10 July 2023
Axle bump stop brackets (or perches) collect mud and corrode away, which is bad news given the load they might take. Jake Shoolheifer shows how to renew them
Need to know
Time: 6 hours
Cost: Materials approximately £15
Difficulty: 3 out of 5 (or 2 out of 5 if just prepping for paint)
Models: Series models.
Tools needed: Angle grinder, cutting disc, grinding disc, flap disc, wire cup brush and/or composite rust removal disc, 1/8 BSP tap, 3/8 BSF die nut (does not apply to all Land Rover models), welder, G-clamp, pen and ruler.
• When using an angle grinder, always wear gloves, preferably cut-proof, ear protection and goggles but ideally a clear face visor.
• Check cutting discs for chips or fractures before use, and always operate the grinder so it won’t kick up at you if it grabs, and ensure the sparks are aimed away from your face.
• When cleaning up the axle case, wear a face mask to reduce the risk of dust inhalation.
• Suitable protection must be worn when welding. Long sleeves and heat-resistant gloves, ideally fire retardant clothing or similar, such as a welding jacket. Always wear a welding helmet/visor. Be careful of stray sparks and flammable items. Never walk away from a hot weld, and always make absolutely sure nothing is on fire or smouldering.
Massively in the firing line from road salt, mud and water, the axle casings on a Land Rover can take a lot of abuse. In this article, I will be showing the repair of the axle case for a 1955 86in Series I that we are re-commissioning. The repair is carried out before preparing the axle case for paint and reassembly.
The bump stop perches and the reinforcing sections (found on fully floating axles) are typically the main cause of concern when it comes to corrosion on an axle case, but sometimes the diff pan can suffer, too. Less common, but still found, is heavy corrosion in the axle tubes. The usual cause is moisture being trapped in layered areas of steel, or areas that sit covered in mud.
In this instance the axle case, although pitted, wasn’t in a poor enough state to be completely written off, especially given that it carried the original stamped numbers that were correct for the vehicle. So it was important to save it. However, the bump stop perches were in a terrible state.
The 86in was the first Series Land Rover to have the back axle case fitted with perches for the bump stops. Prior to this, the bump stop had just collided with the round face of the axle tube when the springs were under full compression. With the increased strength of the perches however, came a dirt trap and, in this case, what was once made from 4mm-thick steel was now under 1mm thick in most areas.
After some searching I couldn’t find any suitable ready-made replacements for the bump stop perches. Options were available, but none matched the original style of that found on the axle case that I was repairing. So I chose to manufacture them in order to retain the original appearance once the repairs had been made. As always, there are a few routes you can choose to take if you’re planning on carrying out similar work. If you’re not too fussed about the final aesthetic, then a much simpler design can be used because the essentials of the perch is a flat face on the top of the axle tube, with two sides notched to fit around the curvature of the tube. The perches found on later axles are a bit simpler and tend to be squarer in form.
Renewing the perches
Unfit for purpose: Heavily corroded and no longer functional, the bump stop perches needed replacing before the axle could be painted and re-fitted to the vehicle.
Corrosion sequence: The passenger side perch was severely corroded. As you can see, dirt and moisture becomes trapped under the perch and pushes out the metal, deforming it.
New part: I took the dimensions off the remaining perch and drew it on CAD software. You could also use a cardboard pattern and power tools, but I wanted to produce a couple of spares for future use. The time taken to draw a CAD file and the cost of having components laser cut, is less than the total cost a client would be charged if I just cut them by hand from a sketch.
Surgery: A cutting disc in an angle grinder was used to cut the old perches off, as close as possible to the axle tube face without damaging the tube itself.
Clean metal: A grinding disc or flap wheel in the angle grinder was used to flatten the remaining material. Then a wire cup brush in the grinder cleaned up the surface of the axle case where the new perch would be attached.
Ready to weld: With the rust removed, I applied a coat of weld-through primer to the area underneath the perch to provide a little more corrosion protection in the future. I then marked out the position for the perch, exactly back where it was fitted before, and used a G-clamp to fix it in place before tack welding. Try to fit the perch back exactly as it was before. The rear perches are pretty much parallel to the spring, but this may be different on other vehicles and axle cases. It certainly isn’t the case with the front bump stop perch, so be sure to check.
Full welds: Tacked and then fully welded into place. Originally this would have been electric arc (stick) welded to the axle case but, as I am more familiar with MIG (GMAW) welding, I chose this method.
Full clean-up: With the perches now welded back onto the axle case, prep can begin prior to painting the axle case. With the risk of getting grit stuck in the axle case through sand blasting, we tend to instead clean up the cases using an angle grinder. A cup brush (left) gets into the pitting much more than the composite type disc (right). But the composite rust removal disc is a perfect level of abrasive to clean the case, without marking it like a grinding disc would. So I tend to use a mix of a wire cup brush and the composite rust removal disc, mainly depending on how much pitting there is.
Thread care: Finally, after cleaning up the axle case, it is always best at this stage to clean the threads of the studs on the axle case. For the studs that fasten the differential, I use a hex-sided 3/8 BSF (for original Series I axles) die nut with a deep socket. You shouldn’t really need to use much force, if any, when turning the die because you are simply clearing the threads of any burring or grease and debris.
Breather tap: The next thread that should be checked is that for the axle breather. Again these are usually not in a terrible state but it is best to check its condition before the axle is painted and built up on the vehicle. Series vehicles (to the best of my knowledge, coil sprung models, too) are tapped using a 1/8 BSP tap. Again, make sure you are square to the hole and the tap is turning reasonably freely. If it isn’t, and the threads don’t look obviously damaged, be sure you are not cross-threaded.
Finished job: This axle assembly looks well after good preparation and a correct painting sequence – this restored vehicle awaits axle straps and brake pipes.
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