A few weeks ago I wrote a technical article explaining the science behind parabolic leaf springs (here). Briefly, parabolic springs eliminate almost all of the disadvantages of standard multi-leaf springs, offering far less internal and inter-leaf friction, plus true progressive action; that is, the spring offers more and more resistance as it compresses. On top of all that, a parabolic spring weighs at least a third less than a comparable multi-leaf spring.
In the article, I lamented the lack of parabolic spring kits for the 40-series Land Cruisers, and particularly the FJ/BJ40. To my surprise (and embarrassment), a few weeks later I received an email from the owner of Terrain Tamer suspension, in Australia—a company I had actually referenced in the article. The email read, “I saw your article on parabolic springs. We manufacture a kit for the FJ40 and can ship to the U.S. I’d like to send you one and have you review it.”
Well . . . okay!
The kit arrived at our commercial mail depot while we were driving from Alaska to Tucson, so our friend Brian generously picked it up and stored it until we arrived. When I retrieved everything from his house, two things were immediately apparent: first, this is a comprehensive kit, comprising springs, shocks, a steering damper, shackles, and bushings. Second, parabolic springs are astonishingly lighter than conventional leaf springs. I’m looking forward to weighing the springs now on our FJ40 and comparing.
I’ll be documenting the conversion process in depth, first measuring ride height, compliance (RTI), handling, and subjective ride comfort. There’s little reason to doubt that the Terrain Tamer kit will transform the ride and compliance of the FJ40, while potentially removing well over a hundred pounds of unsprung weight.
Terrain Tamer is here. The full kit, at the current (extremely favorable) exchange rate, is only $1,625, although shipping will of course add a good chunk. But short of a multi-thousand-dollar bespoke coil-spring conversion, there’s nothing that will do more for the ride of a 40-series Land Cruiser.