked the tightness of the nuts and found the offside was still tight and ok whilst the nearside came away without any need for a hub removal tool at all. Needless to say the hub taper had suffered showing signs of chattering and the key was pretty distressed. I have carried out dye penetrant testing of the hubs and shafts and all sound.
However, examining the hub I note that on the inside of the new outer hub, there is scoring around the hub which I believe indicates that the outer hub, when fully tightened onto the bearing, is actually making contact with the end of the fixed axle. So I have dug out the old hubs and find that both the old outer hubs are badly scored on the inside too, which to me indicates the hubs, old and new were and are coming into contact with the end of the thread which the large nut goes on to lock the inner hub and bearing in place see below, old and new:
Refer pics 3 & 4
So before I do anything else can anyone please offer any words of wisdom and comfort on the following:
Is it considered acceptable to add a washer behind the castellated nut on the half shaft end so as to move the nut to a position where the split pins can lock the nut?
If not any other suggestions......?
And
If the outer portion of the hub is in contact with the fixed axle shaft can the end of the fixed axle be fettled down the minimum required to clear the hub?
FYI, I have checked the depths of the original and new hubs and they are within a few thou of each other.
The length of thread on the half shafts including the runoff is 0.8”
The distance from the end of the taper to the split pin hole is 0.685”
The runoff between the taper and start of the thread is 0.112”
Thanks for taking the time to read this and any comments welcomed.
Best Regards
Denis S