I hail from Scotland and I’m the proud owner of a 1958 Dexta and (dare I say it) a 1963 Massey Ferguson 35X. I have previously owned many tractors one of which was a 1961 Dexta, the rest were red. However iv caught the Dexta bug and really do enjoy working my tractor. It needs a lot of work but is perfectly usable as is. I find the Dexta to be a very comfortable machine to drive and great on the road.
Round these parts Massey Ferguson has always been king, but I have noticed those that have Dextas always seem to stick with them. Ever since I was a boy I always knew Dextas meant one thing- SPEED
Having been used to Mf 35s and 135s the dizzy heights of 16 mph feel like you’re revving to infinity with the engine.
They don’t feel like they want to be going so fast and they aren’t as high geared. However my 58 Dexta seems to zip along effortlessly at 17.5/18 mph. Clearly the early Dextas like my 58 model have a good turn of speed.
Now I have heard stories of Dextas doing 20/25 even 30mph
How can this be?
They must be over revving to the max...
I suppose larger rear wheels would speed things up? For example 13.6x28s..
I have scanned the road speeds for the early Dextas and seem to gather that the top speed on (10x28s) is 16.8mph.
I also saw results from a field test dated from 1959 on(11x28s) that suggests top speed is 17.5mph. That would tie in perfectly with the speeds I have got on my gps tracker. My Rev counter is not working.
Using the (10x28) ratios I figure that for every 200 rpm road speed is increased by 1.68mph. Thus it would need to Rev to 2400rpm to reach 20.16 mph.. so to achieve 30mph 3000rpm+ would be required.
Now running on 11x28s that would increase the speed without so much revving, in theory!
I’ll try and find or work out the speeds/ratios for 11x28s.
I figure by listening to the engine that mine runs around 2000rpm. It seems to be happy with that performs well. However when I acquired the tractor it only ran around 1500rpm, roughly anyway. I tried a few thing cleaning the air filter housing in some detergent and boiling it on stove. Cleaned the gauze in pump too, still no joy, then just by chance removed the air cleaner mushroom and she took off!! On closer inspection it turned out the mushroom was an aftermarket copy. Whilst comparing it to an original, I noticed the gap between the fins on the new one were not as big as the original. Out with a flat head screw driver to prise the fins futher apart and hey presto.
Now judging by the sound of the engine and road speed I reckon I get approx 2000rpm. Result!
The 1961 model I previously owned was a wreck.. it was the first dexta I ever operated. It was a hopeless starter even with me squeezing easy start into the air cleaner. However it would always start with a good tow. It was insanely fast though , it was quite a scary machine coming from a 1961 Mf 35! I wouldn’t run it flat out because it just went bananas!!
On cold frosty morning exasperated trying to start I flattened the battery, hooking up jumpleads I discovered to my amazement the reason behind the failure of the tractor to start with easy start! The rubber hose to the inlet manifold was split in half! All that easy start I had been spraying into the precleaner was not even being sucked in
She got a good spray in the hole then I can assure you and by flip she started.
This hole, I think, also proved to be the cause of my crazy fast tractor, it was pulling too much air.
The poor 61 Dexta has passed on now and is long broken up. My current 58 model is not a thing of beauty but give her 40 secs of heat and she fires up as quick as you like any weather.
Long post I know, just delighted to be on a forum to discuss Dextas with like minded folk!
Look forward to hearing if anyone has theories on dexta top speeds, they seem to differ quite a lot
Is a 30 mph dexta really a thing?
I’m a bit of a newbie to Dextas , but keen to learn from the experts!
Great forum and thank you for reading
