I'm on 33's and had the 10% underdrive done by @cruiseroutfit a few months ago and it's been excellent. Didn't raise the RPM's so much that freeway driving is miserable, but is much easier to maintain freeway speeds.
35" Tires. Ring and Pinion or 10% T-Case Gears?
- Thread starter danmcph
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Now is your opportunity for the 4.88's from Nitro. 75% off
smittycrusher
"Hey big guy, you a golfer" - Roger Dorn
When I had 35s, I did both high and low range gears from @cruiseroutfit through @ACC Toyota . I LOVED THE RESULTS! I had stock gears in the pumpkins and ran 315s. It was a huge improvement. Low range was SIGNIFICANTLY lower than it was before...and lower than it would have been with 4.56s or 4.88s. The high range was almost equivalent to 4.56s in the diffs. Now that I have 37s, I just added 4.56s in the diffs and that equated to a net effect of 5.00 with even lower low range. I couldn't be happier.
Oh and with the 315s, I was very surprised at the MPG difference. I didn't expect any improvement. Look at these four fill ups and see if you can see where the gear change happened (you can ignore the EF, that is just my marker that I filled up with Ethanol Free gas). THAT IS A 15% MPG IMPROVEMENT!!!
Oh, and YES, these numbers are adjusted for speedo differences as my totals miles are taken from the GPS, not the odometer.
Oh and with the 315s, I was very surprised at the MPG difference. I didn't expect any improvement. Look at these four fill ups and see if you can see where the gear change happened (you can ignore the EF, that is just my marker that I filled up with Ethanol Free gas). THAT IS A 15% MPG IMPROVEMENT!!!
Oh, and YES, these numbers are adjusted for speedo differences as my totals miles are taken from the GPS, not the odometer.
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^ this is what I've had a hunch about for a while and it makes perfect sense.
That said, all the other comments saying 'just the t-case gears work' is also encouraging as that's what I've been wanting to do to get to 35's with some sort of power band/control. (read cheapest first)
Of course tho, it's not like we're talking about alot of torque from a 300kmi vintage 1FZ, and certainly not from my own 1FZ that went 'steam-powered' when I put on 33's.
I've read all the other threads on this topic, but thanks to those who responded to this one simply for a modern/recent update on the issue. Great info to chew on.
edit: just went for 4.88 Nitros front and rear @ <$200. Couldn't pass that up!
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Hi Dan, tou tried to help me out in this thread... Trying to remember for sure, but pretty sure I ended up just reusing the original.
Thanks,
Jason
77mustard40
SILVER Star
Yep I pulled the trigger as well, screaming deal!
My wife is going to kick my ass for buying these 4.88 gears but when you can save $400 why not.
My brother and I installed the 10% underdrive Sumo Gears in our transfer cases a few weeks ago. I bought a cheap shop press from Harbor Freight and we got after it. We did not take the entire cases out. We took the backs off to get to the gear sets. The first one took us a while but the second one was done in approximately 3 hours start to finish.
If you are going to tackle this job in your driveway and intend to do it the way we did (taking the case apart under the rig) then be sure to remove the wiring harness from the top of the t-case. Take the CDL actuator off, and get the detent and spring out of the transfer case before re-installing the gears.
Overall the install was simple. I wish the Sumo Gears came with some instructions. That would have been killer.
There is a tiny whine with my Gears at around 70 MPH. I am running some 32 inch tires right now and I run about 2700 rpm at 70 MPH. I installed these Gears in anticipation of running 35 inch tires in the fall. I also have some 4.56 gear sets I will be installing after the tires.
Suuuper great product. Super great price. Best mod on my rig yet. Directions would make this a 5 star product
If you are going to tackle this job in your driveway and intend to do it the way we did (taking the case apart under the rig) then be sure to remove the wiring harness from the top of the t-case. Take the CDL actuator off, and get the detent and spring out of the transfer case before re-installing the gears.
Overall the install was simple. I wish the Sumo Gears came with some instructions. That would have been killer.
There is a tiny whine with my Gears at around 70 MPH. I am running some 32 inch tires right now and I run about 2700 rpm at 70 MPH. I installed these Gears in anticipation of running 35 inch tires in the fall. I also have some 4.56 gear sets I will be installing after the tires.
Suuuper great product. Super great price. Best mod on my rig yet. Directions would make this a 5 star product
Woofythewolf
SILVER Star
Only a few random items are on sale, and you don't know which ones until you open the page. A bit annoying since their site is a bit slow right now, probably because of the sale. For example, 4.37 front gears are also on sale, but not the rears. Or maybe it was the other way around, but you get the idea.
They also have the front solid pinion spacer + shim set on sale for $11.50 (SKU: SKCSTV6), but the rear one is still $70+. But they have the crush sleeve for the rear on sale for $7... But why go through all the effort of a gear install and leave a crush sleeve.
They also have the front solid pinion spacer + shim set on sale for $11.50 (SKU: SKCSTV6), but the rear one is still $70+. But they have the crush sleeve for the rear on sale for $7... But why go through all the effort of a gear install and leave a crush sleeve.
I ordered from justdifferentials.com.
But I just checked and it looks like both front and rear 4.88 are out of stock now. I'd imagine you could still order and they would back fill when possible. But a call first would prob be best.
Cruiser Outfitters has them in stock. They could ship tomorrow.
Came across this thread while doing research on this Sumo underdrive set, very helpful.
Would 34”s put it closer to a 10% increase over stock?
The 10% is based off the gears not the tires. So you might be closer or even over a tad.
Thanks! Understood that the 10% underdrive is based on the gears, so does that mean that a 10% size increase over stock tires would be the ideal pairing?
COS80
SILVER Star
Factory r&p is 4.11. 4.11 * 1.1 = 4.521. closest r&p offering is 4.56.
Now web search "tire gear chart" and open any picture that comes up. Use the chart to see your stock rpm and find the tire size/r&p combo that suits you best.
Thanks. I’m referring to a 2000 LC 100 series, so the factory r&p is 4.30, so at 4.73 I’d be in between the 4.56 & 4.88.
Stock tires / r&p show 2896 on gear ratio chart. Looks like 36” tires gets me closest to that ratio.
I appreciate the guidance.
