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With you using the 465 transmission, I personally would go transfer case gears, and the 5.86's. I'm not a huge fan of doublers (although, if it's the only option, I would take it) and prefer the deep single case gears.Short: one of the three is available; super deep gears (5.86), doubler, or tcase gears. Why would you pick one over the other?
Long:
Setup: Big block cady(472), SM465, and 34mm split case in FJ55. Axles are Dana 60s with 3.54 gearing and rear steer. Front is getting Spartan locker, rear will get selectable locker(leaning toward OX) Tires are 35" and may go 37". Virtually zero highway miles. ~35 miles of Wentworth Springs to get to Rubicon(windy mountain roads).
I have a single set of 5.86 gears and an open carrier to go with them. I have to buy a selectable locker for the rear so cost of 'carrier split' will be a wash.
Use: Rubicon rock crawling. Snow plowing the yard. From previous wheeling with similar drivetrain(5.0L TBI, SM465, one piece case, 4.1 axle gears, and 35" tires), I found it not to be geared low enough.
In actuality, the doubler is off the plate since I've already got the SM465 to split case adapter but I would like to hear some logic on picking that. Last time I priced the Blackbox for split case, it was ~$1800. Not 100% certain it is available for 35 spline SM465. Which possibly puts getting another SM465. Length in an FJ55 isn't a concern nor is there a gas tank in the way issue
The 'super deep' gear of 5.86 puts a pretty good limit on top speed; 3000 rpm gets me to about 55mph. But if I call the locker a 'wash' cost, I have to setup gears(~$300 each end) and cost of quality gears(~$250). So relatively speaking, it is a cheap fix to gearing. But it is a 'lot' of up front costs.
Going to AA gears takes out one gear setup and cost of gears. But it adds in cost of tcase gears(~$1k) and requires a new split case housing($300) plus machining of case(~$300 I think). The requirement of a new case is based upon the thinner casting of the 34mm case being a strength concern(transmission guy recommends 38mm) Side benefit is it gives a 10% underdrive so it brings the 3.54 gears to similar 'feel' as 4.1 gears.
I will temporarily run the 3.54 gears since they are setup but looking for some opinions.
When you machine out the 34mm case for 4:1 gears, it gets very thin or will peek thru My transmission guy doesn't recommend doing it at all.
Cost can absolutely be a negative... I saw more than just a dial indicator from several videos. It is also time that I don't care to spend. As I noted, it is something I'd rather have 100% done correct and not a concern. The $300 is also a guestimate that I've seen thrown around.
What is this "Torque wrench" you speak of? Hahahahahahaaaaaa.... just zap it tight with the big impact.I guess sockets, a beam torque wrench, and a big vise are special tools if you don't already have them
I'm building a lightweight rig with a small diesel and I'm going doubler, transfer case gears and a 5 speed with 4.88 gears in the axle.
I love the 472/500 motors - I ran a 472 in 2 different jet boats and a 500 almost landed in my '40. The only difference between the 472/500 is stroke even the blocks are the same with the same numbers on the outside. I never dynoed them, but comparatively, even the low-compression versions outrun 454s of similar vintage. Fun fact, the ports are close enough to a BBC that you can cut the BBC flange off headers and weld the caddy flange on - which really helps when it's trying to fit one of these beasts in something other than a caddy. That said, outside of the valve-float deal, oiling (or lack thereof) is what kills them - to the point that I'd run a low pressure kill switch.Good info... keep in mind that the ~500 ft-lbs of torque that is usually thrown around about cadillacs is related to the early 1970s and earlier numbers where they did a LOT of fudging. I forget when they normalized to SAE(???) but the more realistic number I've seen dyno'd stock was ~380 ft-lbs for a 500.
I haven't heard of any inherit weakness in the cady crank except that the 472 lends itself to be stronger that a 500 because of larger overlap between mains and rod locations on the crank. I 100% agree that the crank is a heavy MFer... my back still hurts from the one I played with 20 years ago
The engine I'm using has had a Compcam 268H swapped in plus the valves are taken care of:
View attachment 2165536
I forget my book crunching numbers but I think I came up with my low compression 472 coming in at a bit under 300hp but close to 450ft-lbs(cam+edl intake+sanderson header).
As noted, in my particular case, a doubler is off the table because I have the SM465 adapter already... I doubt I will find a buyer for the adapter where I'm not giving it away. I haven't talked to Northwest fab but I'm not sure they do a 35 spline version of their box. This means I'd have to get rid of the 2wd SM465 I have. But I would agree with the assessment that a FJ55 platform lends itself VERY well to doubler: equal length driveshafts is a benefit. One of my 55s does have a Blackbox in it.