Ali SC3

iTrader: (10)

the problem isn't the aggressiveness all over, that can be cured with a rear end change as you said, the problem is the 1-2 shift. changing the rear diff does not cure the problem very much as its the relative spacing of those 2 gears, and spreading it out will help 1 be longer, but it will make going into 2nd worse (I think).

2nd -5th on the r155 is pretty close to an r154... there is only a .05 to .1 ratio difference on those gears.

But 1st is way short on the truck transmissions. you speed through 1st, but when you hit 2nd you feel it bog down unless you were redlining through 1st... even then its not great and redlining 1st even in normal driving gets old. its kind of hard to explain but drive the truck and you will understand. You need that 1st gear ratio when you are hauling a bunch of gear and don't care about how fast you are accelerating, the idea is to get all that extra weight moving and just get you into the range of 2nd gear.

On our cars you want the gears more evenly spaced like the r154 (they designed the r154 ratios rather well), so if you had a turbo you would probably fall out of your powerband going into 2nd on the r155... they are just too far apart. PAst 2nd you probably wont feel the difference.

the truck guys have the opposite problem, they avoid using the r154 cause of the 1st gear, and they like the r151f which has an even higher ratio than the r150/r155. they even discuss changing the 1st gear ratio, how hard that is I am not sure, mybe its possible to do while in there doing the input shaft, then it would be a really good replacement.

the solistice trans there are more things to address like mounting and driveshaft, but it has better ratios so to me its more worth it. as you can see below they are more aggressive ratio wise also, but they are more evenly spaced between 1 and 2, and 2 and 3 etc... so there is no dropping out of the power band in this case. this trans paired with a lower diff ratio would be a nice setup as the gears are close but are quite evenly spaced, and you would get an even better overdrive.

Lots of ways to do it I Just wanted to make it clear for those that have never driven it in the trucks, 1-2 feels odd.

the solistce ratio:
3.75
2.26
1.51
1.00
0.73
3.67

R154 ratio difference between 1-2 shift: 1.3
solstice ratio difference between 1-2 shift: 1.49
R155 ratio difference between 1-2 shift: 1.9

supragt35

first gear r154 toyota part number#3303260081 $142 new from dealer if you really wanted to change out the first gear ratio but with guys running a heavy duty clutch i dont see why starting in 2nd gear will be a problem

supragt35

and for up hills use 1st

Kris9884

iTrader: (7)

Being an Aisin Seiki family trans is enough for me to assume they hold some power but do we have any solid evidence that the Solstice/Sky/Colorado version wouldn't grenade at 300whp?

Ali SC3

iTrader: (10)

there are lots of online videos of upgraded 2jzgte swaps into solstices
heres one at 660hp so yeah 300 should be no problem. All the R series internals can handle similar amounts.

supragt35

We are talking r155 don't get side tracked with the ar5 i just explained to you guys the price difference

Kris9884

iTrader: (7)

Oh there's no confusion on specs or price, the R15x series are proven and we all know what they are capable of, its an old topic.. But since the AR5 was brought up I figured I'd ask.

supragt35

I don't see how this is a old topic if there is not a single post in clublex about a r155 in a sc300

Kris9884

iTrader: (7)

Don't put words in my mouth, I said the R series are proven and we know what they are capable of and THAT was common knowledge. Keep up the good work on the R155 man, we want to know how it turns out.

supragt35

I see it turning out to be jackpot and I will never have to deal with a 25+ year old r154 who people still sell for $800+

Kris9884

iTrader: (7)

Do you know if the Tacoma it came out of was a 4cyl or a 6cyl? Looking through Tacoma options, there's a 5 speed option for both, just wasn't sure if it was the same trans for both.

Edit: Never mind, the 6cyl are all 6 speed and the other options were 4WD which obviously wouldn't work.

supragt35

2005-2014 all work

INTIMAZY

iTrader: (5)

Any idea if these r155 have the rear seal issue when getting close to the 500hp mark?

Ali SC3

iTrader: (10)

The 2wd truck transmission have a slip in rear driveshaft, so I would think it is a real possibility it has a similar rear seal issue.

supragt35

I don't see why there who'd be a rear seal issue