Borg Warner T-35 auto Questions...

[JC.]

I spent an hour on the phone tonight with a guy who has done this conversion to his B.
However, he used a BW65 box. It turns out that all of the MGB specific parts - shifter etc bolt straight to the 65 with no modifications.

That's excelent news and has taken a real weight off my shoulders.

The good news is that now I know the BW65 fits, it means I don't have to compromise on my engine spec. Or do I?
How much power can I put through a standard SD1 spec BW65 box?

I'd like to use a bit of nitrous on a standard 3.5 litre V8. Would the box cope with say 250bhp and a similar amount of torque?
Obviously I'll be using a trans cooler...

Thanks in advance,

JC.

[harvey]

I'd like to use a bit of nitrous on a standard 3.5 litre V8. Would the box cope with say 250bhp and a similar amount of torque?
Obviously I'll be using a trans cooler...

Thanks in advance,

JC.

It won't last for long!

If you want to use that type of power you're better off starting off with a more suitable box in the first place. ZF springs to mind. You can uprate the BW65 to 66 spec and they ran behind the 4.2 Jag engines in the XJ6's, but they only put out about 225bhp IIRC, and they're at the top end of what those boxes can handle.

[JC.]

Cheers, Harvey.

So 225 is my limit with this box, then?
That's not so bad, to be honest. Much better than the 35.

I reccon a decent 3.5 litre will make around 185bhp. So, if I only use a 25hp shot of sniff for the odd excursion to the drag strip, that'll keep me under the limits of what the box will handle.

Just got to start buying the bits now... Roll on pay day!

-JC

[harvey]

So 225 is my limit with this box, then?
That's not so bad, to be honest. Much better than the 35.

-JC

225ish is about the limit for a 66 box, which has a different front pump and torque converter to fit a better (read: bigger) imput shaft, and a deeper sump (with a valve block spacer plate) to increase the fluid capacity. A 65 box will take less than this to break it.

TBH it all depends on how lead-footed you are.

With what's available in the UK the 65/66 will be a better bet than the 35. Start looking further afield though, and there are upgrades that can be made to allow the 35 to take a lot more power than it does in standard UK spec. Still not enough for hard use though IMHO.

[JC.]

A few more questions...

Does the length and number of splines on the input shaft of BW35 boxes vary between applications?
I suppose the question I'm getting at is "If I fitted a V8 belhousing to an MGC spec BW35 would the V8 torque converter etc all bolt up without any mods?"

How much can a BW35 be uprated by? Could it be uprated enough to take 200bhp / 200ftbls?

Cheers,

Jon.

[harvey]

AFAIK all the imput shafts on 35 boxes are the same, so the V8 converter will fit any 35 box in that case.

Youll have to go to Australia to source the parts to enable the 35 box to take that sort of power. They used a 35 box behind V8's of up to about 5 litres, but there are lots of differences, including the main casing, but you should be able to use the Aus. box with the tailshaft and bellhousing of your choice.

I think there was one for sale in the UK on ebay a couple of weeks back, but the pictures were poor and it was incorrectly described in the listing.

[JC.]

Thanks for that.
It seems sensible money should go on the BW65, then, eh?
I'll keep saving!