I have a chance to buy a 86 duke with an Isuzu 5sp. I plan on swapping it in my 86GT with a 3.4 pushrod engine. Is this a good swap? Or should I swap it in the 88 duke?


What do you guys think?

Steve

The isuzu tranny barely holds up to a four cylinder...let alone a warmed up 6

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87 GT...SBC...Fast as hell

Yea unless you plan on driving it like a grandma, I wouldn't do it. It's just not a strong enough transmission for anything other then the duke.

quote Originally posted by jaymelk2: The isuzu tranny barely holds up to a four cylinder...let alone a warmed up 6

Really?? I thought the Isuzu was pretty strong.

Steve

The isuzu is a good tranny for a 3.5 briggs.....but I don't think it could hold up to a 5 horse....seriously Steve...bad choice

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87 GT...SBC...Fast as hell

Thanks guys. Maybe I'll swap it in the 88 duke.

Steve

quote Originally posted by jaymelk2: The isuzu is a good tranny for a 3.5 briggs.....but I don't think it could hold up to a 5 horse....seriously Steve...bad choice

I agree with this, I always see swaps with this transmission and its like waiting for a bomb to explode, not strong at all. Here is a picture of Isuzu 5-speed input and output shafts.


Compared to the Getrag 287 (F23) gears.

[This message has been edited by mattwa (edited 06-08-2011).]

Dang.. those are beefy

I have had an Isuzu 5 speed behind my 2.8 since November of 2007. It has held up to some VERY spirited driving with no issues whatsoever. Mine is daily driven year round.

I also tow a trailer with the car with no issues either.

Yes, the transmissions are weaker than a Getrag, but... Everyone who says they won't hold up to a 5 horse Briggs motor... Do you have any ACTUAL personal experience with the transmissions?

Don't nay-say without personal experience. Anyone can re-post a picture of a shredded second gear in an Isuzu, but that doesn't mean they always fail.

Sure, mine may fail down the road... But for me and my use, it is perfect.

Oh, and for the record, I have averaged 34mpg on the Isuzu with my V6.

quote Originally posted by Synthesis: I have had an Isuzu 5 speed behind my 2.8 since November of 2007. It has held up to some VERY spirited driving with no issues whatsoever. Mine is daily driven year round. I also tow a trailer with the car with no issues either. Yes, the transmissions are weaker than a Getrag, but... Everyone who says they won't hold up to a 5 horse Briggs motor... Do you have any ACTUAL personal experience with the transmissions? Don't nay-say without personal experience. Anyone can re-post a picture of a shredded second gear in an Isuzu, but that doesn't mean they always fail. Sure, mine may fail down the road... But for me and my use, it is perfect. Oh, and for the record, I have averaged 34mpg on the Isuzu with my V6.

I in fact do have personal experience, my dad's 86GT has a 3.4l V6 with the 5-speed Isuzu, and second gear does not work. 1st gear is also too short.

quote Originally posted by mattwa: I in fact do have personal experience, my dad's 86GT has a 3.4l V6 with the 5-speed Isuzu, and second gear does not work. 1st gear is also too short.

I can agree that first gear is a bit short :P

I just simply wanted to make a point though about "Oh it's trash and barely holds up to the duke" isn't exactly factual. GM installed them from the factory on the duke. And it wasn't until people started putting them to use on much larger engines that the problems started...

quote Originally posted by Synthesis: I can agree that first gear is a bit short :P I just simply wanted to make a point though about "Oh it's trash and barely holds up to the duke" isn't exactly factual. GM installed them from the factory on the duke. And it wasn't until people started putting them to use on much larger engines that the problems started...

That part was just a joke, I don't think the duke could break much of anything except itself more or less.

I had an Isuzu in my 3.4 car for a while. (Installed it after I shredded my first Getrag. Long story.)
It held up just fine.

I think that if you don't shock load the tranny you'll be fine. (Of course, that's the hard part.)
Side stepping the clutch and/or speed shifting will take its toll.

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Raydar
88 4.9 Formula IMSA Fastback

Read Nealz Nuze! Praise the Lowered!

Ho Ho that was funny Matt...I always said a duke couldn't pull the hat off of your head too. I too have had experience with the isuzu...as I said it's probably good for a briggs...and I wouldn't try powershifting with that motor either

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87 GT...SBC...Fast as hell