Tech:Drivetrain/Bellhousing

Recently it has become much easier to source upgraded Bellhousings. Here are some of the common ones with information on how / where to obtain them if at all possible.

In a nutshell, people are finding more power from smaller Toyota engines, this extra power tends to break things, the next thing in line after your engine is your gearbox. Rather than buy six million gearboxes for every time you know you will break one, it may be wise to consider upgrading to a stronger Gearbox.

In Terms of strength in Toyotas, the more common boxes are (very generally) ordered here from Weak to Strong.

Weak

K40, K50 (used on K series engines)

T40, T50 (used on T and A series engines)

W50 (different to W5x - used behind R and M? series engines)

W55, W56, W57 (Used on Celicas and Supras)

W58 (Supra Turbo etc)

R154 (Turbo Supras / Soarers etc)

Strong

I found an article that compares the Toyota gearboxes which was apparently scanned from Street Commodores magazine originally and can be found [[1]]

Things to keep in mind / Disclaimer

• Bigger is NOT always better - putting an R154 behind a K series engine is hardly going to be affordable or worthwhile
• Flywheel & Starter - Remember also that you need to find out what flywheel and starter motor are best suited to use with the upgraded bellhousing.
• Tailshaft - If you upgrade your gearbox, chances are that you will need a stonger replacement tailshaft or possibly have yours modified / customised
• Diff / Axles / etc - Remember the weakest link of your drivetrain dictates how much power you can put to the ground. If you keep blowing up gearboxes, chances are that after you upgrade your diff is going to shatter with that big horsepower going through it, it might be time to think about upgrading that as well ;)
• Brakes - Ok well this isn't part of your driveline but I couldn't help but add something here about making your monster-engined-whatever STOP when you hit the brakes. This is something which is too-often overlooked and as far as I am concerned the thing most overlooked in engine conversions. Safety FIRST, not second!

K to T

Now that people are milking out 160 horsepower from the K series engines, it is clear that the K40 / K50 box is no longer up to the task. Fortunately for us, Toyota saved us the hassle and actually made a FACTORY K-To-T bellhousing. This was used in the KT140, KT141, KT142, KT147 series Coronas (as far as I know only in New Zealand) which came from the factory with a 5K-C hooked up to a T50 gearbox! This is quite a sensible package.

K-To-T is the perfect Upgrade for those who have lost faith in the strength of K series gearboxes. I myself have recently purchased one privately for $205 New Zealand Dollars / $184 Australian Dollars / $138 US Dollars from Trademe.co.nz which doesn't include shipping.

Availability : Second hand there are quite a few on the ground in New Zealand, and using Trademe.co.nz will be your best option at this stage. I have not yet heard of Aftermarket (brand new) manufactured K-To-T's but there would probably be someone out there who would have produced them by now if you searched hard enough.

K to W

This is starting to borderline overkill! A W55 gearbox is nearing 43kg alone, to go completely overkill I have heard that some aftermarket manufacturers made a K-engine-to-W5x bellhousing. As it is the W55 is rumoured to be able to withstand about 300 horsepower of punishment, a far cry from the best of 165+HP from a K series engine that I have seen proof of.

Availability :A late KR series townace van has the K-W bellhousing, these will bolt up to a W series box with only a change from cable to hydraulic clutch.

A to T

Standard equipment in rear wheel drive AE86s, AE71s etc. Bellhousing is removable. Not an upgrade as such, but worthwhile mentioning :)

A to W

Very common, probably available second hand all over the place but is available brand new in many places. You have to love aftermarket go-fast-bits and bolt-ons!

Perfect upgrade for anyone looking to put a stonger box behind a particularly rambunctious 4A-GE / 4A-GZE / 4A-GTE / 7AFE / 7AGE / 7AGTE etc etc. With claims of being able to handle upwards of 300 horsepower with ease, the W55 style gearbox is what you want.

Sources:

I am aware of a source in Malaysia that can supply these for approx AUS $~400 landed anywhere in Mainland Australia, but unsure if this offer is still being extended to anyone else.

S to T

came fitted to SA60 celica, possibly ST14# corona. also available aftermarket mostly used in kitcars like the fraser clubman.