Rear disc installation in a 1.4 petrol

Kleynie

A2OC Donor
As some may have seen in the today I... thread, Adam and I have been using our time wisely to change the rear axle on his 1.4i. We have an FSi breaker on the driveway which obviously has a rear disc axle, so this was the donor axle.

We purchased the following parts:

New rear brake lines
2 x LPR 6T47953 Brake Hose, Rear Axle Pivot
1 x Genuine 8Z0611764Q Brake Pipe, Rear Right
1 x Genuine 8Z0611763Q Brake Pipe, Rear Left
Wheel bearings
2 x NTN-SNR R157.31 Wheel Bearing, Rear
Handbrake cables
1 x Genuine 8Z0609721A Handbrake Cable, Left
1 x Genuine 8Z0609722D Handbrake Cable, Right
Splash guards
1 x Genuine 6Q0615611
1 x Genuine 6Q0615612
Rear refurbished calipers
1 x Genuine 6Q0615424A
1 x Genuine 6Q0615423A
New rear swing arm bushes
2 x Genuine 8Z0501541
Handbrake mechanism from the FSi
1 x Genuine 8Z0711303Q
Rear Brembo Pads (Euro Car Parts)
Comma DOT 4 brake fluid 2 litres

Once removed from the FSi the axle was stripped of all component parts and painted with Galvafroid paint and then two coats of Hammerite smooth in black. We had to cut the bushes out as they were rusted in place, the rubber is a bitch to cut!

img_20200420_142957.JPG


Next was to rebuild the axle with all the new parts, the bushes needed a hydraulic puller to get them in place, everything else was straight forwards

One end of the axle with the new bearing and splash guard.

img_20200429_141502.JPG


With the car propped up (axle stands are not very safe on gravel, hence the ramps) we removed the old drum brake axle:


img_20200508_172205.JPG


The new axle was fitted, this was not too difficult, you can see the new bushes here:


Photo 09-05-2020, 12 59 06.jpg

Photo 09-05-2020, 13 00 17.jpg


Now the hard bit was connecting the brake pipes, it took a while to get them to align but the result was good:

IMG_3294.jpg


IMG_3295.jpg


Then the discs from the FSi and the refurbished calipers were installed and the handbrake cables connected. The whole system was bled with 1 litre of Comma DOT 4 and the finished product:

IMG_20200514_142527.jpg


The only things that broke were the nuts that hold the heat shields above the exhaust, you need to remove these to change the handbrake cables. What we did here was carefully drill the floor with a 3mm bit and use a self tapping screw through the original nut as below:

IMG_3290.jpg


Good result we think. Adam may now own the only 1.4i with rear discs in the UK maybe?

The whole job cost around £350 in parts and sundries, it would have been more if we didn't have the FSi breaker.

Its a DIY job for anyone if you are handy with spanners.
 

bretti_kivi

Member
I did seriously think about this at one point, but decided against it, mainly as the amount of actual braking done by the rear axle is minimal under most circumstances, and so it becomes something to fight against in terms of rust. Rear brakes are generally only doing 10% of the braking (remember the weight distribution is 60/40 or so to start with) so you won't necessarily get that much of a performance improvement. I know of a handful of conversions over on the German forum, and most are only to do with bigger engines / power and the requirements from TÜV for that.

- Bret
 

Kleynie

A2OC Donor
I did seriously think about this at one point, but decided against it, mainly as the amount of actual braking done by the rear axle is minimal under most circumstances, and so it becomes something to fight against in terms of rust. Rear brakes are generally only doing 10% of the braking (remember the weight distribution is 60/40 or so to start with) so you won't necessarily get that much of a performance improvement. I know of a handful of conversions over on the German forum, and most are only to do with bigger engines / power and the requirements from TÜV for that.

- Bret
I completely agree, it's a pointless upgrade, and I certainly wouldn't have paid to have it done, the difference is minimal in breaking. However, saying that, the handbrake feels much better and the axle bushes make the suspension noticeably smoother and quieter. The main reasons for doing it were a) we had the axle already and b) it killed a lot of time in lockdown.
 

timmus

A2OC Donor
Well done, @Kleynie. Many thanks for all the photos, parts numbers, etc.

As you've said yourself, it's a pointless upgrade. Although the rear discs look great, their increased maintenance means it's something I'll never do on my own A2. I have, however, got a replacement rear axle for my A2, that's designed for drum brakes, which has been shot-blasted and powder coated, so I'll be following in your footsteps. I'm looking forward to replacing all the bushes and seeing how the car feels. It's done 243,000 miles and is still on the original axle bushes. I'll stick to OEM, as I've also read many complaints about PowerFlex bushes squeaking once they're no longer brand new.

Cheers,

Tom
 
Thanks for posting up this up, i did wonder if you had taken pics to show us, great to see you did with excellent pics and info.

I'm one of those that actually thinks it's a nice upgrade, although appreciate it's expensive if you have to buy the axle ontop. Good to hear you went OEM on the bushings too, did you install them yourself?
 

Kleynie

A2OC Donor
Thanks for posting up this up, i did wonder if you had taken pics to show us, great to see you did with excellent pics and info.

I'm one of those that actually thinks it's a nice upgrade, although appreciate it's expensive if you have to buy the axle ontop. Good to hear you went OEM on the bushings too, did you install them yourself?
Yes, the bushes were installed by us, with a hydraulic puller, it was a pain but we got them installed in the end.
 

Kleynie

A2OC Donor
Thanks for posting up this up, i did wonder if you had taken pics to show us, great to see you did with excellent pics and info.

I'm one of those that actually thinks it's a nice upgrade, although appreciate it's expensive if you have to buy the axle ontop. Good to hear you went OEM on the bushings too, did you install them yourself?
It's worth dismounting the axle just to replace these to be honest, the biggest difference is in the ride quality, which is due to the bushes.
 

BigBang

Member
Nice list of the parts needed. This is how every „to do“ post should look like! :)

And about powerflex bushings - if you want to preserve ride quality you have to stick with OEM rubber bushings. I don't get why to use any PU pushings on daily driven car. It always compromises driving comfort...
 

Jeff Sutcliffe

A2OC Donor
I completely agree, it's a pointless upgrade, and I certainly wouldn't have paid to have it done, the difference is minimal in breaking. However, saying that, the handbrake feels much better and the axle bushes make the suspension noticeably smoother and quieter. The main reasons for doing it were a) we had the axle already and b) it killed a lot of time in lockdown.
Until this morning I'd have agreed with you and everyone else who's commented on the benefit of the disc conversion, i.e. cosmetically great but dynamically probably not, but I just read a post on one of the Faceache A2 pages that 'educated' me to the fact that, unless you drive like a granny, the disc rear brakes are DEFINITELY required and, and this is the major benefit, you can leave '11s' on the road if you pull the handbrake hard enough - it wasn't clarified but I assumed the writer was describing using the handbrake whilst driving rather than setting off with it still applied. So, there you have it, a very worthwhile upgrade if you want to appeal to people who should never be allowed behind the wheel of any car, let alone an A2. 😭 I'm unfamiliar with emojis but I'm guessing this is the one for 'God help us'.
 

A2Steve

A2OC Donor
Until this morning I'd have agreed with you and everyone else who's commented on the benefit of the disc conversion, i.e. cosmetically great but dynamically probably not, but I just read a post on one of the Faceache A2 pages that 'educated' me to the fact that, unless you drive like a granny, the disc rear brakes are DEFINITELY required and, and this is the major benefit, you can leave '11s' on the road if you pull the handbrake hard enough - it wasn't clarified but I assumed the writer was describing using the handbrake whilst driving rather than setting off with it still applied. So, there you have it, a very worthwhile upgrade if you want to appeal to people who should never be allowed behind the wheel of any car, let alone an A2. 😭 I'm unfamiliar with emojis but I'm guessing this is the one for 'God help us'.
Fantastic!!!

I don’t want to spark a turf war, but oh my word some of the things posted on the A2 Facebook pages make me cringe
 

Jeff Sutcliffe

A2OC Donor
Fantastic!!!

I don’t want to spark a turf war, but oh my word some of the things posted on the A2 Facebook pages make me cringe
Sometimes I just can't help myself getting involved.

The 'three bnib Votex seller' is a prime candidate for a dose of sarcasm when I have a bit more spare time.

Someone on one of the sites commented the other day, wondering whether BMW drivers had been buying A2s, judging by recent posts and comments being less than polite, especially by comparison to A2OC. I suspect they're more likely to be former BMX bike or skateboard owners.
 

Pinkythelabrat

A2OC Donor
I used to have a Toyota Celica and it had large discs front and back but, in the centre of the rear disk, was actually a small drum brake! Both types in one. There is a benefit to either style - disks for racing and drums for when you leave the handbrake on for weeks at a time.

The split of braking force and limited involvement of the rear is a little disingenuous as it assumes perfect grip and road surface. If your front wheels are skidding then your rear brakes be doing all the work.

I think it’s a great looking upgrade and salute you. Practical and ‘worthwhile’ and ‘value’ are in the eyes of the beholder.

Ps. I think I can guess where the drums you were selling came from...


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