How-to repair / restore your Audi A2 rear axle

Little Dog

A2OC Donor
European-Union
How-to repair / restore your Audi A2 rear axle.

First decide what you want to achieve, consider your skills / how much labour you are prepared to fund to correct / restore your A2’s rear axle. There are basically three options each listed below with a brief overview of work involved.

Option 1 – Replace bonded rubber bushes.

Support the axle, remove bush to mounting bolts and lower the axle taking care not to strain ABS sensor cables, brake pipes and parking brake cables. Remove old and fit new bushes.

Reassemble in reverse sequence

Option 2 – Restore rear axle (excluding mounting castings)

Disconnect brake pipes, parking brake cables and ABS sensor cables. Support axle remove damper to axle bolts, lower rear of axle and remove springs. Remove bush to mounting bolts, lower axle and remove from car.

Complete restoration of axle, reassemble in reverse sequence, bleed brakes.

Option 3 – Restore rear axle (including mounting castings)

Disconnect brake pipes, parking brake cables and ABS sensor cables. Support axle remove damper to axle bolts, lower rear of axle and remove springs. Remove 6 mounting bolts, lower axle and remove from car.

Complete restoration of axle, reassemble in reverse sequence, bleed brakes. Arrange for 4 wheel geometry to be checked/ corrected.

Guide purpose

The purpose of this guide is to provide guidance on how to perform option 3, restore rear axle including mounting castings. It also includes details of workarounds for unexpected issues. It is quite rewarding when the repairs are done and your axle is back and on its way to being fully functional again:

1.JPG
 
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Required tools, replacement fasteners and order bushes.

This is a straightforward repair, there are very few components that need to be removed. Metric spanners, metric socket sets in ¼ and ½ drive, a suitable torque wrench and two brake pipe clamps cover the vast majority of the work. Consideration needs to be given to, supporting the space frame, the weight of the axle, how the replacement bushes will be fitted and, how the bush will be removed.

Supporting the space frame, I would usually lift on the rear jacking points and provide additional support by putting a stand under the rear axle. For this job the lifting and supporting positions are reversed so I prepared some wooden blocks to protect the aluminium jacking points:

IMG_6420.JPG


I accept they look a little precarious but they fit in the cup of the stands and were absolutely solid.

Supporting and lowering the axle, Audi recommend a gearbox lift but I found a motor bike lift perfect for the job. It lowers the axle right down to the garage floor, lower than if I had used a trolley jack and pad

IMG_6411.jpg


Bush insertion tooling, I used a universal puller / press set. All of the necessary sizes for bush removal and fitting are included in this set:

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Bush removal, the above set will also remove the bushes when combined with a large bearing puller. However if the bush is particularly difficult access to a selection of drill bits, a power drill, large hack saw and possibly oxy acetylene would be useful.

Torque wrench, check that your wrench range is correct for the task. Rear axle fastener sizes and torque specifications (not applicable for 1.2 TDi):
A2 thread data.jpg

Audi recommend that all bolts, screws and nuts applicable to this repair are renewed if removed. The stub axle nut has a RH thread on both axles; it is safety critical that these nuts are renewed if removed.

Order new fasteners or reuse? The Audi manual states that all bolts, screws and nuts, relating to this job, are use once only. It is a good idea to order and collect replacement fasteners before starting work to avoid any risk of work being delayed parts on backorder. However if you are delayed by a fastener backorder or unsure of the need to to replace all fasteners then a summary of an A2OC group discussion on this subject follows:

It is important to replace all self-locking nuts, however some A2OC members suggest that the bolts are not Torque to Yield bolts, more commonly known as stretch bolts, and are therefore safe to reuse. Stretch bolts must not be reused, all bolts stretch but a stretch bolt is stretched beyond the elastic zone into the plastic zone.

Torque 6.jpg


The advantage provided is that the stress strain curve is much flatter in the plastic region so the clamping force is better controlled. The clamping force is set by a characteristic that is manufactured into the bolt; it is not variable depending on the friction felt by a torque wrench. The friction felt by a torque wrench is dependent on the condition and lubrication of the threads and so can be quite variable. Finally a stretch bolt provides a greater clamping force for a given bolt size. Stretch bolts when removed cannot return to their original length and strength and therefore must not be reused. If you have any doubts replace your fasteners as advised in the manual. For others I summarise a debate regarding stretch bolts here on A2OC.

A standard bolt stretched within the elastic zone generally has a single torque figure specified, ie 55Nm. The torque wrench can only respond to friction felt which in turn will be influenced by cleanliness of the threads, lubrication etc. The actual amount of bolt stretch achieved therefore can be variable along with the associated clamping force.

If tighter tolerances are required for the clamping force required from a standard bolt stretched within the elastic region then a lower initial torque followed by an amount of turn can be specified, ie 30 Nm + 90 degrees. A portion of the stretch is determined accurately by an angle of turn after a possibly less accurate torque wrench setting. As the stretch is tighter controlled overall then so too is the clamping force. A torque wrench setting followed by an angle of turn does not necessarily confirm a bolt is a stretch bolt. A screw is unlikely to be a stretch fastener because there is no thread free portion where necking can occur.

A torque wrench only setting cannot be specified for a stretch bolt. A torque wrench that takes a bolt to the point of necking will never click. It will continue stretching the bolt to the point of failure. Torque specifications for stretch bolts specify and initial clamping force followed by an angle of turn. A stretch bolt can generally be identified by a slightly reduced diameter unthreaded portion of its length between the head and the thread. This is a head bolt set supplied by Elring:

Elring.jpg


In the future I will be making a judgment based on this information and only replacing bolts that are likely to be stretch bolts.

Order replacement bushes

I no longer use Audi for parts such as this. I find Febi Bilstein offer a very good quality product at a lesser price. Their Parts Finder site allows you to set up an account, save your vehicles and then search for parts. The site does not take orders so you can then Google the part number for the best price:

Febi.jpg


Please visit the site and input the details of your A2 to ensure that you order the correct bush.
 
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Preparation for a clean axle drop

I have a thing about not getting into a car on stands so I backed the handbrake off before lifting the car

IMG_6324.JPG


I also try to avoid applying unknown large torques to a car on axle stands; my first task therefore was to remove the screws securing the trim at the lower front edge of the rear wheel arches. Some of you may also have to remove heat shields. With the trim lose the bush to mounting bolt can be accessed:

IMG_6406.JPG


Or as in my case a sturdy breaker will break all 6 mounting to space frame bolts, my objective is to break the majority of torque while still leaving sufficient to hold the mountings to the space frame.

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The car was then lifted on the rear axle and stands placed under the jacking points. I like more than one method of support and usually leave jacks in position with the majority of weight on the stands. In this case I put the lift in place before working under the car:

IMG_6333.JPG


I clamped the space frame to axle flexible brake pipes and then cut them with a saw on the axle side of the clamp. The pipe nuts were badly corroded and the flexible cheap to replace (the manual advises that detaching the flexible pipe bracket from the space frame will allow sufficient drop to change bushes without removing the axle from the car). I also cut the solid pipe at the rear of the drums.

ABS sensors were detached and put out of the way.

Drums were removed and hand brake cables detached from the shoe linkage and put out of the way; threaded through the stands (the manual advises that detaching the cable claps from the space frame in front of the fuel tank will allow sufficient drop to change bushes without removing the axle from the car)

It is now safe to drop the axle without straining brake pipes, hand brake cables or ABS sensor wires.
 
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Drop the axle

Remove the damper bottom securing bolts and remove the springs. The manual recommends spring compressors but I simply held the axle to remove the bolt, lowered the axle and manoeuvred the springs out.

IMG_6332.JPG


Remove 6 mounting to space frame bolts, I first raised my lift a little to ensure the mounting bracket would be held against the space frame. If you are removing the mounting bracket to bush long bolt then please give some consideration as to how to do this safely (I had the axle assembly in effect clamped against the space frame, which is not possible if you are removing the 2 long bolts). The manual advises the use of straps to secure the axle, then remove the bolts safely.

Remove straps if you have used them, lower the axle. I did this onto cardboard bike boxes and then dragged the whole thing out, cardboard, the axle, axle still on the lowered lift; the whole lot on cardboard.

My axle was a bit of a mess:

IMG_6334.jpg
 
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Removing the bush (part 1)

If you are working on a bench and the intention is to blast and refinish the axle, remove stub axles, back plates, brake pipes pipe clips, hand brake clips etc. Makes the axle easier to handle and takes away the risk of accidentally damaging components. Items that need to be replaced can be on order as work progresses.

Note, the orientation of the bush is important. I recommend taking photographs to record the correct positioning of the bush in the axle before removal. These should be referred to when fitting the new bushes.

If the mounting bracket is still attached to the bush remove the long bolt through the bush along with the mounting bracket. In my case the bolt head and nut were so far gone I had to saw between the nut and the washer beneath it. The bolt then came out very easily and the mounting bracket was removed:

IMG_6342.JPG


Removal by destruction

There is a method of removing the bush that is posted regularly on the internet, drill the rubber from within the bush and then saw through the resin outer sleeve of the bush in two places along the whole length, cuts should be roughly diametrically opposite and be careful not to cut into the steel of the axle. The two halves now knockout.

A quick and dirty method, again regularly reported on the internet, is to burn the rubber with oxy acetylene; not sure about this one but if you go for this method make sure you have PPE and understanding neighbours. Cut the outer resin as above.

There are two things to consider before you go down this route. Firstly the tools that fit the bush also remove the bush, so unless you have a tool that will only fit bushes, the tools you need to buy to fit are also likely to remove and keep the bush in one piece. Secondly keeping the bush in one piece is good if you intend to restore the axle by blasting it. The old bush can be refitted to protect the bush location surfaces of the axle from blasting grit and paint spray or powder coat.

Removing as described in the manual

DIY tools set up to provide the method of removal described in the manual:

IMG_6370 (1).jpg


To set this tool up select the largest sleeve that will pass through the bush location on the axle. It is not possible to select the correct sleeve by measuring the new bush. 71mm suggests a 70mm sleeve would be correct.

IMG_6412.jpg


However the resin bush compresses as it enters the housing so the correct bush is one that just slides inside the bush location.

IMG_6339.jpg


68 mm OD is the correct sleeve

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Now select the smallest sleeve that the larger diameter end of the bush will slide inside.

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A large bearing puller clamped to the axle provides a thrust surface for the last sleeve selected.

IMG_6419.JPG


Set it all up around the bush

IMG_6370.JPG


Get the spanners out and start winding, the bushes come out easily when the axle is in good condition.

The next section describes how to remove the bush if the method described in the manual is unsuccessful.
 
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Bush removal (part 2)

The bush removal method described in the manual may not succeed, his can occur for example when the axle is badly corroded. Rust build up can prevent the sleeve positioned to push the bush out from even contacting the bush. The forces required cause the bearing puller to slip damaging the outer surface of the bush housing / tube. This section describes an alternative method of removing the bush in a reasonably complete condition.
Heavy rust build up preventing bush removal:

IMG_6336.JPG


The bush is flexible though and can be pushed over the rust form the other side providing the larger diameter rim of the bush is first cut off. A hacksaw should cut the resin easily and quickly. I used a sharp woodworking chisel.

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Then it is a matter selecting the smallest sleeve that will slide over the new relaxed bush:

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Set up the sleeves around the bush, take a big ratchet and start winding:

IMG_6338.JPG


The sleeve to receive the bush was not quite deep enough so the bush was drifted over the last few mm of rust.

If this fails I suspect destruction of the bush is your only option, destruction of the bush is described in Bush removal (part 1).
 
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Axle rust removal and refinishing

Your axle will probably be showing signs of aging and would benefit from having the rust removed and a new surface coating applied. My axle was quite a mess and at this stage I did not know that the rust was so bad that the steel had perforated:

IMG_6341.JPG


Now is time to decide on your preferred approach to rust removal, your preferred surface coat and to select your suppliers. I understand that the rust can be removed from the axle using a wire wheel and an impact chisel. That approach sounds dirty, drawn out and unreliable. I chose to have the axle sand blasted. Powder coat is a popular surface coat but opted for a high zinc primer, after blasting, to be top coated by myself. I have had good results with Smoothrite in the past, two coats of satin black were applied.

Axle preparation for blasting

It is best to avoid blasting and coating the inside of bush location tube and this is best avoided by refitting the old bush. Leaving the old bush in position until after blasting is a possibility but the first removal can be difficult, damaging the new coating, and the inside of the bush location tube can be badly corroded requiring rust removal. Again there is a risk of damaging the new coating

Inside the bush location tube was also badly corroded on my axle, I couldn’t differentiate between rust and good metal and there also appeared to be an adhesive in there:

IMG_6346.JPG


Emery cloth removes good metal as well as rust so there was a risk I could leave the bush location tube internal diameter oversize once the rust was fully removed. I therefore opted for electrolytic rust conversion.

IMG_6347.JPG


The rust is converted and good metal remains intact maintaining tolerances as far as possible:

IMG_6349.JPG


I now refit the old bushes leaving them slightly shallow so that, once the new bushes have fitted, all visible surfaces will have been blasted and painted; there will be no bare metal:

IMG_6351 (1).JPG


The stub axle location was carefully cleaned with a file and the threads cleaned with a tap:

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To avoid blasting and painting the sub axle location and to protect the threads an aluminium mask was made to the size of the stub axle and bolted in place:

IMG_6433.JPG


Mask plates created for the A2 being reused on a MK2 Golf rear axle.

Deliver your axle for blasting.

Painting the axle.

Not required if you have opted for powder coat, I simply allowed the primer to dry, fitted the new bushes then painted the axle using a brush. The two tiny spots of perforation were protected with acrylic seam sealer before painting.
 
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Fitting new bushes

The new bushes have to be correctly orientated in the axle. Refer to your photographs taken before the old bushes were removed. If you didn’t take pictures guidance is provided in the Audi A2 manual but you need to be careful to interpret this diagram correctly:

A2 Bush.jpg


Select a sleeve that fits over the rubber portion of the bush and rests on the flange:

[
IMG_6434.JPG


Mark the sleeve, or position the sleeve slot, to indicate the bush location tab position. The tape or slot is used to align the bush correctly to the axle. The tape is removed once the bush has been drawn in approx 10mm.

IMG_6436.JPG


Before fitting the bush I lightly lubricated the inside of the sleeve location tube with Dynax UC cavity wax. It sets stiff and should provide some corrosion protection. This method is not recommended by Audi but the bushes benefited from being slightly lubricated and remain firmly secured in the axle.

Set up the sleeve and bush correctly orientating the bush relative to the axle then start winding, it looks a bit of a squeeze but the bush deforms easily. Tap occasional with a soft mallet when starting to correct any misalignment and ensure the bush pulls in square and as smoothly as possible. Also as soon as the bush is square and secure check the orientation, it is easy to correct at this stage.

IMG_6367.JPG


If all is good continue winding:

IMG_6368.jpg


Stop winding when a 0.2mm gap remains between the bush and axle.

IMG_6369.jpg


Remove fitting tools, job done.

Edit 13/03/22, at this stage the manual advises that the kidney shaped holes should be lubricated with a suitable rubber grease. The bushes I bought came ready greased so this step was not necessary and was omitted from the guide.
 
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Off car axle reassembly.

After bush fitting two coats of paint were applied to the axle.

I decided to fit brake pipes and mounting brackets (finger tight) before refitting the axle. Back plates, sub axles etc. would be fitted when the axle is back on the car. Reduces weight, reduces risk of damage and makes it easier to apply the recommended torques, to the stub axle screws for example.

Brake pipes

Fitting brake pipes with the axle on a bench is so much easier than working on the car. Also it is much easier to achieve the correct bends and length of pipe. My first choice for brake pipe material is Kunifer, a cupro nickel alloy, it looks like I have been supplied copper but it is BS marked so I decided to use it. My first flare is always on the bench, these tools produce the best flares:

IMG_6385.JPG


I then fitted the flexibles:

IMG_6387.JPG


I then connected the new pipes and started bending (I bend using my fingers). The last flares were made on the axle so that the pipe length would be exactly right:

IMG_6388.JPG


Audi can supply the pipes ready made and they are not expensive (Edit 10/2023; I understand brake pipes are NLA at Audi) if you prefer not to make your own flares or don't have access to the tools.

Mounting brackets

Just put the the mounting brackets on and nip them up:

IMG_6392.jpg


The axle is now ready to be fitted to the car
 
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Fitting the axle and associated components.

This is a reversal of the disassembly process. Position the axle under the car on a lifting device and lift it up to the car. At this stage consider if the axle could fall off and if additional straps are required. Go under the car and insert the screws / bolts. Nip the axle up to the space frame. Check that both rear springs are seated correctly and insert the damper lower securing screws and nip up the nuts.

Stub axles were then fitted and torqued, brakes assemble, brake pipes connected and ABS sensors fitted:

IMG_6403.JPG


Wheel bearings were fitted with a new nut and torqued, drums were fitted, the brakes bled and the car lowered to the ground, the hand brake was then adjusted.

Get a volunteer to sit in the rear of the car, yes this is in the manual, I went for two of less than average weight to keep things balanced. Torque the 6 mounting to space frame bolts then torque the 2 long through bush bolts:

IMG_6406.JPG


Finally torque the damper lower securing bolts:

IMG_6407.JPG


I want this repair to last as long as possible so underbody sealing wax was applied to the whole assembly, excluding the drums:

IMG_6409.JPG


If you have removed the axle including the mounting castings it is now time to arrange for 4 wheel alignment.

Job done, enjoy the new smooth ride at the rear.
 
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Great comprehensive detailed write up Phil ? couldn’t you sleep all done in the early hours of this morning ?...
Thank you, bodyclock didn't understand that the clocks have moved. Also it was the best chance I had to upload the whole guide without comments appearing between the posts.
 
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Great write up Phil. I have just started down the same route. A couple of question for you! The front mounting brackets appear to have a special finish on the mating surface, you can see it on your photo entitled "my axle was a bit of a mess" and on my brackets, photo attached. Is that a specific washer/gasket/Audi glup to stop the steel and aluminium reacting? Your brackets look new, did you replace them or blast & paint?
Thanks in advance.
 

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Great write up Phil. I have just started down the same route. A couple of question for you! The front mounting brackets appear to have a special finish on the mating surface, you can see it on your photo entitled "my axle was a bit of a mess" and on my brackets, photo attached. Is that a specific washer/gasket/Audi glup to stop the steel and aluminium reacting? Your brackets look new, did you replace them or blast & paint?
Thanks in advance.
My brackets had reacted with the aluminium. The aluminium was quite badly corroded. I considered fitting a nylon washer or helicopter tape but decided instead to paint. The brackets are original, I used electrolytic rust conversion to remove the rust, the whole bracket was etch primed black, then the non mating surfaces further finished in satin black Smoothrite.
 
hi Phil.
Great in detail explanation.

Only one question: can you provide the part number for the bussing?
Searching for the oem number does not return any parts available (not even febi). Maybe some on ebay but I wouldn't go there. Audi tradition has some but they are as usual a bit to expensive.

Here is the thread where this is discussed: https://www.a2oc.net/community/inde...compatible-with-1j0501541c.49280/#post-481602

The suggested part number: 1J0501541C seems to fit but what is very interesting is that some manufacturers post 11 mm or 12 mm inner bore. Do you have any idea if the 12 or 11 screw are interchangeable? If you remember...since you changed yours.

And another question: where is this(from elsawin)? "before installing rear axle in mounting brackets grease kidney shaped cavities of bonded rubber bushes with assembly paste" (since English is not my birth language i do not really get what this means). I cannot find this step in your pictures.
 
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hi Phil.
Great in detail explanation.

Only one question: can you provide the part number for the bussing?
Searching for the oem number does not return any parts available (not even febi). Maybe some on ebay but I wouldn't go there. Audi tradition has some but they are as usual a bit to expensive.

Here is the thread where this is discussed: https://www.a2oc.net/community/inde...compatible-with-1j0501541c.49280/#post-481602

The suggested part number: 1J0501541C seems to fit but what is very interesting is that some manufacturers post 11 mm or 12 mm inner bore. Do you have any idea if the 12 or 11 screw are interchangeable? If you remember...since you changed yours.

And another question: where is this(from elsawin)? "before installing rear axle in mounting brackets grease kidney shaped cavities of bonded rubber bushes with assembly paste" (since English is not my birth language i do not really get what this means). I cannot find this step in your pictures.
I'll see if I can find the part details. I'm fairly certain I fit Febi bushes and the kidney shaped cavities came ready greased so there was no need to apply additional grease / paste.

Edit, guide updated thank you.
 
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Febi list this part for my A2. I no longer have the packaging or receipt for my bushes so I can't check.

Febi list this part as compatible with item 7 https://audi.7zap.com/en/rdw/audi+a2/a2/2003-248/5/500-500020/

Edit, I found my purchase record; I fit two Febi 29664
No longer available...this set (or oem code) cannot be bought on normal channels. Maybe ebay has some.
You were lucky...back then it was available.

Maybe on the new versions they forgot to put the "old" ones as compatible.
I ordered: MEYLE 1147100001/S - without S is normal kit without bolt - I will use the new nut and shims from the kit.
The code for the oem bolt - still available today: N90710501 - the bolt is longer than normal kit and should be replaced.
 
I found lots of options for Febi 29664 earlier today, about £20 each on eBay. I paid £20 for two two years ago.
 
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