Some ZF 4HP22 questions...

[auto660]

Hello everyone,

I've been doing some research on the ZF 4HP22/24 transmissions and information seems to be scarce on them. This forum seems to be one of the few places where people have actually been swapping and modifying them so i dared to register myself here without actually owning a V8... I'm just hoping some members here can help me out for a bit.

I'm currently driving a Volvo 240 with a turbo conversion for which i'm searching a nice automatic trans setup. This pointed me towards the ZF 4HP22 transmission that came in the later Volvo 740's and fits relatively easily in the 240, albeit with some minor mods. The 4HP22 isn't strong enough though from what i've read, especially the early full hydraulic boxes. But the bellhousing and tailhousing are said to be swappable between the different 4HP22/24 variations, which gives some room for mixing and matching of parts. The car is already running a MS3 ECU so it would be even greater if the trans could be controlled electronically via the Megasquirt trans control system.

TL;DR

So my question is... Can the Volvo 4HP22 bellhousing and tailhousing be swapped over to an electronically controlled 4HP24? The Volvo comes with an 11" torque converter, that should fit the 4HP24 right? This would make for a relatively cheap automatic transmission swap that's quite tough and controllable with the Megasquirt system.

[stevieturbo]

In this day and age, do the ZF8HP70, although it will require a transmission controller for the box itself.

It's becoming a very common swap these days for all manner of vehicles

[ChrisJC]

Yes, the bellhousing for a 4HP22 will fit the 4HP24.

I believe the only physical difference on the outside is a thicker pump plate on the 4HP24, which makes the whole unit a shade longer.

But everything else fits just fine.

Of course you'll need a controller for the 4HP24, although it might be possible to fit a mechanical 'brain' to it from the 4HP22.

The tailcones should interchange as well.

Chris.

[auto660]

In this day and age, do the ZF8HP70, although it will require a transmission controller for the box itself.

It's becoming a very common swap these days for all manner of vehicles

You're totally right there, that would be the right way to do it. I've been considering that option but it's just too expensive for me currently, i'm still doing all this on a student budget.

I made a rough estimation for the cost of an 8HP70 conversion, €2700 in total:
- 8HP70 trans: €1000
- Bellhousing adapter: €250
- Custom flexplate: €250
- Aftermarket TCU: €1200

The 4HP24 route would be a bit cheaper, €1300 in total:
- Volvo 4HP22 trans: €250
- 4HP24 trans: €450
- 4HP24 rebuild kit: €300
- MS3 GPIO TCU extension: €300

Because of the cost benefit i'm kinda tempted to try the 4HP transmission. The engine is making around 280HP/420NM currently with a wide powerband (260HP+ from 4800 till ~6700) and a small turbo, so it might not be affected too much by the wider gear spacing of the 4 speed i think.

Yes, the bellhousing for a 4HP22 will fit the 4HP24.

I believe the only physical difference on the outside is a thicker pump plate on the 4HP24, which makes the whole unit a shade longer.

But everything else fits just fine.

Of course you'll need a controller for the 4HP24, although it might be possible to fit a mechanical 'brain' to it from the 4HP22.

The tailcones should interchange as well.

Chris.

That sound great! I'm currently running an aftermarket Megasquirt3 ECU which can be extended with a relatively cheap trans controller box. Support for the 4HP24 trans was added recently, making it quite an attractive option. This should give full control over line pressure, shift points, converter lock-up and even adds support for manual shifting and flappy pedals.