Gearbox/overdrive question

Clutch, Gearbox, Overdrive, Propshaft, Differential, Drive Shafts, Hubs.
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Sal
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Gearbox/overdrive question

#1 Post by Sal » Sat Feb 06, 2021 7:03 pm

Hello there,

As some of you on here are aware I bought a 1973 2.5 PI as an unfinished project, loads of spares but loads of bits missing, unfinished or just not there at all so have been going through it when I have time and making good with a view to getting the engine running and then I’ll decide if i finish the project or flick it on.

I assumed it was an overdrive box because there were wires coming up through where the gearshift is but there was no gear knob so couldn’t tell. I now think it’s not as I was underneath a later triumph 2500 S today with an overdrive box and my box is totally different.

Question is: is my box original? did they produce a 1973 2.5 PI without a Overdrive box? Was it simply an optional extra?

Thoughts?

Cheers
Sal

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Re: Gearbox/overdrive question

#2 Post by johnnydog » Sat Feb 06, 2021 8:02 pm

A 1973 Mk2 PI had 3 options when new -
Manual (non overdrive), Manual with an 'A' type overdrive (22% reduction), and Borg Warner 35 automatic.
The chassis no. and V5 (registration document) should give you an indication what was in when new. The VIN plate shouldn't have been touched, even if the transmission type has changed, or PAS has been added over the years.
If a straight manual box, the chassis no. will end with the letters 'DL'
If originally overdrive, it will end with 'DLO'
If originally built as an auto but converted at some stage, the chassis no. should still end in 'DLBW'
If it was built with PAS, the chassis no. will have a 'P' at the end of any other configuration of letters.
The 'S' models were only fitted with 'J' type overdrive gearboxes usually with either 25% or 28% reduction. They physically look different which is probably causing the confusion.
Last edited by johnnydog on Sat Feb 06, 2021 8:08 pm, edited 2 times in total.
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1967 Mk1 2000 in Gunmetal Grey
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Re: Gearbox/overdrive question

#3 Post by Tinsmith_Skippy » Sat Feb 06, 2021 8:03 pm

My 71 car has a factory bank job getaway box.

Image

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Re: Gearbox/overdrive question

#4 Post by johnnydog » Sat Feb 06, 2021 8:10 pm

My 1972 PI has an identical non overdrive gearbox too..!
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Jonathan Lewis
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Re: Gearbox/overdrive question

#5 Post by Jonathan Lewis » Mon Feb 08, 2021 10:10 am

johnnydog wrote:
Sat Feb 06, 2021 8:02 pm
A 1973 Mk2 PI had 3 options when new -
Manual (non overdrive), Manual with an 'A' type overdrive (22% reduction), and Borg Warner 35 automatic.
The chassis no. and V5 (registration document) should give you an indication what was in when new. The VIN plate shouldn't have been touched, even if the transmission type has changed, or PAS has been added over the years.
A minor point, but I believe that that Triumph standardised the fitment of overdrive on manual PIs from late 1972, using the 25% version of the J-Type o/d. According to the factory manual, J-Types were fitted on PIs from c/n MG75604, which would seem to agree with a build date in the last quarter of 1972, but I must admit that I'm not sure whether standard fitment of o/d on PIs and the introduction of the J-Type 'box occurred from the very same car. Even so, I would guess that there were probably relatively few non-overdrive post-MG75000 PIs made, though I suppose it is possible that you could still get a straight manual transmission car to special order?

In any case, and as John quite rightly says, the chassis plate should provide the best indication of what was originally fitted by the factory.

In terms of identifying the three types of gearbox, the straight manual is as shown in the preceding photo, the A-Type overdrive is located in place of the extension housing under the gear lever turret and has a large circular brass plug on its lower surface, whilst the J-Type is located similarly but characterised by a ribbed rectangular sump on its bottom.

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Re: Gearbox/overdrive question

#6 Post by Sal » Tue Feb 09, 2021 7:14 pm

Right then..... sorry it took a while to come back...

So my gearbox looks just like the one in TinSmith_skippy’s post and below are my engine chassis numbers.

Engine: MG78314E BW
Drivers side strut plate numbers: BCSR 168528
Passengers side strut plate numbers: comm no. M682770 DLO

So was mine originally born with an overdrive box and I think I’m right that the box I have in it Is a non overdrive, correct?

Thanks in advance

Sal

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Re: Gearbox/overdrive question

#7 Post by Sal » Tue Feb 09, 2021 7:20 pm

Looking at Johnnydog’s post and his amazing plethora of knowledge mine was born with an overdrive box but now no longer has one, shame but that’s what you get when you buy a car in bits I guess!!

Like I’ve said before on here I’ll get the engine running properly and on the button and then I’ll make a decision on the rest.

Thanks fellas

Sal

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Re: Gearbox/overdrive question

#8 Post by johnnydog » Tue Feb 09, 2021 11:47 pm

Hi Sal,
The body numbers aren't much help to you really, as there are no known (so I believe) records of specific vehicles they related to.
It looks like the engine isn't the original from new - the BW at the end indicates it originally was mated to an auto box. That in itself isn't really an issue as they are exceptionally easy to convert from auto to manual and vice versa, and there is no difference to the engine itself - it was just 'bolt on' bits that differed between the two relative to the appropriate gearbox. It could be a good thing in some respects as it may have had an easier life than with a manual gearbox ? :) ?
Just as an aside, a friend of mine had a 2000 with an overdrive box, and swapped it for a non overdrive gearbox, to do away with the overdrive. My 1970 2000 and 1972 PI both have their original non overdrive gearboxes, and I'm leaving them as they are, as I don't have any problem with the standard non overdrive gearbox.
The parts book is a bit of a minefield and confuses things even more :roll: , but it only refers to the 'J' type as being fitted from a particular gearbox number rather than chassis number, but I think Jonathan is right with his period of change from 'A' type to 'J' type, although some cars will be registered well into 1973 with 'A' types.
The 1974 brochures confirms overdrive was standard on the (facelift) PI's - the 1972 brochure still lists overdrive as an option. Unfortunately, I haven't got a 1973 dated PI brochure....
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Re: Gearbox/overdrive question

#9 Post by Jonathan Lewis » Wed Feb 10, 2021 11:37 am

johnnydog wrote:
Tue Feb 09, 2021 11:47 pm
The parts book is a bit of a minefield and confuses things even more :roll: , but it only refers to the 'J' type as being fitted from a particular gearbox number rather than chassis number
That it does - not helped by quoting a changeover point for PIs against what is evidently a 2000 gearbox series... :? On a later sheet, however, it quotes the J-Type o/d as being applicable from gearbox numbers ME73261 and MG75604, which corresponds (exactly, in the case of the PI) with the chassis numbers quoted as changeover points in the J-Type overdrive section of the factory workshop manual (AKM3974). I am, therefore, inclined to believe that this was indeed where the change between A- and J-Types took place.

Regarding standardisation of o/d as a fitment, I have somewhere (though can't presently lay my hands on it :roll: ) a contemporary magazine feature (think it was a 'Buying Secondhand' or similar article) which I'm sure suggests that it accompanied the introduction of the revised 120bhp engine (twin balance pipes etc). That said, the production summary published in Six Appeal some years ago gives a date of October 1972 (sadly, without accompanying chassis number) for standardisation of o/d on PIs so, on the balance of probability, I suggest that this and the changeover from A- to J-Type o/d probably occurred at much the same time...

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Re: Gearbox/overdrive question

#10 Post by Dave B » Wed Feb 10, 2021 4:33 pm

Jonathan Lewis wrote:
Wed Feb 10, 2021 11:37 am
That said, the production summary published in Six Appeal some years ago gives a date of October 1972 (sadly, without accompanying chassis number) for standardisation of o/d on PIs so, on the balance of probability, I suggest that this and the changeover from A- to J-Type o/d probably occurred at much the same time...
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.
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