BW35/40 Weirdness!

[enigmas]

Hi Richard...we're in agreement for most of that (one of us is mellowing) and I do have a second pan from the trans I removed. The pan is also designed to maintain the valve body tubes in place with several internal pressings. So lowering it would negate this. Later BW35 transmissions as fitted to XE Falcons used a metal strap to provide additional security for the valve body tubes.



Additionally, the current oil pickup within the pan is immersed in trans fluid. The suction point isn't flush with the screen, but is an orifice/hole 1" above the mesh screen when in situ.

Note: If you remove the valve body there's a large tube that accesses the front pump intake and fits snugly into this hole underneath. This tube would need to be lengthened to take into account the deeper sump. This would also ensure that the pump intake resides fully in the reservoir of ATF and not above it.

Hope the above comment isn't too confusing.

* Just as an aside...the current valve body (XF Ford Falcon) fitted to this (MK3) transmission also allows for a part throttle downshift into 2nd and 1st gear (say when rounding a corner) at light throttle, not kickdown...and consequently is much more responsive to both throttle position and speed than earlier BW35 transmissions.

[enigmas]

BW35 Cross Shaft Leak/Weep

Since replacing the first new transmission pan gasket and carefully filing down the irregularities on the sealing surfaces of the pan, it seemed to be leak free. I left a tray underneath overnight and discovered a small quantity of ATF in the morning. Investigating this further I discovered that it was weeping past the cross shaft seal on the linkage side (MK3 P5). The seal on the other side is perfectly oil tight.

Interestingly the weep is miniscule but persistent.

The cross shaft seal although new was weeping past the shaft...not the outer perimeter of its housing.
The fix was effected by fitting a small O ring followed by 2 fibre washers. The selector arm is then replaced and the securing nut tightened. This slightly compresses the O ring against the cross shaft lip seal.

Method:
Use 2 fibre washers and 1 O ring.
First fibre washer is 3/8" ID and approx .070" thick. (Dark colour)
Second Fibre washer is 3/8" ID and approx .030" thick.
The O ring is a No. 011. 1/16" W. 5/16" ID. 7/16" OD.

The outer diameter of the fibre washer may need to be slightly reduced to match the OD of the lip seal as it sits in a slight cavity.

Note the very slight weep past the cross shaft seal in the photo below...pinkish colour of ATF.


The O ring and fibre washers in place on the linkage side.







Note: Fit the o ring, then the thin fibre washer and finally the thick fibre washer. Fit the selector lever and tighten the nut.
This seems to effect a fix and stop the weeping ATF.

NB. As a brief aside I use thread sealant (a teflon paste....not loctite) on every screw, bolt and fitting that accesses the case internals. I also use Blue Hylomar on the trans pan sealing surface but not on the alloy case trans sealing surface...just a light smear of vaseline.

[projectrover]

Jun 8, 2017 2:48:42 GMT enigmas said:

Here are the final images of the hybrid BW35/40/51 transmission for my MK3 coupe. It's now ready to fit after I pull the engine gearbox combo out of the car.








Note
The gearbox is a hybrid due to the following changes.

Complete BW40 gear train, heavy duty clutches & bands (Source XF Ford Falcon) in a MK3 case.
Largest input shaft and torque convertor (XF) from the 3 versions of each available. (The P5 MK3 runs the smallest of the input shafts and convertors. The stator support is often found with stripped splines on this version)
BW51 one way clutch fitted. This has more individual sprags than the 35/40 versions.
Composite BW40 XF & P5 Mk3 valve body to incorporate the rear pump, more throttle responsive shift valves (from 3 - 2 & 2 - 1) and the GTS selector pattern (PRND21)
The primary valve spring in the XF Valve body produces the highest system pressure. (See photo below comparing the various spring lengths)
BW51 3 mount rear servo fitted.
BW40 front servo (largest in diameter...for maximum clamping)
BW40 transmission pan. (Required to clear the larger front servo.
The MK3 rear pump is also still incorporated.



That's all I can recall for the moment.

Top notch job.

[enigmas]

For those with a technical interest. I've been doing a bit of house keeping, tidying and organising my stash of BW35/40/51 parts. I thought I'd repost these images of the PRV (primary regulator valve) springs in various BW35 versions/iterations. Changing any of these springs for a heavier version ups the internal working pressure overall increasing the clamping of the clutches and bands. The SRV (secondary regulator valve) springs are all the same across the range of transmissions.

One additional PRV spring is not shown as it's currently fitted to my trans. It's from a BW51 valve body and is the longest at 3 1/4" (same wire diameter and pitch as the others) from an EA Ford Falcon.

[enigmas]

I finally got around to dismantling the damaged BW35 transmission in my coupe.

This is what can happen to a case. All the internals, geartrain, valve body, front and rear pump are in good order, as are the drum surfaces of the front and rear clutches that the bands work against. Similarly the clutch plates and steels are fine but ideally would be replaced if I were to fit the internals to another case.