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Help choosing gear ratios please!


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Hey everyone.

 

I've slowly been accumulating a lot of parts!

 

I plan to run an LS3 crate engine with a T56 Magnum transmission. I just had a few questions before I order my transmission which I plan to do today!

 

I just want to verify that I need the 26 spline input, 31 spline output.

 

Then also which set of ratios would be better suited to the Z car. Car will be used for weekend drives and some time at the drag strip.

 

Here were my two options.

 

Option 1:

 

1st - 2.66

2nd - 1.78

3rd - 1.3

4th - 1

5th - 0.8

6th - 0.63

 

Option 2:

 

1st - 2.97

2nd - 2.10

3rd - 1.46

4th - 1

5th - 0.74

6th - 0.50

 

Any help would be greatly appreciated! I do plan to start a project thread as soon as my garage wiring is finish and I can really tear into the car!

 

Thanks

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The T56 Magnum has to have a different tail shaft housing installed to fit properly. I'd say it's pretty expensive. Having said that, I'd go with option 1.

Could you elaborate a little more on this please? What do I need, and can you buy it ready to go for what we need? I can't find any half local transmissions which is why I decided to go this route.

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The shifter sits about 2.5" too far forward on the Magnum. The Magnum is the lower trans in the pic. Take a look at the tail housing. The Magnum looks to be a regular T56 that was rebuilt and retrofit with another type of tail housing. There is a company that sells a T56 Magnum with the correct tail housing to use in the Z but I can't remember who it was. But I do remember it being about $3700 with the correct piece.

 

I just checked, it's D&D Performance...$3,995.
 

qcks.jpg

Edited by WarlordZ
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Two things.  If you go with a differential gearing of 3.545 or lower use option 2 for your tranny.  If you go with an R230 with the 3.69:1 gearing found in most turbo Z32's then I'd go with option 1 or 2 depending on what you are planning for tires. Option 1 has tighter gear ratios but the Z is light enough and the LS motor torquey enough that the wider ration Option 2 will also work well. The only real issue is 1st gear which smokes tires in option 2.

What are you using for gauges in your car?  If you're trying to stick with stock then get a tranny with a tails haft that has a mechanical speedometer output.  If you're converting over to all new gauges then stick with the electronic speedo output.

Edited by Phantom
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I was planning on sticking with the stock gauges. I thought I read somewhere that the new t56 magnum you could use either electronic or manual for speedo. Maybe I misunderstood.

 

So ideally, the transmission if like to get my hands on is a '98-'02 f-body t56. Am I right in thinking this?

 

Just unfortunately for me I live in the middle of nowhere and haven't been able to locate one :(

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The T56 Magnum has to have a different tail shaft housing installed to fit properly. I'd say it's pretty expensive. Having said that, I'd go with option 1.

 

You're thinking of the TR6060 which comes in the new corvettes and camaros. The "magnum t56" is a TR6060 with a standard slip yoke style tailshaft housing.

 

I was planning on sticking with the stock gauges. I thought I read somewhere that the new t56 magnum you could use either electronic or manual for speedo. Maybe I misunderstood.

So ideally, the transmission if like to get my hands on is a '98-'02 f-body t56. Am I right in thinking this?

Just unfortunately for me I live in the middle of nowhere and haven't been able to locate one :(

 

This is true on the speedo. However, you'd have to play with the gears to get it to track correctly with the z gauge I'd guess.

 

If you aren't making big power, an F body transmission will do fine for you. The problem lies with finding one that is in good running order for less than a mint.

 

 

On the subject of gears -  go with the 2.66 - 1st gear set. this is a great setup for a street Z. 

 

The .50 overdrive that comes with the stock t56 is ok, but depending on your setup can produce a lot of droning.

 

Solution:  You buy a Magnum T56 and have it shipped to my house, I'll ship you my built T56! bingo! hahaha

 

You might be able to find a running F body T56 for around 1500, but its always a mystery unless you can drive it before. The magnum is 2500ish + bellhousing.

 

 IF I could do it over, I'd absolutely have a magnum in my car - no questions asked. They're overall a better, stronger transmission, and they aren't "Mystery Mile"!

 

That's my $ .02

Edited by SUNNY Z
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Like I said, the Magnum can be modified to look like and to have the same shifter location as the regular T56. Or you could just use the Magnum without the mod and have a poor fit in your stock console.

 

Also, it looks like there's a huge difference in price depending on where you shop. If I knew where the T56 Magnum trans with the regular T56 tail housing was for $2500, I'd sell mine and I'd be all over that.

Edited by WarlordZ
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So far, everybody I know (three guys) who has purchased a used T56 separate from a full pull-out has gotten screwed and had to rebuild it. After that, they have spent as much as they would have for a lower mileage full motor/trans pullout. Just like it is when buying a chassis, "pay me now or pay me later." Buy well and get on the street with less agony.

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Like I said, the Magnum can be modified to look like and to have the same shifter location as the regular T56. Or you could just use the Magnum without the mod and have a poor fit in your stock console.

 

Also, it looks like there's a huge difference in price depending on where you shop. If I knew where the T56 Magnum trans with the regular T56 tail housing was for $2500, I'd sell mine and I'd be all over that.

 

Found several at the 3K mark FWIW.

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That's not an F-body/GTO style tail housing. Read the link above where Tick Performance explains how it's done. Go ahead and add $1000 to that price.

 

Oh, you're wanting an actual F body tailshaft housing that would allow the use of a torque arm ridiculously mounted to the transmission. 

 

For a swap, you don't need that...... so i'm missing your point here i guess?

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Did you read the thread by Tick? The shifter does not sit in the same location. That would be a problem for MOST people. But I'm sure it's no problem for someone with master fabrication skills such as yourself. Have you even looked at the two transmissions side by side? I'm trying to help the guy so he doesn't waste his money on a trans that doesn't fit.

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Oh, you're wanting an actual F body tailshaft housing that would allow the use of a torque arm ridiculously mounted to the transmission.

 

For a swap, you don't need that...... so i'm missing your point here i guess?

Does shifter location mean anything to you? You are clearly missing my point.
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