67 FJ45 Original rear axle strong enough for V8?

[UKFJ]

Hello everyone,

First of all thanks for this priceless forum: I haven't posted here before but have learnt plenty reading so many great threads over the years. I've been a member since '09.

I'm cleaning up and rebuilding a '67 RHD 45 long bed in the UK. Here's a picture of it when it first arrived from Australia last year.

Amongst other things, I'm putting in a 350 chevy small block which should have over 400bhp and about 430 - 450 ft lbs torque.

I'm using a H55f transmission which I think should be good enough (feel free to add comments!) and am no wondering if I the original rear axle will be ok for the power / torque increase? I mean the differential internals.

What if anything can you do to strengthen the diff?

What do you all think?

Advice greatly appreciated!

cheers,

Simon

 

[Gumby]

seems to be

Mall cruising

Thats a stock 64 rear with a limited slip carrier. The 350 is a 84 truck Gen II block with Vortec heads, a mild cam, headers and a well tuned quadrajunk. Somewhere between 200-250 HP is a WAG.

currently laying on the floor of my shop as I just fitted the 99 6.0L in the 45 today. Should come close to double the HP. I'm more worried about the transfer case. A case saver would be the least I'd do there.

If you get spring wrap you're going to need an antiwrap bar or you'll break your pinion.

 

[Chamba]

Both will be very adequate so long as you're not planning on hooning about the place. I also assume given you're in the UK that you'll run her on gas - unless you're rich enough to dump five star petrol into that massive lump - and that will drop your horsepower and torque some due to the lower BTUs.

I ran a 350 vortec V8 through an h55 to my stock rear axle on my '84 hj47 troopy for 12 years and many, many miles. My troopy weighed 6,800 lbs and I frequently towed thousands of pounds. I also wheeled it hard.

I'd try to use a transfer case from an '86 or '87 fj/Hj60 as it has the larger idler shaft. I'd also look for a newer front axle both for the disc brakes to help stop that fast bugger but also for the stronger Birfield; I reckon that's where the weakness actually will be on your rig.

 

[UKFJ]

Thanks for you thoughts. So I hadn't even heard of a transfer saver but will investigate more, thanks for heads up.

I have disc set up all round, traction bars and the transfer case is later I believe so thats good.

Good to hear similar set up ran well for so long......I do want to hoon sometimes! I don't want to always nurse the throttle for fear of a breakage. Yes it will be on petrol as its just an occasional toy.

I guess if there is no way of strengthening I'll just have to run it and see what happens.

What do you think about the clutch while we're at it? It will use Toyota clutch. I've seen Centreforce do an upgraded one. I want this thing to be robust!

 

[Gumby]

If it's a later split case then a saver isn't available or necessary.

 

[tornadoalleycruiser]

he said H55 so should be fine there.

 

[Chamba]

I ran the Centreforce HD clutch in my setup with no dramas. The bloke I sold it to now tows a decent sailboat with her and is still on the same clutch. I regularly towed my 5000 lb fj40 with her at 75 mph on a trailer; no dramas.

And agreed, split case (especially said '86 or '87) is plenty strong enough for your V8. Again though, your front ball and claw Birfield is not.