Q: BF with 6 sp Auto - Usable ratios? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

tonyk · 10-22-2005, 22:06

Theres a lot to be said for the new 6 speed 'box being fitted to the FPV range. (A pity it wasnt a 7 speed just to get that extra jump ahead).

A question for those who know how to calculate these things out though...

Two ratios in the box are overdrive. With the the rear end gearing and the available torque versus weight of the car are the ratios in the 'box usable in the real sense or is this a case of a 4 speed auto with a couple of overdrives.

The final drive is a 2.73 whereas the manual 6 speed has a ratio of 3.46.
This seems to render the final gear at least of the auto a bit impotent.

Jabba · 10-23-2005, 03:23

Why don't you wait until you drive one before make comments, I have spoken to someone who has driven the bf 6sp auto and the new is, It it will thump a ba with a decent set of diff gears of the line.

mattyc · 10-23-2005, 04:57

Quote:

Originally Posted by Jabba

Why don't you wait until you drive one before make comments, I have spoken to someone who has driven the bf 6sp auto and the new is, It it will thump a ba with a decent set of diff gears of the line.

Probably wont even need change in diff-ratio's to do that.

Its a far-cry smarter and faster than the BTR/ION 4 speed box of old, wouldnt be supprised if it pulls away at launch, mainains the gap between gears, then does it again between 1-2 shifts and so on - comparing two of the same model cars. ie. BA Turbo to BF Turbo, BA GT to BF GT.

In answer the the first quesiton about usable ratio's. Comparing the 4 speed to the 6, the first 2 gears probably have exactly the same final drive ratio anyway. And You'll find whilst in 'D' the torque converter stays unlocked so you basically can't tell the difference between it changing gears, so its going be totally irrelevant what the final 2 ratios are anyway.

bossxr8 · 10-23-2005, 05:04

They are all usable. First is quite low and every other gear after that is very closely matched to the next ratio.

xr220 · 10-23-2005, 06:15

1st gear is a launch gear which will help rectify the lack of bottom end torque on the boss.

Jabba · 10-23-2005, 12:55

Quote:

Originally Posted by mattyc

Probably wont even need change in diff-ratio's to do that.

Its a far-cry smarter and faster than the BTR/ION 4 speed box of old, wouldnt be supprised if it pulls away at launch, mainains the gap between gears, then does it again between 1-2 shifts and so on - comparing two of the same model cars. ie. BA Turbo to BF Turbo, BA GT to BF GT.

In answer the the first quesiton about usable ratio's. Comparing the 4 speed to the 6, the first 2 gears probably have exactly the same final drive ratio anyway. And You'll find whilst in 'D' the torque converter stays unlocked so you basically can't tell the difference between it changing gears, so its going be totally irrelevant what the final 2 ratios are anyway.

Your right, You don't need to change diff gears. The word I got was, in standard config and a set of sticky tyres, you should be looking a 1.6-1.7 60ft. How bloody good is that for a stocker.

mattyc · 10-23-2005, 17:55

Quote:

Originally Posted by Jabba

Your right, You don't need to change diff gears. The word I got was, in standard config and a set of sticky tyres, you should be looking a 1.6-1.7 60ft. How bloody good is that for a stocker.

Bloody awsome. I'm kicking myself I didnt wait for the 6 Speed AUTO.

Tornado · 10-23-2005, 22:38

If it has 18" wheels then the tire diameter is roughly 25" (18 + 3.54 + 3.54).
Tire diameter 25 (in.)
@ 6000RPM
F6 Manual with 3.73 Diff Ratio:
1st = 2.66 = 72kmh
2nd = 1.78 = 108kmh
3rd = 1.30 = 147kmh
4th = 1.00 = 191kmh
5th = 0.80 = 239kmh
6th = 0.63 = 304kmh
Rev = 2.90 = 66kmh
GT Manual with 3.46 Diff Ratio:
1st = 2.66 = 69kmh
2nd = 1.78 = 116kmh
3rd = 1.30 = 159kmh
4th = 1.00 = 206kmh
5th = 0.80 = 258kmh
6th = 0.63 = 328kmh
Rev = 2.90 = 71kmh

GT & F6 Auto with 2.73 Diff Ratio:
1st = 4.17 = 63kmh
2nd = 2.34 = 112kmh
3rd = 1.52 = 172kmh
4th = 1.14 = 229kmh
5th = 0.87 = 301kmh
6th = 0.69 = 379kmh
Rev = 3.40 = 77kmh

110kmh V’s RPM roughly
GT & F6 Auto with 2.73 Diff Ratio: = 1735 Rpm
GT Manual with 3.46 Diff Ratio: = 2010 Rpm
F6 Manual with 3.73 Diff Ratio: = 2165 Rpm

These are roughly and were done quickly so there maybe some errors so don’t hold me to them.
Go here if you want to check them yourself:
http://davewin.com/tech/gear_ratios.shtml

tonyk · 10-25-2005, 04:18

1 error... the manual 6 speed first gear at 2.66 and a rear end of 3.46 yeilds a 78km/h max speed at 6000rpm.

Quote:

Originally Posted by Jabba

Why don't you wait until you drive one before make comments, I have spoken to someone who has driven the bf 6sp auto and the new is, It it will thump a ba with a decent set of diff gears of the line.

I dont need to wait to drive one to make comments. The post was a question from a theory perspective.

As per the calculations (which is the question that I actually asked) that were given...

Quote:

110kmh V’s RPM roughly
GT & F6 Auto with 2.73 Diff Ratio: = 1735 Rpm

These numbers suggest 6th is pure cruise. 5th not far off cruise either. If overtaking was to be done rapidly at 110km/h you'd be looking at 4th to get a around a b-double quickly.

The first three gears dont suggest any substantial advantage over the manual either other than theoretical gear change speeds. Theres no calculation there that says how FAST the car gets to the speed just that its max speed is obviously clipped by the ratios. It could be said the auto will be heavily reliant on traction control in first gear.

Quote:

If it has 18" wheels then the tire diameter is roughly 25" (18 + 3.54 + 3.54).
Tire diameter 25 (in.)
@ 6000RPM
F6 Manual with 3.73 Diff Ratio:
1st = 2.66 = 72kmh
2nd = 1.78 = 108kmh
3rd = 1.30 = 147kmh
4th = 1.00 = 191kmh
5th = 0.80 = 239kmh
6th = 0.63 = 304kmh
Rev = 2.90 = 66kmh
GT Manual with 3.46 Diff Ratio:
1st = 2.66 = 69kmh
2nd = 1.78 = 116kmh
3rd = 1.30 = 159kmh
4th = 1.00 = 206kmh
5th = 0.80 = 258kmh
6th = 0.63 = 328kmh
Rev = 2.90 = 71kmh

GT & F6 Auto with 2.73 Diff Ratio:
1st = 4.17 = 63kmh
2nd = 2.34 = 112kmh
3rd = 1.52 = 172kmh
4th = 1.14 = 229kmh
5th = 0.87 = 301kmh
6th = 0.69 = 379kmh
Rev = 3.40 = 77kmh

110kmh V’s RPM roughly
GT & F6 Auto with 2.73 Diff Ratio: = 1735 Rpm
GT Manual with 3.46 Diff Ratio: = 2010 Rpm
F6 Manual with 3.73 Diff Ratio: = 2165 Rpm

Noboss · 10-26-2005, 13:09

I was very suprised at the 2.73 diff to. Its very high which would only slow the takeoff, I'll be driving an XR6T soon so i'll see for myself. A friend drove one the other day he was dissapointed in it..Time will tell...