4 wheel alignment

simufly

A2OC Donor
Just about to start a rear axle refurbish. Thanks for an excellent write up. I have the “new axle“ in the workshop ready for strip down. I will get it powder coated so will leave the old bushes in place and replace before refitting.
A couple (Well 4 actually). of questions.
Is is practical to leave the axle mounting brackets in place, just remove the two long bolts from each side And dropping the axle?
Are the long bolts single use?. I will replace the nuts as they are single nylock type.
Is there a possibility of renting a puller set to get the old bushes out and the new ones in? The recommended set seems to be NLA. and £70.00 is a bit expensive for a single use tool.
Polybush or Audi for the replacement bushes? I seem to recall that polybushes were a bit suspect in the A2.
Thanks
Simon
 
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philward

A2OC Donor
Hey all, good debate and exactly the reason I wanted to develop the How To here. I’ll copy all the best practice over when we are finished.
Just about to start a rear axle refurbish. Thanks for an excellent write up. I have the “new axle“ in the workshop ready for strip down. I will get it powder coated so will leave the old bushes in place and replace before refitting.
A couple (Well 4 actually). of questions.
Is is practical to leave the axle mounting brackets in place, just remove the two long bolts from each side And dropping the axle?
Are the long bolts single use?. I will replace the nuts as they are single nylock type.
Is there a possibility of renting a puller set to get the old bushes out and the new ones in? The recommended set seems to be NLA. and £70.00 is a bit expensive for a single use tool.
Polybush or Audi for the replacement bushes? I seem to recall that polybushes were a bit suspect in the A2.
Thanks
Simon
Yes, leaving the mounting brackets in place will avoid the need for 4 wheel alignment.
The manual specifies the long bolts as single use. However the specified torque is XXNm with no additional angle. There is a debate in this thread that may help you decide. As I had to cut my nuts off :eek: I had no choice but to replace. Yes replace the nylock definitely.
I don't know, Google search, ask if members local to you can help.
I used Febi bushes, not expensive, possibly OEM (part numbers and branding removed).

Could I suggest you remove the old bushes and refit them prior to blasting and powder coat? The reasons will become clear when I write up the next section of the How To, Axle rust removal and refinishing.
 

cheechy

A2OC Donor
Just about to start a rear axle refurbish. Thanks for an excellent write up. I have the “new axle“ in the workshop ready for strip down. I will get it powder coated so will leave the old bushes in place and replace before refitting.
A couple (Well 4 actually). of questions.
Is is practical to leave the axle mounting brackets in place, just remove the two long bolts from each side And dropping the axle?
Are the long bolts single use?. I will replace the nuts as they are single nylock type.
Is there a possibility of renting a puller set to get the old bushes out and the new ones in? The recommended set seems to be NLA. and £70.00 is a bit expensive for a single use tool.
Polybush or Audi for the replacement bushes? I seem to recall that polybushes were a bit suspect in the A2.
Thanks
Simon
Whlist not a perfect fit we were able to use the cheap Audi sets you can pick up for 20 to 30 pounds to install the new bush, whilst using the destructive method to remove existing. They explicitly dont mention Audi A2 as the new bush doesnt sit that neatly in the cup - but in reality it works fine. The external bush size compared to an A3, polo or fabia of the same period is identical.

So something like this

Quality is likely poor but its fine for a one off job.

I went for Febi bushes also - quality and fit seemed good. The more I run on the bushes the better the ride quality feels...I potentially underestimated the improvement in the overall ride improvement post install.
 
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philward

A2OC Donor
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.JPG


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

IMG_6350.JPG


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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philward

A2OC Donor
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.
 
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philward

A2OC Donor
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 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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simufly

A2OC Donor
Excellent write up. Thanks. Took the old axle to the powder coaters yesterday. Left the old bushes in position.
What is the reason for the .2mm gap on the bush insertion?
FWIW Audi can supply the pipes ready made and they are not expensive if you feel unhappy about making your own flares. Totally agree re kunifer.
 

philward

A2OC Donor
Excellent write up. Thanks. Took the old axle to the powder coaters yesterday. Left the old bushes in position.
What is the reason for the .2mm gap on the bush insertion?
FWIW Audi can supply the pipes ready made and they are not expensive if you feel unhappy about making your own flares. Totally agree re kunifer.
I think the 0.2mm is to stop a heavy handed mechanics winding until the resin bush lip breaks off. I have copied some of your words into the How To.
 

philward

A2OC Donor
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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Rusty911

A2OC Donor
Fitting the axle to the car

New screws or use old?


The Audi manual states that all bolts, screws and nuts, relating to this job, are use once only. 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.

Picture

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:

View attachment 69291

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

Fitting the axle and associated components.

This is a reversal of the assembly 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 fitted and torqued, brakes assemble, brake pipes connected and ABS sensors fitted:

View attachment 69289

Wheel bearings 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:

View attachment 69287

Finally torque the damper lower securing bolts:

View attachment 69288

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

View attachment 69290

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

Enjoy the new smooth ride at the rear.
Absolutely fantastic write up! Thank you :)
 

Alan_uk

A2OC Donor
Excellent thread Phil. Seems some of the pictures have disappeared. Any chance you could reinstated them please.
 

philward

A2OC Donor
Excellent thread Phil. Seems some of the pictures have disappeared. Any chance you could reinstated them please.
My next task is to put together a reference table for fastener sizes and torques. I was then going to work through the posts, check my terminology is consistent, that the instructions are complete and also upload the missing pictures. Some of them I still have to take. Once completed I will transfer the instructions only to the How To section.
 

philward

A2OC Donor
Not quite complete but I have been asked for this information.

Rear axle fastener sizes and torque specifications (not applicable for 1.2 TDi)


A2 thread data.jpg
 

philward

A2OC Donor
Could somebody just check for me please, the socket size for the 12 point self locking stub axle nut is 32mm? From memory it is but I don't want to have to knock a sealing cap off to check. Thank you.
 
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