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

[Foulsmell 120]

I've got the 4.67 and I will guarantee it's quicker acceleration than stock over those speeds. 4.44 wouldn't be worth the cost.

[Tareim 343]

I've heard people say there is a whine to the new final drive, is it that noticeable?

[DanJ 374]

I've heard people say there is a whine to the new final drive, is it that noticeable?

Very noticable whine, while I still had a stock exhaust my car almost sounded like an electric vehicle! It's not offensive but might not be to some people's taste.

[Tareim 343]

37 minutes ago, DanJ said:

Very noticable whine, while I still had a stock exhaust my car almost sounded like an electric vehicle! It's not offensive but might not be to some people's taste.

did you have it when you where last at Curborough? as I don't remember hearing a whine

[DanJ 374]

37 minutes ago, DanJ said: Very noticable whine, while I still had a stock exhaust my car almost sounded like an electric vehicle! It's not offensive but might not be to some people's taste.

did you have it when you where last at Curborough? as I don't remember hearing a whine

Yes it was fitted then, it's more noticable when you're cruising around rather than flat chat.

[Foulsmell 120]

I've heard people say there is a whine to the new final drive, is it that noticeable?

Yes it is noticeable. It's only at light revs on the pedal. The better the fit the less the whine but you can never get rid of it. It's due to the square cut tips instead of rounded ones.

I've got to like it now. Yes it sounds sort of electric. Any other noise like your music though will easily disguise it.

[Mike@TD.co.uk 467]

4.44 & 4.67 Final Drive kits in stock for next day delivery or installation in house  

 

Thanks

 

Mike

[Rich 378]

On 12/22/2016 at 7:10 PM, Foulsmell said:

I've got the 4.67 and I will guarantee it's quicker acceleration than stock over those speeds. 4.44 wouldn't be worth the cost.

I was interested in this, so I did a few calculations of acceleration over various speed ranges for the different final drives. There are a couple of simplifying assumptons: no wheel slip, all tractive effort is used to accelerate the car, car mass of 1240 kg, shift times are 0.5s.

There's a lot less in it than I expected, across a variety of acceleration scenarios. Something I didn't graph that's interesting is that the fastest setup for a 40-80 pull is 4.1 final drive as you can do it in third. It;s very slightly faster than a 5.1 FD in fourth over those speeds.

[DanJ 374]

It would be interesting to see what its like with 250ms and 1s shift times as well.

I assume you did that with torque at the wheels from a rolling road printout? Have you got longitudinal load transfer in the model or just aero and rolling resistance?

[Rich 378]

3 hours ago, DanJ said:

It would be interesting to see what its like with 250ms and 1s shift times as well.

I assume you did that with torque at the wheels from a rolling road printout? Have you got longitudinal load transfer in the model or just aero and rolling resistance?

Nope, much simpler than that, just F=ma on the tractive effort. The numbers are very optimistic relative to actual performance, but they should be comparable (all drives have equal rolling / aero resistance so it doesn't matter if they are factored).

I'm using stock torque figures, I have considered plugging in some dyno numbers, but that makes it much more car specific. I may give my car's numbers a try though.

Shift times make fairly minimal differences - there's only a few instances where there is an additional shift with one FD vs another (10-30 with 5.1 is an obvious one, as is 30-60).

[Rich 378]

New graph! This one has a comparison of 0.25s shifts vs 1s shifts. Also it's using dyno numbers from my car. Nothing too surprising, the main thing is that shifts costs you way more than a FFD saves, so if you're introducing a shift, it's going to be worse than otherwise. This tends to favour longer ratios as you have to shift less often.

So for instance 50-80 is much quicker with a 4.1 FD as you can hit 80 in 3rd; with the other options you have to upshift in the 70s.

30-60 is interesting as there's a shift for all FDs (except 5.1) but it shows the advantage of staying in lower gear longer.

[Foulsmell 120]

All credit to you for the graphs. Very interesting.

 

In the real world that has corners in it the extra torque is of more advantage when exiting and the timing of gear changes has more significance.

 

For track use there is a harder decision to make.

 

For road it's easier. It's faster.

[KevinA 695]

You need to drive both in road and track conditions, I have done this and decided to go back to 4.67 on my car as I like the balance of torque and urgency that it gives. And as I do limited motorway work it was my choice, horses for courses they say.

[Lauren 2259]

I tried Kev's car with the shorter final drive just on the road only for ten minutes. It made me think it wasn't worth it. I like doing Euro trips in my car, so high speed cruising is important, plus I do travel around a bit. I didn't think it offered enough to make me want to change it for the track as I sprint of course. So whilst I may lose out there, I didn't really like the shortened 1st and 2nd gear. The advantage of the shorter final drive seemed to decrease the faster you were going, though I didn't really get beyond the limits of third I admit. 

[Rich 378]

Something that's not obvious from my graphs above is that it's very dependent on shift point and speeds. The numbers above are somewhat of a best case for longer FDs as I had it setup with redline (7400 rpm) shifts and always using the highest gear possible. In the real world you wouldn't downshift to 1st at 30 with a 4.1 FD, so the 30-X numbers are a little misleading.

This graph is a better representation - the shift points are 5k RPM 1st-2nd and 7k RPM for 2nd-3rd, 7.2k for 3rd-4th and 4th-5th, 7.3k for 5th-6th. Shift times are 0.5s and 0s (to illustrate how much difference is in the gearing rather than shift times).

Results are a bit more as you'd expect - at lower speeds the increased torque at the wheels tends to favour the higher ratios, though 5.1 is somewhat hampered by needing to shift all the time. At high speeds, 4.1 is better as you're able to sit in 4th up to 120 mph, whereas all other FDs are in fifth.

The early few numbers are intended to be typical overtaking scenarios - sitting at 25-35 in 2nd and accelerating up to NSL speeds (ish). The shorter drives are definitely better here, though the ability of the 4.1 to hit 75+ in third helps for the faster 45-75 sprint.

60-100 and 60-120 are interesting track figures as they're fairly typical of coming off a third gear corner and accelerating down a straight.

 

Overall I think 4.556 is the best compromise choice for me, pity the Cusco one is so overpriced compared to MFactory.

[Kodename47 446]

I might be tempted by a 3.9 in the long run, found in certain Lexus' so even cheaper if you can get them used. Not sure if we can find the LSD version but if so you don't even need to have the cost of pulling the diff apart.

[MikeB 79]

4.67 transforms the auto into a more usable car and one of the best mods you can do to it. I can't comment on how it effects a manual.

[Foulsmell 120]

Something that's not obvious from my graphs above is that it's very dependent on shift point and speeds. The numbers above are somewhat of a best case for longer FDs as I had it setup with redline (7400 rpm) shifts and always using the highest gear possible. In the real world you wouldn't downshift to 1st at 30 with a 4.1 FD, so the 30-X numbers are a little misleading.

This graph is a better representation - the shift points are 5k RPM 1st-2nd and 7k RPM for 2nd-3rd, 7.2k for 3rd-4th and 4th-5th, 7.3k for 5th-6th. Shift times are 0.5s and 0s (to illustrate how much difference is in the gearing rather than shift times).

Results are a bit more as you'd expect - at lower speeds the increased torque at the wheels tends to favour the higher ratios, though 5.1 is somewhat hampered by needing to shift all the time. At high speeds, 4.1 is better as you're able to sit in 4th up to 120 mph, whereas all other FDs are in fifth.

The early few numbers are intended to be typical overtaking scenarios - sitting at 25-35 in 2nd and accelerating up to NSL speeds (ish). The shorter drives are definitely better here, though the ability of the 4.1 to hit 75+ in third helps for the faster 45-75 sprint.

60-100 and 60-120 are interesting track figures as they're fairly typical of coming off a third gear corner and accelerating down a straight.

 

Overall I think 4.556 is the best compromise choice for me, pity the Cusco one is so overpriced compared to MFactory.

 

Just go for the 4.67. There is only around 2% difference in performance and as you say a lot cheaper.

[Rich 378]

12 hours ago, Foulsmell said:

Just go for the 4.67. There is only around 2% difference in performance and as you say a lot cheaper.

I may well do. I think I need to hear one to see how annoying the whine is to me. The 4.556 being OEM is going to be quieter.

[Foulsmell 120]

12 hours ago, Foulsmell said: Just go for the 4.67. There is only around 2% difference in performance and as you say a lot cheaper.

I may well do. I think I need to hear one to see how annoying the whine is to me. The 4.556 being OEM is going to be quieter.

 

Yep best to try one out first. It's not that noticeable when you have an aftermarket exhaust and it's only at light rev increases.

[Varelco 211]

Get the Weir performance 4.56 drive. Sourced from the US but it's cheap and they don't whine like the Mfactory. 

[Foulsmell 120]

 

Get the Weir performance 4.56 drive. Sourced from the US but it's cheap and they don't whine like the Mfactory. 

 

 

 

 

Yeah not bad at around £190 but then there is shipping and import tax. And the aftercare will be none existent.

 

[Paul 442]

52 minutes ago, Foulsmell said:

Yeah not bad at around £190 but then there is shipping and import tax. And the aftercare will be none existent.

After the 1320 mess I'm not sourcing parts from the US unless it's through an official distributor in the UK. Was left well and truly out to dry on that.

[Foulsmell 120]

What other mods do you have Paul?

[Paul 442]

1 hour ago, Foulsmell said:

What other mods do you have Paul?

Perrin cold air intake and intake hose, remap, UEL manifold, Berk HFC pipe, Invidia Q300 catback.

I assuming you only wanted the performance bits otherwise that list goes on for a while.