Gears for v8 towing… 4.56 or 4.88

[wrekreate]

Hello all, I am looking for some discussion regarding re-gearing my 08 v8.

Currently does not have much added weight beyond wheels, tires, roof rack, family, and trip/recovery essentials. Will be adding skids, sliders, bumpers, winch…

Running 285/70/17 Nitto Trail Grapplers (larger and heavier side of the 33’s spectrum) with a 2-2.5” lift.

We have just added an Opus OP4LE (off road pop up travel trailer with 3100 lb dry weight and 4200 lb GVWR) to the equation and while I already wanted to re-gear, now it seems more of a must.

My trips involve all terrains but feature many high mountain passes, mountain roads, and long steep grades.

We aim for as much dirt and off grid time as possible but do long highway drives frequently still.

There seem to be a good amount of threads/discussion revolving around the v6 but I am looking for discussion related specifically to the v8.

I am leaning more towards the 4.88 gear set but want to hear from some first hand experience with the v8 and 33’s when loaded down.

Yes, I very well may go to larger tires at some point but for the time being I am wanting to focus this on 4.56 or 4.88 gears, the v8, and 33’s.

Cheers!

 

[Runnin on E]

There are a number of gear ratio calculators. Here is one. Pick your gears and enter in the tires. I have the V8 but I couldn't tell you what RPM is peak torque. Try to put your MPH and RPM somewhere in the max torque range if possible.

Engine RPM / Engine Speed Calculator

 

[wrekreate]

Thank you for the reply. Yes I am well aware of the plethora of gear calculators out there. I am looking for firsthand experience from owners of v8 runners who have re-geared and their personal experience and perspective on the matter. I know the 4.88 gear set will have the revs up when cruising on the interstate. But I also have not found any input with regards to towing.

 

[kyle_pc_75]

For what it's worth, my V8 is similarly setup to how yours will be built out with skids, bumpers, tires, etc. I flat tow my Baja Bug up and down mountain passes with stock gears no problem. I'm guessing the Baja weighs about 2000 lbs.

 

[wrekreate]

Thank you for that answer. With the truck as it sits now, the transmission is hunting constantly on any grades and keeping the rpms between up in the 3-4k range with higher temps than I am comfortable with for any prolonged period. This is all while attempting to keep the vehicle between 60-65 mph on mild grades. Nothing too steep yet like we will be running over the next few months (4k - 10k climbs etc.)

Are you towing in 4 or D out of curiosity?

Perhaps I am just too sensitive as I am a big believer in mechanical sympathy, extra timely pm, and keeping this truck in tip top for a long while.

Will be changing all diff, transmission, and transfer case fluids again within next week or two before next towing trip.

 

[kyle_pc_75]

I put it in 4 when going up a grade, towing or not. The pass between Park City and SLC maxes out at 6%, and it pulls just fine. 235K miles on the odometer.

 

[Inv4drZm]

Get an upgraded trans cooler like my brother's Iconic Fabrication one. I don't have experience towing but a trans cooler is cheap insurance.

 

[Boort]

I can't speak to regearing your question.
But can say I've never thought about it since my 06 v8 sport, with stock engine and trans, running with ~600lbs of passengers, 150lbs of camping drawers, another ~200 lbs of gear/food, Sherpa Rack, sliders, on 33's, and a 2.5" lift tows my 3200 lb camper all around Colorado's mountains with no hunting. Towed it from Denver to California, All around the Sierras for 2 weeks and back. Ran at 85MPH where allowed and other than getting noticeably thirsty above about 70MPH she Did fine.

I'd recommend an ODB2 sensor to watch the Trans and other temps (I use a ScanGuage2) but had no problems on any of my trips so far.

Boort

 

[wrekreate]

I can't speak to regearing your question.
But can say I've never thought about it since my 06 v8 sport, with stock engine and trans, running with ~600lbs of passengers, 150lbs of camping drawers, another ~200 lbs of gear/food, Sherpa Rack, sliders, on 33's, and a 2.5" lift tows my 3200 lb camper all around Colorado's mountains with no hunting. Towed it from Denver to California, All around the Sierras for 2 weeks and back. Ran at 85MPH where allowed and other than getting noticeably thirsty above about 70MPH she Did fine.

I'd recommend an ODB2 sensor to watch the Trans and other temps (I use a ScanGuage2) but had no problems on any of my trips so far.

Boort

Good to know. What trans temps are you seeing and are you towing in 4 or D on these trips? Thank you.

I have an OBD link that I use to monitor both trans temps (two temp sensors in the a750f).

 

[Dave_in_VA]

This is a subject I have given a lot of thought to, in a couple of years post retirement I'm planning a Virginia to Alaska and back using my 08 v8 4runner pulling a travel trailer. I'm currently running 275/65r20s.

As an FYI, I didn't look it up, but I think your tires are 33s.

To fix the gear hunting, you need a:
GX470 - 5 Speed Nomad Valve Body - OPTIONAL LOCK-UP KIT – Cruisers & Company

This is a manual torque converter lockup kit. It is designed to keep trans temps cool by not using the torque converter. It also holds gears better.

There are two versions, one locks up 1 to 5 gears.this is good if you do hard core iff roading and need to control down hill dissent. IT requires an upgraded trans valve body kit.

The other does 2 to 5th gear lockup. The upgraded valve body is not required. If money isn't a big issue I would do both.

Attached/below are thee gear ratio comparisons. With the lighter trailer you're using, the 456s will allow better cruising. The 488s will limit highway cruising more when not towing.

My thinking was to focus highway speed towing somewhere between 2000 and 2100 RPMs. That's the yellow highlighted ranges.

 

[Boort]

Good to know. What trans temps are you seeing and are you towing in 4 or D on these trips? Thank you.

I have an OBD link that I use to monitor both trans temps (two temp sensors in the a750f).

Towing in D most of the time but drop to 4 for climbs where any warning is given to truckers for grade.

Interesting to learn about the 2 temp sensors as the ScanguageII only shows a single "TFT" value. Will have to look around and see if there are new codes to add the 2nd sensor if mine has it. (When I got the Scanguage in 2018 they had just finished adding the Toyota Trans programming codes to the microcode.)

Most of my long trips with the trailer are Spring/Fall (Summer is generally tent season for me, so the trailer stays at home.)

I generally try to keep the Tranny temps under the 200* F mark at the top end. I remember stopping in Utah near the Black Dragon Viewpoint on a trip to California after climbing from the basin up the San Rafael Reef. This is a 5 mile stretch of I-70 that averages out to about a 6% grade but has a a few climbs in like the 10-12%, (it's been a while so I might be off but that is what I recall). Temps on a 75* day got up to low 220's.

I also remember watching closely while running 395 in CA from Bishop up to Mono Lake, which is a long crawl at 55MPH from 4500' to like 8000' but not getting warm enough to stop cause there it's like climbing a few steps with big landings so you have a climb then a few miles of flat followed by a climb and a bit more flat...

Don't recall any issues towing through the CO mountains including the run up from Silverthorne to the Eisenhower Tunnels (7 mile stretch climbing from ~9200-~11200), Red Mtn Pass or Hoosier passes both 11k+ altitude 8% grade passes. the Air is thinner but often much cooler than 80* on all of these passes.

In coming back from the Solar Eclipse in Aug 2017 on an 80* day, we burned out the trans in my dad's Ford Van towing this trailer. The ride in that case was mostly flat with rolling hills, on Freeway pushing 80-85 MPH. We believe that the actions that killed the Trans in that Ford was STOPPING and turning it OFF to put away the trailer at the storage lot after pushing it hard on the way home. It was maintaining good temps (per the gauges) on the drive but between the storage lot and home started acting up. Basically we cut off the circulation of the trans fluid so if sat there soaked up the heat and broke down, damaging the trans as it turned to burnt gloop.

After this costly experience, I tried to get a good answer before towing with the T4R. The best I found were the posts by [MENTION=149207]AuSeeker[/MENTION] in this thread What is the upper limit of safe transmission temps?

TLR Keep it under 210, and cool her off by running on flat ground.

Now when I unhook I get off the highway early and take the back streets tot eh lot to keep her rolling till the temp drops below 200 and don't turn off the engine while unhooking and storing the trailer. (same for stopping for gas etc... try to keep her running till the temp is below 200. This can work in your favor by getting to lower cost gas away from the highway )

Since then I've talked to a friend who is a Toyota Master Mechanic and he agreed that this was a good plan to keep the Trans in the 4Runner happy. So this is what I do.

Boort

 

[AceSpades]

i tow a 2400lb boat on a 900lb trailer also through mountains, its a 40min drive through the inclines and with an aftermarket additional cooler it peaked at 207 degrees, i think it tows just fine with stock gearing and tires. I do row through the gears for the inclines but it does it without complaint. IMO the gear spacing in our 4Rs with 5-speed auto are perfectly spaced out, in fact it tows better than my 04 Expedition with 4-speed auto up the same mountain hills. Because of the 4-speed i had to select 3rd and 2nd where 3rd is kinda bogged down and 2nd is screaming. On the 4R i can find that perfect happy spot