Question on changing discs and pads please

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 7:33 pm

Sorry, me again.

I think I am going to change the discs and pads all round on my e89 myself. I have had a look at how to do it, looks pretty straightforward as long as the caliper bolts come off fairly easily and I can compress the pistons when putting calipers back!

I have decided on TRW discs and pads (as they are an OEM supplier, are mid-range pricing and do some nice black painted ones).
I can get the parts for 1/2 the quote from my local "specialist" and they will supply inferior parts.

I have three questions:
Do I need to replace the wear sensors, or can the existing ones be re-used? Am I right in thinking only one side per axle has them? They are not anywhere near down to the sensors on any wheel.

If I do replace, will they need to be "addressed" to the car? As I obviously can't do this.

Any advice appreciated

mr.tourette · Post by **mr.tourette** » Thu Feb 04, 2021 7:44 pm

You can reuse them if you can remove them without any damage to them. Yes only one per side. Don't think you need to register new ones but not 100% on that

Bombardino · Post by **Bombardino** » Thu Feb 04, 2021 7:55 pm

On the grand scale of things it’s worth replacing them as they don’t exactly cost the kings ransom.
One per axle.

Smartbear · Post by **Smartbear** » Thu Feb 04, 2021 8:00 pm

You can use the sensors again as long as they haven’t triggered a red wear warning, you need new ones when that happens

Rob

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 8:03 pm

Thanks guys (as usual).

So we don't think they have to be addressed if changed?

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 8:04 pm

Bombardino wrote: ↑Thu Feb 04, 2021 7:55 pm On the grand scale of things it’s worth replacing them as they don’t exactly cost the kings ransom.
One per axle.

It's an extra £23.86 for the two. I'm not made of money!

Smartbear · Post by **Smartbear** » Thu Feb 04, 2021 8:09 pm

Pondrew wrote: ↑Thu Feb 04, 2021 8:03 pm Thanks guys (as usual).

So we don't think they have to be addressed if changed?

If replacing pads it’s possible to reset the wear sensors (a maximum of two times i think)
Rob

flybobbie · Post by **flybobbie** » Thu Feb 04, 2021 8:15 pm

My experience they generally break when you take them off. I would buy new ones and fit and save a lot of aggro and delay finishing the job.

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 8:18 pm

flybobbie wrote: ↑Thu Feb 04, 2021 8:15 pm My experience they generally break when you take them off. I would buy new ones and fit and save a lot of aggro and delay finishing the job

OK I will order them with the big round lumps of steel. If I can manage to save the old ones, I will have a spare new set, so win, win I suppose.

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 10:13 pm

Just had a thought.

I presume the electric handbrake uses the rear discs? If so I will have to release this to do the rears; does it automatically reset itself after a period of time and will I have to disconnect the battery? My other cars put the handbrake on if I forget.

Ta

Smartbear · Post by **Smartbear** » Thu Feb 04, 2021 10:31 pm

Pondrew wrote: ↑Thu Feb 04, 2021 10:13 pm Just had a thought.

I presume the electric handbrake uses the rear discs? If so I will have to release this to do the rears; does it automatically reset itself after a period of time and will I have to disconnect the battery? My other cars put the handbrake on if I forget.

Ta

The best way is to unbolt the motor from the caliper

Rob

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 10:53 pm

I just watched a you tube video regards re-setting the handbrake; it looked bl00dy complicated. I will have a look, as I've ordered all the parts now. If the worst comes to the worst, I'll take it (carefully) to my local bloke. Luckily he's only a mile up the road!

Pondrew · Post by **Pondrew** » Thu Feb 04, 2021 10:55 pm

I should take note of my own signature

Chris_D · Post by **Chris_D** » Thu Feb 04, 2021 11:09 pm

It's worth getting clued up and having a crack at it yourself as once dis-assembled you can spend time cleaning everything up and painting the calipers if required. Your local indy won't even think about doing this and if you asked him he'd only probably get poundsigns ringing in his eyeballs!

Make sure you use plenty of copper grease on applicable surfaces to prevent bonding in the future.

ajguk · Post by **ajguk** » Fri Feb 05, 2021 10:58 am

I haven't done the rears on mine yet, but I did do the front discs and pads (and sensor). One thing to watch out for is the guide bolt on the disc, mine was completely seized and I rounded the allen bit off which caused a few nervous minutes, had to drive (other car) to the local indy and buy some bolt extractors, basically a chisel you hammer in, then it came straight off. From memory I put the new bolts in using some copper grease on the bolts in case I ever have to do them again.

Just worth being prepared and careful with those bolts, they seemed quite soft on mine hence the easy rounding. Good luck, hope the electric handbrake is easy as I might want to do mine this year.

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