39.5s or 42s?

RKBJR

RKBJR

Well-Known Member
Joined
Mar 21, 2005
Location
Roxboro, NC
I am trying to decide whether I want to run 39.5" IROKs or 42" IROKs on my Cruiser. Currently I have 39.5/17 IROKs. I would like to run 42/17 IROKs, I just don't know if my rig can handle them.

My rig is what's left of an FJ40 after having Jim tube the back half and 4-linking the rear suspension with air shocks. I have a 5.7 Vortec/SM465/LoMax205. I'm still on FJ40 axles - somewhat built. The front has 30 spline Longs with chromo hub gears, ARP knuckle and hub studs, LockRight, etc. The rear axle is a hybrid - centered Cruiser diff with mini truck shafts, fine spline pinion, welded, disk brakes, etc.

My axles held up well last year with the 39.5s, I just don't know if they'd like the 42s. I have the clearance and power to run 42s, and I think I have the gearing at 80:1.

The things I would worry about are the rear pinion and the birfs. I'm not a hammer-down driver, but I will get into the gas if I need to. I don't want to be back to worrying about breakage when I have to get on it. I have to talked to several guys running 42s on Toyota axles that say to go for it.

What do you think?
 
if your current axles are'nt equal to built 60s i would think twice about it. your power curve gets all changed too & and for only a 1 1/4" extra under the diffs. when i went from 35 to 37" tires i broke more parts & had to upgrade axle hardware.imo if you like the truck as is & it goes where you want it to find other ways to improve it other than bigger donuts. myself i have stopped at 37's. good luck w/it however you go.
 
Wheres the guys runnin 4-2's on Yotas? I know There are a few on here.
 
I have been running 42,s on my yota for a year and half. The onley problem i have had is breaking stock 410 ring gears. But i was breaking them with 35in boggers to. I would go with 42,s if i wer u. The ring gear is a lot stronger in cruser axle.
 
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