BW35 help needed

Alley Kat · Post by **Alley Kat** » Thu Jan 19, 2012 9:59 am

First thing is does anyone know of a BW35-equipped car, that I can get a workshop manual/Haynes for? No idea how to adjust / check the kickdown and the inhibitor.

Got a feeling the kickdown is not working, but no idea how to set the cable etc.
And the inhibitor is either dead or needs adjusting too.

DaveEFI · Post by **DaveEFI** » Thu Jan 19, 2012 10:21 am

Assuming this is a factory installation:-

First make sure the carb(s) is opening fully with pedal to metal. So no wear in the linkage, and correctly adjusted. This is critical.

If you pull out the BW35 control cable by hand, you'll feel the kickdown valve operate by extra resistance at near fully out.

Set the cable with no lost motion and road test. Fine adjustment will be needed to get smooth slip free changes at low throttle openings. The speeds these occur at will depend on the vehicle. But should be roughly 10 mph 1-2 and 16 mph 2-3 Better to err on the cable being too tight than too slack, to prevent the clutches etc slipping on changes. The kickdown will look after itself if all this is correct.

FWIW, most of the problems with these is down to wear/incorrect adjustment of the throttle linkage. Not the control cable. The relationship between these is all important.

A very common problem with the BW35 is the main valve sticking at near close throttle, as it is simply spring loaded onto a cam. This results in hanging on to the low gears and rough changes at low speeds.

Note than with many BW35 boxes, the kickdown to 1st won't operate much above half the speed the car can achieve in 1st gear. Nor can 1st be selected manually above this speed.

JSF55 · Post by **JSF55** » Thu Jan 19, 2012 10:22 am

Hi Bill, the only thing i remember about them is when you pull them fully out the cable stops. another pull on it should let you feel the kickdown, this needs to be tied in with the mechanism on the carb, i'm sure there was a secification for the crimp, if it's an old cable, too the outer casing.
The inhibit switch is a pair of contacts in a silver cylider on the side of the box, these normally corrode internally and are unobtainable, adjustment is made on by screwing the body in or out. hth john
Edit:- must type faster ....

Alley Kat · Post by **Alley Kat** » Thu Jan 19, 2012 10:52 am

Dave, thanks very much for that, most helpful. I'll check linkages and everything out. Appreciated.

John, ta, I did find some pattern inhibitors on the net but haven't bought one. It looks adjustable (locknut?) but no idea what to be looking for.
Starts in Neutral, won't start in Park - dead or needs adjustment? Was fine before being laid up so I'm thinking it's more likely browners...

cheers chaps
Bill

JSF55 · Post by **JSF55** » Thu Jan 19, 2012 12:17 pm

Same contactors on same circuit, would think thats adjustment, slacken lock nut turn in 1/8 of a turn nip up and try, thats my best guess

Alley Kat · Post by **Alley Kat** » Thu Jan 19, 2012 2:36 pm

Ta John, I'll have a play later.

DaveEFI · Post by **DaveEFI** » Thu Jan 19, 2012 3:29 pm

Alley Kat wrote:First thing is does anyone know of a BW35-equipped car, that I can get a workshop manual/Haynes for?

[snip]

With Haynes and autos it's generally 'take it to your dealer'

The BL manuals of the period have full overhaul and checking instructions - Rover P5/6, Jaguar XJ6, etc. B-W also issued training manuals - probably worth doing a search on Ebay and saving it. You'll then get emails when things come up.

Alley Kat · Post by **Alley Kat** » Thu Jan 19, 2012 10:49 pm

Thanks again Dave,
cheers,
Bill

mike-b · Post by **mike-b** » Fri Jan 20, 2012 9:40 pm

Hi, I have the BW 35 manual here reading from it this is the info for setting the kick down cable.
What MUST be remembered is the KD cable MUST move with your accelerator cable. i.e. the further tour fast pedal goes down so must the KD cable be pulled. I assume you have the linkage fitted.
The crimped stop on the inner cable must be set 1 to 1.5 mm ( 1/16" ) from the outer cable collar.
I used this with my BW35 and it worked fine.
I almost didn`t fit a KD cable after using a Ford C3 auto without one but I was advised my a Pro expert without it the `box would be doomed.
If someone ( Coops ... help! ) can explain how - I will gladly post the full copy of the BW35 manual with its 70 odd pages.
mike ( mike-B )

Alley Kat · Post by **Alley Kat** » Fri Jan 20, 2012 10:56 pm

Thanks a lot Mike. Gonna have a look tomorrow.
Not sure if the manial is still in copyright? Might be iffy to host it somewhere, though I could do that. If you don't mind Mike I'll bung you a PM with an email address,
cheers,
Bill

mike-b · Post by **mike-b** » Sat Jan 21, 2012 9:52 am

Hi Bill, Got you no problem, PM to me = Ok

mike-b · Post by **mike-b** » Sat Jan 21, 2012 10:34 am

Hi Bill .... Check you e-mail ... Mike

DaveEFI · Post by **DaveEFI** » Sat Jan 21, 2012 11:23 am

mike-b wrote:Hi, I have the BW 35 manual here reading from it this is the info for setting the kick down cable.
What MUST be remembered is the KD cable MUST move with your accelerator cable. i.e. the further tour fast pedal goes down so must the KD cable be pulled. I assume you have the linkage fitted.
The crimped stop on the inner cable must be set 1 to 1.5 mm ( 1/16" ) from the outer cable collar.
I used this with my BW35 and it worked fine.
I almost didn`t fit a KD cable after using a Ford C3 auto without one but I was advised my a Pro expert without it the `box would be doomed.
If someone ( Coops ... help! ) can explain how - I will gladly post the full copy of the BW35 manual with its 70 odd pages.
mike ( mike-B )

Thing is calling it a kickdown cable gives the impression that is its sole function. But on many boxes it is a control cable, which effectively adjusts the pressure on the clutches etc. Higher pressure needed as the throttle is opened (and therefore the torque they have to handle).

Some boxes - like the GM unit fitted to the SD1 - use engine vacuum for this job and have a cable which is purely for kickdown.

The crimped stop is just to limit the minimum pressure in event of the cable being disconnected or mechanism being well out of adjustment. Ideally, it is set to the correct pressure, rather than as a distance from the stop.

Alley Kat · Post by **Alley Kat** » Sat Jan 21, 2012 2:48 pm

Mike - just replied - many thanks.

Dave, I'd come to understand that and at the same time knowing nothing, made me paranoid about killing the box. Seems OK, cable seems Ok (though no idea about pressures of course) and it shifts well.
For some reason I had it in my head that there was a definite kickdown "click", and trying things after it's layoff got me worrying when there wasn't one...

Inhibitor is still iffy but I'll get on to that.

DaveEFI · Post by **DaveEFI** » Sat Jan 21, 2012 3:42 pm

Alley Kat wrote:Mike - just replied - many thanks.

Dave, I'd come to understand that and at the same time knowing nothing, made me paranoid about killing the box. Seems OK, cable seems Ok (though no idea about pressures of course) and it shifts well.
For some reason I had it in my head that there was a definite kickdown "click", and trying things after it's layoff got me worrying when there wasn't one... Inhibitor is still iffy but I'll get on to that.

On the Rover P6. there was a sort of ball and spring thingie on the throttle pedal to give a more definite feel that you had hit kick-down. It didn't actually do anything, though.

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