Citroen BX - Modifying rear arm bearings.

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Alan S

1000+ Posts
Just posted this on an overseas board. Should be some help to any BX owner wanting a permanent fix to those annoying rear arm bearings that constantly cause problems particularly in wetter climates.

Alan S


Added from the overseas site in case there are any problems accessing.

The bane of every BX owners life seems to have been these rear (swing) arm bearings. Few have mamanged ownership over any amount of time without having to do them, some more than once.

The symptoms: When the car is set at its highest suspension position, the rear wheels when viewed from about 20 feet away look like this / \ or ! \.
Creaking and/or cracking sounds coming from the rear when the car rises first thing in the morning. Clunking from rear when going over small bumps at low speeds.
Tyres scrubbing on the rear as though they were on the front with a misaligned front wheel setting or tyres wearing on the inside edge.
Car staying "up" even though the ride indicates the spheres feel flat (rough ride) and if still up next morning, a push down manually will see the car suddenly drop at the rear.
The spoke on the steering wheel seemingly altering it's vertical position from one day to the next. (Caused by intermittent rear wheel steering.)

Removing the arm; Not a difficult job.
Pump up car, fit axle stands and then depressurise the entire system.
Remove:- Backing plate to brakes, slacken bleed screw and remove line from caliper (both need 8mm spanner)remove both bolts from the say bar bracket 13mm, remove spring clip to rear suspension cylinder, remove brake caliper. Using a 24MM socket (preferrably a hexagonal type similar to those used on impact guns) and a second to hold the head, slip the socket with a small extension through the coil of brake piping and onto the Nyloc nut and loosen and remove the main bolt holding the arm. Wriggle and remove from car.

NOW, the fun begins: If you own a cheap socket set, grab the 15mm 3/8" drive socket and tap out the spacer tube; the 15mm socket in my case was a perfect fit. Carefully prise out the seals and thrust washers. The inner cones and rollers by now will be a rusty heap on the floor or bench.
If these are all handled carefully, the seals and thrusts will be re-useable, if not a kit including them will have to be bought. Remove (carefully) the plastic sleeve that fits inside the arm. This should leave you with an arm with 2 outer races still in place in the arm and nothing to hit to remove them as there is only about 1/2mm ridge showing. Grab a stick or MIG welder (or go see someone who has one) and weld a solid washer inside the outer cone.
As it cools, using either a 3/4" steel rod or a drift, tap the centre of the washer; it will come out fairly easy. If there's damage to the area from the outer cones top edge to the outer edge of the arm, polish the dags off with a Dremel or similar.
The washer and outer cone will end up looking like this:


Now, clean & polish the bolt and find a friendly fitter to do a spot of lathe work for you.
I made a blue here when I took this pic; I should have had the tape at the outside of the head, but never the less, you can see the dimensions.

A relief almost 20mm turned about 20 thou deep with a hole approx 4 - 5 mm drilled through the arm.


From the head end:

A hole 3mm deep is bored into the bolt through the head to a depth of approx. 50 - 55mm and a short threaded grease nipple is fitted into the head requiring a hole capable of taking a 1/4" Whit tap or similar size is fitted. Only take this hole to around half depth of the head of the bolt as a maximun.


The bolt ready to be refitted, should look like this:


Before reassembling:

Take the spacer tube and drill a couple of 5mm holes in along its length. Refit the plastic tube and stuff as much grease as is possible in it before refitting the spacer tube and bearings. Pump up with a grease gun once assembled so that the entire area between the spacer tube and the insides of the plastic tube are full of grease. Prior to this, check the pre-load on the bench and adjust if necessary.
Re-instal in the car and then give it a couple of pumps with the grease gun until the gun feels slightly hard, (This way you don't blow the seals out) and you will find that the grease is now feeding to the bearings from inside the plastic sheath and if given a couple of pumps a year, the bearings should now outlast the rest of the car.

Previous grease nipple modifications: Common practice in the past (and recommended by me) has been to fit grease nipples to the outsides of the arms and pump them with grease; these have shown varying degrees of success. The reason for this has been that rather than lubricate the bearings (which is something I have mentioned often) the main purpose of these external arm grease points was to fill a void with grease that normally would get water and contaminents in (in particular salt in the UK & Europe) and these can get in via two sources. One from the outside where the bolt passes through and the second via a hole that is moulder into the arms ar rhe hub end that is there obviously to allow the water to drain out. The old system replaced this potential with grease that at worst would leak out over a period of time. This system takes it one step furtherby not only preventing moisture frm accessing via the drain hole, but also to lube the bearing from the inside outwards and therefore push the contaminents out of the bearing area.
Worthy of note is that the system was examined by a couple of engineers one of who is a structural engineer and both agree this does not compromise the strength of the axle due to its design and ability to keep the load constantly on the actual suspension and not on these bearings that play only a minor (if any) role in its operation as regards load bearing.
Important final note:-

I have been advised by both the engineers and theguy from the Oil company I discussed this with that a good axle grease, preferrably one that is somewhat water resistent, be used but under no circumstances has a Moly grease to be emplyed.

There are good reasons for it that I won't go into, but these guys made a big point of that; it's apparently a NO - NO.
Any further questions please enquire via the Citroen forum on this site.

Alan S
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