MFactory Final Drive Kits in stock at Tuning Developments for GT86 and BRZ

[DanJ 374]

2 hours ago, knightryder said:

What I'd be interested in is seeing graphs of just the Harrop 4.1/4.44/4.67. The top graph suggests that 3rd-5th gear there is little in it between 4.1 and 4.67 but then the Cossie has a little extra torque at the top end based on the dyno plots.

As requested.....I've only added 1st and 2nd Gear for the 4.44 as the trend is obviously the same in all gears. I've also done a 4.1 vs 4.67 comparison for Stock NA with the same y-axis and a rescaled y-axis so we can't be accused of hijacking Mike's thread 

 

[Ade 517]

4 minutes ago, MikeB said: The issue is is not to be to wrapped in the figures it's how you want your car to perform and what you are using it for. It's the same when changing exhaust and air filter for the ecu map to match so you get the best from upgrades working together.

I have noticed in sport mode with auto (4.67) you are changing down a lot earlier than you might want to so its gaining in accelerating but losing out in braking. Which would be fine in tight track/road but keep in normal mode for longer less twisty track.

It will be interesting to see how performs on the first two sprints at Blyton.

Agreed, its all "horses for courses", I spent a lot of time playing about with my various spreadsheets before deciding that the 4.67 would be fine for how I use my car, but its definitely not a "no brainer" mod for everyone.

The two graphs are based on Abbey dyno plots for the Harrop and Cosworth with different final drive combos.

 

Mine will be about 10hp down on the full 2.3. Depending how good my engine is I could be similar to the Harrop. Cosworth has two engines which were 10hp different on their engine dyno.

[Keethos 842]

This maybe a silly question but would a remap be necessary or beneficial at all when you've changed final drive? I'm assuming not but I'm not sure weather timing for x y z could be adjusted etc for the shorter gear changes etc

[Kodename47 446]

3 hours ago, Keethos said:

This maybe a silly question but would a remap be necessary or beneficial at all when you've changed final drive? I'm assuming not but I'm not sure weather timing for x y z could be adjusted etc for the shorter gear changes etc

It's a silly question....

[Keethos 842]

Ok

[long-gone 152]

Silly or not, what's the answer?

[S18 RSG 429]

38 minutes ago, daidaiiro said:

Silly or not, what's the answer?

A remap is completely unnecessary. Changing the final drive physically changes the mechanics of the drivetrain. A higher final drive is, after all, in effect just a bigger cog which turns a bit quicker with less effort, but has the downside of lower potential top speed. Think of it in terms of a bike and it makes more sense. The larger cog makes acceleration easier, but you can only go so fast before your legs can't keep up. The smaller cogs are harder to turn, but allow you to go much faster top end. The engine, in this analogy, is the person. Changing the cog doesn't make the person fitter, or faster, just means their effort produces different results. Tuning the engine (going to the gym) means the engine can go faster, but has no bearing on the drivetrain.

In simple terms, the engine tune has basically no bearing on the performance of that part, and does no more to the car than it would do with a stock FD.

[DanJ 374]

Only thing that requires an edit ECU wise are the gear speed thresholds. These are used so the dash gear indicator is correct and other engine speed vs wheel speed calculations you may have.

[Kodename47 446]

2 hours ago, DanJ said:

Only thing that requires an edit ECU wise are the gear speed thresholds. These are used so the dash gear indicator is correct and other engine speed vs wheel speed calculations you may have.

 

AFAIK it's only the gear indicator that's affected as wheel speed is not determined via gearbox.

[smudge 1020]

5 hours ago, knightryder said:

AFAIK it's only the gear indicator that's affected as wheel speed is not determined via gearbox.

Speedo is done from ABS sensor

Gearbox has 2 connections on it. 1 for reverse switch and I assume the 2nd is for the gear change indicator on the dash?

[Kodename47 446]

8 hours ago, smudge said:

Speedo is done from ABS sensor

Gearbox has 2 connections on it. 1 for reverse switch and I assume the 2nd is for the gear change indicator on the dash?

Displayed speed is done by the rear wheels, averaged I would expect.

Guys in the states have said that the dash display indicator is thrown off by a change in FD, however I'm not sure if there is a sensor on the box too. Realistically it's not going to make a huge difference to a manual car as there aren't any important gear calculations on a standard calibration. ECUtek logs gear parameters so I guess if I change the ratios in the table I would be able to tell....

 

Edit - Had a look at the Gear Threshold table. I think this is for AT only, can an auto guy confirm?

Table is km/h per 1k RPM

		MPH @7000
1	10.77	47
2	16.25	71
3	21.65	94
4	26.81	117
5/6.	33.86	147

[alucardo 55]

Interesting thread. I had a shorter gear ration in the my old dc5 which made a big difference in the car although it messed up a few corners at Donnington. The new 2017 model has had its gear ratio adjusted does anyone know what that is? To compare with the 4.44 and 4.67 offering here.

[Foulsmell 120]

Interesting thread. I had a shorter gear ration in the my old dc5 which made a big difference in the car although it messed up a few corners at Donnington. The new 2017 model has had its gear ratio adjusted does anyone know what that is? To compare with the 4.44 and 4.67 offering here.

Don't know about the 2017 model but I've got the 4.67. It's a great mod. I wouldn't bother with the 4.44. It wouldn't be enough.

[Lauren 2259]

The EU models have not had any changes to the final drive. 

[KevinA 695]

I believe the 2017 is 4.3 from what I have read, sure somebody will confirm UK spec.

[Lauren 2259]

UK spec is as it was before, Kev. 

[Kodename47 446]

The new ones are 4.3 if they get the new FD.

The 4.4 FD would suit a manual well IMO, the 67 more so for autos.

[Lauren 2259]

The UK and Euro specs don't get the altered final drive. 

[Kodename47 446]

1 minute ago, Lauren said:

The UK and Euro specs don't get the altered final drive. 

You already said that..... And it's correct. My above statement is true however.

[Foulsmell 120]

The new ones are 4.3 if they get the new FD.

The 4.4 FD would suit a manual well IMO, the 67 more so for autos.

Mine is a manual with 4.67. I don't think you'd notice the 4.44 enough to warrant the cost.

[Lauren 2259]

Yes, okay. But it reads as if you're questioning whether the UK spec has the new final drive that is applied to other markets. I know I'm correct. 

I get what you're saying now. I was quite close to banging my head against a wall! 

I only repeated myself because Kev didn't listen. 

 

[Kodename47 446]

1 minute ago, Lauren said:

Yes, okay. But it reads as if you're questioning whether the UK spec has the new final drive that is applied to other markets. I know I'm correct. 

The autos get different specs to the manual cars in all other markets, in fact the Euro spec manual is the same as the autos everywhere else. So it's only select markets that get the changed gearing.

[Rich 378]

Time for a thread bump!

I'm considering final drives for my next year upgrade plans. Still not 100% sure on which (if any), So I knocked up some numbers based on @DanJ's spreadsheet above. The graphs show tractive effort vs speed for three different final drives on a stock MT car, where you shift at redline.

Some interesting things are evident. One is that a stock FD is much quicker 50-60 than a 4.67. The later upshift really helps out there. In fact there's a lot more ranges of speed where the stock FD is better than I'd anticipated. I was thinking 4.67 was the way to go, but I'm thinking 4.44 might be a better bet now.

[Varelco 211]

Can you stick 4.56 on there? I'm thinking about getting the Weir Performance FD although its only obtainable from the states its half the price of the Mfactory.

[Rich 378]

33 minutes ago, Varelco said:

Can you stick 4.56 on there? I'm thinking about getting the Weir Performance FD although its only obtainable from the states its half the price of the Mfactory.

I did have it on as well but it got a bit busy. It's between the red and green lines.

EDIT: Here's stock vs 4.55: