4 speed automatic....

[djw113uk]

I have had a trawl through old threads, but can not see anything other than a suggestion to try this;

I have 2 1850 automatics - One the autobox died years ago, so is now manual o.d but still with auto ratio axle.
The second is Ken Chandler's old blue car - been garaged since it blew out a spark plug which must have been helicoiled at some time in its past.

The man o/d car really needs a diff swap, but it does cruise nicely at dual carriageway speeds. Ken's car was very nippy as an auto, but was not so comfortable at high speed.


On stag's people have adapted the 4HP22 auto box from old BMWs and Jaguars. My own Triumph 2000 runs a rover V8 and until I removed it this was connected to the diff via a 4 speed auto. They have a torque lockup converter so much reduced energy losses at high speeds, and the 4th gear is actually even taller than overdrive.

I guess the starting point would be an 1850 bell housing, then join this to the HP autobox? Has this been attempted by anyone else? perhaps it wont fit, or there is good reason why it has not been done. Did all dolomites have the BW35, or all have the BW65 gearbox, or is it like the 2000 range where early cars had 35 and later had 65? I believe the 65 has a removable bell housing, whereas the 35 does not?

I think the 1850 (or sprint) with modern type 4 speed auto, would be a lovely car. The benefit of auto around town, but with the quieter and economic cruising of o/d at motoray speeds?

[Carledo]

My Sprint is getting an Aisin/Warner 4 speed, 3 range autobox (Normal/winter/sports) courtesy of a 2001 Vauxhall Omega.
But i'm cheating and using the 147bhp 2.2 ltr Vauxhall engine to pull it!

AFAIK all Dolomite autos came with the BW65 3 speed autobox, even the 1500. It's much harder to mix-n-match autoboxes cos the position of the converter in the bellhousing is critical and much more precise than a manual.

Steve

[Toledo Man]

Steve's right. All Dolomites has the BW65. Most automatic Stags has the BW35 with the late ones getting the BW65. How about the ZF 4-speed auto? That could be a possible alternative...

[Jon Tilson]

The Jag XJ40 box is used in a lot of stag conversions.

Jonners

[djw113uk]

So, I should be able to remove my 1850 BW65 bell-housing, graft it onto the zf-4HP22 and then refit, with a few spacers and aligning issues sorted?

At least the tunnel doesn't become an issue on the dolomite!

Anyone got a 1850 auto box bell-housing that I can experiment with before I take the box out of my car? I have a BMW 320 torque converter on my ZF-4HP22. I need to make sure it fits into the bell housing!

[Jon Tilson]

Err good luck with that...

IIRC the bell housing and box on the BW65 is all one casting, or am I having a senior moment?

Jonners

[wiggybum]

So, I should be able to remove my 1850 BW65 bell-housing, graft it onto the zf-4HP22 and then refit, with a few spacers and aligning issues sorted?

At least the tunnel doesn't become an issue on the dolomite!

Anyone got a 1850 auto box bell-housing that I can experiment with before I take the box out of my car? I have a BMW 320 torque converter on my ZF-4HP22. I need to make sure it fits into the bell housing!

Just an idea (and I am anticipating the usual scoffing) but could you save a lot of hassle and fit one of these in place of the propshaft centre bearing:



http://www.odspares.com/phdi/p1.nsf/sup ... ent&part=4

they are popular with pre war cars where there isn't room in the gearbox tunnel. I haven't been out to look under my car to gauge how much room there is but I would guess this would be less hassle than changing the whole box over - eliminating the torque converter swap (unlike a clutch, they are supposed to be "matched" to the engine torque curve - which may work on a Stag but could be horrible in something with less umph), kickdown and gearchange linkage issues. It's a laycock overdrive so sort of original too. The only gearbox mod is to run the speedo cable from the overdrive rather than the auto box. The whole thing is reversible in a day or so if you don't like it.

If you're really clever, it must be possible to retrofit the overdrive to an auto transmission. It's been done in the US:

[djw113uk]

I already have the BMW 4 speed auto (ZF box, and torque converter, flex-plate etc), and I know its done pretty regularly on the Stag. I have seen those o/d units and they are pretty chunky (and expensive!), I think it might confuse the poor old BW box too!

I thought the BW65 had removable bellhousing, whereas the BW35 does not? Anyone have one out of a car, or able to look underneath so they can check for me?

[wiggybum]

I already have the BMW 4 speed auto (ZF box, and torque converter, flex-plate etc), and I know its done pretty regularly on the Stag. I have seen those o/d units and they are pretty chunky (and expensive!), I think it might confuse the poor old BW box too!

I thought the BW65 had removable bellhousing, whereas the BW35 does not? Anyone have one out of a car, or able to look underneath so they can check for me?

I have a spare BW65 and the bell housing is integral I'm afraid. Incidentally, it looks tiny compared to the manual Sprint gearbox!

Don't forget torque converters are tuned for an engine's torque curve. The Stag probably pumps out similar figures to a Jag XJ40 hence they are a good match. The 1850 auto is commended as having an excellent match of torque for that converter and its a shame to lose that from a driving experience point of view. I'm wary because you could end up going through a lot of hassle only to have a car which drives horrible and changes gear at the wrong time etc. Then again, I'm not gearbox expert. You'll have plenty of fun along the way regardless.

[djw113uk]

Just looked at a Lincolshire supplier's website and they show 1850 auto supplied without bellhousing..... that looks hopeful to me! Oddly the sprint auto is listed s BW65, 1500 and 1850 do not mention a type.

[wiggybum]

Just looked at a Lincolshire supplier's website and they show 1850 auto supplied without bellhousing..... that looks hopeful to me! Oddly the sprint auto is listed s BW65, 1500 and 1850 do not mention a type.

I've just been back in the garage and rechecked my spare auto box. You're right, the bellhousing does unbolt.

The 35 and 65 this is purely age related ie after about 76, the old BW35 was obsolete. Just as well because compared to the BW65, it's massive and bulges into the gearbox tunnel!

[djw113uk]

Thank you for that As I suggested at the beginning, one 1850 auto has had a manual o/d box for some years now - it always feels like its pulling away in 2nd, because the auto diff is still present. To combat this we fitted a sprint diff into father in law's ex 1850 auto last year (purchased as manual o/d but with broken diff) Whilst better this is still hard work off the line.
Ken's car is still as built, but the engine is broken. If I extract the engine and box together I can mess with the bellhousing, bmw toque converter and alignment, unless anyone has a auto bellhousing I could "borrow" for a while. Does the sprint have a larger bellhousing? Does the auto sprint still using the 2" engine adaptor at the back?

[wiggybum]

Lower profile tyres will help the gearing....

As far as I'm aware, the 1850 and Sprint auto boxes are identical (although I think the Sprint has an oil cooler) and neither use the 2" spacer.

As I'm fascinated to see how this project pans out, you're welcome to borrow this gearbox if you don't mind a drive down the A46 to Lydney in the Forest of Dean to collect. I work in Gloucester, which is 25 miles closer (but nowhere near as pretty, obviously)

[harvey]

The Stag ZF conversions use the BW35 bellhousing, mating the same box to a BW65 bellhousing would be a lot more difficult if it was even possible.

The stand alone overdrive unit is a good solution if there is the room to fit it. I note there's no price for it on the website. I was involved in the development of that.

[wiggybum]

The propshaft tunnel is snug and some remodelling may be required. Must be way easier than mixing and matching torque converters etc though.

I'd have thought that if you have a spare J Type overdrive - not exactly rare - then I imagine O/D Spares would be able to supply the special input shaft and front plate at a fraction of the price of a stand alone unit.

Only fear I would have is how you prevent it engaging in 1st, 2nd or worse still, reverse gears. I know Land Rover used to use a weird J Type overdrive for the Defender. To tackle this issue, they have a box of tricks to ensure the solenoid is not energised in reverse or at road speeds <30mph. From what I've heard, this box of tricks causes most of the problems too!