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SORN
by OldSkrote - 31/07/25 02:07 PM
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Joined: Nov 2018
Posts: 6,065 Likes: 163
Talk Morgan Sage
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OP
Talk Morgan Sage
Joined: Nov 2018
Posts: 6,065 Likes: 163 |
A post from Arwyn some time ago has had me pondering for a while, and considering I spend quite a lot of time bimbling around in 4th at 60mph, the thought of a 20% reduction in rpm is quite appealling. In real terms it would reduce revs from 3100 to 2600 and if I did want to boot it, 70mph could be had at 3000 revs rather than 3650 (based on a 5th gear ratio of 0.82)
On my recent hoilday (did 1000+ miles in the week) at times I was averaging 38mpg so a reduction in revs should stick her into the low 40s.
Anyone know anywhere/anyone that would be able to carry out a 5spd conversion? Rather avoid main stealers as their prices are ludicrous.
Although I probably have the ability to carry out the swap myself, I lack the space - not something I could do on my 4m front drive, especially as I'm not able to leave anything out overnight.
The other option would be changing the rear diff ratio. Anyone done this before?
As I said before, my driving style is pretty relaxed - not bothered by mad acceleration or breaking the national speed limit. I have bikes for that.
1972 4/4 4 seater, 1981 MGB GT 1984 Harley Davidson Electra Glide, 1990 Kawasaki ZX10
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Joined: Aug 2015
Posts: 1,578 Likes: 106
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: Aug 2015
Posts: 1,578 Likes: 106 |
Not sure you can readily change the rear diff ratio, not too sure theres an alternative.
I've sent you an PM as I've got a pretty comprehensive how to guide which I can send you.
Arwyn
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Joined: Nov 2018
Posts: 6,065 Likes: 163
Talk Morgan Sage
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Talk Morgan Sage
Joined: Nov 2018
Posts: 6,065 Likes: 163 |
Thanks Arwyn, Just need to find a tame mechanic to do the conversion 
1972 4/4 4 seater, 1981 MGB GT 1984 Harley Davidson Electra Glide, 1990 Kawasaki ZX10
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Joined: Apr 2014
Posts: 5,181 Likes: 2
Charter Member
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Charter Member
Joined: Apr 2014
Posts: 5,181 Likes: 2 |
Probably easier to go for a change to a ford five speed gear box.
.+8 Now gone for a 1800 4/4. Duratec in bright yellow.
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Joined: Feb 2010
Posts: 1,415
Has a lot to Say!
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Has a lot to Say!
Joined: Feb 2010
Posts: 1,415 |
Thanks Arwyn, Just need to find a tame mechanic to do the conversion  Have you considered us?
Simon @ Sifab.co.uk
Sifabtemporary@gmail.com
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Joined: Nov 2018
Posts: 6,065 Likes: 163
Talk Morgan Sage
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OP
Talk Morgan Sage
Joined: Nov 2018
Posts: 6,065 Likes: 163 |
Thanks Arwyn, Just need to find a tame mechanic to do the conversion  Have you considered us? I hadn't but have now  I know Rugby well, my other halfs family live there, and she works on Swift Valley. I'll drop you an email.
1972 4/4 4 seater, 1981 MGB GT 1984 Harley Davidson Electra Glide, 1990 Kawasaki ZX10
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Joined: Apr 2017
Posts: 1,799 Likes: 3
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: Apr 2017
Posts: 1,799 Likes: 3 |
Don't rule out the Mazda MX5 gearbox. Much better ratios than the Ford boxes and still in keeping with Morgan as the current 4/4's use this box.
Bob
2009 Black Roadster 1999 4/4 2 litre Zetec
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Joined: Nov 2018
Posts: 6,065 Likes: 163
Talk Morgan Sage
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OP
Talk Morgan Sage
Joined: Nov 2018
Posts: 6,065 Likes: 163 |
Don't rule out the Mazda MX5 gearbox. Much better ratios than the Ford boxes and still in keeping with Morgan as the current 4/4's use this box. Not sure how easy it would be to fit to a Ford Crossflow? The type 9 5spd conversion is quite commonplace (lots of lotus/westfields/locosts have done this) and as far as I've read doesn't require 'too much' fettling. Have you got any references to a Mazda/Crossflow union? Would be useful to see.
1972 4/4 4 seater, 1981 MGB GT 1984 Harley Davidson Electra Glide, 1990 Kawasaki ZX10
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Joined: Dec 2011
Posts: 374
Learner Plates Off!
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Learner Plates Off!
Joined: Dec 2011
Posts: 374 |
You are the happy owner of a car with the right gear ratios. Don't change. Modern cars have too hight gear ratios due to low emissions restriction, inducing lower accelerations. My 2005 PLUS 4 has quite the same 5th ratio than the last Porsche which wins Le Mans... but not with the same power. The theoretical maximun speed of my PLUS 4 with the Ford gearbox is 160 mph at maximun rev!!!
Last edited by CBY; 08/09/20 09:13 AM.
Regards 2005 PLUS 4
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Joined: Nov 2018
Posts: 6,065 Likes: 163
Talk Morgan Sage
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OP
Talk Morgan Sage
Joined: Nov 2018
Posts: 6,065 Likes: 163 |
You are the happy owner of a car with the right gear ratios. Don't change. Modern cars have too hight gear ratios due to low emissions restriction, inducing lower accelerations. My 2005 PLUS 4 has quite the same 5th ratio than the last Porsche which wins Le Mans... but not with the same power. The theoretical maximun speed of my PLUS 4 with the Ford gearbox is 160 mph at maximun rev!!! The Type 9 has identical gear ratios as the standard 4spd box for gears 1 to 4 (3.65:1, 1.97:1, 1.37:1 and 1:1). The additional 5 gear gives a ratio of 0.82:1 Thankfully, there's more than enough power to handle the lower ratio. Not looking to increase top speed, but will be less strain to bimble along at 60mph at 2600rpm, rather than 3100rpm.
1972 4/4 4 seater, 1981 MGB GT 1984 Harley Davidson Electra Glide, 1990 Kawasaki ZX10
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