4HP22 for sale - would it be worth making a bid?

[chrisyork]

We were asked what Lock Up is on another thread, thought it might be helpfull here:

To put a bit of detail on that.

First thing to understand is that the body, or stator, of the torque convertor is bolted to the engine crankshaft and takes the place of the flywheel on a manual car. Inside the torque convertor is a rotor or turbine. This is connected to the gearbox in a normal automatic like the Borg Warner.

The gerarbox itself is just that. In a manual transmission there is a mainshaft and a layshft with different sets of helical gears connecting the two. Gears are changed by different sets of gears being released or locked to the two shafts. In an automatic gearbox the gears are epicyclic. A gear is engaged by locking the outer ring of the gear with a brake or band. Daimler used to produce manual gearboxes like this - they were known as pre-selector gearboxes. This type of gearbox is particularely suitable for an automatic because the gears can be merged into each other by slipping the brake bands on two adjacent gear sets until only one is engaged.

Back to the torque convertor. When drive is engaged, the convertor is filled with oil, and the churn between the stator and rotor transmits drive to the gearbox. But as with any churning motion in a fluid, heat is produced too and therefore the TQ wastes some of the energy - it slips.

In a torque convertor fitted with lock up there are two shafts entering the convertor instead of one. The normal one engaging with the rotor is still there, but there is a second saft, concentric with the first, that engages with the body or stator of the TQ. in normal drive the shaft engaging with the rotor transmits drive to the gearbox. When lock up is engaged the concentric outer shaft that is coupled to the stator or casing of the torque convertor is locked to the inner shaft by a clutch so that direct drive is established from the crankshaft, through the casing of the torqe convertor to the input shaft of the gearbox.

Simples!

Chris

 

[WarrenL]

I think you're right, Ron. Having slept on the matter, I've figured that even if it's pretty poked, it might at least provide the tailcone bits to apply to a RR box. Worth stashing in the garage until I'm ready to go further down the path of conversion.

As for the lock-up torque converter Chris, I was reading up on it in my trusty old Reader's Digest guide to cars. Great book that, lots of exquisitely drawn diagrams that help make the basics clear to a dummy. I used it to get to grips with how my SU carburettors worked when they were being overhauled.

**** UPDATE!!! ****

I've bought that box. Too cheap to pass up, even if it's poked.

 

[WarrenL]

You ought also to ask the seller for a better photo of the rear of the box and to sell you the prop shaft from the car to go with it if possible. Then you'll be able to merge the two prop shafts if necessary. Also make sure that the seller gives you the dipstick and tube - even if they are wrong for the Rover you need to have a datum point to depart from.

Do you know, in my hurry yesterday I forgot about all what you said there, and have no tube, no dipstick and no shaft. Duh! Not to worry, I'll give him a call and ask him if he has them. He was a very helpful guy. He's bound to be keen on a few extra dollars.

 

[testrider]

I hadn't clocked the Volvo use of these boxes before. So far I have spotted the following different tailshaft assemblies on cable control boxes - Volvo, BMW, Jaguar and LDV. Of these BMW and LDV have mechanical speedo drive outputs (I can't see one on the Volvo?)

The Volvo's all take speedo drive from an electronic sensor on the diff casing hence there not being anything obvious on the transmission casing. They have electronic dials on the dash even though they look like a conventional mechanical drive speedo.

 

[WarrenL]

That reminded me to reread Chris's post. The implication is that I have a mechanical speedo drive output on mine - I'm going to have to take a closer look. What am I looking for? Google has not been helpful this time around.