Calling all gearing experts! (1 Viewer)

[2mountainfish]

I currently have a FJ60 with a good and strong 2F, stock 4 speed and t-case, running 4:11 gears and 33s. I would like to put in a 5 speed to gain a little lower first and of course the 5th gear overdrive. I would also like to change my t-case to 3:1 gearing. My question is, given that it will drop my gearing roughly 7-8% when the t-case is in 2 high , will that negate the gain of 5th gear overdrive for the highway? Also is there a more cost effective way to lower off road ratios without killing highway ratios. Thank you for your time, Jerry.

 

[Seth S]

I’m sure the gurus will answer soon....but there are some handy gear ratio calculators online to make life really easy. You can look up the 4sp gear ratios and the 5 speed gear ratios and just do the math with your 33” tire size. You should be able to see the difference quickly and answer your question.

Also a pencil and a pad of paper and you can just do the calf yourself once you have the ratios handy

 

[2mountainfish]

I agree the gearing calculators will give the ratios for the stock t-case but I am unfamiliar with the 3:1 t-case gearing and how it affects the high range ratios.

 

[Seth S]

having never thought about or looked at this mod I did some reading. I came across one site offering 4:1 and 3:1 ratios. They say the 4:1 will drop high range by 10% and the 3:1 will drop high range by 7%.

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[2mountainfish]

So I found this chart and it shows all the trans ratios. I believe you are correct about the t-case being 1:1 in high , but I seem to have read somewhere that when you do the conversion to 3:1 or 4:1 it lowers your high final drive. So I guess that is my real question, thanks for your input .

 

[Seth S]

Also I think the H42 4th is 1:1 and it looks like the h55f 5th is .845:1. So the 3:1 would take away some of the 5 speed benefits but would still be better than the 4 speed. Those ratios look correct?

 

[FJ60Seth]

I had the same thought as Seth S, the 3:1 gear set is only for low range. If that’s the case, it’s the route I’d go.

I have an h55 with 4.11 diffs. It felt great on 33’s. Now I’m running 35’s and I feel like I have to run at 75mph to comfortably keep the rpm’s in 5th gear’s sweet spot.

 

[2mountainfish]

If I did the math correctly that would give me a final drive in 5th of .785:1 with 3:1 t-case gearing, which is still better then the 1:1 that I currently have. Now I just have to figure out what the RPM difference will be and will it be worth the $$$$$$$ to convert.

 

[Seth S]

If the H55F has a .845 ratio and you go to the 3:1 and lose 7% off high then I think your equivalent 5th becomes .904:1 going into the diff.

 

[2mountainfish]

If the H55F has a .845 ratio and you go to the 3:1 and lose 7% off high then I think your equivalent 5th becomes .904:1 going into the diff.

You are correct sir, I went the wrong way,haha. So it looks like I will be running almost the same rpm in 5th, after all the gearing and trans changes, as I am running now in 4th, but with kick a** low off road gearing. The hard part will be the $4,000 dollar pill to swallow.haha

 

[Seth S]

.9:1 for 5th is still a nice drop from the 1:1 of 4th in the 4 speed. 10% lower. I saw about an 8% change iirc when I went from stock tires to 31’s and that was a major improvement.

 

[2mountainfish]

That's good to hear. Numbers on a page don't compare to real world experience, thanks again for the knowledge. .

 

[cruiserpilot]

I have the 3:1 low range gear set. I have a 5 speed. This particular gear set is 3:1 low range,
No effect to high range. So full advantage from 5th gear over drive.

That being said. READ THIS: the kits are listed half way down the page.

Cruiser Outfitters

Then call Kurt @cruiseroutfit

This is your best source for parts and knowledge to complete this idea.
Also, Georg who is, @orangefj45 is the installation guy to do this as well if
you aren’t up to it. It’s intimidating to do it yourself, I did mine and it’s quite intense
to get into it.

In the end, it’s not the cost - it’s the value you get from it!

 

[2mountainfish]

Thank you, (In the end, it’s not the cost - it’s the value you get from it!) very well put. I will definitely have Georg clearance the case. I am fortunate to have a shop to work in, so swapping the trans and t-case wont be an issue. Did you experience any drivability or noise issues after the swap that I should be aware of?

 

[cruiserpilot]

No drivability issues at all. No reason to effect anything else about driving the truck.
My kit is from Australia and it’s an older version so my gear noise is higher than these new
Sumo kits. I’m actually thinking of trading up to a new set!

 

[too tall]

Why not leave the gears in the t-case the same and put a toy box or or some other doubler in there at the same time as the 5 speed? Then you get better low range and your top end will see the benefit of the h55.

 

[GeologistFelix]

So I found this chart and it shows all the trans ratios. I believe you are correct about the t-case being 1:1 in high , but I seem to have read somewhere that when you do the conversion to 3:1 or 4:1 it lowers your high final drive. So I guess that is my real question, thanks for your input .

View attachment 2124619

Just FYI, those numbers are wrong for the stock t-case ratios. FJ40 cases often had the ~2:1 low range, but all US model (and, I'm pretty sure, all other market models?) of the 60-series wagons had ~2.28:1 low range on the split case.

Looking at that table in more detail, and it looks like they have incorrect numbers for the H42 as well. Should be 3.6 for first gear, 2.3 for 2nd, 1.4 for 3rd, and 1:1 for 4th. Pretty sure they have the ratios swapped between the 40-series 4-speeds and 60-series 4-speeds.

So, keep that in mind when you're choosing numbers to compare between the stock/3:1 t-case gearing and H42 vs. H55.

Just for fun, though, here are some numbers to think about:

- RPMs at 65 mph in 5th gear with H55/3:1 low range kit/4.11 axles (assuming 33" tires = 32.7" actual diameter): 2319
- RPMs at 65 with 3:1 low range/7% underdrive: 2481
- RPMs at 65 with H42 and 3.70 gears (my setup): 2472 (and feels pretty happy until you hit a mountain pass/other steep uphill)
- RPMs at 65 with H55/3:1/3.70 gears: 2234 in 5th gear, 2644 in 4th
- RPMs at 65 with H55/stock t-case/3.70 gears: 2038 in 5th, 2471 in 4th

Realistically, I think you could skip the 3:1 gearset if you're getting the H55 and only ever plan to play on the rocks your 33s are sufficient for. Meanwhile, with my 3.70 gears, that 3:1 low range would work pretty awesomely with an H55 and 33s, and even better with the 35s I'd like to end up with eventually. Food for thought!

 

[2mountainfish]

Realistically, I think you could skip the 3:1 gearset if you're getting the H55 and only ever plan to play on the rocks your 33s are sufficient for

I hadn't really looked at it that way, very good point. I will never be running anything bigger then 33s due to the amount of lift and everything else that goes into shoving 35s or 37s underneath.

 

[cruiserpilot]

Why not leave the gears in the t-case the same and put a toy box or or some other doubler in there at the same time as the 5 speed? Then you get better low range and your top end will see the benefit of the h55.

Would that not entail relocation of transfer brackets? Rebuilding of drive shafts? Probably have to rebuild
transfer case while you are in there. How many companies are there out there who reliably build and
actually supply either doubler or model specific toy box? I looked when I did mine, but ultimately with
the selection now available in reduction gear sets this is a more conservative way of accomplishing that.
I think most guys, such as myself want the low range on hand. I’m not picking the hard line on the
Rubicon, just slowly getting through that one particular s***hole.
Maintenance wise, gear replacement is simpler more viable I think. Anyhow, that’s my thought on it. J

 

[FJ60Seth]

Why not leave the gears in the t-case the same and put a toy box or or some other doubler in there at the same time as the 5 speed? Then you get better low range and your top end will see the benefit of the h55.

That’s what I did and I wouldn’t do it again. The Toybox won’t clearance the trans hump so I installed a 2” body lift. The Toybox needs it’s own trans mount so I built that into a custom skid plate. The added length of the Toybox caused the front drive shaft, even with a double cardon joint, to hit the front cross member requiring the cross member to be notched. The Toybox requires that the H55F output shaft be cut. Both driveshafts had to be resized. Granted, the cool factor is high, but it was a *lot* of work. I’d go with the 3:1 low range gears or an Orion.