AboutJim Expertise My area of specialty is the Triumph Spitfire 1500 (1973-1980) although I have some technical experience with the GT6 and TR6 models also.
I can cover questions on all areas of the Spitfire, from basic mechanical questions to where to find original style seat covers and soft tops.
I am not an expert on the TR2/3/4 models. If you need specific detailed help with these models I first recommend obtaining a good repair manual such as the Robert Bentley manual for your particular model.
Experience I have been a Spitfire owner for 20 years and have done all my own repair work. On the Spitfire I've done just about everything except mount and balance tires.
In addition to street use I have been autocrossing a Spitfire with the SCCA (Sports Car Club of America) in Modified class since 1997.
Organizations Red River Triumph Club
SCCA (Sports Car Club of America)
NASS (North American Spitfire Squadron)
FOT (Friends of Triumph)
Question Hi Jim, I have a 77 Spitfire, the overdrive works up to 50 mph; once I go over 50 mph, it slips in and out of overdrive consistently; running between 40 and 50 mph, the overdrive will stay engaged. What is causing this? Many thanks!
Answer Howard,
The overdrive works by using gear oil pumped into the engagement pistons, with an electrically operatated control valve.
What it sounds like is that at higher speeds something is causing the o/d unit to disengage, either hydraulically or electrically.
Does the problem happen in both 3rd and 4th gears? Or only 4th?
My first guess would be that the oil level is a bit low, and at higher speeds you're starving the pump for fluid.
Otherwise there may be an electrical fault that's de-energizing the control solenoid, allowing the o/d unit to drop back into non-o/d mode.
While you're checking the fluid level it's worth hooking up a test lead at the overdrive solenoid and running with a voltmeter hooked up. If you see the voltage dropping as you're moving around then it's a sign there is some sort of electrical fault.
