Upgrade(?) from 4S gearbox to FN or 7D? UPDATED!

[Turftech]

I'm looking at pulling one of either a FN or a 7D gearbox to replace a 4S from my 90 GL TD.  Is there anywhere that gives the cross over for this?  I have the http://www.scirocco.org/gears/ page, and it doesn't indicate much beyond minimal specs.  I am wondering if the lower 5th gear number for both of the above (FN, 7D) will give me lower revs @ highway speeds.  I guess I can keep an eye out for an ACN or ATH, DFP, CHD?  Trouble is, do the flanges and mounts match up with the 90 GL TD?

I have been running on the original 4S way to long here.  I'm gonna throw a shaft soon if I don't deal with it now.  Loses 1 litre oil in 2=3 days!  Final drive side to side is like a teeter totter...

Cheers!

[theman53]

The FN more than the 7D as the ring and pinion is .06 higher geared as well. But yes both will be lower cruising than your strainer 4S. The other trans you have listed would be the same pretty much as the FN and 7D, except I was thinking they are for the MKIII and might not be plug and play. The A2resource.com or something like that may help you on the input shafts and what cars they came in. At the bottom of the site you listed is the 100mm vs. 90mm chart too.

[Turftech]

I guess I have twins now.  Yesterday morning another '90 Jetta TD virtually identical to mine fell into my lap.  The guy's garage told him the fuel pump had quit and it would cost him another $1200 to fix.  The guy had given up and was going to dump it at the wrecker.  I happened to be there when he arrived, and got it for $300!  Towed it home and replaced the fuel shutoff and she fired right up!  Gotta love it.  Cracked windshield, noisy valves, and it looks like the head gasket is blown, but thats easy stuff.  It's really clean and tight and was clearly well maintained.  I'm gonna rob it for some goodies for now, then fix it up over the winter and give it to the wife.  His and her identical white Jetta's!

Man am I hooked...

And by the way, I found an FN transaxle on the ground at the wrecker.  95 bucks.  Guess it was my lucky day.

Thanks for the advice!

[Turftech]

Just a test to see if this works.  Pic of the twins.



Hope that worked...  It does in the preview.

[ventureforth]

I have a later style (.71 5th) FN in my 82 1.6NA Rabbit.  Very happy with it.  I also have a 7A sitting in the wings for a rebuild and install when the FN starts winding down.  I don't think you can go wrong with either.  They seem so similar for all intents and purposes that in the real world you won't notice much difference.  At least that's what I was told when I asked the same question you are now asking.