Transmissions and Drivetrain Need help with your trans? Problems with your axle?

5-speed from a V6 to my V8

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Old Aug 19, 2006 | 04:24 AM
  #1  
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From: San Antonio, Texas
Car: Red 1984 Z-28
Engine: 4.8 LS
Transmission: 4L60E
Axle/Gears: 3.73
5-speed from a V6 to my V8

Will a 5-speed tranny from a 1986 S/C swap into my automatic 1984 5.0 305 H.O.? I really hope it can. I am buying the complete 1986 S/C for $150. It's in fantastic shape for its price. Motor is not running though, but its a V6, who cares. No offense to V6 owners, I love ya . And yea, I searched a lot on this topic. Thanks a lot!
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Old Aug 19, 2006 | 06:11 AM
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I can't honestly believe you'd actually have to post this, if you'd really searched. It gets asked so often it ought to be a sticky.

Here's one from just a few days ago. Seems like this one would have popped up in any kind of search, judging by the title.

https://www.thirdgen.org/forums/tran...6-v8-swap.html
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Old Aug 20, 2006 | 02:33 PM
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From: Tampa, FL, USA
Car: 93 240SX
Engine: LQ9
Transmission: T56
Axle/Gears: 3.54 R200 IRS
Yes it can be used, also most of the information in the previous persons link is mere speculation, based on his own guesses and no actual experience.

You need a V8 bellhousing, flywheel (correct for your engine rear main seal), clutch fork, pressure plate, and summit carrys the correct clutch disc, it is by a company called "advanced adapters" , 10.4" diameter with a 1" 14 spline hub.

The rest is the same v6/v8 (pedals, shifter, hydraulics, hardware)
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Old Aug 20, 2006 | 03:37 PM
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From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
You have to change so much to make it work, its not worth it.
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Old Aug 20, 2006 | 05:01 PM
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From: Tampa, FL, USA
Car: 93 240SX
Engine: LQ9
Transmission: T56
Axle/Gears: 3.54 R200 IRS
Originally Posted by Kevin91Z
You have to change so much to make it work, its not worth it.
Change what ? Its no different than a swap using a V8 T5 other than the clutch disc itself, its just fine for someone who wants / needs to convert but cant find or afford a T5 from a V8 right away, everything but the clutch disc can be reused once the person gets a V8 T5, or a tremec 5 spd...
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Old Aug 20, 2006 | 06:56 PM
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From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
You just said yourself you need to find a V8 bellhousing and flywheel. I would think finding a T5 V8 bellhousing would be as tough as finding the whole tranny. And you still have to use the V6 clutch and input shaft.
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Old Aug 20, 2006 | 07:15 PM
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From: Tampa, FL, USA
Car: 93 240SX
Engine: LQ9
Transmission: T56
Axle/Gears: 3.54 R200 IRS
Originally Posted by Kevin91Z
You just said yourself you need to find a V8 bellhousing and flywheel. I would think finding a T5 V8 bellhousing would be as tough as finding the whole tranny. And you still have to use the V6 clutch and input shaft.
Bellhousings are far more plentiful since people do break T5's and just pull the setup, far more often than people break a bellhousing and do the same.

The clutch disc I mentioned is only "V6" in the aspect that it has the correct center hub for the V6 T5 input shaft, otherwise it is the same as a V8 setup.
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Old Aug 20, 2006 | 07:19 PM
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no actual experience


That's the best one I've heard all day!!! I appreciate that.

As I've often posted, just because a thing is possible, doesn't make it a good idea. Most reasonable people would consider that rigging a weaker and otherwise inferior transmission into an application where the RIGHT transmission is already widely known to be inadequate, is definitely one of that type of situation. After all....
people do break T5's

Last edited by sofakingdom; Aug 20, 2006 at 07:23 PM.
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Old Aug 20, 2006 | 08:18 PM
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From: Tampa, FL, USA
Car: 93 240SX
Engine: LQ9
Transmission: T56
Axle/Gears: 3.54 R200 IRS
Originally Posted by sofakingdom


That's the best one I've heard all day!!! I appreciate that.

As I've often posted, just because a thing is possible, doesn't make it a good idea. Most reasonable people would consider that rigging a weaker and otherwise inferior transmission into an application where the RIGHT transmission is already widely known to be inadequate, is definitely one of that type of situation. After all....
Indeed, they do break, people do put them behind higher HP motors, some people cant drive a stick and tear them up, people go running slicks with a transmission that isnt designed for an all out race car.

Of course as you dont seem to be able to acknowledge, people do also run them hard behind a lot of performance engines without extremely high HP levels, such as the original posters 190 HP "HO" 305, I had no problems with many hard miles on a V6 T5 behind my 230HP/300TQ 92' 305.

To further illustrate how you are speaking without actual evidence

Originally Posted by sofakingdom
It will bolt right up; but the clutch gear splines won't engage a V8 clutch.

There's some clutch disc that people talk about that you can use to rig a 6-cyl transmission behind a V8. It's small, like an inch or more smaller than the right clutch, so it's weak.

THe 6-cyl transmission has the crappy wide-ratio 6-cyl gears; so you end up with the typical 6-cyl situation where EVERY shift is like the 1-2 shift int he 700 automatic. The motor goes from "scream" to "lug", with nothing in between. In other words, the ratios are too wide for a "performance" application; they're set up for a gas mileage application.

The 6-cyl transmission is also weaker than the V8 one, because the gear tooth part of the clutch gear is smaller in diameter.

The T-5 is already entirely weak enough: even the strongest V8 version is amazingly easy to tear up with a stock 305. While it's possible to make one live indefinitely by babying it sufficiently, I doubt that most of us here would go to all the trouble of a V8 swap, with the express intent of babying the car forever afterwards. We would probably like to equip the car in such a way that we could actually make use of the newly installed power.

Bottom line, just because it's "possible", doesn't make it "a good idea".

You need a V8 transmission, flywheel, and clutch, if you're expecting V8-like results.

Or, if you have a T-56, that's an even better way to go.
You state that the disc available but its "like an inch smaller than a V8 one" yes ther is one that can be used from the early v6 cars, which is 9-11/16 diameter so yes if someone used that its .75" different than a "v8" disc, of course as i mentioned advance adapters makes the correct 10.4" diameter 1" 14 spline hub disc.

You then state that the V6 T5 has some spectacularly different "wide ratio gears" and are "too wide for a "performance" application; they're set up for a gas mileage application."

Yet the only gear that is different is 1st, which is 4.05, to help get the engine with less torque off the line, other than that they are the same, no magical "gas mileage application" gearset.

The we move on to this one "The 6-cyl transmission is also weaker than the V8 one, because the gear tooth part of the clutch gear is smaller in diameter."

Well you better run out and let all the owners of T56s, T10's, and mustang T5's know that they beter upgrade cause their 1" 10 spline input is smaller than that of BW's rediculously weak 1" 14 spline V6 transmission which is a such a piece of glass comparedd to the V8 T5....
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Old Aug 20, 2006 | 09:22 PM
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1st, which is 4.05
Right; 1st is 4.05, compared to 2.95; and the other 2 intermediate gears are proportionately different as well, because the thing that makes the 1st gear ratio different isn't 1st gear, it's the clutch gear/countergear combo. The part that's smaller and weaker in the 6-cyl transmission is the gear section of the clutch gear, which is of course also the part that's responsible for the different intermediate gear ratios (the clutch gear is smaller and the countergear is larger); the shaft part is only marginally weaker. But the shaft isn't the failure point, so its diameter and spline count aren't the issue, the gear part is, like I said.

Back in the 70s when I did a thriving business in rebuilding Muncies and T-10s, I saw quite a few destroyed clutch gears. My favorite was where the shaft part had got twisted out of the gear part. As you no doubt are aware at your advanced experience level, the clutch gear is a 2-piece assembly, not one continuous forging. I've been driving and then professionally rebuilding stick shift transmissions since evidently some time long before you were born, by the way you talk. I've owned the car I have now since you were probably still in diapers or possibly before. In fact I suspect I've probably thrown away more broken T-5s than all of the T-5s you've even seen in your limited lifetime.

I shredded my first 4 or 5 T-5s with a 305 HO motor. I bought one once whose mainshaft was twisted off, for a core, one of the multiple times I rebuilt them while I had them in my car. That particular one had been transplanted from about an 84 HO Z28 into about an 82 S-10. Needless to say, their failure rate in my car did nothing but increase after I put a larger and more powerful motor in it. Although, after a time, I resigned myself to the fact that they weren't going to last if I treated them like a 4-speed (speed shifting especially...); and after I quit abusing them like that, they started lasting quite a bit longer.

The T-5 is entirely weak enough in its strongest form, simply because all the parts are so small in that model of gearbox. I don't think it's doing anybody any kind of favor to talk them into half-assing one of the most inappropriate versions of it into their "performance" car, since all that's going to happen, is they'll tear it up that much faster.
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