42s on my FJ40?

[R.K.]

I am trying to decide if I should run 42s on my FJ40. Currently, I am running 39.5" IROKs on 17" beadlocks. I love the IROKs, I would be going to a 42" IROK if I do go larger.

I have a 5.7L Vortec/SM465/LoMax NP205. I am still running Toyota axles, somewhat built. The front has 30 spline Longfield birfs/inners, cromo hub gears, ARP hub studs and knuckle studs, a LockRight, armored removable diff cover, is cut & turned, etc. The rear is a Cruiser/mini truck hybrid with an FJ40 4.11 fine spline diff, welded spiders, mini truck axle shafts, disc brakes, etc.

My Cruiser is sprung-over/shackle reversed in the front, and has just been 4-linked in the rear with air shocks. The crawl ratio is 80:1, and the wheelbase is 105". It weighs around 4000 pounds.

I know my driveline will hold up to the 42s, it's the axles I'm concerned with. The axles worked fine with the 39.5s last year, 18 days on the trail with no breakage. I know a couple of guys running 42s on Toyota axles in light weight buggies with no problems. My main concern is the rear pinion and/or rear axle shafts.

Should I leave well enough alone with the 39.5s, or try the 42s?

 

[Mace]

I would leave well enough alone.

42's are too big for toy stuff imho.

 

[Sputnik40]

Ha! You first and tell us how it goes. Seriously thought - with stock width axles I'm wondering if you won't also start running out of room for upward travel. My 39"s with flipped springs both ends are rubbing on the wheelwells up front at full stuff (cut off fenders). Even with bumpstops moved out how much upward travel do you have now?

I think I have a pic of a 3 and 4 linked FJ40 with no front fenders sitting on 42" IROC's - looks awesome.

I'd like to see some pics of your 4-link and the shocks. What's the benefit of air shocks over high end ($$$) coil overs?

Lastly - You've seen my pic of the busted Poly axle - hopefully just a defective one - but might be time to get some Chromo shafts. Good luck with the pinion.

 

[LC_Hamma]

You already broke thru the D60 barrier runnin 39.5's. I'm actually SHOCKED you haven't had any breakage so far. You've had good luck pushing the limits, what's stopping you now? What trails you runnin anyway? Done Peckerwood & Lower 2? ;p

 

[Isotel]

The Home Grown Crew Runs 42's on Supper beefy Toyota stuff.. but they break stuff! they also run those rigs very hard..

Remember, with 42's and 1 tons you will have similar diff clearance as Toyota stuff with 39's!

 

[R.K.]

You already broke thru the D60 barrier runnin 39.5's. I'm actually SHOCKED you haven't had any breakage so far. You've had good luck pushing the limits, what's stopping you now? What trails you runnin anyway? Done Peckerwood & Lower 2? ;p

I wheeled at Tellico twice this year - 6 days during the GSMTR and 3 days in October. I think I met you on Guardrail during the GSMTR. BTW, Lower 2 isn't very impressive any more. We ran it 4 times during the GSMTR with no winching.

 

[R.K.]

Ha! You first and tell us how it goes. Seriously thought - with stock width axles I'm wondering if you won't also start running out of room for upward travel. My 39"s with flipped springs both ends are rubbing on the wheelwells up front at full stuff (cut off fenders). Even with bumpstops moved out how much upward travel do you have now?

I think I have a pic of a 3 and 4 linked FJ40 with no front fenders sitting on 42" IROC's - looks awesome.

I'd like to see some pics of your 4-link and the shocks. What's the benefit of air shocks over high end ($$$) coil overs?

Lastly - You've seen my pic of the busted Poly axle - hopefully just a defective one - but might be time to get some Chromo shafts. Good luck with the pinion.

My tires can flex into the fender aprons in the front, I don't run any fenders. I don't have bumpstops currently, I do plan to add some in the front though.

I'll post pics of the rear 4-link soon. The air shocks cost about half as much as coil-overs.

I've seen your broken rear axle pics. You Florida boys are hard on rear axles! You and Jim both broke rear axle shafts at the GSMTR in 2004 I think. I've only seen one other off-set rear axle shaft broken. I have never personally seen anyone break a mini truck rear axle shaft, although I know it's been done. I have had good luck with the fine spline pinion in the rear so far.

 

[LC_Hamma]

I wheeled at Tellico twice this year - 6 days during the GSMTR and 3 days in October. I think I met you on Guardrail during the GSMTR. BTW, Lower 2 isn't very impressive any more. We ran it 4 times during the GSMTR with no winching.

May have I do remember an N.C. crew atop helipad. Who was that guy burnin up his boggers tryin to get up to the top of helipad? Too much traffic & breakage on Lower 2 so I bypassed it this year

 

[Tapage]

you can hope your front axle can hold and handle this power and tires .. more concern about the rear, could a poly performance axles be a option just to keep the Toy rear . . with no real guarantee ..

 

[brokenparts]

Isnt LT running 42s on his toy junk?

 

[fj40forlife]

no he has like 37 and wants to go 40s or 42

Eric

 

[Fast Eddy]

more concern about the rear, could a poly performance axles be a option just to keep the Toy rear . . with no real guarantee ..

I think that just moves the worry spot to the pinion shaft.

 

[bustanutley]

Ben is running 44's with a 2UZFE on toy parts incased in diamond housings on the raisin/pipebomb.

No axle failures to date since the v8 other than a knuckle that got loose and wallowed out the studs. He is running 35 spline shafts in the back with a landcruiser diff. If you run cromo shafts the rear should be pretty stout, with a 4 link I wouldn't worry about the pinon shaft popping given that it is a fine spline, but I think the gear set will be the weak point.

Joey has been running 42s on toy parts for quite a few years with a supercharged 3.4L

He has broken a bunch of 8" rear diffsand a few IFS rear shafts. The fj80 front hasn't had any problems that I know about other than a ripped up knuckle. He switched to a tacoma rear with the 8.4 rear diff and it hasn't failed, but it hasn't been wheeled that much, spitwad is now becoming a buggy with the same parts.

Making 42s work with stock width axles is going to be a chore, I rub on my bib with 40s with fj60 axles 1.5" spaces with 3" BS wheels. The 42s are a lot bigger... I personally would put your money for 42s toward a dana60 front if I were you...

 

[Sputnik40]

I wheeled at Tellico twice this year - 6 days during the GSMTR and 3 days in October. I think I met you on Guardrail during the GSMTR. BTW, Lower 2 isn't very impressive any more. We ran it 4 times during the GSMTR with no winching.

Lower 2 is near to being a highway except for the last little remnants of the big rock that's still pretty fun. Blitzed it several times in May and again in August this year - only stopping twice to fool around on the big rock, but took it easy having already busted a pinion playing around with the skinny pedal elsewhere...

I'm running almost no bumpstops with just the inner fender wells - and I'm hitting the front of the bib at full stuff and when turning - stock axles, WE beadlocks and 2" spacers. I really think 42's will severely limit your up travel - unless you go wider. I think 39's are the perfect compromise and make for just an incredibly flexy ride for springs.

 

[R.K.]

I'm running almost no bumpstops with just the inner fender wells - and I'm hitting the front of the bib at full stuff and when turning - stock axles, WE beadlocks and 2" spacers. I really think 42's will severely limit your up travel - unless you go wider. I think 39's are the perfect compromise and make for just an incredibly flexy ride for springs.

My front tires hit the corner of the bib when turned and stuffed, but I trimmed the bib to prevent it. Between the bumpstops I'm going to add and the trimming, I hope it doen't rub any more (with 39s). My front axle is stock width with 1.5" spacers and 3.5" bs wheels.

 

[R.K.]

May have I do remember an N.C. crew atop helipad. Who was that guy burnin up his boggers tryin to get up to the top of helipad? Too much traffic & breakage on Lower 2 so I bypassed it this year

Here is my Cruiser on Guardrail.

Is this the Cruiser you're referring to that smoked the Boggers? He is Jonathan Lehman - '69 FJ40, 2F/SM420/Cruiser t-case, 4 linked rear, 38.5 Boggers, exo-cage.

 

[fj40forlife]

any pics of your rig linked?

 

[fj401ton]

Go with the 42's and upgrade to d60 and 14ff or d60 in rear. I have a d60 and 14 ff locked both ends 4340's in and out with 42" iroks in my 68 fj40. this combo is excellent and not all that expensive. I have a crawl ratio of 138:1 and nothing has broke ,,,,yet. love the 42's

 

[R.K.]

I talked to a guy who runs 42" IROKs on his FJ40 today. The back half of his 40 is tubed and the rear is 4-linked. He runs the straight 6/SM465/Cruiser t-case on FJ40 axles with 27 spline chromo birfs/axles. I think he's been running these tires for about a year now. The only breakage he's had is the stock t-case.

After talking to him, it kinda makes me want to try the 42s again!

 

[Mace]

Then do it and see how it works out for you..