Shorten a bellhousing or get a tiny propshaft

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DaveEFI
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Re: Shorten a bellhousing or get a tiny propshaft

Post by DaveEFI »

The TC only really does any work below about 2000 rpm. And IIRC on the ZF gets locked out in top gear anyway. It would be doing its hardest work towing at low speeds in mud, etc. And is likely specced for that sort of thing. A Range Rover is a pretty heavy vehicle with a good towing capability. And that total weight is going to determine how strong the transmission needs to be.


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Re: Shorten a bellhousing or get a tiny propshaft

Post by ratwing »

You raise some good points, I know next to nothing about automatics and just assumed I'd need a big converter because of the big torquey engine but I see what you mean about it having to be designed to handle the extra work of towing, off-roading and so on - I won't be doing this so one of the smaller sizes should be perfectly adequate.
I've found maximum torque figures from 280 to 295 for the 4HP22, my engine was 290 when tested and I'm most likely well under even half the weight of a 4.6 Range Rover so it could well be that I really don't need all the stronger/bigger HP24 bits either.

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Re: Shorten a bellhousing or get a tiny propshaft

Post by paul c »

ratwing wrote:
Tue Sep 28, 2021 9:25 am


A nice idea but I'm pretty sure the Rotoflex PCD bolt pattern is too big to drill on my gearbox and diff flanges so will need adapter rings. I think this gearbox flange/adapter ring/rotoflex/splined joint/rotoflex/adapter ring/diff flange combo will be quite long.
Unless there's some way to have the input and output flanges on the same side so the splined section is inside the rotoflex?
Would you need a splined joint, if you cant make a flange to suit the rotoflex and have to use adaptors then could you just use a plate between the two rotoflex couplings? The couplings would still have a little give to allow for lateral movement of the engine/trans, which is probably minimal anyway.

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Re: Shorten a bellhousing or get a tiny propshaft

Post by ratwing »

My concern with a single rotoflex or two back-to-back is that if the gearbox and diff shafts aren't perfectly in line there'll be a constant sideways force which might affect bearing life. Also being a fixed length might be constantly putting a slight pull or push on the bearings with the same result.

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Re: Shorten a bellhousing or get a tiny propshaft

Post by ratwing »

I think I've solved the problem - the rear end is a complete Ford Granada irs assembly with the beam welded in place and if I take the differential out I can plate over the bolt holes and re-drill them further back.
Yes, this'll alter the angle of the driveshafts but only by around 3 degrees so that'll be ok.
Thanks for all the suggestions on getting round this but I think this is the simplest option (and cheap too!).

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Re: Shorten a bellhousing or get a tiny propshaft

Post by ChrisJC »

My 2p worth is that you don't need a 4HP24 on a trike. a 4HP22 was perfectly OK in Range Rover classics. The mechanically controlled one (i.e. pre P38) is simplest, it just works! And lasts for ever.

You could save a lot of distance (well, 100mm ish) if you got a bellhousing made up. I would fix the converter directly to the ring gear for shortest distance, and get the bellhousing made to suit. I have seen one fabricated in ally by cutting the middle out of a Range Rover bellhousing and TIG welding some plate into the gap! Alignment being key here!!

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Re: Shorten a bellhousing or get a tiny propshaft

Post by DaveEFI »

Looking at mine, I reckoned you'd not need a plate after cutting out the unwanted bit - just weld the two 'halves' together. But beyond my expertise to say how you'd keep them aligned.
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Re: Shorten a bellhousing or get a tiny propshaft

Post by paul c »

ratwing wrote:
Tue Sep 28, 2021 3:38 pm
You raise some good points, I know next to nothing about automatics and just assumed I'd need a big converter because of the big torquey engine but I see what you mean about it having to be designed to handle the extra work of towing, off-roading and so on - I won't be doing this so one of the smaller sizes should be perfectly adequate.
I've found maximum torque figures from 280 to 295 for the 4HP22, my engine was 290 when tested and I'm most likely well under even half the weight of a 4.6 Range Rover so it could well be that I really don't need all the stronger/bigger HP24 bits either.
4HP22 has been working for my 3.9l 110 for 12 years, and it was in a disco before that (1996 box) running a 1.2 transfer case till recently and towing max weight trailers all over. I am fitting an Ashcroft upgraded box with my new 4.6 and 1.3 transfer case as it was too slow on hills, it also runs on 32in tyres, yet was trouble free so I think should be okay for your trike.

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Re: Shorten a bellhousing or get a tiny propshaft

Post by paul c »

ratwing wrote:
Wed Sep 29, 2021 3:09 pm
I think I've solved the problem - the rear end is a complete Ford Granada irs assembly with the beam welded in place and if I take the differential out I can plate over the bolt holes and re-drill them further back.
Yes, this'll alter the angle of the driveshafts but only by around 3 degrees so that'll be ok.
Thanks for all the suggestions on getting round this but I think this is the simplest option (and cheap too!).
Can you not get a rotoflex flange for that diff? Lots of the Ford cars of that era had them.

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Re: Shorten a bellhousing or get a tiny propshaft

Post by ratwing »

Not knowing what I'm talking about regarding automatics meant I thought I'd need to use the uprated HP24 bits because the engine puts out more torque than the HP22 is rated to take but I'm realising there's a Iot more to it than that and what's being said here is making me reconsider.
These modifications are what everyone seems to think are worth doing but all the info I've come across is about cars and my gearbox won't be moving anything like the same weight around so a properly rebuilt to as-new standard spec HP22 could very likely be all I need.
Plus points for the HP22 are it'll be cheaper without all the HP24 bits and being just that little bit shorter means my original propshaft should fit too.
This is giving me a headache....

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Re: Shorten a bellhousing or get a tiny propshaft

Post by ChrisJC »

Yeah, if you can fit the 'box with completely standard parts (i.e. bellhousing, torque converter, flex plate, spacer, blah blah), and get away with the only custom part being a short propshaft, that sounds great to me!

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Re: Shorten a bellhousing or get a tiny propshaft

Post by ratwing »

Ok, I've eventually decided on a 4HP22 with a 4HP24 middle and 4HP22 front - being just that little bit shorter makes all the difference and can't see any downsides to having some stronger bits included when it's being rebuilt.
From what I can see, if these are overloaded and wearing out they start showing symptoms of failure, they don't suddenly pack up altogether or explode or anything dramatic like that so if it turns out I've made the wrong choice I'll get some warning.

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