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MG Performance Forum

BW 35 Transmission

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ron neal Avatar
Coastal, SC, USA   USA
1962 MG MGA MkII
1968 MG MGC
1969 MG MGC
1969 MG MGC    & more
George
They used the BW 35 in a lot of different Volvo models so would think your friend can help.
Ron

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Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
Jim. One thing I do remember about the BW 35 is that Dextron is an absolute no-no. Can cause clutch pack frailer. Denis



68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.07 LSD.

Dandare Avatar
Dandare Danny H
Sydney, Australia   AUS
OZ BW35 info.

There may be some points of interest in this link, mostly from around post #43

Danny

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galotis Avatar
galotis George Van Horn
Collegeville,, PA, USA   USA
1980 MG MGB "Ms. Blue"
Thanks for the info

gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
i have a BW35 with my supercharger, but only 110 RWHP

John Caffin, as Denis referred to also runs one on his supercharged MGC i am guessing John must have somewhere over 160? they sat behind many V8's here in UK

from what i have read, and i have no first hand knowledge of this, is that the BW65 is essentially the same box as a BW35 - although filler is on the opposite side and (replaceable) internals are more robust (in 65). I have read that the 3/4/6 in BW35/45/65 is a 'level' of it's power handling capability.

anyhow, i have seen kits advertised to 'upgrade' a 35 to a 65. i have only seen them for sale in AU. there were some on ebay a few weeks ago but cannot find them now.

G

shoalsgary Avatar
shoalsgary Gary Simpson
Killen, AL, USA   USA
1954 MG TF "Junior" ~ For Sale ! ~
1954 MG TF
I agree - 2004R


In reply to # 3692197 by V8MGBV8 Depends on your driving style. May hold up, but I have read of a BW35 being trashed with just 150HP.

"Early Rover 3500 had BW35 then they changed to the BW65 (better box) then they changed to GM180 (even better box) all are 3 speed."

I have also read that a C4 is a much better option & bolts up.

Personally, if I wanted to go with an autobox I would be looking into an upgraded TH200-4R with OD.

https://www.hemmings.com/magazine/hmn/2011/01/GM-TH-200-4R-Transmissions/3694151.html

More tranny options:

http://forum.britishv8.org/read.php?6,37744

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd, Florence, KY, USA   USA
There have been some suggestions that the 2004r and possibly the 700r4 could fit into the transmission tunnel without modifying it. IDK. Seems to me sort of like some claims the LT4 could be made to fit without cutting the firewall. Could be, but so far as I am aware nobody has done it yet. I really have to wonder why if it is possible. Are all of us really that eager to slash and bash? Is it some sort of contagious disease among MG owners? Is it perhaps even the origin of the conversion bug? Inquiring minds and all that.

Anyway, the ones I've seen had some intrusion into the passenger's floor area. If anyone has done it without, please speak up. My understanding is that the pan is too wide and there are things on the side that stick out. Photos would be great.

In some ways the 2004r is a great transmission for a sporting vehicle. It has good gears and a pretty close spacing between them, unlike the 700r4 which has a huge jump from 1st to second, and I think the jump from 3rd to OD is a bit of a step as well. It is a dual pattern gearbox, which means it matches the BOP and the Chevy bellhousing patterns. It was used behind big block Buicks and Olds and with minimal parts upgrades can easily handle more torque that anyone is ever going to put in these cars. It's also pretty efficient, and performance parts are widely available.

I think it is probably a good choice for the MGB even if you have to bash in the floor edge a bit to get it to fit. Because the 1800 uses a steel rear plate, matching the bellhousing should not be difficult. You can stand the 2004r on it's tail. lay the plate on top, center it on the input shaft and transfer the holes. Might need to do a little fiddling with the flexplate but that's not particularly difficult. Worst case you might have to space the bell back some. If a MGB automatic flexplate is available that will probably make the job easy.

As with all manual control automatics the shift characteristics are not going to be what we generally think of as sporty, but with the lock-up converter you do have the working equivalent of 5 gears and the torque multiplication of the converter for starting out. All in all not a bad trade off, and probably the best choice of automatics available.

Jim

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shoalsgary Avatar
shoalsgary Gary Simpson
Killen, AL, USA   USA
1954 MG TF "Junior" ~ For Sale ! ~
1954 MG TF
I used a Chrysler Torqueflite behind a 327. The firewall had to be cut to the back of the battery box and there was considerable intrusion of the transmission and custom tunnel fabrication. But if your physical condition prohibits use of a clutch, it's worth it. I also have a Harley with an automatic clutch.

In reply to # 3696503 by Jim Blackwood There have been some suggestions that the 2004r and possibly the 700r4 could fit into the transmission tunnel without modifying it. IDK. Seems to me sort of like some claims the LT4 could be made to fit without cutting the firewall. Could be, but so far as I am aware nobody has done it yet. I really have to wonder why if it is possible. Are all of us really that eager to slash and bash? Is it some sort of contagious disease among MG owners? Is it perhaps even the origin of the conversion bug? Inquiring minds and all that.

Anyway, the ones I've seen had some intrusion into the passenger's floor area. If anyone has done it without, please speak up. My understanding is that the pan is too wide and there are things on the side that stick out. Photos would be great.

In some ways the 2004r is a great transmission for a sporting vehicle. It has good gears and a pretty close spacing between them, unlike the 700r4 which has a huge jump from 1st to second, and I think the jump from 3rd to OD is a bit of a step as well. It is a dual pattern gearbox, which means it matches the BOP and the Chevy bellhousing patterns. It was used behind big block Buicks and Olds and with minimal parts upgrades can easily handle more torque that anyone is ever going to put in these cars. It's also pretty efficient, and performance parts are widely available.

I think it is probably a good choice for the MGB even if you have to bash in the floor edge a bit to get it to fit. Because the 1800 uses a steel rear plate, matching the bellhousing should not be difficult. You can stand the 2004r on it's tail. lay the plate on top, center it on the input shaft and transfer the holes. Might need to do a little fiddling with the flexplate but that's not particularly difficult. Worst case you might have to space the bell back some. If a MGB automatic flexplate is available that will probably make the job easy.

As with all manual control automatics the shift characteristics are not going to be what we generally think of as sporty, but with the lock-up converter you do have the working equivalent of 5 gears and the torque multiplication of the converter for starting out. All in all not a bad trade off, and probably the best choice of automatics available.

Jim

Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
The Hemi 6 was a giant killer here in oz and still popular. There were RT models with 3 side draft Weber that won many big races against much larger displacement V8s. In fact they still do in in the "classic vehicle" races. Denis



68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.07 LSD.

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gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
Brown & Gammons UK have a pile of flexplates for MGB/BW35. New.

Seems they made them for BL back in the day. and still have quite a few left over. I bought one, but pricey at £167. mine was very tired.



G


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FLEXPLATE (2).jpg

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