Gearbox/overdrive question

Clutch, Gearbox, Overdrive, Propshaft, Differential, Drive Shafts, Hubs.
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Jonathan Lewis
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Re: Gearbox/overdrive question

#11 Post by Jonathan Lewis » Thu Feb 11, 2021 10:40 am

Dave B wrote:
Wed Feb 10, 2021 4:33 pm
Just to muddy the waters a little, I used to have a pfl M regd (so post August 73) 2.5PI without o/d, and it was original, only 21000 miles when I got it.
The exception that proves the rule? :wink: :lol:

Perhaps - a possibility that John has already noted - a late registration of a car built sometime earlier? By 1973, BL was having to work at selling its cars and - sadly - Triumph was no exception... :(

Sal
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Re: Gearbox/overdrive question

#12 Post by Sal » Fri Feb 12, 2021 10:14 pm

Getting a little lost in the technicalities again, not that I’m complaining I’m just learning (not helped by a few ciders on board of course!!!)
But I’m guessing when you speak of A box you mean it’s a manual non overdrive and J is overdrive box, correct?

Cheers Sal

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Re: Gearbox/overdrive question

#13 Post by tony » Sat Feb 13, 2021 3:51 am

A type and J type are both overdrive 'boxes but different models. They do similar jobs but the parts are not interchangeable. Hope this doesn't confuse things further. :D
Tony.
1976 2500 TC. converted to S specs.

Lots of bits

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Hopefully not needing too many bits.




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Re: Gearbox/overdrive question

#14 Post by johnnydog » Sat Feb 13, 2021 11:57 am

As Tony says both are overdrive gearboxes but fitted during different eras of production. The A type was fitted to earlier cars, and then from 1973 ish, the J type overdrive was fitted although as discussed the A type was still found in 1974 registered cars. There are relatively minor visual differences, but in driving them, the A type tended to be more of an abrupt engagement, whereas the J type was a smoother engagement.
The other difference between the two was that in the Triumph 2000 /2500 and PI range the reduction ratio in A types was usually 22%, whereas the J type was either 25 or 28%. In other words, in my S, at around 70 mph, engaging the J type overdrive reduces the engine revs by approx 500 rpm. A types can suffer from electrical connection issues to the solenoid as they are exposed and therefore more susceptible to the elements.
There should be a riveted plate on the side of the actual overdrive unit which will identify which type it is.
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Re: Gearbox/overdrive question

#15 Post by Charles H » Mon Feb 15, 2021 10:09 am

But Sal will not have that plate, because she says she has a non overdrive gearbox!
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Re: Gearbox/overdrive question

#16 Post by wild bill » Mon Feb 15, 2021 6:33 pm

Emmmmmm Charles,
Sal could be a bloke...... :shock: :roll:
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Re: Gearbox/overdrive question

#17 Post by Sal » Mon Feb 15, 2021 6:37 pm

I am a bloke!

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Re: Gearbox/overdrive question

#18 Post by Sal » Mon Feb 15, 2021 6:41 pm

Thanks for all your help guys, I now know I have a none overdrive box, annoying but hey ho onwards and upwards.

On the left hand side of my box (if sitting in the car) there is a slot where I believe the speedo cable goes but nothing is there to attach it to! Is there a gear that attaches to the box that the speedo cable attaches to? What’s its name? And if anyone had a part number that would be great

As always.... many thanks in advance.

Sal (Mr)

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Re: Gearbox/overdrive question

#19 Post by johnnydog » Mon Feb 15, 2021 11:11 pm

Charles H wrote:
Mon Feb 15, 2021 10:09 am
But Sal will not have that plate, because she says she has a non overdrive gearbox!
Doh! You're right Charles! I must have got in a 'fog' with all the overdrive chat.... :roll:
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: Gearbox/overdrive question

#20 Post by Charles H » Tue Feb 16, 2021 10:11 am

Sal wrote:
Mon Feb 15, 2021 6:37 pm
I am a bloke!
Oops, sorry. :oops:
Charles Harrison
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Mallard Blue 2.5PI
Sapphire Blue GT6 Mk3
Vermillion Red Spitfire 1500
Pimento Red TR6
Inky Blue VW Passat B5.5
Arctic Blue Jaguar XJ40
Silver Range Rover Vogue SE

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