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devnet H120
United Kingdom
81 Posts |
 Posted - 11 Jan 2013 : 21:48:46
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Happy New Year All,
I'm starting to put the old H120 Fastback back together and I am in need of a new H120 diff. If anyone has a spare and is willing to sell it to me it would be greatly appreciated.
Many Thanks
devnet H120 |
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1922
United Kingdom
549 Posts |
Posted - 13 Jan 2013 : 10:49:20
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Sorry, don't have one.
But remember that all the 3.89 diffs are the same, it's not special for the H120.
There were also fitted to Humber Sceptre saloon, fastback Alpine, Hunter estate cars, Hunter 1500. Probably any Hunter with a 1725 and an overdrive box will have one.
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devnet H120
United Kingdom
81 Posts |
Posted - 13 Jan 2013 : 12:10:29
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Thanks for the info, will help with my search!
devnet H120 |
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JPSH120
United Kingdom
1180 Posts |
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1922
United Kingdom
549 Posts |
Posted - 16 Jan 2013 : 09:10:23
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It has a drain plug so it's before 1975.
Can't see the rear wheel cylinders so can't tell if it's the early sliding cylinders or the later twin piston ones.
According to the '72 parts book - a GT with overdrive had a 3.89 and a GT without has a 3.7.
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devnet H120
United Kingdom
81 Posts |
Posted - 16 Jan 2013 : 20:19:52
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Thanks for that I am going to keep an eye on it.
How much does the diff rating matter in regards to overdrive? I.e. if it came off a car without an overdrive and I put it on one with...
devnet H120 |
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1922
United Kingdom
549 Posts |
Posted - 17 Jan 2013 : 11:33:48
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If you use a 3.7 it will make the revs 5% lower for any speed.
So your speedo will read 5% low but it will make the car a bit more relaxed at motorway speeds.
It means 5% more speed in first, second and third; so you will change up a little later.
Apart from the speedo I don't see any of this as a problem, if fact if my 3.89 diff was worn out I would consider replacing it with a 3.7 and getting the speedo recalibrated.
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JPSH120
United Kingdom
1180 Posts |
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devnet H120
United Kingdom
81 Posts |
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1922
United Kingdom
549 Posts |
Posted - 18 Jan 2013 : 10:21:55
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I've got a parts book for Series VI Rapier (closest I can get to a Gazelle VI) and compared the part numbers in '72 Hunter Range parts book.
The part number of 4.22 crown wheel and pinion for a Series VI Rapier is listed as 5220640 same as the fastback Rapier (there is no 3.89 listed for the Series Rapier).
The differential box (the bit the crown wheel bolts to) also has the same number, as does the front bearing.
The drive flange is a different number.
No numbers listed for the casing.
I would say that you can certainly use the internals of that unit and maybe the whole differential assembly.
Worth a try if you can get it cheap.
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JPSH120
United Kingdom
1180 Posts |
Posted - 18 Jan 2013 : 11:34:48
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Series VI Rapier??!!
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1922
United Kingdom
549 Posts |
Posted - 18 Jan 2013 : 12:18:58
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Hmmm - The Parts Book is "SUNBEAM RAPIER SERIES I-V" but the page (see plate ref AB24 near the top) clearly lists "VI".
Perhaps it should be "IV"?
There's no such thing as a series VI - doh.
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Edited by - 1922 on 18 Jan 2013 12:21:26 |
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JPSH120
United Kingdom
1180 Posts |
Posted - 18 Jan 2013 : 12:24:21
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I reckon it must be a typo, it should read IV
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arrocuda
United Kingdom
501 Posts |
Posted - 19 Jan 2013 : 09:23:18
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 Series VI = Fastback (Mk 1)!
Building the 'Mark II' fastback Rapier ('Arrocuda'). |
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JPSH120
United Kingdom
1180 Posts |
Posted - 25 Feb 2013 : 11:15:47
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quote:
Originally posted by 1922
Sorry, don't have one.
But remember that all the 3.89 diffs are the same, it's not special for the H120.
There were also fitted to Humber Sceptre saloon, fastback Alpine, Hunter estate cars, Hunter 1500. Probably any Hunter with a 1725 and an overdrive box will have one.
I was looking at the workshop manual over the weekend and the diff is listed as different on the H120 compared to the std rapier 3.89 v 4.22, unless I am reading it wrong??
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Edited by - JPSH120 on 25 Feb 2013 11:18:43 |
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1922
United Kingdom
549 Posts |
Posted - 26 Feb 2013 : 13:17:10
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Nooo - you are reading the manual correctly. The standard manual gearbox Rapier was always built with a 4.22 diff. It isn't one of the cars they fitted the 3.89 to.
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Topic |
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H120 Diff Needed
