2000 Estate - 4.1 Diff

Clutch, Gearbox, Overdrive, Propshaft, Differential, Drive Shafts, Hubs.
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vaultsman
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2000 Estate - 4.1 Diff

#1 Post by vaultsman » Sun Jul 22, 2018 5:15 pm

Hi,

New to the forum and, indeed, Triumph ownership.

Bought a '72 Mk II 2000 Estate manual with J-Type O/D recently and, from counting the turns, the fitted differential is a 3.45 which I believe to be from a 2500. The 3.45 is borne out by the fact that, having fitted a new cable to the inoperative speedo, the instrument is under-reading by around 18%. Currently on 14" wheels with 185/70 tyres - so fairly close to the original rolling radius.

Am I right in thinking the original diff would have been a 4.1? If I go down the road of reverting to this, is the engine likely to be a bit busy at motorway speeds?


Stan
1972 Mk 2 2000 Estate in Honeysuckle
1966 Jaguar 3.8 S-Type - Manual with Overdrive
1973 Rover 3500S P6B - now 3.9 litre and 5-speed
1978 Maxi 1750

harvey
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Re: 2000 Estate - 4.1 Diff

#2 Post by harvey » Sun Jul 22, 2018 5:32 pm

So, what have you sold then, or have you increased the size of your fleet? :D
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.

vaultsman
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Re: 2000 Estate - 4.1 Diff

#3 Post by vaultsman » Sun Jul 22, 2018 5:34 pm

Yes, I knew you were on here, H. :)

Nothing sold, P6B now upengined to 3.9, S-Type still here, Maxi being loved by my daughter - supposedly on loan.
1972 Mk 2 2000 Estate in Honeysuckle
1966 Jaguar 3.8 S-Type - Manual with Overdrive
1973 Rover 3500S P6B - now 3.9 litre and 5-speed
1978 Maxi 1750

harvey
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Re: 2000 Estate - 4.1 Diff

#4 Post by harvey » Sun Jul 22, 2018 5:41 pm

I am Omnipresent. :lol:

Good to hear the Rover and jag are still on the fleet. I must have missed the aquisition of the Maxi. (Or forgotten about it).
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.

harvey
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Re: 2000 Estate - 4.1 Diff

#5 Post by harvey » Sun Jul 22, 2018 8:33 pm

Back to the original question, I have a 1972 databook, and it is in line with everything you have said.
Personally I would keep the higher 3.45 diff, the car will easily pull the higher first gear, and although the accelleration will be marginally slower, I would prefer the more relaxed high speed cruising.
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.

vaultsman
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Re: 2000 Estate - 4.1 Diff

#6 Post by vaultsman » Sun Jul 22, 2018 9:00 pm

Thanks Harvey,

I've done a bit more digging. Seems all Mk I 2000's, and Mk II 2000's up to 1975 were 4.11 for manuals and 3.7 for autos. From the 1975 MY, manuals were changed to 3.7 in line with autos.

All 2500's were 3.45.

I'll have to pull the existing diff soon anyway as there's a slight oil leak at the nose piece.....I'll have a think about it again then. The O/D's not pulling in at the moment, but I'm pretty sure that's electrical. Once I get that sorted it would bring the 4.11 down to around 3.28 overall, so the swap back to spec might be worth doing.

Can't argue with your line of thought though.

Cheers,
Stan
1972 Mk 2 2000 Estate in Honeysuckle
1966 Jaguar 3.8 S-Type - Manual with Overdrive
1973 Rover 3500S P6B - now 3.9 litre and 5-speed
1978 Maxi 1750

Mike Stevens
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Re: 2000 Estate - 4.1 Diff

#7 Post by Mike Stevens » Mon Aug 06, 2018 11:05 am

Hi vaultsman,

You are correct about the diff ratios. If you did keep the 3.45, you could change the speedo for a 3.45 (2.5/2500) type. This should have 840 on the speedo dial face (somewhere near the bottom). The 2000 one should have 1000. This is the turn per mile figure for the speedo cable input.

You can also change the speedo pinion in the 'J' type overdrive to get a slightly different ratio there too.

Good luck!

Cheers,
Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)

johnnydog
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Re: 2000 Estate - 4.1 Diff

#8 Post by johnnydog » Mon Aug 06, 2018 10:18 pm

A friend of mine has a 1972 2000 manual with overdrive. Due to an issue with the original diff, he replaced it with a 3.45 from a 2.5. He found that motorway cruising was more relaxed due to the higher overall gearing, but he found that it struggled with motorway inclines without changing down into straight 4th, and was lethargic at lower revs. As the car was mainly used on urban driving rather than motorways, he ended up replacing the 3.45 diff with a the correct 4.11, and states that the car is now much more pleasant to drive.
I have a 1970 2000 with a non overdrive box, which does seem to rev a little at motorway speeds, but with the 25% reduction available with an 'A' type box, it would improve motorway driving, but as the car is virtually original, I will be keeping it as non overdrive.
I personally would keep it with the correct diff and have a bit more flexibility at lower speeds, rather than have lower revs at cruising speeds.
Register Member no. 1596

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

vaultsman
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Re: 2000 Estate - 4.1 Diff

#9 Post by vaultsman » Thu Aug 09, 2018 9:34 am

Thanks, Mike & johnnydog.

The existing 3.45 diff will have to come out at some point as there's a slight leak from the nose oil seal. I'll decide which way to go then. I also need to get the O/D working before then (electrical, I believe). Maybe end up spinning a coin!

I've got a rebuilt 3.45 unit, and also a very good 4.11 to choose from but the job will have to wait a while, as I'm now rebuilding the front suspension on the Jag.

Thanks again,
Stan
1972 Mk 2 2000 Estate in Honeysuckle
1966 Jaguar 3.8 S-Type - Manual with Overdrive
1973 Rover 3500S P6B - now 3.9 litre and 5-speed
1978 Maxi 1750

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