Seat bushes done on an early '98, quick guide;

[earthwormjim]

I replaced my seat bushes recently and took some pics, so I thought I'd have a go at a short guide.
There are youtube vids available but they are a bit long winded and seemed to miss key parts.
Its from memory so I expect I've forgotten bits, but hopefully will help someone.

Before you start, make sure you have the following tools;

T50 Torx bit
T25 Torx bit
13mm socket
5/8" Socket (Possibly should be 16mm which I don't have, but I do have 5/8" and it works fine)

preferably 1/2" drive for the sockets. A torque wrench is useful too.

I followed the advice given in other threads, that is;

*Once your car is unlocked put the keys away - don't put key in ignition until complete*
There is a risk of getting the air bag light on otherwise apparently.

With the seat fully back, undo the two 13mm nuts from the front of the runners;



Now put the seat fully forward, and remove two 5/8" bolts from the back of the runners;



Lift the seat off the threaded bolts at the front so it is loose on the floor and then slide the seat as far back as it will go on the runners.

Disconnect the seatbelt from the seat using the 5/8" bolt.

Now carefully tip the seat forward, and either put some blocks under the back to wedge it forward, or turn it towards the centre of the car, remembering that it is still connected to the seat wiring loom;

You might want to cover your door sills at this point to prevent scratches etc.



Now look under the seat and disconnect the wiring loom;



2 connectors on my car, but you might have more if you have heated seats perhaps.

Now lift the seat clear of the car and put it facing downwards where you can work on it.

Now is a great time to clear out and vacuum the space in the car where the seat was. There was almost 3 quid under my drivers chair. This is the job that just keeps on giving.

Pick a side (left/right), and undo 2 T25 torx screws from the runner, and the T50 torx from the threaded bar;
The left and right hand sides look similar but not quite identical. The procedure is the same for each though.

Now measure the position of the runner. There are a few ways of doing this, here's a couple of suggestions;






Now gently pull up the threaded bar, and move the runner with it to help it out.

You should now have something like this;





Measure the position of the inner threaded block on the thread itself to use as a guide when re-assembling.

Now unscrew the lot;




Yes, that mess in the middle is a BMW seat bush...

Replace the bush;




I've used acemans replacement bushes, they need to be sanded down to around half their original thickness to fit, and you need to do them as evenly as possible so the threaded block is in the middle of the cage. P60 sandpaper does the job, careful not to go too far.

Heres one finished next to an old one;



And heres both done;



Screw the cage back on to the thread, to the same position from which you removed it.

Put it all back together - refitting is pretty much the reverse of removal.

I torqued the seatbelt bolt and the rear seat bolts back up to about 50Nm, based on values I got from a 3 series E36 service manual. (haven't got a Z manual yet).

[aceman]

Excellent writeup

I never got around to doing a guide before I sold my Z3 so thanks for that I am sure many people will appreciate that.

You should PM Phil and get it moved into the Z3 Knowledge Base.

[pingu]

A good write-up.

I have some additional comments...

1. The runners don't want to be at either extreme when you remove them, as it will make reassembly more difficult. You can move the seat runners by disconnecting the white connector near the motor and carefully connecting two wires to the motor. You need a 12v supply. Connect one way for forward, the other way for reverse.

2. With the spindle assembly removed, count the turns to unscrew the metal block. After fitting the new shims, screw the block back on by the same number of turns.

3. Ensure the shims are fitted properly and that they clear the screw hole. The thread was tight when I did it and this was because the shim was rubbing on the spindle thread.

4. Put the square drive in the small gearbox on the seat runner. Slide the spindle assembly along the runner and use a small screwdriver through the small square access hole to engage the square drive in the end of the spindle assembly.

5. Using a circular motion to sand down the shims will help avoid tapering the shim.

HTH

[SpaceMonkey]

I've still got to do mine.
I'd happily pay someone to do them tbh. I managed to scratch my drivers sill when I redyed my seat

[si-forks]

Great wright up going to do mine bank holiday weekend just the help I needed

[swamper]

done mine yesterday........great improvement

[LJSteve]

earthwormjim, thank you very much for the brilliant step by step guide. I did the job today, passenger seat went great, drivers seat not so great. I was lazy about the measuring business - could error in this be the reason I can't get all 4 fixings back into the seat base? I'm running on 3 currently. This should not detract from my comment on the guide and is a reflection of a) my general mechanical crapness and b) my refusal (inability) to pay BMW technicians £150 per hour.
Also, the bushes I bought from Ian, via this site were excellent.

[earthwormjim]

Thanks for the comments LJSteve, great to hear that its helped. This forum has been invaluable to me for these kind of jobs, so If I've managed to give something back I don't feel so bad!

With your 3 out of 4 fixings problem, it sounds like it could be the measuring, I think* it should be possible to fix it easily by trial and error though as follows...

( provided that you have the runners as far back as the can go when you took/take it all apart, and you have them in that position this procedure)

- turn the threaded cage until it looks roughly in the right position then slot it into the runner, line up the 'fixed' fixing holes, and then look through the fixing hole for the cage at where the cage is - e.g. to far up or down? take it out, adjust accordingly and try again. repeat until you've got it just right.

I think it might be easier to do than to describe in writing...

let us know how you get on anyway.

[LJSteve]

Thanks again ewj, I'll let you know how I get on

[alan-c]

Thanks for this guide, which I only discovered after changing the seat bushes on my son's z3. I would also add that the leadscrews are left and right handed and if you put them back on the wrong sides the seats will slide forward when you push the switch back and vise versa - guess what I did?

To the poster who could't get all fasteners back in the seat mount, may I suggest that you take the seat out again and manually align the holes. If one of the rear fasteners is missing the seat may fail in a crash,

Now I'm off to the water in the boot post.....

[Z3C]

Hello,

Thanks for the nice guide earthwormjim! One question though, did you deactivated the seat belt pyrotechnic tensioner when removing the seats?
(see TIS instructions: http://tis.spaghetticoder.org/s/view.pl?1/01/82/81 )
Also did you have the battery connected while working?

[aceman]

Maybe I can answer this for you.

It is always advisable to disconnect the battery when removing the seats for safety reasons but this procedure can be performed with the battery still connected and is advantagious to a certain extent. In able to get to all the bolts holding the seat down you need to slide the seat backward and forward to gain access hence if you have disconnected the battery with electric seats you are unable to do this.

If you do decide to leave the battery connected you must not switch the ignition on when you have disconnected the wires under the seat. If you do switch the ignition on accidently you will trigger an airbag fault which will need resetting. Only switch the ignition on once you have the seats back in and reconnected. A good tip would be to put the ignition keys out of the way and don't leave them in the ignition so you won't be tempted to switch it on if you decide to say switch the radio on to listen to some music.

I hope that is clear but other than that it is not too difficult a task to complete. Good luck.

[pingu]

Another reason for leaving the battery connected - Life is made a lot easier if you can remove / install the seats with the roof down.

[TonyOB1]

I would not have attempted this task without with excellent guide. I hope some of issues I experienced may help refine things even further

1. After fitting the new bushings I found it necessary to use a vice to press the metal block back fully into position. Without doing this it stood slightly proud and would not push past the internal rivet heads of the runner. I lost quite a bit of time before I realised this was the cause

2. I would also recommend removing only one runner at time. I read somewhere that it can take around 20 mins to waggle it all back together. Try 2 hours!!! By which time it late and I was cold, tired and hungry left the other side for the following day.

3. While my seat was upside down I noticed a coiled cable, like a small phone handset cable hanging loose and terminating with a small jack plug close to the seat belt mount. I resisted the temptation to stick the into anything looking like a socket but does anyone know what this is?

Cheers guys - I hope some of you (if not all!) will be attending the ZedFest this year

[Snow Mole]

Hi

Did the seat bushes following the guide and all was good. Made a profit out of the job as found £5.42 under the seat.

Rubbing down the new bushes takes time but best to keep them the same width to help position the runners afterwards.

A great article and easy to follow.

Richard

[aceman]

Good to know you got them done ok.

Yes it is only the thickness of the bushes that need adjusting to fit the outside dimensions should be OK as I have machined them to be the correct fit in that respect.