Violent Hopping And Shaking Deep Snow Steep Grade

2010 Tacoma
20,000 miles
Manual Transmission
SR5 4 cyl
Yellow Wire Mod for Trac in 4lo
Bridgestone Blizzacks
Sandbags over wheel wells no cables or chains

Earlier this winter I braved an unplowed road with 14" on snow and a thin layer of ice underneath. I have a very steep grade to climb with one gnarly S curve. The run is about a mile. With a 4.7 litre it soon became clear that 4hI was getting me nowhere. I switched to 4lo and still had Trac and VSC available since I did the yellow wire mod. In 4lo on a steeper part of the road I began seriously bogging down almost to a stand still like in 4hi. I accelerated with the tac hitting 7 as I was getting stuck. The rear end of the truck began violently jumping with the gear shift shaking back and forth. Then I noted the engine RPM raising and lowering even with my foot constant on the gas pedal. This is not the only time I have experienced the hopping of the rear end.

Through another thread I find I may have had axle wrap. Question is what is the most effective way of curing the hopping and shaking? I really need to travel this road in the winter and several times a year the road is going to be like this... that's why I bought the truck. I don't do any off roading just snow.

 

I won't field the obvious questions here particularly the 4.7? (4.0 i assume) and trac differences but you do realize the front diff on standard tires has about 9-10 inches of clearance. 14" inches of snow will turn you into a plow instantly if that was the case, but probably wasn't as big of a deal then the other items you listed.

I have had this happen to me on ice under snow in 4hi and usually going into 4Lo resolved and hop or vsc/trac activation lights that was going on. I believe the rpm control you saw was the engine regulation which happens with vsc trac if you've done the mod. This normally only happens in 2wd sans the mod you made. Check out the numerous trac threads and I'm sure you will find better information.

 

wheel hop. rear leaf spring characteristic.

if you start feeling wheel hop GET OFF THE GAS! it beats the crap out of the driveline

 

Yes I was pushing snow on this one. This was not the first time I experienced the hopping although the other time was less snow. I have read that the engine regulation may have been a byproduct of Trac and VSC. Thanks for confirming. I think I tried switching off VSC and got nowhere fast. Looks like a lift is in certainly in order. Yes 4.0. Doink. Thanks!

 

What are you running for tires? Tires that are better suited to your use may be more beneficial than a lift in some instances.

 

Even after getting off the gas and with just enough acceleration to barely move I started hopping again. Would upgrading the rear leaf springs make a difference?

 

Bridgestone Blizzacks DMV1

 

Changing your leaf springs will make the biggest difference. Upgrade to a pack with more leaves.

 

^^x2

 

You're spinning the wheels for all they're worth, which is what TRAC is trying to prevent with the throttle and brake control.

 

Yeah, that's the info. But his description sure sounds like throttle control, doesn't it?

 

Couldn't the rev spikes coincide with the tires breaking traction ? On ice or airborne ?

 

My rear end was hopping these past couple of days when driving through deeper snow. Wasn't as much an issue when it was fresh snow.

I did some reading and found that wheel hop was the most likely cause. People were emphasizing the problem of shock loading the driveline when this happens, so I just back off the gas when the shaking starts.

More weight in the back and lower tire pressures will help, since traction will be maintained and the rear tires will be less prone to breaking free of their grip. Mashing the gas pedal will only cause the tires to break free.

 

Been up in the hills for a few days (no snow) and came back to a lot of responses to ponder. This is all great info.

There are a few things that I read that I would like to do but.... as far as chains I had to sign something when I bought the truck that said basically if I used chains it would void warranty. Also I'm not sure I could get them in the space if I wanted to. So I bought cables but haven't used them. The part of this story I didn't relay that I was a week out of knee surgery and in no way was getting stuck or cabling up. Fact is like someone else said I shouldn't have been up there in the first place. However there are times when I have to get up this mountain. That being said and the fact that 14 inches isn't uncommon a few times a year I think lifting the truck is a must. Any reccomendations on leaf springs?

Again thanks for all the info particularly the common sense stuff that non offroaders and first time 4 wheelers like me are tards about like

Backing off the throttle and getting another run at it
Airing down

AFA 4Lo I wouldn't have made it had I not had that option.

I will do do some experimentation in not so rugged conditions with Trac off maybe as early as next week according to National Weather Service.

Fact is we have a very very steep long grade and the conditions when in deep snow are somewhat unusual to most people. So thanks again!

 

I used to live for "wheelin" in the snow. The hopping you are experiencing is plain old axle wrap. My 84 4X4 did it, my 89 4X4 did it, my Prerunner does it and my sprung over trail rig will do it.

Snow changes day to day and hour to hour. What worked for getting up the hill in the morning might not get you home in afternoon. Up here 90 miles North of Sacramento the snow wheeling starts at 4800 feet and goes up from there. In the morning you might get away with high range and 30mph to get to the lake. In the afternoon when it's warm and the snow is soft you might drive for miles is 1st gear low range (66 to 1 ratio. 4000rpm in 5th = 18mph, twice as low as a Toyota) with your foot off the gas. It's also not uncommon to adjust tire (32 x 10.50 Swamper Radials cut to hell with a tire grooving tool on 15x8 steel wheels) pressures 3 or 4 time during the day, ranging anywhere from 5psi down to 1.5psi.

I was breaking trail around Christmas in about 3 feet of soft almost dry snow. Playing with the gears and the gas resulted in 2psi in the tires and 2nd gear low range 2200rpm allowing forward movement with no spinning. The drifts were leaving snow on the hood which is about 3 1/2 to 4 feet off the ground. 2400rpm and I got wheel hop. 2000rpm and it bogged down and started to dig in. On the way home 3hrs later the sun was out and the snow had some moisture in it. This turned it into a 2nd gear high range full throttle giggle fest back UP the same trail.... Still at 2psi with no bead locks and no tire issues.

Long and the short of it play with it, try different gears, diff throttle settings and RPM, diff tire pressures and vary the speed. As long as your carefull most tires will stay on most rims down to about 5 psi. If you don't have a way to air back up you should probably stick to the plowed and/or packed roads. Don't be afraid to "crawl" snow as some days it won't provide enuf grip or support to handle any speed or power........ YMMV RON