Post by p5andrew on Mar 20, 2024 12:49:26 GMT
As some on the forum may remember from a previous post, I am restoring and rebuilding a subframe for my P5B. It seems to have been rather quiet on the forum of late, so I thought I would post the fuller story in the hope that one or two might find it of interest.
The reason for the replacement is principally because the existing subframe is distorted, apparently as a result of historic accident damage. The result is some very odd handling characteristics and, more particularly, heavy tyre wear. I could have straightened the existing subframe on our (rather ancient – but it works!) body jig but was attracted by the idea of completely rebuilding a subframe/suspension/steering and then swapping the assemblies over. Simple? A good plan? Probably not…we shall see!
I purchased a second-hand subframe via Ebay and it came complete with all suspension except the torsion bar height adjuster bolts which were missing, and with almost all the steering components except the steering box. Other than some surface rust, the subframe appeared essentially corrosion-free and careful measurement indicated that it was straight and true. There were only two areas of damage, one being the middle crossmember which had been badly dented, apparently by ham-fisted use of a trolley jack – not uncommon! The other area of damage was one of the bumper iron attachment points which had at some point been bent during storage off the parent car; it looked like something heavy had probably fallen on it, the subframe rail fortunately being unaffected.
Dismantling of swivels using homemade special tool. It looks a bit of a lash-up but it worked well!
After shotblasting
The first job was to strip off all components. I have never been a fan of the method of relieving torsion rod tension laid out in the WSM using a trolley jack and a chain; not so bad when the subframe is still assembled on the car but very cumbersome if off the car. I therefore fabricated a tool consisting of top and bottom rails and two long lengths of studding to hold the top wishbone and bottom link together in compression and, after releasing the swivel joints, allowing the remaining tension in the torsion bar to be slowly released. I added a short length of studding through an existing hole in the bottom link to prevent any possibility of the tool sliding off the bottom link. This arrangement worked very well and all came apart in a nicely controlled manner.
After stripping off all components I cleaned off all old oil/grease contamination and then delivered the subframe to the shotblaster. Happily, the shotblasting did not uncover any horrors. After some localised straightening, a piece of heavy plate was shaped up and welded to the bottom of the middle crossmember. The bent bumper mounting was heated with a gas torch and straightened. I then ran taps through all tapped holes to the subframe to clean up the threads and all holes were then plugged to prevent paint ingress.
I spent some time spent researching possible paint systems for the subframe and after endorsement by a fellow forum member (thanks Vince!) eventually decided to use POR15. Unfortunately though, I needed it quickly and the supplier was quoting a week or so for delivery. By this stage the subframe was back from the shotblaster and needed painting quickly to prevent the risk of corrosion breaking out - always a potential problem with shotblasted steelwork. I therefore resorted to spraying all up with two coats of etch primer and, after curing, three coats of two-pack primer/filler were sprayed on. Finally, three coats of gloss black two-pack acrylic were applied. An awkward thing to paint by spraying due to all the nooks and crannies but it came up pretty well and I’m pleased with the result. I now just need to Waxoyl the box sections and open parts of the rear crossmember and will do this once it is on the car. Time will tell as to how robust the paint system will prove to be, though it must surely be better than the original finish.
All the suspension and steering components were cleaned back to clean metal and were primed and painted as per the subframe. All rubber bushes have been replaced throughout and a complete set of new trackrod ends fitted. I already had to hand a set of swivel joints which I had stripped down and reconditioned, all complete with new internals and boots. New Spax gas shock absorbers and anti-roll bar pins and bushes together with new brake discs completed the main purchases. I have replaced virtually all securing nuts throughout in stainless steel and those bolts which needed to be replaced are also in stainless steel, all threads being smeared with copper grease to help prevent galling. I rebuilt the steering idler with a new seal. The hub bearings to one side have been washed out, fitted with a new seal and charged with new lithium-based grease. The bearings to the other side were initially thought to be good but on close inspection were found to have slight water damage/corrosion due to a damaged seal so replacements have been obtained and fitted along with a new seal.
One task still to be done over coming days is the manufacture of a pair of torsion bar gaiters. Unfortunately Wadhams are out of stock of gaiters, no other the source offering them as far as I can find, otherwise I would have bought them in. I shall therefore resort to making gaiters from leather which will then be heavily waxed externally and of course greased internally. Fortunately, I still have some high-quality hide left over from when I retrimmed the interior during the covid lockdown. Far too good really to be used for gaiters but at least I have it here.
The steering box currently on the car will be transferred over to the replacement subframe when the time comes. I rebuilt the ‘box about three years ago and modified it to take an improved seal arrangement as I know others have done in the past and so far this has proved to be leak-free – result!
I undertook a complete rebuild of the engine and gearbox just over three years ago. I shall nevertheless undertake a minor cosmetic refresh while all is out of the car. The one thing I do need to tackle is replacement of the gear selector shaft seal which, despite replacement during the rebuild, has always leaked badly. It may be that I accidentally damaged the current seal during reassembly of the gearbox, or perhaps the shaft is damaged – we shall see.
I now just have a few final things to assemble and I will then go round and touch up the paintwork as required.
Assuming the weather is reasonably kind, the plan is to make the swap over the Easter long weekend. I do not have enough height in the home workshop to allow the body to be lifted high enough to release the subframe assembly from below, so the job will need to be done on the drive using our mobile gantry and a couple of chain blocks. Should be fun…!
More pictures to follow...
The reason for the replacement is principally because the existing subframe is distorted, apparently as a result of historic accident damage. The result is some very odd handling characteristics and, more particularly, heavy tyre wear. I could have straightened the existing subframe on our (rather ancient – but it works!) body jig but was attracted by the idea of completely rebuilding a subframe/suspension/steering and then swapping the assemblies over. Simple? A good plan? Probably not…we shall see!
I purchased a second-hand subframe via Ebay and it came complete with all suspension except the torsion bar height adjuster bolts which were missing, and with almost all the steering components except the steering box. Other than some surface rust, the subframe appeared essentially corrosion-free and careful measurement indicated that it was straight and true. There were only two areas of damage, one being the middle crossmember which had been badly dented, apparently by ham-fisted use of a trolley jack – not uncommon! The other area of damage was one of the bumper iron attachment points which had at some point been bent during storage off the parent car; it looked like something heavy had probably fallen on it, the subframe rail fortunately being unaffected.
Dismantling of swivels using homemade special tool. It looks a bit of a lash-up but it worked well!
After shotblasting
The first job was to strip off all components. I have never been a fan of the method of relieving torsion rod tension laid out in the WSM using a trolley jack and a chain; not so bad when the subframe is still assembled on the car but very cumbersome if off the car. I therefore fabricated a tool consisting of top and bottom rails and two long lengths of studding to hold the top wishbone and bottom link together in compression and, after releasing the swivel joints, allowing the remaining tension in the torsion bar to be slowly released. I added a short length of studding through an existing hole in the bottom link to prevent any possibility of the tool sliding off the bottom link. This arrangement worked very well and all came apart in a nicely controlled manner.
After stripping off all components I cleaned off all old oil/grease contamination and then delivered the subframe to the shotblaster. Happily, the shotblasting did not uncover any horrors. After some localised straightening, a piece of heavy plate was shaped up and welded to the bottom of the middle crossmember. The bent bumper mounting was heated with a gas torch and straightened. I then ran taps through all tapped holes to the subframe to clean up the threads and all holes were then plugged to prevent paint ingress.
I spent some time spent researching possible paint systems for the subframe and after endorsement by a fellow forum member (thanks Vince!) eventually decided to use POR15. Unfortunately though, I needed it quickly and the supplier was quoting a week or so for delivery. By this stage the subframe was back from the shotblaster and needed painting quickly to prevent the risk of corrosion breaking out - always a potential problem with shotblasted steelwork. I therefore resorted to spraying all up with two coats of etch primer and, after curing, three coats of two-pack primer/filler were sprayed on. Finally, three coats of gloss black two-pack acrylic were applied. An awkward thing to paint by spraying due to all the nooks and crannies but it came up pretty well and I’m pleased with the result. I now just need to Waxoyl the box sections and open parts of the rear crossmember and will do this once it is on the car. Time will tell as to how robust the paint system will prove to be, though it must surely be better than the original finish.
All the suspension and steering components were cleaned back to clean metal and were primed and painted as per the subframe. All rubber bushes have been replaced throughout and a complete set of new trackrod ends fitted. I already had to hand a set of swivel joints which I had stripped down and reconditioned, all complete with new internals and boots. New Spax gas shock absorbers and anti-roll bar pins and bushes together with new brake discs completed the main purchases. I have replaced virtually all securing nuts throughout in stainless steel and those bolts which needed to be replaced are also in stainless steel, all threads being smeared with copper grease to help prevent galling. I rebuilt the steering idler with a new seal. The hub bearings to one side have been washed out, fitted with a new seal and charged with new lithium-based grease. The bearings to the other side were initially thought to be good but on close inspection were found to have slight water damage/corrosion due to a damaged seal so replacements have been obtained and fitted along with a new seal.
One task still to be done over coming days is the manufacture of a pair of torsion bar gaiters. Unfortunately Wadhams are out of stock of gaiters, no other the source offering them as far as I can find, otherwise I would have bought them in. I shall therefore resort to making gaiters from leather which will then be heavily waxed externally and of course greased internally. Fortunately, I still have some high-quality hide left over from when I retrimmed the interior during the covid lockdown. Far too good really to be used for gaiters but at least I have it here.
The steering box currently on the car will be transferred over to the replacement subframe when the time comes. I rebuilt the ‘box about three years ago and modified it to take an improved seal arrangement as I know others have done in the past and so far this has proved to be leak-free – result!
I undertook a complete rebuild of the engine and gearbox just over three years ago. I shall nevertheless undertake a minor cosmetic refresh while all is out of the car. The one thing I do need to tackle is replacement of the gear selector shaft seal which, despite replacement during the rebuild, has always leaked badly. It may be that I accidentally damaged the current seal during reassembly of the gearbox, or perhaps the shaft is damaged – we shall see.
I now just have a few final things to assemble and I will then go round and touch up the paintwork as required.
Assuming the weather is reasonably kind, the plan is to make the swap over the Easter long weekend. I do not have enough height in the home workshop to allow the body to be lifted high enough to release the subframe assembly from below, so the job will need to be done on the drive using our mobile gantry and a couple of chain blocks. Should be fun…!
More pictures to follow...
