Guide - Swapping Rear Arms

All aspects of tuning,modification and repairs to the BX 16valve.
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cammmy
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Guide - Swapping Rear Arms

Post by cammmy »

Okay. Here is my write up on swapping BX rear arms.

Important notes:

I had another set of arms refurbished and ready to go so this is only a guide to swapping arms. Not changing bearings. I would HIGHLY recommend you do this as if left too long the arms WILL wear and need bushing (as evident in the pic of my fresh arms). If yours are worn and you don't have any others ready to go then quite frankly, you're fucked.

I was in a hurry when I did this so haven't taken photo's at every step. Some of the photo's (i.e at the stage where I was removing the arm bolts) are taken on the other side of the car, but the steps are still in order. I'll also be re-using pics for the re-assembly process.

1:

Loosen the rear wheel bolts, get the car up on stands, set the hight corrector to bumps, take the rear wheels off
and jack up the rear arms one at a time to remove the pressure from the suspension.

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2:

Remove the brake shields. Noting the ABS wire clipped on.

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3:

unclip the brake lines from the plastic holder on the arms and undo the calipers. Tie them to the car body so they are well supported (around the door latch and also anywhere appropriate under the car). This will remove the need to undo the brake pipes from the calipers.

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4:

Remove the rotors.

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5:

If you have ABS, lift the rear seats and disconnect the cables. If you try to undo the sensors from the arms you are likely to destroy them after the years of corrosion seizes the bolt in there.

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Feed the cables/grommets through the car body

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6:

It's hard to see but undo the small holder that secures the brake line next to where it is coiled (already removed in this pic :-[).

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7:

Where the suspension ram attaches to the arm, remove the pin and push the ram into the strut and out of the way.

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8:

Undo the anti-roll bar shackles and remove the brake pipe holder thing under the ARB (you'll know what I mean when you see it)

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9:

Undo the arm bolt

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10:

Check to see if there is anything still attached/I have forgotten to put in this guide

11:

Remove the old arms

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12:

Prop the arms up and feed the ABS wires through the suspension/brake pipes attached to the body

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13:

Remove the old arms from the car, run the back of your arm across your forehead, crack open a bacon butty and chomp through a nice dark stout (or a french roll\cheese board and some carbonated grape juice if you're that way inclined)

14:

Wipe your hands on your trousers (or the wife's good tea-towels that you're using for rags) and get your tools ready.

15:

Get your nice, fresh arms (if you were smart about it) or otherwise I'm going to assume you are coming back to this a week later after discovering that your old arms are shagged (which if you're camber has changed, they probably are by now).

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Feed them back into the car and get the bolt through (I used a bar with a tapered point to line them up.), then tighten... a lot... like get a breaker bar on it.

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16:

Feed the ABS wires back through the pipes:

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17:

Put the brake pipe holder thing back under the ARB and put the shackles back. Make sure the bolts go through both holes in the holder thing. I had to re-do them both on mine as I'd only got one bolt through each without noticing. If this happens you'll see that your brake pipes will rub when the arm goes up and down.

18: Put the little peice back that secures the brake line to the holder:

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19:

Attach the suspension rams back to the arms:

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20:

Put the rotors back on

21:

Put the calipers back on:

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21:

Put the shields back on (attaching the ABS wire)

22:

Put the brake pipes back into the plastic holders on the arms

23:

Feed the ABS cables back into the car and connect up again:

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24:

Move the arms up and down and check no wires are caught and nothing is rubbing.

Put the wheels back on

25:

Check absolutely everything

26:

start the car, set the hight corrector to high, get the car off the stands and tighten the wheel nuts.

27:

Have a bevvy or 14 (after driving home, not before, unless it coke, in which case have fun at the dentist)
'89 BX 16v
'91 Peugeot Mi16x4 x2
'74 Triumph TC2500
cammmy
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Post by cammmy »

Let me know if I have missed anything. I'm no good at proof reading my own work
'89 BX 16v
'91 Peugeot Mi16x4 x2
'74 Triumph TC2500
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frog
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Post by frog »

Looks good Cam,

Am I right in thinking the only part of the inner part of the arm that you should be worried about being stuffed is the bearing cup seat?
I'm not sure If I have it right but It's the bearing cups that are taking all the weight/need to be aligned properly right? Mine were fine though.

Also when I did mine, rather than taking off the disc and calliper, I just undid the rear brake line, but you were changing the discs over on the arms so that makes sense.

+1 on ABS wires, I cleaned mine up and wrapped them in tape as well to make the old rubber insulation a little stronger.
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Post by cammmy »

You can see in the picture of the fresh arm where it wears. These arms were particularly bad. You can see where it was machined and the brass bush put in.

Image

You may get away without having to machine them if you catch it early. I just didn't want to risk being stuck 50 miles from home (at the garage where I was doing the work) with a car that I couldn't put back together because the arms were worn. Also makes the job much easier having fresh ones ready to go.
'89 BX 16v
'91 Peugeot Mi16x4 x2
'74 Triumph TC2500
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Post by Vanny »

Thats a pretty detailed write up, with some good pics.

My only concern is step 15 then tighten... a lot... like get a breaker bar on it. . They are trailing arms which are meant to rotate. if you over tighten them, especially if you dont replace the packing washer (which i dont think there is mention of), you can actually clamp onto the tube through the middle and not the bearing, resulting in no pivot!

Otherwise, thats a pretty complete write up! THanks.
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Post by cammmy »

^They were very tight when getting them off and the guy advising me on this was a Citroen mechanic of 40 years. He said to get a breaker bar on it and do them up tight. My car definitely seems to drive better now so hopefully it stays that way :lol: If you have done them up too tight, should it be evident when moving the arms up and down to check nothing is rubbing? Mine were free and moved easily.

Which peice is the packing washer sorry? The Citroen mechanic assembled the arms for me and there was a washer used with the arm bolts. I just thought it was self explanatory that where a washer came off a washer should go back on :lol:
'89 BX 16v
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frog
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Post by frog »

The packing washer Vanny mentions is the "shim" labelled and coloured light blue in the diagram below. It's a little metal spacer around .45 of a mm (though they may be different for each side, theres one for each rear arm) that sits between the armbush and bearing cone on the outer side of each rear arm.

Also IIRC the torque setting for the rear arm pivot bolts is 94 lbf ft.

Vanny I'm just wondering (and sorry, I know how much you love the topic of rear arms) but the bolt/nut/washer should just tighten up against the metal spacer tube that has the bearing armbush on it so he wont have over tightened the bearings themselves right?
frog wrote: New bearing cup.
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Pressed in.
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In.
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Other side (remembering to place the plastic protector into the arm before installing the second bearing cup.
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Second bearing cup.
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Diagram courtesy of Y. Narabayashi
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Rollers, Cone, Armbush, Seal, Grease, all on the metal spacer tube.
Don't forget to put the original shim back between the Armbush and cone on the outer side of the rear arm.
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Then this goes in here.
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The other sides seal/armbush/cone/bearings/grease being pressed onto the metal spacer tube that is now in the arm, silicon sealant on the seal.
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Pressed; not the whole way, don't want to smush bearings into cups.
They will tighten up in line with the metal spacer tube once in the car and torqued up.
Image
cammmy
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Post by cammmy »

That would come under a guide to rebuilding the arms right? I didn't change the bearings myself, only swapped the arms (and that's all this guide is supposed to cover).
'89 BX 16v
'91 Peugeot Mi16x4 x2
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jayw
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Post by jayw »

I think you're just lucky that over there you're only just now having to replace them! Over here it must just be the sh*t weather helping to wear them that means we've all got it down to a days work (including tea breaks :wink: ) to do the swap & bearings :roll:

Gets easier after your 6th set :lol: :lol:
Now listen here you mullet...
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Post by Vanny »

Frog, your quite right, it should clamp on the tube.
Without the spacer you can end up clamping the beam flanges to the sides of the arm, and i guess ultimately it shouldn't kill the arm, but it will make a hell of a din as it eats through the flanges and the arm its self.

Either way the shim is vital, and shouldn't be overlooked!

There is a very complicated procedure to set the rear arms up correctly. Your meant to put the bearings in with a special tool (6322-T), which sets the correct tension about two measuing points on the tool. You then remove the tool and measure the distance. The difference between this and the metal tube give you the width for the shim. You then build up the arm, use the relevant shim from a pack, and set the tension in the bolt.

I have the special tool, but as yet i've not used it. I normally just bash it all together and tighten it up.


EDIT

I've uploaded the manual here;

BXProject - Manuals - Rear Arm
cammmy
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Post by cammmy »

I think this is the second time these have been done. The car is at very nearly 300,000km now :D
'89 BX 16v
'91 Peugeot Mi16x4 x2
'74 Triumph TC2500
cammmy
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Post by cammmy »

Also, they guy who did the arms is a Citroen mechanic of 40 years so I'm confident he's done a good job on them. They certainly aren't making noise
'89 BX 16v
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'74 Triumph TC2500
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Post by ollie »

just to add my two pennys worth,
One important consideration on the abs ones is its easier to recon an arm with a working ABS sensor so as no need to disturb the rusted in bit!

I've only ever found 1 shim inside the countless BX arms I've done I think its usually set to account for machineing differences in arms.
You can get the same effect by measuring up how much the central tube projects by with the baerings all preloaded and then machine that much off the tube.

In reality I just bang all the bits in with plenty of grease and have never had any problems at all.

You cant make the subframe touch the arm unless somethings very wrong as all the bolt does is clamp up the frame onto the ends of the tube so unless you belly the tube or compress the frame ouyt of the join - or its kanckered by being done up too gently in the past........ you want thsi to be quite tight, I use an impact gun and then check with breaker bar.

one paractical point is its generally best to leave the caliper attached to the pipe and supported with a tie wire and leave the pipe attached to the little plate under the arm as well.

also if you recon the arm you have there no need to remove the ( rusted on) discs or the wheel hub
cammmy
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Post by cammmy »

I recon'd different arms so that I could do a straight swap. There was no way I could practically have my arms done as the garage was a loooooooooooong way from my house (different area code even)
'89 BX 16v
'91 Peugeot Mi16x4 x2
'74 Triumph TC2500
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