Tranny gearing...

[Supra]

OK, as several of you know, I broke my tranny 2-3 weeks ago. I bought and swapped in a tranny from a member here that was supposed to have been bought from Tim @ Sound Performance, and possibly rebuilt by them (?). The rest of it's history is unknown.

Here's the interesting bit. 5 years ago, on my stock tranny I ran several 13.0@106mph passes at a local track in my 87T. This put me at the very top of 3rd gear and if I shifted to 4th made no differance in my times... The same holds true for my GF's 90T. 13.0@104mph in her car.

At chi2k6, I datalogged my runs and was thumbing through them last night. I noticed that I'm running to the middle of 4th gear with 111mph trap speeds. That's a 5mph differance. I was shifting out of 3rd 3/4 way down the track.

When cruising @ 60mph in 5th gear the car sits at ~2,700rpm which is the same as before so I never noticed any gear change. I have always said that this engine feels more torquey than any other though, so this must be why.

Questions:
Is this tranny from a pick-up or other?
Are the short gears benefitial? I'm leaning towards "no" since i have an extra shift in the 1/4 mile.

 

[Nick M]

The Tacoma/Pick up used both the W and R series, which is typical of auto manufacturing. I think the newer V6 Tacoma had the R150, which had ratios to reflect displacement.

 

[Supra]

The Tacoma/Pick up used both the W and R series, which is typical of auto manufacturing. I think the newer V6 Tacoma had the R150, which had ratios to reflect displacement.

This new tranny looked exactly like the R154 that came out of the car. I swapped my sensors and stuff to be safe. I'm surprized there isn't a list of R154's with different gearing.

The diffy is the OEM unit, so the tranny has to be the differance.

 

[boost PSSH boost]

It's a supra r154, Rich. Definitely not out of a truck. I know the trans was opened up before, I don't know if they rebuilt it, changed up gearing, or were just inspecting it. I know it was 100% the same as my old blown r154.

 

[Supra]

It's a supra r154, Rich. Definitely not out of a truck. I know the trans was opened up before, I don't know if they rebuilt it, changed up gearing, or were just inspecting it. I know it was 100% the same as my old blown r154.

Just talked to Tim. He has one hell of a memory. He remembered your last name, the color of the tranny and every detail about it.

The short version is that it's a 130,000 mile tranny from his early 89T that worked fine and never was rebuilt. As far as gearing, he thinks I'm just putting out more power and getting well into 4th should be normal for my car.

I need to go drag my GF's car to 110MPH just to be sure... :evil2:

 

[Nick M]

The factory repair manaul will have the ratios for the Tacoma. So will the TSB's we don't have.

 

[Supra]

The factory repair manaul will have the ratios for the Tacoma. So will the TSB's we don't have.

I think I may have accidently started a bogus thread. The gearing is stock if you calulate the ratio. I *am* shifting into fourth very early compared to my 2003 passes, but I'm not pushing as much RPM as I thought I was. The extra HP must be getting me to 4th much sooner, but the car isn't climbing from 104mph - 111MPH very quickly - hence the feeling like I'm shifting early and "deep" into fourth gear at the end of the track.

Sorry... :3d_frown:

 

[dbsupra90]

well, i was also gonna mention about tire size. that will have an effect. but it sounds like its all that mad powa!

also, ive noticed the stock tach vs afc/mpro/etc to be about ~200 rpm off

 

[Adjuster]

OK, when I had my R154 rebuilt, we looked at "upgrading" the 5th gear set to one used in the ASIN R150 for the V6 Tacoma pickup truck. It is slightly more overdrive by a few points.

In the end, it would have been about 230.00 to have it done, and IIRC, the final gear ratio difference would have gone from .70 to .68? (It was like .02 difference anyway.) I figured it would not slow down the motor that much at highway speeds to make very much difference with gas mileage, and it would not have been any problem power wise as my motor is not stock at all.

What would be cool is a final drive for the ASIN R150 series transmissions that puts the ratio into the .60 or .62 range. That would make a real difference in the RPM your engine would be turning at to tool along at say 83mph here in Idaho, a very common speed when driving for 4 hours straight across the state. It also would make my commute to the airport every week fun at 73mph, and improve on fuel use I'd have to belive. (Slower engine speed results in great fuel savings when your computer can trim fuel based on 02 sensor feedback while under low load contditions, and the TCCS does that now, but the stock ratio's are geared around the 230hp and tourqe figures of the stock engine.)

 

[Nick M]

I am pretty sure the stock R154 is .75:1, the A340E was .70:1.

I like the .62 idea. But I would want it as a 6th speed then. The T56 can come with a .62 I think.

 

[Greg55_99]

I am pretty sure the stock R154 is .75:1, the A340E was .70:1.

I like the .62 idea. But I would want it as a 6th speed then. The T56 can come with a .62 I think.

AX15 - 3.83 2.33 1.44 1.00 0.79
AR5 - 3.753 2.26 1.37 1.00 0.729
MA5 - 3.753 2.26 1.37 1.00 0.729
R150 - 3.83 2.062 1.436 1.00 0.838
R151 - 4.31 3.32 1.52 1.00 0.83
R154 - 3.25 1.95 1.30 1.00 0.75

Greg

 

[Mick91MkIII]

1993 F-body T56 had a .62 6th gear. I believe the 03+ Cobras have a similar ratio to this. Something like .63

The 94-97 F-body T56 had a .50 6th gear. Also found in Vipers.

 

[Nick M]

If I did a manual swap, which I won't, I would do a TKO or T56.