Blog

WHAT we’re doing, and HOW we’re doing it!

October 13, 2025

Adding an overdrive to a TR which didn’t originally have it is a “relatively” simple task, but there are several related parts which will be necessary if you want it to work! While the front gearbox case is the same (o.d -vs- non-o.d.) and the unit will easily bolt onto the rear of the engine, the rear mounts are only that simple as long as you install an A-type overdrive into a pre-1973 TR6 and a J-type in a 73-76 version. The gearbox mainshaft is the biggest difference internally, so that leaves us with all of the peripheral pieces. Dash or steering column switches and an unseen voltage relay to operate an engagement solenoid, and wiring sub- harnesses to connect them all together. Isolation switches have to be added to the top so the overdrive can only be engaged in certain forward gears, and then there’s the longer speedometer cable and a 90 degree cable adaptor (TR4A-TR6 only) that’s needed to keep your speedometer working. Thankfully, your original driveshaft will still work with an overdrive upgrade! While none of this is rocket science, it won’t be as simple as buying an overdrive gearbox from eBay with plans to ‘throw-it-in’ on a Saturday afternoon. Want to simplify the process even more? Give us a call and let the folks here (who know the ins-and-outs like the back of their hands) do it all for you!

October 6, 2025

We are well known among the sidescreen community for rebuilding TR2-TR3B steering boxes, averaging 2 per month over the last 15-16 years, but did you also know that we rebuild all of our own TR4-TR6 steering racks as well? Special bushing reamers are required to rebuild the early steering boxes, and we had to make a couple of our own special tools to be able to work on the steering racks. (Another good excuse to have our own machine shop!) Careful measurements and adjustment of shim packs are required to rebuild the early boxes, and the same task is also repeated with the steering racks. Here you see the setup for measuring pinion end float, and then this float is adjusted by adding or removing shims from the stack. The more things change, the more they stay the same! While we don’t recommend rack and pinion steering conversions for the sidescreen cars (due to incorrect geometry changes), we are equally well versed on the racks for the Triumphs that were designed to use them.