Gearing mk 10/420g
#1
Gearing mk 10/420g
I have a 40,000 mileage 420G with the BW 3 speed auto box. I just want to get an idea of what sort of speeds should produce what revs as the car has a really high rev at motorway speeds.
As I pull away and accelerate, it feels that I get two gear changes, one around 10mph then another at 20-25mph then that is it. As a result, the car is doing approximately 4500 revs for 65mph - which is almost red lining and I'm sure is completely wrong.
The car has had some changes over the years (No major changes under my watch, except electronic ignition) and I don't know if the rear diff may have been changed? I'm not a great technical man, so any suggestions may have to be explained with kid gloves, but I chatted to a Bentley owner the other day who also had the 3 speed and he said he cruised at 70mph with 1800 revs, (I appreciate different engines/torque) but it seems a much more appropriate level!
Someone has suggested that it may not be moving up into third gear - but I do feel two changes - should there be three changes?
Any suggestions would be gratefully received!
As I pull away and accelerate, it feels that I get two gear changes, one around 10mph then another at 20-25mph then that is it. As a result, the car is doing approximately 4500 revs for 65mph - which is almost red lining and I'm sure is completely wrong.
The car has had some changes over the years (No major changes under my watch, except electronic ignition) and I don't know if the rear diff may have been changed? I'm not a great technical man, so any suggestions may have to be explained with kid gloves, but I chatted to a Bentley owner the other day who also had the 3 speed and he said he cruised at 70mph with 1800 revs, (I appreciate different engines/torque) but it seems a much more appropriate level!
Someone has suggested that it may not be moving up into third gear - but I do feel two changes - should there be three changes?
Any suggestions would be gratefully received!
#2
#3
#5
BW8 shift info
From the Mark X manual:
In D1: Upshift from 1st to 2nd at 6-7, 2nd to 3rd at 10-12. Starting in D2, shift into 3rd at 10-12. These are both for minimum acceleration.
The BW8 has a 3.54:1 rear axle ratio. The manual shows 2780 rpm at 60 and 3241 at 70mph. My Mark X tach shows 3200 at 68 mph.
Phil
In D1: Upshift from 1st to 2nd at 6-7, 2nd to 3rd at 10-12. Starting in D2, shift into 3rd at 10-12. These are both for minimum acceleration.
The BW8 has a 3.54:1 rear axle ratio. The manual shows 2780 rpm at 60 and 3241 at 70mph. My Mark X tach shows 3200 at 68 mph.
Phil
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WayneCountyBill
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04-03-2014 07:00 AM
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