Discussion
E-bmw said:
Two questions:
1. I suspect those that know about these things will want just a bit more info than that to give meaningful advice.
Not really. Everything required for some basic advice is in there. 1. I suspect those that know about these things will want just a bit more info than that to give meaningful advice.
ST170 is basically a Zetec even though it says Duratec on the beauty cover. As such any Type 9 bell housing will fit giving you a huge range of possibilities for gearbox. As it's likely going in a 7 alike you can use anything from a boggo type 9 Sierra box to a posh ally bell housing with some sort of sequential Quaife/Elite/Hewland behind it.
If going the Sierra box route you can use an 1800 Mondeo/Zetec flywheel and redrill it to take the 2 litre Sierra clutch. You can use the standard 1800 clutch with a CCT133 release bearing but it's a touch marginal on sticky tyres.
Type 9 is the most common fitment but make sure it’s the right type as there were diesel & P100 versions with tragic gear ratios.
If you google Type 9 gearbox types and look at the input shaft variants it’s a good start, popping the top off and counting teeth also gives you a clue.
The V6 variant gives the best ratios but the input shaft is to long and the bellhousing doesn’t fit inline Ford engines however a simple 30mm spacer between an inline bellhousing and box will correct this.
The MT75 is a stronger bigger box with all ally case but has gear ratios suited to a longer diff.
It’s at this point you should download a gear speed spreadsheet which will allow you to play with all the things that affect speed and acceleration.
Gear ratios, diff ratio, wheel & tyre combinations and what is often overlooked your engine rev limit as a higher reving engine can mask a gap between gears to some extent.
You can get Type 9 gear kits or have a box built with closer ratios but for the most part a Type 9 for the road just needs a longer 1st gear
If you google Type 9 gearbox types and look at the input shaft variants it’s a good start, popping the top off and counting teeth also gives you a clue.
The V6 variant gives the best ratios but the input shaft is to long and the bellhousing doesn’t fit inline Ford engines however a simple 30mm spacer between an inline bellhousing and box will correct this.
The MT75 is a stronger bigger box with all ally case but has gear ratios suited to a longer diff.
It’s at this point you should download a gear speed spreadsheet which will allow you to play with all the things that affect speed and acceleration.
Gear ratios, diff ratio, wheel & tyre combinations and what is often overlooked your engine rev limit as a higher reving engine can mask a gap between gears to some extent.
You can get Type 9 gear kits or have a box built with closer ratios but for the most part a Type 9 for the road just needs a longer 1st gear
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