Removal of the AB Gearbox in preparation for the AT box .

9th march 2008
The proposed IRS conversion was going well I had the A-Frame Arms ready to be fitted to the chassis. I had bought a 1302s IRS gearbox with AT code that had a higher ratio drive as it was originally made for a 1600 engine. This would better suit my engine. I had bought brackets to fit the IRS arms on a visit to the new SSP/VW heritage site.The brackets would need to be cut into the chassis and welded onto the torsion tube. To make way for the brackets to be welded into the chassis the gearbox would have to come out.

The removal of the gearbox is something best done with two people. I must thank my friend John for his help this morning. The removal process is quite straight forward, it is not necessary to remove the brakes from the drive shafts, however the brake hydraulic lines must be removed from the slave cylinders and the handbrake cables must be undone at the handbrake. I have already removed the drums as I wanted to lose the weight from the gearbox, additionally I was intending in replacing the drum brakes with a rear disk conversion. I had also removed the flexible hydraulic lines at this time.

Before undoing the gearbox bolts you need to remove the three bolts that hold the lower part of the drive shaft to the drive shaft. These are torqued up so you will need to use quite a lot of force to get them undone. You can use a length of tube on the end of a socket wrench, but in practice they can be undone with two 19mm spanners. With the three bolts undone you can unclip the rear bump stop. This will allow the drive shaft to separate from the swing axle. With the three bolts undone you must ensure that you have no cables or wiring attached to the gearbox. This usually comprises of the reversing light switch at the front of the box, the starter motor wiring and the clutch cable. You will need to release the gear linkage where it is connected to the gearbox. This is located under a small cover plate behind the rear seat and is secured down with a small Philips screw. With the cover plate off the linkage will be exposed. The linkage is secured by a 9mm square bolt that goes through the linkage, it may have a locking wire securing it which will needed to be cut off. With the bolt removed the linkage can be separated from the gearbox. With all these items removed you are ready to get at the gearbox bolts.

The front gearbox bolts are situated on and below the torsion bar tube in the centre. The two bolts can be undone with a 19mm spanner. The rear gearbox bolts are 27mm and you will need to get the proper spanner or socket to get them out. They are also torqued up to 166ft/lbs and will need a large amount of effort to get them undone. With all the bolts removed the gearbox can be pulled backwards and out of the car. You must first pull the drive shafts from the swing arms and then with a friend get a good grip on the box and pull it backwards. The gearbox will come backwards out of the rear arms. Be careful as it comes out as its weight will increase as its manoeuvred out and the gearbox is free. You will also find it quite awkward as it shifts out . Ensure you both have a good grip and be careful not to drop it.

With the gearbox out it is noticeable that the front mount on the new and old gearbox is different. The AT gearbox has a 1302s mount which has three bolts on the gearbox. The AB box has only two. I would have to swap the front nose cones from the two boxes.

With the gearbox removed it is noticeable how far the battery box comes down . I would have to cut this back and re fibreglass a new base in the box higher up.

It was also noticeable that the area that the IRS brackets would be quite difficult to cut into the chassis with the body on.

I was beginning to wonder if this was the best opportunity to have the chassis Zinc hot flame coated. With the chassis out the welding would be easier to do as I could weld up the IRS brackets on my drive way before taking the Chassis to have it blasted and zinc coated. This would also allow me time in the garage with the body of the car to re-fibreglass the underneath.