Frontline Developments 5-link rear suspension fitting – part 1

Frontline Developments 5-link rear suspension fitting – part 1

Here’s a job I’ve been looking forward to, and one that has to be done before I start prepping the bodyshell for paint. This modification is definitely a bit of an extravagance, but it’s all part of my master plan to create the ultimate “sleeper” rubber bumper GT. I believe there will also be some important performance and safety benefits from fitting this kit when it comes to dealing with the increased power from the V8 conversion, so I’m very hopeful that it’s a sound long term investment for the project.

Frontline Developments describe this as “the ultimate rear suspesnsion set up for the MGB“, and my first impression upon unboxing it is certainly that it is a beautifully designed and constructed piece of engineering. With all the main components smartly finished in satin black, several clearly labelled bags of bright zinc-plated bolts and hardware, and reasonably comprehensive fitting instructions included, it’s also very nicely packaged. The instructions would benefit from a few more diagrams and higher resolution photographs perhaps, but largely the fitting process is self-explanatory and easy to follow.

At this stage, my goal is only to do a basic dry install of the main subframes and bracketry where they meet the shell, to make sure I’m drilling all the necessary holes now, rather than mess up any new paintwork later on. There will be a follow-up post at a later date when I install everything for real.

After unboxing everything and familiarising myself with the components, the first step is fitting the new spring hanger brackets onto the existing forward leaf spring mounting brackets. On a rubber bumper car, these brackets have this inner strengthening webbing, which has to be cut out before the new bracket can be offered up (the instructions do give some good guidance on dealing with these slight differences between models).

I sliced the webbing on either side with a hacksaw, and then used a die grinder to remove the bottom edge and clean up the remains. Once removed, the new bracket can be slotted into place, and two 10mm holes drilled into the shell for it to bolt into.

Next up, the main subframe can be fitted. I found this a bit of a tight fit in places, and the shell needed a bit of adjustment to get it to seat squarely, but was not too much of a problem. The biggest issue was that the rubber bumper spring hanger brackets are dimpled on the sides for strength, which as you can see in the picture above, prevents the new subframe (on the left) from sitting flush against it. I solved this by grinding a slot in the dimple, hammering it flat, and then welding up the gap again. The picture below shows it properly seated. Each subframe also requires three more 10mm holes to be drilled into the shell to secure it, so you can start to see why it’s a good idea to do this before paint!

The next step was to fit the mounting bracket for the Panhard rod. This bolts through the front left hand corner of the boot floor as pictured below, using 10 more bolts. The kit includes two strengthening plates which the bolts pass through on the inside of the boot.

The final job for this stage was to test fit the torque reaction bars. These are not part of the main 5-link conversion, but can be purchased as an additional kit from Frontline, and seem to be particularly recommended for high-powered cars to help spread some of the forces from the rear end into the shell. They perform a similar function to some of the “home brew” strengthening solutions outlined in Roger Williams’ V8 conversion book, and having heeded the warnings in that book about the need for that extra strength when performing a V8 conversion, they seem like another good investment.

I mentioned these bars in a previous post when I modified the new jacking points to accommodate them, so it’s good to now prove that that adjustment was worthwhile. The rear of the bar bolts through the new spring hanger bracket I fitted at the beginning of the post, but the front bolts straight into the central crossmember, through a pair of supplied crush tubes, with one more bolt passing upwards into the floor for good measure.

A view from the other side showing it fully bolted into place, and sitting square against the crossmember without fouling the jacking point, thankfully.

And here’s how the full installation looks so far. It took me the best part of a day to get to this point, including the few adjustments I had to make to the shell, but that should be most of the hard work done. There are a couple of modifications that also need to be made to the rear axle when it comes to hanging it, but for now I’m just going to remove the whole lot and box it up again out of the way whilst I get on with painting!

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