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Honda DOHC V SOHC Gearbox
Posted: Tue Jan 25, 2011 11:58 pm
by rwd fan 2
I'm trying to find the ratio's for each gear on these two gearboxes also do they use a different diff ratio? is there a way of telling externally which gearbox is from which engine i.e dohc or sohc? any info appreciated.
Re: Honda DOHC V SOHC Gearbox
Posted: Wed Jan 26, 2011 8:12 pm
by 220 GSi turbo
From the official Rover repair manual (AKM 6987):
1.6 SOHC: gearbox code P7 (PP7A-S3)
1st: 3.250:1
2nd: 1.894:1
3rd: 1.259:1
4th: 0.937:1
5th: 0.771:1
Rev: 3.153:1.
Final drive (diff) ratio 4.437:1
19mph per 1000 rpm in top gear.
1.6 DOHC: gearbox code P7 (PP7A-M4)
1st: 3.250:1
2nd: 1.944:1
3rd: 1.345:1
4th: 1.033:1
5th: 0.848:1
Rev: 3.153:1.
Final drive (diff) ratio 4.250:1
18mph per 1000 rpm in top gear.
HTH!
Re: Honda DOHC V SOHC Gearbox
Posted: Wed Jan 26, 2011 10:16 pm
by rwd fan 2
Brilliant, thanks for that!!
Re: Honda DOHC V SOHC Gearbox
Posted: Thu Jan 27, 2011 12:17 am
by 416tourer
Hi, I would also like to know if there is a difference in the ratios with the Honda AUTO for the SOHC and DOHC engines.
Graeme
Re: Honda DOHC V SOHC Gearbox
Posted: Thu Jan 27, 2011 7:44 pm
by 220 GSi turbo
For AUTOMATIC gearboxes on the Honda engines:
1.6 SOHC: gearbox code P6 (PP6A-E4)
1st: 2.705:1
2nd: 1.560:1
3rd: 1.027:1
4th: 0.780:1
Rev: 1.954:1.
Final drive (diff) ratio 4.214:1
20mph per 1000 rpm in top gear.
1.6 DOHC: gearbox code P6 (PP6A-E5)
1st: 2.705:1
2nd: 1.560:1
3rd: 1.085:1
4th: 0.825:1
Rev: 1.954:1.
Final drive (diff) ratio 4.214:1
19mph per 1000 rpm in top gear.
Re: Honda DOHC V SOHC Gearbox
Posted: Sat Feb 26, 2011 8:39 am
by richard moss
It must be said that like most Rovers these are ridiculously under geared. Fifth should be at least 22mph/1000 rpm.
I fitted a diesel 420 box to my 820 Sterling and took fifth from 20mph/1000 to 26mph/1000 and it made longer runs much more civilised.
Re: Honda DOHC V SOHC Gearbox
Posted: Sat Feb 26, 2011 10:38 am
by GTiJohn
It's all down to torque....
The Honda 1600 engine, and most other Japanese engines, doesn't have much torque at all and the torque peak is higher up the rev range - this explains why you've got to rev the nuts off them to go anywhere fast. These engines will have a shorter stroke and larger diameter pistons to allow them to rev like this - this may be because of their motorcyle manufacturer background.
Putting a higher final drive in would up the gearing on all gears and generally slow the car down in terms of accelaration.
On the other hand there's the 'European approach' of long-stoke but low revving engine design which allows you to have much higher gearing. The long stoke generates more torque but isn't able to rev as much. The Rover M16/T16 engines are examples of this. Of course an extra 400cc helps but you feel the difference immediately you move from one of these to a Honda-engined car.
You pays you're money and you takes your choice - Honda engine for that second 'banzai' kick at 5500rpm or Rover for that elastic pull from 1500rpm