bw35 doesn't want to go into 3rd

[bob_drinks_beer]

Hi all

I've recently bought a 1968 p6 3500 auto. It runs great, but doesn't want to go into 3rd. I've done the checks as mentioned at the start of this section, but with a couple of exceptions...

The car had a holey carb at one point (now back to the twin su's), and as such the throttle linkage design was changed (different pedal, cable from this pedal to carb linkage via home made bracket). This setup operates the carbs fine (fully closes and fully opens).

The only issue with this setup is that the kickdown cable wasn't attached. A further issue occurred as we got the car out the garage to look it over, and the kickdown cable fell onto the fuse box :roll: . No damage to the electrical system luckily, but it did burn the end off the kickdown cable and melted the outer cover of this cable (and a bit of my hand). At the time we were under the assumption that all we would loose was the kickdown function, which could be sorted at a later date, but now I'm not so sure... :?

One of the future plans is to swap to a 5 speed manual, however until I have all the bits together to do the conversion I'd like the autobox to behave its self so I can use the car. Is there anything I can check/adjust so I can get the box working, minus kickdown, for now? Or am I going to have to find replacement original throttle linkages etc?

Thanks in advance.

Bob

 

[SydneyRoverP6B]

Hi Bob,

My understanding is until Harvey pops along is that the connection of the downshift or kickdown cable with the correct adjustment is crucial to the correct working and ultimate reliability of the BW35. The kickdown cable establishes the correct operating pressure hence the reason your box won't change into top.

Ron.

 

[NickDunning]

One of our customers cars has a Holley with the kickdown disconnected - it does change into top but the changes themselves are pretty bad.

 

[bob_drinks_beer]

Hi Bob,

My understanding is until Harvey pops along is that the connection of the downshift or kickdown cable with the correct adjustment is crucial to the correct working and ultimate reliability of the BW35. The kickdown cable establishes the correct operating pressure hence the reason your box won't change into top.

Ron.

I was thinking this may be the case...

One of our customers cars has a Holley with the kickdown disconnected - it does change into top but the changes themselves are pretty bad.

What do you mean by bad? My box changes from 1st to 2nd, and back down fine (all be it without kickdown obviously), but just wont go to 3rd...

I have a feeling the manual conversion may be heading up the list of priorities! :roll:

 

[harveyp6]

If you run with the kickdown cable disconnected and the cable isn't seized, it will change up very early, so you should be into TOP almost immediately. Two questions, 1) are you absolutely certain that you're not getting TOP, If you're not the car will be absolutely flat-out by about 60-70mph (if you're lucky.) and 2) how does REVERSE function?

If you're not flat out at those sorts of speeds, and you're only feeling one gearchange, my guess is you've got a PRND21 selector plate with a PRND2D1L gearbox. Otherwise all I could think of without a lot more info would be a sticking 2-3 shift valve, but that would be a rarity.

 

[NickDunning]

If you're not flat out at those sorts of speeds, and you're only feeling one gearchange, my guess is you've got a PRND21 selector plate with a PRND2D1L gearbox. Otherwise all I could think of without a lot more info would be a sticking 2-3 shift valve, but that would be a rarity.

This would be an 'A' suffix car on the chassis number (e.g 42500019A). Up to September 1968. The 'A' suffix cars have the 'lock-up' gearboxes, which will hold either of the first two gears when selected.

D1 cuts out first gear
D2 uses all three forward gears.
L holds intermediate gears.

 

[harveyp6]

D1 cuts out first gear
D2 uses all three forward gears.
L holds intermediate gears.

Wrong!

D1 = Fully auto
D2= Second gear start, permanently locking out out FIRST
L= Locks the box in whichever out of FIRST and SECOND the box is in when "L" is selected.

Chassis suffixes and even gearbox series types are no guarantee of what box is fitted, all replacement boxes had the later selector pattern once it was introduced, regardless of the year of the car it was going in to.

 

[NickDunning]

D1 cuts out first gear
D2 uses all three forward gears.
L holds intermediate gears.

Wrong!

D1 = Fully auto
D2= Second gear start, permanently locking out out FIRST
L= Locks the box in whichever out of FIRST and SECOND the box is in when "L" is selected.

Chassis suffixes and even gearbox series types are no guarantee of what box is fitted, all replacement boxes had the later selector pattern once it was introduced, regardless of the year of the car it was going in to.

Ooops. I was going from memory. Thanks Harvey.

'A' suffix Three Thousand Fives had the box with D1 D2 from new.

 

[bob_drinks_beer]

1) are you absolutely certain that you're not getting TOP, If you're not the car will be absolutely flat-out by about 60-70mph (if you're lucky.)

Well it certainly doesnt feel like its flat out at those speeds as I've had it a bit quicker, so now i think it could be going to top early...

2) how does REVERSE function?

Reverse is fine

If you're not flat out at those sorts of speeds, and you're only feeling one gearchange, my guess is you've got a PRND21 selector plate with a PRND2D1L gearbox. Otherwise all I could think of without a lot more info would be a sticking 2-3 shift valve, but that would be a rarity.

Interesting... I never thought of such a possibility!

D1 = Fully auto
D2= Second gear start, permanently locking out out FIRST
L= Locks the box in whichever out of FIRST and SECOND the box is in when "L" is selected.

Ill try taking it out for a drive at the weekend (I'm away with work during the week) with the selector in "2" as this should then be D1 if I have the wrong selector plate?

Thanks very much for the advice everyone, this is my first classic, and also my first auto, so im on a steep learning curve!

 

[harveyp6]

Ill try taking it out for a drive at the weekend (I'm away with work during the week) with the selector in "2" as this should then be D1 if I have the wrong selector plate?

Correct.

 

[NickDunning]

Well after the debate last week where Harvey put me right on the D1 D2 scenario and said that there were some cars with different changes, and not nescessarily early early ones - we've just dragged in a dead early 1970 Three Thousand Five with this note stuck into the handbook:

The book has also been amended by the original owner to say that it does indeed do first and second gear in '2', but no top.

I learn something new every day

 

[harveyp6]

I learn something new every day

I don't know about every day but I've certainly not heard of that one on Rovers. Strange because that can only be with the later PRND21 selector pattern according to the way it's written, so they must have used some boxes with the later selector pattern as used on other makes, presumably because they hadn't got round to designing the Range Control Valve. That as shown wouldn't have SECOND gear start, or anti-rollback.

 

[colnerov]

Hi, now I come to think about it my first P6b a '69 G reg had the same change
pattern because some times I used to drive it like a manual and hold in each
gear using the 1. 2. and D.

Colin

 

[harveyp6]

Hi, now I come to think about it my first P6b a '69 G reg had the same change
pattern because some times I used to drive it like a manual and hold in each
gear using the 1. 2. and D.

Colin

The only way to be certain would be to drive it and see whether selecting "2" gives you 1-2 2-1 not SECOND gear only and it's probably a bit late for that......

You could drive both types the way you suggest, in the same way that you can with the same box in any other (inferior) make.

 

[NickDunning]

I learn something new every day

I don't know about every day but I've certainly not heard of that one on Rovers. Strange because that can only be with the later PRND21 selector pattern according to the way it's written, so they must have used some boxes with the later selector pattern as used on other makes, presumably because they hadn't got round to designing the Range Control Valve. That as shown wouldn't have SECOND gear start, or anti-rollback.

This car is a 1970 model, probably built in about December 1969.

I suspect Rover may have had a supply problem here. I don't personally have a copy of the factory service bulletins for that time - although I know where one is and I may well go and check it this weekend, but I suspect there'll be something there, in approx January 1970, saying that due to supply problems some boxes have gone out with this arrangement.

This was a time of heavy production (NADA building was in full swing then as well) so maybe they ran short and used an alternative source. Did Jaguar use a BW35 with position two having first and second gears?

Thanks
Nick

 

[colnerov]

Sorry to confuse, yes 2 did give 1-2 2-1. I just used it hold the gear on the way up
and down the 'box. It also had an original stainless steel exhaust system with very
little packing left, very rorty...... very naughty but my first V8 see.

Colin

 

[harveyp6]

Did Jaguar use a BW35 with position two having first and second gears?

Yes, and Triumph, along with everything else other than Rover. Doesn't it warm the cockles of your heart that Rover was still run by engineers (and pedants) rather than bean counters. Well, I'd like to think so....

 

[NickDunning]

I suspect this explains it. There should be a note in the service bulletins at that time and I'll try and find this.

With this facility you wouldn't have the anti-rollback then Harvey?

 

[rp61973]

As Harvey is aware, I have just had the BW35 (303 Series) rebuild on my 1973 V8.

Since it has been overhauled the car is very nice to drive. Well setup, quick off the mark and pretty smooth changes. This brings me onto why an ever increasing number of folk hanker after the 5 speed SDI setup. OK, horses for courses and personal preference aside, I suspect many folk feel the need to consign the trusty BW35 to the scrapyard simply because it is not either setup correctly or it simply needs a rebuild after 40 or so years. Christ, I could do with one myself after 40+ years!

OK by modern standards the car is low(ish) geared, but not that low. 3000 rpm at 70mph. Although higher geared than my other half's Honda S2000is in top (6th); and that carries on to 150 mph!

With the ever-decreasing standards of driving and the advent of some of the more 'important' players in society whistling along the BMW lane at 100+ mph, the standard set up of the P6 suits me nicely! gets me there leisurely but has the power to overtake on motorways quickly if required.

 

[harveyp6]

Sorry to confuse, yes 2 did give 1-2 2-1. I just used it hold the gear on the way up and down the 'box.

Well as we've discussed, not the way Rover would have normally had it, but it seems some did come out of the factory like it, but depending on when you owned the car there's also a good chance that it could have been "got at" at some time.