BW35 and BW45 Automatic Gearbox tech

[JoKer]

seems these are becoming more common on the forums 

4 speed? 3 speed with over drive?

post your knowledge / tips / info here please (will try find/copy paste stuff from when I BOUGHT MINE)

Those borg warner autos are pretty bullet proof, are often used behind 6 cyl Fords and Chryslers.
The only problem I've heard of is losing reverse, just caused by a broken spring in the valve body...easy to fix...lol

Yeah I have a BW35 in my Valiant Charger (the 3 speed version of the BW45 in an Avenger) and it goes really well.

P
R
N
D
3
2/1

some wires under mine (linkage to lever broke so I have to know/guess what gear I am in)

is there a light?

and I can start in any gear (pending testing of broken linkage/wires)

[kierbear]

knowledge: They go pretty good on the straights

[JoKer]

googled it and got

http://cobratransmission.com/index.php?main_page=page&id=81

says 4 speed! cant say I have "found" 4

In October 1973, the 1250cc version was extended to 1300cc and the 1500cc version, to 1600cc. The cylinder head design was revised too to improve fuel economy. The automatic option was now the new four-speed Borg Warner BW45 gearbox rather than the previous three speed model.

http://www.rootes-chrysler.co.uk/car-development/dev-avenger.html

and

Retro Rides - Any Borg Warner Auto box Experts on here?

[oldschool]

There's been a few discussions on here about the autos. They were only an option on 1500 and 1600 Avengers.
The consensus is that all the NZ 1500 avengers were manuals, so no 3 speed BW35's in NZ Avengers.
The 4 speed BW45 auto was introduced in the UK with the 1600 upgrade in October 1973, but didn't appear in NZ 1600 models until 1975?
My son Logan's auto was registered Feb. 1975 and may be the oldest Avenger auto on the road?
If anyone's heard of or seen a 1974 NZ new auto...let us know?!

In typical Chrysler penny-pinching fashion they used the same T bar with 6 positions for the 3 speed and 4 speed auto.
The mathematicians among us will realise that a 4 speed auto needs 7 positions, PRND321...lol
That's why the lowest position in the 4 speed is a siamese 2/1...meaning you can't hold the auto in 1st gear, like you could in a 3 speed.
There's a light in the gear selector display attached to the long narrow plastic strip that goes around the T bar. The display selector/light holder often breaks off the strip from fatigue and by the light holder fouling on the carpeted tranny tunnel when putting the T bar into the 2/1 position.
I cut up a 2 litre ice cream lid to make a new strip, taping it to the light holder.

Starting in any gear indicates a faulty or disconnected inhibitor switch on the side of the auto, as they normally can only be started in P or N.
No lockup/overdrive on the auto, so stuck with the 5% slip, which is why they rev higher and suck more juice than manuals.
I put 14" Sierra wheels with 175/80 tyres on Logan's to drop the revs back from 3700 @ 100 km/h to 3300.

I wasn't aware of a cylinder head re-design between the 1250/1300 and 1500/1600 models to help fuel economy?
I know the inlet and exhaust manifolds were changed to a free-flow design for a small increase in power and economy.
The inlet manifold got smoother bends, while the exhaust manifold changed to a 4 into 2 outlet from the old 4 into 1.

[JoKer]

yea was gunna lookinto Diff ratios next too

3500rpm @ 100 kph (speedo / try GPS out this weekend) isnt too bad I reckoned hence fuelly data interest

[JoKer]

good for 153 km/h
Max power is at 5500 rpm.
http://www.automobile-catalog.com/car/1975/1029170/hillman_avenger_alpine_automatic.html

now I need to read my Manual for a bit of a service, sticking in low gears when cold/40kph for a few blocks is not fun (hope not wrecked anything proper)

[oldschool]

I wonder if an early Sierra lock up/overdrive auto will fit an Avenger?
If they're like the 5 speed type 9 manual and have a separate bell housing, they could be adapted.
I know they've been fitted into Mk3 Capri's, just bolt on to the Pinto OHC motor.
There's a whole auto Sierra wagon for sale on TradeMe...just swap the motor and box over...Pinto motor is a bit of a boat anchor though...lol

http://www.trademe.co.nz/motors/used-cars/ford/sierra/auction-514652176.htm

[JoKer]

anyreason why I cant substitute this BW35 for my 45?




My doorstop




top one is out of a Triumph

is it as simple as it looks/unbolt/bolt on my Bell and output etc?

or is there something inside mine I should check 1st

[oldschool]

The Triumph one might have different bell housing mounts, different splines and a different length affecting your drive shaft, plus it's designed for a 6 cylinder motor.
What happened to the Hunter one...it would be a straight swap onto your Avenger bell housing as the original 1500 Avenger auto probably used a Hunter BW35...a much stronger box than the BW45.

[JoKer]

good to know : hunter is at disadvantage of being on the bottom and 16 cars deep in a yard with only a forklift

at $50 squid reckon the trumph one might be a worthwhile gamble

[JoKer]

OK

Have a 35 coming from Tirau for $100 and a reply from the other source as follows

Hi Jared



I have two B/W 35s for sale from Hunters, I did have a B/W 45 but it is sold



The B/W 35s are definitely a better auto , there should be no difficulties in swapping bell housings , both Autos work fine and have around 70,000 original KM on them , there are the usual small oil leaks though !



I think a fair price for each auto would be $250   



Shipping will be $80 - $100 , depends on how much time is spent on making a small crate or pallet , I can fit onto a standard pallet , but a pallet is to large I would make a smaller pallet to reduce cost , needs to be well protected .



Let me know what you want to do , as the transmission is still in the car , so I have to remove and clean etc



Regards



Andrew Shaw

Assistant Engineering Manager

Progressive Enterprises Limited

CRM Plant [\quote

[kierbear]

sounds promising. xmas present to self?

[JoKer]

hells yea, waiting a few weeks for the $100 version (inc. delivery!

[JoKer]

soooooo Parts availability?

Mine got returned form the "experts" with no valve body

have sent it down to OS user Borgweiser who rebuilt it last, keen to put feelers out there to see if I can assit (idiot who owned it between me and him was doing 5k rpms shift dump launches apparently, hence diff also being dodge when I got it)

[oldschool]

Hang in there old boy...I know of an auto Avenger wreck in Wairoa, just waiting to hear if the gearbox is available.