De Deon Tube illustrated


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Being new to this Rover thing I've discovered they had some unusual and quirky ways of building the P6. All rather fascinating but none more than the De Dion setup at the rear. Having scoured this forum looking for what's involved in giving said item an overhaul, I managed to build up enough info to start this minor job.
My one was leaking (oil in the rubber boot) and creaking. Ordered the kit, waited a month or so and made a plan. As mentioned various times in this forum, photo's are good. Actually they're great, you know, picture=thousand words stuff. And that is what I found lacking for a De Dion novice like me.
Sooooo, had my camera handy and started my little adventure.
Now, this is my first post here so still finding my way around and if it turns out a little odd, please forgive me. Also, the way I did the overhaul isn't gospel by any means. There are many here that can do this job in their sleep. I'm just sticking my photo's up for anyone else tackling this job for the first time to have something to work with.

My car is a 73 New Zealand assembled P6B that started life as an auto. (just in case that makes a difference or not:hmm:)

Here I have raised the car on the rear jacking point (solid rust less car) to allow the wheels to swing together compressing the tube to its shortest.
Also have removed the large hose clamp and drained the oil from behind the boot.

Have removed the bolts and the nuts from the studs. For some reason, or not, there were 3 studs on one side and one on the other.

Now I have lowered the car back onto it's wheels, thereby pulling the suspension apart again releasing the tube. (too easy, where's the catch....?)

This is where I cleaned out the tube elbows of years of built up road dust, Wire brushed them out and treated them with my favourite rust penetrator-preventer-sealer stuff. (technical term). No problems with these, just thin surface rust.
Rover special tool #1
Rover special tool #2
20200714_191801.jpg 20200714_193945.jpg

This is where the fun begins. Cleaning and seeing what I've got to work with as far as a 47 year old De Dion tube goes.
Little bit of scuffing/wear here (other end of the tube was the same). If you were to to jack the car up by the De Dion tube:hmm:, this is where the weight if the car will bear upon. I suspect the yellow bush is a plastic but I'm probably wrong. (again)
And spotless this side.

Cleaned out the air hole. This is to allow air to enter and leave the inside of the rubber gaiter/boot when the suspension is working. 20200714_213111.jpg
All cleaned up ready to assemble. Replaced all the bolts and studs with new high tensile bolts and lock washers. (don't throw your studs away though)
This is the position where the seal sits on the inner tube at normal road height when on the car. It squishes (another technical term) in and out when driving so the shiny part of the inner tube must be free from any defects otherwise the new seals will just leak again. Same again with the other end of the tube. If there is a problem, I'd suggest going the grease filled tube direction. (info elsewhere on the forum). Mine seemed perfect so oil fill for me (until proven otherwise).
The reason mine had leaked oil was the seals had hardened over time. When removed, they had about half the flexibility of new ones.
Note - I still have a serviceable retaining spring that I prefer to the cable tie that came with the kit. (it sits in the boot grove nicely:thumb:)

End plat and top hat (love technical terms) cleaned and treated for reassembly.

Filling the tube with 189.42 ml approx. (1/3 imperial pint for those not in the colonies) of the finest 20-60 mineral oil money can buy. This takes a bit of time as the gap between the inner and outer tubes is about 2 mm, the oil is thick and the air is trying to come out as the oil goes in.
This is the interesting bit. This is the exact angel the tube sits when mounted on the car. The oil is right up to the filler hole, just like in a gearbox and a diff. So there proves a point that has been discussed many times before. The filler hole is at this angle for a reason...:cool:

The tube now contains oil so care must be taken not to pull it apart although the retaining clip should stop it from doing so.
My choice is to seal the gaskets with a non hardening sealant to keep moisture from creeping in.

Before putting the tube completely together, I loosely reinstalled 2 studs on each elbow. This made realignment of the bolt holes very easy. After a couple of the bolts were installed, the studs were removed and stored for a later day (but where did I put them I will be asking myself). As well as the lock washers, I put a drop of loctite on each bolt. (overkill, I know).
The tubes have a spacing pattern for the bolt holes that allows it to be mated to the elbows one way only. This way the oil fill hole will be at the correct angle and facing upward toward the rear of the car. I didn't try it, but if the tube were to be mounted with the boot on the left (looking forward), the oil filler hole would be facing down towards the rear of the car. (and the air hole for the boot would be wrong too but that shouldn't be a big problem).
These last findings are for MY car. I haven't seen or worked on any other P6's and as many have stated, their boots are on the left. (Maybe grease filled with no filler hole, maybe different hole patterns, I don't know :rolleyes:(possible survey topic))
All done and pretty. No more squeak, no more leak???? will let you know over time. If it does leak again, I'll head the grease filled direction.

Have reached the maximum photo's for a post and have culled a few of the lesser images to make this fit. Hope this will be of use to someone one day.
I am happy to be corrected on any of my findings, This was how I tackled it first time round. It all went smoothly and, touch wood, stays fixed.
Cheers all,
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Well-Known Member
Good post.
Regarding elbow rust, it is the other end of the elbow where the lower link attaches that needs careful examination. Removing the link is the only way to see if that area has corrosion.


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If you've tightened the clamp on the boot to the tube with the car still on the ramp, you may find that the clamp is in the wrong position, or the boot is twisted once the car has been driven. Other than that a good job with nice pictures, and it shows that the WM saying that an elbow has to be removed to the job is rubbish.


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My 74 (chassis suffix D) has no oil filler plug, my parts book (73) and WSM (72) make no mention of this, so whats different for me? Peter mentions above grease filling as an alternative - is there any documentation of this version please?


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Staff member
Yes indeed, that is a great post Peterv!

My 74 (chassis suffix D) has no oil filler plug, my parts book (73) and WSM (72) make no mention of this, so whats different for me? Peter mentions above grease filling as an alternative - is there any documentation of this version please?
Hi JP,

We tend not to see too many oil type de dion tubes here in Australia, so yours being a grease type like mine tends to be the norm. The grease type has the advantage of not leaking oil, there is nothing really in them, just some seals and a thin layer of grease over the parts and tube. I use Castrol EPL-2, applying a light coating each time I replace the boot, cleaning off the old stuff first. You can always spot the difference as there is no oil filler with the grease type.



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JP, no filler plug = grease filled De Dion. Unless it makes awful noises or is visibly damaged, "Fuggedaboutit!". Someone more trustworthy will be along to refute that and explain why I'm wrong again in due course.
Ron (Forum admin and therefore to be trusted!) just said pretty much the same whilst I was typing!


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So to clarify, a grease type is built the same as an oil type, same seals, same 'bearing', same construction bar the fill hole, just uses grease as a lube instead of oil ?


Active Member
Hi All
Thanks for the encouraging comments. This forum is so much more positive than others that I don't mind putting some effort into a post.

C.B. Will have a good look at that soon. Although as I'm starting to clean some of the road grime away, I'm finding red Poly?? bushes. So looks like some work has already been done in this area.:thumb:

MrT, A hoist makes working on classic cars a dream. But it did take some years of groveling to get the ok from my lovely wife. (not just a hoist but a new garage door was required to get that extra meter of headroom. Those mufflers are called Cobys down here. (brand name in folk-law) and what a sound they make:LOL: when you put your foot down. Use to put them on our Mini's back in the 70's/80's. (no good for sneaking home late). Squeaking has gone:D.

Harvey, Checked the boot after a drive and the moulding line is almost straight. Having the spring retainer rather than a cable tie allowed me to rotate that end of the boot about 2mm so spot on now. Guess it doesn't have to be super tight any way as its only holding the boot in its grove a bit more positively. I will keep an eye on it anyway although the old boot had no issues (and held the oil in nicely:hmm:).
Cheers Guys


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Thanks guys, much reassured now. Will wait until I sense something awry up the back.
Edit:- When I knew guys on the rover trade, for P4s that developed weepy kingpin seals they used a mixture of EP90 with some grease to thicken it up. These had a thrust ball race in them that needed something thinner than grease.
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Well-Known Member
I went the grease route ages ago. Everything appears to be working as normal.
the major plus for me - one less oil drop on the garage floor
other plus - have not had to change the rubber boot in that time
Peterv, I am just about to do mine for the first time and found your post very informative . One Question, do the wheels have to be on the ground to remove the tube ? I could achieve this by putting the car on ramps I suppose. Thank you for your very enlightening post . Jim
Thank you Harvey . I spotted the leak when I was changing the Shockers and Springs . One Job always leads to another. Jim
Hi Harvey , The leak is the other end to the boot . I try never to do part of a job especially as we now have plenty of time on our hands . I have just replaced the rear shocks and springs .I took the spring support arms off and painted them and it all looks good under there . Taking the de-Dion tube off and painting it would finish off the rear end . Thank you for your support. Jim


Active Member
Having the wheels bearing weight pulls the elbows apart making taking the tube out easy. (See photos). If you have oil leaking, the seals are shot and needs replacing. Do the boot too as these seem to have a finite life. Hope you've managed to get the parts before they locked you down. This job is one of the easy ones to do on a p6.
New oil can't do any harm either. Filling it on the work bench is much easier than when on the car. But do replace the studs with bolts and nuts. Makes reassembling a breeze for minimal cost.
Put the rear on your ramps, chock the front wheels and think safety first.
Cheers, Peter
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Peterv, I am just about to do mine for the first time and found your post very informative . One Question, do the wheels have to be on the ground to remove the tube ? I could achieve this by putting the car on ramps I suppose. Thank you for your very enlightening post . Jim
I have done it with wheels on ramps. I supported the elbows with a scissor jack, when the time came to put it back together.


Active Member
That's fantastic Jim. Hopefully it wasn't too much of a mission and the inner's of the tube were still okay. Glad to have been of service.
Cheers, Peter


Active Member
Hi All
It's been less than a year since I completed this and have noticed the boot is starting to crack.
There is no oil in there so the seals are holding out, just the boot......
This was sourced from one of the major P6 parts suppliers in the UK . This isn't an unusual occurrence from what I've read here but I don't particularly want to replace it on an annual basis.
My question is, has anyone found a source of a quality boot? If someone has, could you please PM me with where to get one. (so as not to upset any suppliers)
That would be much appreciated .