BW35 changing unusually

Oldskoolrob

Active Member
Hi Gurus,
My BW35 has always cycled quickly through 1-3 when cruising, but after a service on the box it is now cycling even quicker - to the point where if I accelerate more than softly it's mostly done in 3rd. The only way to have it change 'normally' is to do it manually. It even appears to start in 3rd sometimes? Any advice? Cheers, Rob.
 
I've only had one box start in TOP and that was aproblem that wouldn't fix itself. I would check the kickdown cable adjustment and the throttle rod bushes.
 
Oh, I should mention that as I'm now running a Holley it no longer has a throttle kickdown cable...maybe that's the reason?
 
That sounds ominous. Can you please elaborate when you have the time? I think the box needs rebuilding regardless but the last guy I took it to has (I think) permanently removed the kickdown linkage....
 
I’ll let Harvey explain fully, but it’s to do with it’s inherent control over internal pressures.
I have a fabricated throttle/kick down bracket which came with my Edelbrock 500 and Performer manifold that the previous owners had made. I’m going to make my own version so would sell this if it’s compatible with your setup.
What Holley carb is it?
Jim
 
That sounds ominous. Can you please elaborate when you have the time?

The cable controls the line pressure inside the box. With the cable fitted correctly, the line pressure increases in proportion to how far the throttle opens. The line pressure is what clamps the clutches together. Running with the cable disconnected means that regardless of the throttle opening, you only have idle speed line pressure clamping the clutches, so you will get slip/judder under high throttle applications, which will burn the clutches out quickly.
 
Well.....................................sh!t.
That explains a few things. Old-mate that serviced it was obviously not the right guy for the job. Might have to chase another box as I can't afford a rebuild at the moment, but that sounds like a bit of a time-bomb now. Thanks for the advice Harvey!
 
I wonder if I take it to a real mechanic if they can save the box? Only other option in my budget is to put in a second hand one and cross my fingers. Grrr :(
 
Hey @harveyp6 is there an external way to identify the 'australian' borg warner 35? In another thread it was mentioned that the rear servo is held by 3 bolts - is that visible from the outside?
 
Hey @harveyp6 is there an external way to identify the 'australian' borg warner 35? In another thread it was mentioned that the rear servo is held by 3 bolts - is that visible from the outside?

AFAIK that's not visible from the outside, the sump would need to be dropped. I think some of the Australian boxes (fitted to Australian models, not Rover), had vacuum modulators fitted.
 
Is replacing a kick-down cable a tricky job?

Not particularly, but not something I'd advise a complete novice to do. The gearbox sump has to be removed, and access to the fitting on the bottom of the cable where it screws into the casing can be tricky. The one plus point is that with the sump off setting the cable is much easier.
 
I wonder if I take it to a real mechanic if they can save the box? Only other option in my budget is to put in a second hand one and cross my fingers. Grrr :(
I've just had my 35 taken out to be replaced by a ZF box. Selecting gear was very imprecise, probably because the lever and linkage needed attention, but the box itself was doing its stuff despite having been topped up with Dexron a few weeks before Christmas. It cost me a fortune flushing it through with ATF G. If you would be interested in the box for a modest sum despite that, I can put you in touch with the garage doing the ZF conversion near Barnsley. Pat Seaward, '71 P6B.
 
Bear in mind that unless you already have something suitable, it won't just be replacing the cable in the box Rob. You'll need to make or buy a linkage to connect the throttle to kickdown cable up top to work correctly with the Holley.
Jim
 
Here’s the one I was talking about, it came with my used edelbrock carb and manifold, originally on a US nada car that was imported to the UK. This was made by somebody over there.
It has an adjustable slider for cable outer which locates down the back of the head, the main fixing being two manifold bolts.
I have a couple of very short videos (5 second long) showing the actuation but don’t think the forum supports uploading vids?

A63D4B07-C1AE-4EA7-832A-FB4AD11BAF1C.jpegF2747BF5-5CB9-484C-A3CB-4696BBCDA6EE.jpeg
Jim
 
That Rpi one assumes a throttle cable setup by the looks of it
Jim

Possibly, but it does mention P6 in the listing, and P5B and SD1 had cable throttles and they still have the same kickdown cable. All that said, I wouldn't want to shell out that kind of cash to find out that it didn't work....
 
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