Ole Yellar-T56??.

[doyoulikeithere]

I would say that #1, you need to plan on how to hang a clutch pedal, and are you gonna use hydraulic or linkage?.
Once you cross that bridge and it works properly, it doesnt really matter what transmission you eventually decide to use, except that it has to satisfy YOU.
Maybe thats a truck 5 speed, or a sports car 5 or 6 speed or a semi truck 15 speed
Either way, if it bolts yo your 383, your gonna have to make it mount it to the frame crossbar and cut a hole in the floor.
As for the hole where the shifter goes? your astro never had a hole for one, so your gonna have to cut a hole wherever it needs to be. Its a big floor.
If there is one of those wimpy floor stringers in the way, you could cut it out and weld a small support around it, or just cut it. The tough old chev isn't gonna fold up and die if you do.
But the most important thing is to use your own judgment to decide whats right for you, then DO IT.

[1Gary]

Still collecting info:

http://en.wikipedia.org/wiki/Borg-Warne ... ansmission

From a Ebay listing that builds T56's:

I thought the T56 was a performance trans that stock was ready for use.I have to admit I haven't been paying much attention to the T56's so I have alot to learn.

This a copy of a Ebay add of a company that does work on T56's and it seems they need alot of work to get them to work correctly.I am looking for input from you guys.So here is the copy from the ad.

Here is what we do:

Transmissions are completely disassembled, de-greased, all parts carefully inspected. Rebuilt using performance upgraded parts, with severe use in mind!


Performance parts list:

Upgraded 1-6 carbon fiber/kevlar blocker / synchronizer rings
Reverse synchronizer ring
Bronze fork pads for the 1-2 & 3-4
Billet keys for the 3-4 with upgraded springs
Billet keys for the 1-2 with upgraded springs
Bronze shifter bushing / isolator cup
Snap ring kit
3-4 steel shift fork
Stock 5-6 & reverse fork pads
Stock 5-6 & reverse keys & springs
front & rear seals


·Carbon fiber/kevlar blocker / synchronizer rings
Carbon fiber/kevlar blocker / synchronizer rings provide much better shifting than stock paper lined parts.
·Bronze fork pads 1-2 and 3-4
Bronze fork pads are a necessary upgrade for all T56 high performance and racing applications! These will not fail or wear like the stock Teflon pads.
·Billet Synchronizer Keys 1-2 and 3-4
Billet keys are a necessary upgrade for high performance and race applications. Replace the weak stamped steel keys with a superior billet material.
·Steel 3-4 shift fork.
This is the upgraded T56 3-4 steel shift fork used in the Vipers and will fits all T56 transmissions. It replaces the weaker aluminum shift fork with a much stronger steel fork.

And then from a end user:

Do you have a Gen I or Gen III/IV engine?

If Gen I, you can use a stock LT1 T56, flywheel, and hydraulics with no issue as long as you have a 1 pc RMS engine. The 2 pc RMS engines require a $400ish conversion flywheel. The 93 T56's had slightly shorter gears all around and were rated for less torque. Generally the concensus is to avoid them.

If Gen III/IV, the LS1 F-body T56 is the ticket. All 94-02 F-body T56's had the same gear ratios as far as I am aware.

You can convert a 98-02 F-body T56 to work with a Gen I engine but it requires an adapter plate at least, maybe other issues too. A 94-97 T56 costs around $600-$1000 for parts to convert it for use with a Gen III/IV engine down the road. That may affect your decision.

The LT1 T56 uses a strange clutch with a reverse-pointed slave cylinder. They're fairly unique and there arent many clutch options out there. There are enough, but aside from maybe the high end Mcleods, they all use the exact same Valeo pressure plates. They increase grip by changing the clutch disc material, not by increasing clamping force. Normally this isnt a big deal, but its a transmission they only made for 5 years, you're just not gonna have a TON of options on it. But there is enough available that it isnt a huge concern. the clutches do cost a little more though it seems. $250 is about the starting point.

The LS1 T56's seemed to have crappy hydraulics from the factory. I think i read that GM didnt allow full pressure to the slave cylinder, so you never got complete clutch disengagement... something weird like that? Hence things like the "drill mod". LS1 T56's seem to go through synchros a lot faster, but that could be because of crappy hydraulics or because LS1's make oodles and caboodles of power. Nothing a fancy aftermarket $300 Tick master cylinder cant fix. The LT1 T56's despite being older and more worn out seem to last just as long, but they are getting very old now.

CTS-V and GTO T56's can work, but they require a lot of conversions to get them into other vehicles. The F-body ones are a direct drop in. If this is for a non F-body, then it may not matter so much. Corvette T56's are integrated into the rear axle and IRS, so they pretty much only work in corvettes.

I have a T56 from a 94 TA that was bracket raced and power shifted hard. I learned how to drive a stick with it in my car, and the thing makes noises, but it's held up great over the years Ive had it. They're very tough transmissions, and I think everything from 94+ had at least a 450 ft lb rating.

I do investigate in detail as much as I can.I know without a substantial investment a T5 won't cut it.

[1Gary]

Still more info:

The aftermarket T56 couldn't be considered because best price is in the range of $3,000.

This is a post for a FYI if someone is considering it later:


http://www.tremec.com/performance/t56.html

[1Gary]

But then are the TKO's 5 speeds that would handle the kind of torque of my 383:

http://www.5speedtransmissions.com/tr-3550.html

Much cheaper too.

Oh,Ole Yellar is a 1989,so hanging the clutch isn't a problem.

[Mr_Roboto]

What about the NV4500? It's a super HD 5 speed used behind torquey engines like the Cummins 6BT. The ratios spread out to be ~8.7 which is a 6.34 first (pre-95) or ~7.7 with the later 5.61 first gear. This compares to the ~5.34 spread of the T56. For a truck the ratios being a wider spread would be a lot more valuable IMO. My buddy who stuck a T56 in his extended cab S10 is not a huge fan of it in retrospect, and wishes he would have gone with a TKO or other 5 speed instead. He also doesn't like the LT-1 style clutch setup that's aparrently a bastard child compared to other systems which means you're pretty much stuck with limited parts selections.

[doyoulikeithere]

What about the NV4500? It's a super HD 5 speed used behind torquey engines like the Cummins 6BT. The ratios spread out to be ~8.7 which is a 6.34 first (pre-95) or ~7.7 with the later 5.61 first gear. This compares to the ~5.34 spread of the T56. For a truck the ratios being a wider spread would be a lot more valuable IMO. My buddy who stuck a T56 in his extended cab S10 is not a huge fan of it in retrospect, and wishes he would have gone with a TKO or other 5 speed instead. He also doesn't like the LT-1 style clutch setup that's aparrently a bastard child compared to other systems which means you're pretty much stuck with limited parts selections.

Isnt the NV4500 basically a 3/4 ton chev truck trans? I know they come in various gear ranges....

about your suggestion about a 3/4 ton 5 speed is wouldn't first gear be a creeper gear to a 2 gear that would be a steep jump up. What would the 5th gear be??.

[Mr_Roboto]

Yes the NV4500 is a truck trans. For a hauler though it's not a TERRIBLE bet at all. There is some aftermarket for it too, not a ton like the T56 high performance but I thought we were doing more of a "hauler" with this build. I can tell you my buddy does not like the closeness of ratios in his S10 extended cab with the T56, it makes the gearing very finicky, he hasn't really found a ratio he is truly happy with yet honestly.

[1Gary]

One of the things I have been considering is how much power loss is involved when making a choice of which trans.