8 Speed Transmission

[CheechDogg.0n37s]

do you understand how tire size affects trans ratios?

How about you just explain it to him

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[tjfdesmo]

Does the 8 speed keep searching for the right gear while cruising at highway speeds? Any input on how it reacts with 37s?

He has made no mention of it doing any gear hunting, but his truck is 100% stock.

 

[Alloway]

How about you just explain it to him

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2nd

 

[crazy jerry]

look at a gear calculator and input all the necesarry info. larger tires change all the effective ratios through the trans. axle regear is needed to get the effective ratio back to near where it was before the larger tires. do some research brotha

 

[Alloway]

look at a gear calculator and input all the necesarry info. larger tires change all the effective ratios through the trans. axle regear is needed to get the effective ratio back to near where it was before the larger tires. do some research brotha

why do research when we have an expert like you to ask for advice?

 

[RVGuy]

8spd is fantastic. My wife’s 1500 is fracking awesome. I have drove 2 new hd with the 8spd and it’s equally as impressive. I really really hate my 6spd

Agreed, I delivered a Ram 1500 with the 8 speed for my boss the other day, now I hate my 6. Counting down for the day I trade it in on an 8 speed.

 

[TheEnder]

Agreed, I delivered a Ram 1500 with the 8 speed for my boss the other day, now I hate my 6. Counting down for the day I trade it in on an 8 speed.

Personally i can’t say the same.

The 8 Speed 845RE in my Chrysler 300 is amazing, don’t get me wrong, but i prefer the 65RFE in my 2013 1500 just a tad over it as i feel that it’ll last forever (459K on the clock) and she drives beautifully.

Considering the 65RFE has the same final drive ratios as the 8HP70 there’s really no benefits for me personally other than more gears to shift through.


Sent from my iPhone XS Max in my 2013 Magnum 4.7L V8

 

[crazy jerry]

why do research when we have an expert like you to ask for advice?

this isnt a engineering forum dealing with complex matters.

as the number of gears increase in a transmission, so will the amount of shifting, unless it has the ability to skip gears , not sure if rams 8spd has that abilty or not. but anyways, a 8spd would shift 7times from a stop to high gear. 6spd shifts 5times. i hope we all understand that part? since the gear spacing is closer when you increase the total number of gears in the trans, it will shift up and down much more. some people mistake the frequent up/ down shifting for gear hunting. really the trans is just doing what its supposed to do and keep the engine in a more desirable point of the power curve, made possible by increasing the total number of gears and decreasing each gears gap spacing

how a transmission reacts to 37s from a electric or computer perspective is hard to say. im sure new transmissions rely on many inputs through the computer to tell the trans what to do. 37 tires throw off all those inputs

from a effective gear ratio perspective, its easy to see what 37s do to the trans. just find any gear calculator and put in the numbers

 

[RVGuy]

Personally i can’t say the same.

The 8 Speed 845RE in my Chrysler 300 is amazing, don’t get me wrong, but i prefer the 65RFE in my 2013 1500 just a tad over it as i feel that it’ll last forever (459K on the clock) and she drives beautifully.

Considering the 65RFE has the same final drive ratios as the 8HP70 there’s really no benefits for me personally other than more gears to shift through.


Sent from my iPhone XS Max in my 2013 Magnum 4.7L V8

I find that my trans is never in the right gear, really the 6 speed is a 5 speed since 2nd and 3rd are so close in ratio that it doesn't even use it for anything except engine breaking. That leaves 3 gears below overdrive. Even then, 5th and 6th are pretty close together too. Top gears between the 6 and 8 are really close to the same, but the benefit comes from the deeper first gear and the increased number of options of gear ratios between them. It's much easier for the engine to keep to the power band when there's 6 options below overdrive instead of 3.
I haven't really heard anything bad about the 8 speed and higher miles, considering it's been around for 7 years now I'd think it must be pretty reliable then.

 

[OCDTech]

unless it has the ability to skip gears

I know its possible the Ford 10spd auto does this. Not sure our 8 does.

 

[Dodge 1500 4X4]

I came from the Ford 10 Speed all new in 2018, its a roll of the dice to what gear you're going into next upshifting and downshifting, worst when its cold, I had 4 reflash of the PCM to replacing the valve body problem went away for a little while only to come back again, never solved for me that made me come to FCA and the ZF 8 speed.

 

[OCDTech]

I really like my 8spd.

 

[Chris_]

do you understand how tire size affects trans ratios?

Yes, somewhat. I know that the drive ratio changes, that's why most people go to 4.88 or 5.13 in the axle when stepping up. I'd heard that the 8-speed has a lower 1st,and hope that would be sufficient until other factors cause a reason to dig into the axles.

Thank you for the follow-up information.

 

[crazy jerry]

I know its possible the Ford 10spd auto does this. Not sure our 8 does.

im not familiar with either trans but i do know that if you increase the number of gears, the spacing (if its designed logically) gets smaller and should make gear skipping a decent idea. the zf8 may not have close enough spacing to allow for gear skipping

 

[crazy jerry]

Yes, somewhat. I know that the drive ratio changes, that's why most people go to 4.88 or 5.13 in the axle when stepping up. I'd heard that the 8-speed has a lower 1st,and hope that would be sufficient until other factors cause a reason to dig into the axles.

the lower gears arent so much the problem as the higher gears. although if your towing heavy it can be a problem in lower gears as well. without regearing the axles, i suspect youll lose top gear as it becomes so far out there that the engine just cant pull it

with the 6spd trans ive basically lost top gear after going to 37s. luckily ive got new gears sitting in the garage waiting to get installed

 

[Tom8]

8spd is fantastic. My wife’s 1500 is fracking awesome. I have drove 2 new hd with the 8spd and it’s equally as impressive. I really really hate my 6spd

Then get a 8spd ram.

 

[unxpctd]

I love the 8 speed ZF. I've driven 3 of them for a total of over 100K

2014 Dodge Durango V6: Work vehicle. This is what introduced me to RAM and the 8 speed. Loved it.
2014 Dodge Durango R/T Hemi: Loved it....drove it to all 4 corners of the US on various vacations, just wanted something with a larger cab.
2017 Ram Rebel Hemi: Again...just love it. 37K miles now...have it set up the way I want...enjoying the heck out of this truck.

The Rebel doesn't get the mileage that the Durango with the Hemi did. Larger truck, Rebel has the 3.92 gears. I get about 17-18mpg now...was able to squeeze 20-21 out of the Durango.

Either way...it's more comfortable and larger than the Durango. Wouldn't change a thing.

Can't wait until my next truck...2500/3500 with the ZF (even possibly a CTD when they hopefully come out with a ZF for the Cummins in a year or two).

 

[Sandevino]

OP - is your paid off or close to it? If so, the ZF is absolute trash and stay away from it.

If not....well, go drive one and bring your wallet.

 

[SkeeterBait]

My 2020 PW is only a couple of weeks old, and I must say that compared to my 2007 4x4 2500 diesel this monster will push me back into the seat with this 6.4 hemi combination. The tranny shifts right into the powerband with each gear change. Amazing powertrain to say the least! I especially like the manual + & - steering wheel buttons, using them to slow down on highway offramps instead of using the brakes. My 07 RAM had a Jake Brake and using that allowed 95k miles before the first brake job.