Dropping rear sub frame

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Tinkley
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Dropping rear sub frame

Post by Tinkley » Mon Jun 23, 2014 7:26 pm

Is there a definitive guide to dropping the rear sub frame? I know I am going to have to deal with a little er corrosion issue to get through the MOT this year. I don't think it is too bad but needs a good clean and a bit of cosmetic and real protection. Got a couple of weeks + before MOT or so would like to deal with it sooner rather than later. Unfortunately do not have ramp but should be able to grovel under the car!. Dremel, Fein, arbors, angle grinder, flap wheels etc all bar welder at the ready....

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Re: Dropping rear sub frame

Post by citronut » Mon Jun 23, 2014 8:10 pm

rear half of exhaust off ( both box's and the intermediate pipe ) gently unclip the front to rear hydraulic pipes all the way along the N/S chassis rail, jack the rear as high as you can get it,
i have a tall pair of axle stands and either a length of scaffold tube ( if you have the reserve fuel tank under the O/S rear corner the scaffold tube will not fit ) so in thus case i have a solid steel bar about 3/4 of an inch in diameter, slide this through and between the two tow eyes at the very back end of the rear chassis rails,

then sit this onto the axle stands ( my stands have a nice deep V shaped head ) the bar sits nicely into these,
i place the stands so there heads sit just inside both tow eyes,

make up a jacking beam to sit across the trolly jack, and across both side members of the rear sub frame,
on lowering the sub frame you will need to adjust were it sits on the jacking beam so it comes down and out of the mounting points square, if you dont do this the mounting studs snag up as they try to come out of the body on the skew,

have fun,

i certainly will on lowering the sub frame on Andys N/A estate,

i have already spent about three hours removing one of the forward mounting nuts that was in a real bad way, and could not get/bash any sockets on to undo it, ( lots of cold chile and big hammering and drilling later, and it finally gave in,

as i am going to attempt to re/construct the forward rear sub frame mounting points and there substructure on the body shell

:shock: :evil: :roll: [-o< [-o< letsbefriends letsbefriends

regards malcolml
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Re: Dropping rear sub frame

Post by Mothman » Mon Jun 23, 2014 10:27 pm

OO Errr.

Andy

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David
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Re: Dropping rear sub frame

Post by David » Tue Jun 24, 2014 1:22 am

Good luck on doing this.

I would say citronut has about covered everything.

When I removed mine I didn't have any axle stands or strong scaffolding poles to use, so I backed the car up ramps, put the suspension in high, then stacked concrete blocks under the box sections under the boot & lowered the car on to them, Although if your welding you might need it higher than that.

The boot carpet & plastics ether side of the rear seats will have to be removed. As I completely removed my axle, I removed the bottom pipe from the height corrector, undid the corrector itself & tied it to something (I'd have to look again to see what). Removed the plastic return pipes, a main pipe from the 4 way union that goes to the front, the feed for the rear brakes, & the height control rod. That can be tricky. All the hydraulics were now disconnected. Don't forget the exhaust as citronut said ether in the middle or at the front if easier.

I then stacked old tyres under the axle to lower it down. It is heavy so be careful.

I would also recommend removing the fuel tank to tackle any rust efficiently.

The bolts on ether side of the rear seats can sometimes be awkward & rusty, Although I didn't have a problem with mine.

If possible get assistants to help you put it back on. I used Jehovah's witnesses & tyres.
1992 Citroën BX 1.9 Diesel Meteor 4x4 - The Project.

1992 Citroën BX 1.9 TXD (with GTI engine; Mulleys old car) - Parts car.

2004 Citroën Xsara Desire. (Now gone).

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Tinkley
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Re: Dropping rear sub frame

Post by Tinkley » Tue Jun 24, 2014 8:03 am

Thanks Malcolm, and David. It presumably means dropping the towbar too? (official Citroen BX one). I have my ways of getting those beasts on and off. I do hawever know that the sub frame was dropped 6 years ago to do some welding in the boot floor area. I suspect i will have more trouble with corrodede screws on the interior!

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Re: Dropping rear sub frame

Post by citronut » Tue Jun 24, 2014 8:11 am

the only point i think i had not covered is unhook the front to rear height rod, were it hooks into the link under the rear axle,

if using concrete blocks i would place timber on the very top of the blocks,

regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special

no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)

Tinkley
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Re: Dropping rear sub frame

Post by Tinkley » Tue Jun 24, 2014 8:54 am

Thanks Malcolm. getting and refeeding the front rod through the front subframe was a bit of a pain, but the rear one does not look too bad. I have a feeling that the 5 yr+ old exhaust system is going to get wrecked on removal, still at least they are available. Just that rust and old age will ensure the by now somewhat thin steel will give up somewhere along the line... :wink:

I'll check those rear arm bearings too while I'm at it. Not done them on this car - yet. Certainly worth a peek and maybe regrease.

I have a reasonable ammount of timber to hand. Pretty much rely on it as a cushion for placing metal parts like engines etc. Not only that, but decent sections are more than capable of holding the car up on their own. The rear end can't weigh more than about 400kg tops - total bare shell is 500, engine/gearbox say 200-225 then all the rest -glass, trim, fixtures etc. Yes you could support the entire car on a 25mm square piece of high quality Sitka Spruce. Not that I will be trying that experiment.... :lol:

I should not have the reserve tank as it's a 1.6 TGS petrol. I do have some scaffold tubing around. Last used to undo the front hub nuts when attached to the socket handle....

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Re: Dropping rear sub frame

Post by citronut » Tue Jun 24, 2014 1:55 pm

Tinkley wrote:Thanks Malcolm. getting and refeeding the front rod through the front subframe was a bit of a pain, but the rear one does not look too bad.

I have a feeling that the 5 yr+ old exhaust system is going to get wrecked on removal, still at least they are available. Just that rust and old age will ensure the by now somewhat thin steel will give up somewhere along the line... :wink:
Tinkley wrote: i just grab it with a decent set of VICE GRIPS close the the lever/bracket and rotate it whilst swinging the lever/bracket clear,
just heat up the joint between the front/down pipe to the rear section/intermediate pipe, and drop both box's and intermediate down in one lump,
Tinkley wrote: I do have some scaffold tubing around. Last used to undo the front hub nuts when attached to the socket handle....
thats what i use one of my lengths of scaffold tube for all the time

regards malcolm
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K reg BX 17TD TZD est
also own
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no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)

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citsncycles
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Re: Dropping rear sub frame

Post by citsncycles » Sat Jul 05, 2014 10:48 am

The only bit I did differently to the above was that I used a pair of scissor jacks (one each side) to lower the rear subframe. I've got the same welding job on Timex in the next few weeks - seems to be a recurring theme on BX's this year!
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Re: Dropping rear sub frame

Post by Tinkley » Wed Jul 09, 2014 8:45 am

Well, I have had a good look at the offending part. Bad news is that the rear corner of the sub frame mount o/s is rusted through, n/s is OK. So that will be a certain fail as the corner 'fillet' has all but gone. The plastic grommet to rear of sill has gone walk about but the silll itself is fine apart from missing a little metal that links to the upright inboard end where it appears 3 lots of sheet are all folded and welded together.

Good news is that it could be a lot worse, everything to the mount nut above looks clean and dry inside. Also knowing this sub frame has been dropped before, gives some confidence it will shift with less of a battle than the one outlined by Malcolm!. However I just don't have the welding kit, so will seek someone local who can do this, even if a mobile welder and I drop the bits at home. There are some DS specialists a few miles away in Kingsley (Burton Bros) so I will enquire there, also some classic Brit car guys (Morris Minor and old MGs'), not far either.

This one will have to be done properly, it needs the strength. Some of the other bits ie panel holes are so so for strength and my composite repairs are fine. BTW my glass/carbon sill repair on the n/s has held up perfectly, even looks like original as the paint has toned down fractioanlly with UV!.

I'll be trying to keep this one on the road.

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Re: Dropping rear sub frame

Post by citronut » Thu Jul 10, 2014 9:17 am

i think the tank will also need to come down to sort the O/S mount reinforcing plate/panel

regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special

no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
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Re: Dropping rear sub frame

Post by Tinkley » Thu Jul 10, 2014 10:48 am

Thanks, Malcom, I suspect you are right as the tank is pretty close and any welding torch is going to either melt the plastic or worse!. I think the car will need some surgery, but to get it done properly will be a little wait. So in the interim and because I need to use her and get the MOT, like yesterday a certain 'creativity' may be called for.... :wink:

I did talk to the DS specialist (he had a BX with well over 500k not long ago) and he said 'did I have the pipes?'. I assume he is considering replacing all the hard feeds as a matter of course. Is this actually a prerequisite for dropping the sub frame? I would have thought they would flex a little as per the rear brake rigid feeds (coils) so allow a limited drop, for access.

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Re: Dropping rear sub frame

Post by rutter123 » Thu Jul 10, 2014 7:45 pm

I have the same job to do on my tzd, i did the n/s about 7 yrs ago, managed to drop the beam just enough, about 6 inches just enough to get the grinder/ torch in.
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Re: Dropping rear sub frame

Post by citsncycles » Sat Jul 12, 2014 6:40 pm

Pipe replacement depends on condition - they can go really badly above the subframe while looking good everywhere else. It'd at least be worth checking availability before stripdown.
Mike Sims
BX 19RD Estate Mk1 - Timex!
BX 4X4 Estate - Oh god, I've done it again!
BX 17RD MK1 - it called to me!
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Re: Dropping rear sub frame

Post by Tinkley » Sat Jul 12, 2014 7:09 pm

Thanks Mike. For the time being, I have been getting 'creative' so this Citroen has a little more composite materials than most.....ah well, they used to be ahead of their time....

However, there is one small bit that will need the correct treatment, so I will be getting it done, even if it needs new pipes. Knowing this one it will be a b*stard. My Sorn'ed one would be easy as everything has come off that like a textbook. But this ex northern one is much more corroded but sometimes in funny places, and say one side but not the other! Like one sill perfect except back face, the other one used to have a hole in the side as well as the back face only recently going. Like rutter I am beginning to curse that yellowy 'sealant' - horrible stuff to dig out and it seems semi porous giving rise to more corrosion than it is preventing.

For the time being, I'd take the advisory, but will need to get it sorted for peace of mind if nothing else.