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Discussion Starter · #1 ·
I was wondering what was involved in this swap. I presently have an ACN tranny (jetta tranny) that sorta went south on me this weekend. Since I was thinking of changing it this summer anyways, I thought I might as well do it now. The only problem is that I was told you had to either change the clutch or the flanges for the drive axles( the 4K has 90mm whereas the ACN has 100mm drive axles).
I just wanted some more input on this, maybe get a clearer picture.
Thanks
 

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Re: ACN to 4K tranny swap (87jetta8v)

other way around...the acn has 90mm and the 4k has 100mm....honestly i dont think its worth it....the 4k is good and all..but all it does for ure car is have it doing like 60mph on the highway like at 3000rpms almost...it almost kills ure top end....just pick up like a 9a...nice close gears down low..and a nice 4-5th gear for highway cruising...cruising on the highway with a stock 5th gear is just plain old ugly...almost everyone here will tel lu to get a 4k..BUT...to swap out the 5th..too much trouble... http://****************.com/smile/emthdown.gif
 

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Discussion Starter · #3 ·
Re: ACN to 4K tranny swap (MyBlackGti)

Thanks for the input, blackgti. I thought that swapping the 5th gears wasn't that much of a headache, guess I was wrong. Please excuse my poor knowledge of tranny codes, but what does a 9a come of of ? The reason I wanted to go 4K is that I need all the help I can get (I love the 8v, but it ain't the most powerful engine out there), and a closer ratio tranny would definitely not hurt.
 

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Re: ACN to 4K tranny swap (87jetta8v)

the 4K and the 9A are very similar. The gears are the same, but the 4K uses the 3.91 final, which is a bit over 5% shorter than the 9A. The 9A will have you at [email protected], the 4K is more like 75mph @ 4000 (in 5th). I like the 9A in my 86 gti, got it out of an 87 cabrio of all things. All the early A2 8v GTIs came with 9As too. 4K is a little rare, coming only from the later A1 GTIs.
As far as replacing 5th, it's in that end case, so it's much easier than a full rebuild, but you still need to pull the end off the tranny, so it's not exactly easy.
 
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