Objective: Consider fitting a ST180 6 speed box in my Sylva J15

I have attached the gearbox ratios/speed comparison charts.


Puma ratios
ST180 ratios


In summary I can have been offered a brand new ST180 box at a cost (good deal).

Pro's vs cons

Pro
* It is a more modern more efficient box
* Sequential shifter arrangement (this could be worth a lot)
* 70K miles less wear
* 2nd and third ratios are marginally better

Con's
* 1st gear is a bit low topping out at 32mph (existing 1st 38mph)
* Lot of cost and effort
* Uncertainty re gear change linkage, cable drives could be horribly long.
Consider inversion problem in gear stick?
* Would have to drive a Fiesta with that box and tuned engine similar to
mine to consider advantages.

1.7 Puma:

1) 3.15
2) 1.93
3) 1.41
4) 1.11
5) 0.88
final 3.82

Standard Six-speed manual fiesta st180

1) 3.727
2) 2.098
3) 1.357
4) 1.030
5) 0.821
6) 0.690
final 3.82

Comments welcome

Looking at the ratios unless you do lots of high speed cruising it wouldn't be worth it.

Puma ratios are the best IMHO - 5th is a bit low for cruising and can be swapped for the .76 in standard Fiesta box (easiest one to change as 5th sits on top)

The Puma box looks better overall
The 6 speed is to wide similar to an MT75 but with a very very long 6th

The idea is to get the longest 1st you can get and run a lower diff that way you get great acceleration and can hang on to first longer
2nd needs to be 1.8 or less
1.2 for 3rd
4th usually 1:1
The closer 5th is to 4th the better for the track
Longer 5th better for long road runs
Other factors are engine torque, more torque the higher gears you can pull effectively
Engine max revs, if you can hang on to the revs longer you are effectivly making the gearbox feel closer

The Puma was ST160 not ST180, I've never heard of an ST180.

ST180 is the box they fit with the Ecoboost version of the Sigma engine in a Fiesta ST. It has a sequential type shift I believe cable driven. However as pointed out on this forum the ratios of the Puma 1.7 box are better. I guess the issue is weather the better shift is worth the effort as I already have the better ratios. I have more or less concluded NOT thanks again to the comments made in this forum.

One of the main reasons i swapped my 1.4 zetec to a 1.7 puma was for the puma gearbox
It has proven to be a great swap, love the gears from the puma, and extra power

quote:

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Originally posted by monkeyarms
One of the main reasons i swapped my 1.4 zetec to a 1.7 puma was for the puma gearbox
It has proven to be a great swap, love the gears from the puma, and extra power

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I was under the impression that the Ecoboost engines use the IB6 box as standard, which is cable operated in a conventional manner as this is what we have in our Riot demo car. These engines are really all about torque hence the long ratio's, our 1.6 kicks out 300nm, enough to eat up an IB5 very quickly.
If the box you mention is different, I would like to know more as it would probably be an easier install, tho we have already sorted the IB6. The only problem with a our conventional 6 speed version was the gear lever end, which requires an area a little wider than the tunnel offers. This is part of the reason why we are using a GRP tunnel cover.
Quafie manufacture a fwd sequential box based around the IB5 and allows for the selector cable to exit forwards of the box, maybe a bit pricey, but an easy swap and also removes the rather vulnerable rod change of course. We are looking at this as an option on our Zetec powered Riots.

id stick with the puma box and wait for the 6 speed to come up second hand in a breakers after you get used to the 5 speed

its nice to have low rpm motorway gear though