The Problem
While refurbishing my 1989 VW Transporter T25, I discovered that the spring clips which hold the halves of the airbox together were so badly corroded that they were unusable. Crumbling to dust would be a good description of them. I tried various sources but could find no replacement which claimed to be for this specific vehicle.
This refers to Air Filter Box 025129607J, although the clips I have seen advertised which look identical seem to be described as “Air Cleaner Filter Case Housing Closing Spring Clips For JCB GEc” and “Spring Clips for Golf MK2 + MK3 + Corrado”. I put these long descriptions in here for the benefit of search engines.
I can understand that, as JCB and Volkswagen seem to be related, and it is common for a manufacturer to re-use parts. I had the same story when the windscreen washer pump failed on my Honda S2000. You can’t get them anymore, but they are apparently the same pump as the Honda Accord. After all, there’s nothing specifically to gain performance-wise by designing a new windscreen washer pump. The problem with these other clips is that there are no specifications or dimensions, and no drawing, so whether they fit or not is unknown.
The Solution
Anyway, the long and short of it was that I decided to make my own set of new clips because all the ones I could find online that might have fitted were all just steel, and my old steel ones corroded. All the ones I could find that specifically stated that they fitted this airbox were either out-of-stock, or were used ones. I thought I could do better than that and it wouldn’t be too difficult.
I found a supplier of austenitic spring steel wire, which has a high resistance to corrosion. I wasn’t able to measure the diameter of the wire used on the original clips accurately because they were too corroded, but they seemed to be somewhere between 1.5mm and 2mm. Given that I wanted to use a high grade spring steel, I settled on 1.8mm “Piano Wire” because it seemed a good compromise. I was to regret ever bothering to embark upon this project because I seriously underestimated the effort that would be required to accurately form that wire into anything resembling an accurate and repeatable shape. However, having decided to do it, I was not about to give up easily, and the end result is very satisfying.
The clips are made in two parts, which spring together. One of them, the lower section, forms the handle of the clip, while the upper section has a hooked lip.
After many damaged fingers and puncture wounds, I decided I would have to make a jig, firstly to bend the coiled spring part of the clip, but also to ensure that the shapes were repeatable.
The Jig
I didn’t want to spend too much time or expense making a production-quality jig, because I’ll probably only use it a few times, so what I decided to do was make something simple. It’s a bit rough in places, but it doesn’t have to look good – it just has to work.
The airbox clip is made in two pieces, which spring together. After a bit of tweaking, the final jig gives me the ability to make both parts repeatably with an acceptable degree of accuracy. They turn out to the nearest half millimeter, which is fine for their intended purpose. They’re not part of some mission-critical piece of hardware that takes people to the moon. There are small inaccuracies, but some fettling with two pairs of grips is enough to adjust their shape to the required fit.
Steps – Pictures
Steps – Video
The following video shows how to make the lower section of the clip using the jig, and a double-ended tool which I made to form the spring loops. I was rather frustrated when I made the tool and it worked fine, but then realised that I’d need to repeat it with the taper the other way round because it wouldn’t work in reverse. It’s obvious when you think about it, but naughty words were spoken.
If, or when, I need to use the jig to make any number of these I will tidy it up, but it was designed as a one-off bit of tooling for making four clips.
This implies that, if you really want clips for an 025129607J air filter box, I’d make you some, just because I’ve done all this work and might as well put it to good use.