Information Rear axle conversion to discs on a 75.

Birchall

Dick Chown Award 2016
Hi,

Rather than add this to my main project thread I thought it better to post a new thread specifically for the axle conversion.

I purchased a secondhand 1.6 FSI axle (the tdi 90 one is the same set up and can be used instead)

Since it is going on my "holy grail" project car I have gone OTT with the parts and I have purchased every part (including nuts and bolts and clips etc.) brand new. So it is no good as an example of the cost to do the conversion because if you get a good axle you can resuse most of the parts.

One thing you basically have to replace is the handbrake assembly, the 1.6 and 90's have a different one because of the discs. But I bought a new one from Audi and it was only around £40 (which was a pleasant surprise).

You should also fit new brake cables and ideally new brake pipes as a minimum. Reusing the discs, pads and callipers from the donor axle is ok if they are in good nick, similar with shockers and springs I had a broken spring and so I bought new ones. But I bought mine from Audi because I found the sport springs to be perfect for me and so I did not want to alter the spring rates etc. (same for the shockers).

Replacing the rubber front mounts is probably a good idea too, they have a hard life.

I have fitted some uprated bits too (of course) I went for the uprated flexi hoses (colour coded white to match the car). I am also fitting grooved uprated discs and ceramic brake pads (to keep the dust down)

Gary (the mechanic who is doing this for me) suggested painting the axle white to match the car, I hessitated a LOT, because it sounded a but chavvy, but since all of the parts on it will be shiny and new (for now) I decided "what the heck" and agreed.

He is going to take lots of pictures of the build for info on here.

Oh and he is going to ensure maximum tyre clearance for my new wheels. They will be 19" wheels and so need every bit of clearance we can get!.

I will be posting the first few pictures soon (of the bare axle painted) and the job will be complete (I hope) for the VAG in the Manor social later this month.

Steve B
 
Looking forward to seeing this one Steve. You won't be disappointed with the ceramic brakes, the brake dust is non-existant.
 
I fully understand the desire to have a really nice rear brake set up, but is there any reason other than I can so I will? Is the drum set up bad enought to warrant such an upgrade? Speaking personally, i have always been very pleased with the way the 75 stops on the standard system. I dont do track days (any more!) and even the journey through France in the TDi I never had any quarms about the stoppng power available. No fade, even on the long hot descent into Monte Carlo!
 
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I fully understand the desire to have a really nice rear brake set up, but is there any reason other than I can so I will? Is the drum set up bad enought to warrant such an upgrade? Speaking personally, i have always been very pleased with the way the 75 stops on the standard system. I dont do track days (any more!) and even the journey through France in the TDi I never had any quarms about the stoppng power available. No fade, even on the long hot descent into Monte Carlo!
A fair and sensible question.

But logic has nothing to do with it. Yes the 75 brakes are fine and possibly even slightly better than the discs, especially for the handbrake operation.


It is mainly cosmetic.
The wheels I will be using are very open and the rear drums are puny in appearance and will be very "exposed".
I much prefer the look of discs, especially when they are on view.

But also with my car I have virtually every conceivable extra and it just seemed that discs would complete the project.

It ialso gives me chance to squeeze the 19" wheels on while it is all stripped. The mechanic can "massage" the wheel tubs to ensure clearance.

When you have spent as much as I have on an A2 (please don't ask "how much" it is embarrassing to admit that total).

It is not such a big spend (proportionately) to add the disc conversion.

So no common sense involved and you are right that there is no sense behind it from a performance viewpoint.
It just kinda "had" to be done.

Steve B
 
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I fully understand the desire to have a really nice rear brake set up, but is there any reason other than I can so I will? Is the drum set up bad enought to warrant such an upgrade? Speaking personally, i have always been very pleased with the way the 75 stops on the standard system. I dont do track days (any more!) and even the journey through France in the TDi I never had any quarms about the stoppng power available. No fade, even on the long hot descent into Monte Carlo!
Regarding balance - 90%+ of the work is done generally by the front axle. Especially, though, at higher speeds on dodgy surfaces - gravel and snow spring to mind - then I can easily understand wanting less wag and more braking ability at the rear. It's exactly the reason why I'd do it. Try braking from 50mph on gravel and you'll feel what I mean.

- Bret
 
image.jpeg

I told you it was going to be white !!!!!
With all of the new parts on it it should look ok I think.
Great to see the work starting!

VAG in the Manor is very close.

Steve B
 
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I think it will look good when fitted Steve and sit nicely with new silver and black parts. Looking forward to seeing the end result. :)
 
I am convinced that the extra inch in diameter of the tyres will make the ride height look too high, so I have ordered some lowered springs (-25) hopefully that will malke it look a bit better too.

Steve B
 
There's just no stopping you Steve once you get going... :cool:
I hope the new grooved discs and ceramic pads will stop me !!!;)

To be honest I am genuinely running out of mods I want to do. I am not going for power improvements, the remap is perfect on the 75.

When Tom (Timmus) is darn sarf again I will be asking him to fit the camera in the passenger door mirror, pointed down, so I can check the clearance to my wheels when parking. That noise and vibration when you kerb your shiny new wheels is worse than the sound of someone scraping their fingernails down a blackboard, or worse still scraping the bottom of a pan with a fork!!

The last job will be to refit the bixenons properly and some decent DRLs when I find them (another wiring job for Tom) .

Other than that I can't think of anything else I want now. (at least when I told my wife about the new wheels, I told her that there was nothing else I would need to spend my money on!)

Steve B
 
I am convinced that the extra inch in diameter of the tyres will make the ride height look too high, so I have ordered some lowered springs (-25) hopefully that will malke it look a bit better too.

Steve B

What make did you go for Steve?
 
Big Day on Wednesday

The axle should be provisionally in place and the new wheels should have been delivered.

My idea is to have the axle fitted without springs and shocks first, put the wheels on and then we can swing the axle from one extreme to the other and check to see where the wheels will bind (they will even if it is only slightly) and so we can sort that all properly before fitting the springs (lowered 25mm) and shocks.

If the wheels dont then rub anywhere, I will know for a fact that the lowered springs will not be a problem!! (and 25mm is only an inch after all!)

Steve B
 
First of all I want to tell you that I really dig what I saw bout your A2 already.
I will take the time to read it all later.

Since I did a lot to my A2 (also the rear axle conversion) I feel I could contribute a little. :)

(...)

One thing you basically have to replace is the handbrake assembly, the 1.6 and 90's have a different one because of the discs. But I bought a new one from Audi and it was only around £40 (which was a pleasant surprise).

(...)

You can keep the handbrake lever and front handbrake line (assuming it is rust free) from the drum brake. Yes, it is a little different from the disc brake one but it will result in an exceptionally good handling.
You will pull the lever three klicks and the car jumps from the brake test stand. This is awesome and I strongly recommend that.


before:
drum.JPG

after:
disc.jpg

However you will notice that the FSI/90 disc is still too small, therefore I will upgrade the brake to the 256mm disc once my rotors/pads are worn.
I also strongly recommend to NOT use ceramic pads as they have considerable lower brake performance. Yes, they do cause little brake dust, but I prefer better performance.

I fully understand the desire to have a really nice rear brake set up, but is there any reason other than I can so I will? Is the drum set up bad enought to warrant such an upgrade? Speaking personally, i have always been very pleased with the way the 75 stops on the standard system. I dont do track days (any more!) and even the journey through France in the TDi I never had any quarms about the stoppng power available. No fade, even on the long hot descent into Monte Carlo!


Yes, there is. Theoretically you are right: We think that 90% of the A2 braking is happening at the front. However I ask you to try the additional thought about that matter: What happens when you let your car roll and just pull the handbrake lever? The car dives down at the back, right? Right. The very same thing happens when you brake normally. This means until some extend raising the brake power at the back will not cause overbraking in the rear but considerably even out the brake distribution. This results in a much better brake feeling especially when braking down from high speeds. You will feel the rear not wriggling around that much.
 
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It's a lovely A2 you have Nagah. Have seen photos of it before when searching for other things on Google.
 
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