MK3 GTI ABF Engine 16v Port Polish

[Ess_Three]

Glen, how difficult is it to fit a 3.94FD? Is it something average tools and knowledge can change?

If you can strip and rebuild a gearbox, then yeah.
You have to drill the rivets off the old diff/crownwheel, which takes a bit of effort...on bith the Mk3 16v 'box and the donor 'box with the 3.94 (unless you fancy paying £400+ for a new FD kit from VW)
You then need a bolt kit to replace the drilled off rivets.
Rebuild the 'box with new seals and bearings...and job done. That's the time to drop a LSD in there too for some power-on-turn-in loveliness.

(I don't build mine...it's beyond me  )

[VW BUSH]

Glen, how difficult is it to fit a 3.94FD? Is it something average tools and knowledge can change?

If you can strip and rebuild a gearbox, then yeah.
You have to drill the rivets off the old diff/crownwheel, which takes a bit of effort...on bith the Mk3 16v 'box and the donor 'box with the 3.94 (unless you fancy paying £400+ for a new FD kit from VW)
You then need a bolt kit to replace the drilled off rivets.
Rebuild the 'box with new seals and bearings...and job done. That's the time to drop a LSD in there too for some power-on-turn-in loveliness.

(I don't build mine...it's beyond me  )

What donor box did you use?

[Ess_Three]

What donor box did you use?

I didn't...
I bought a new FD when they were approx £200.
Then I bought a 4.2 at £280ish...any by the time I was doing my VW Motorsport 6 speed 'box, they were up to £400+. Gulp.

I believe the Passat AGC or AYH gearboxes have the 3.94 FDs in.

[F17BAD]

I have a 3.94 FD spare.....

came out of my EMR 2,0  MK4 GTI gearbox iv just had rebuilt

if anyones interested make me a offer..

[DanChave]

For someone who has a mk3 16v, and will be attending to the gearbox in the new year, what is a 3.94 FD?  And how does it compare to what ever is in the original gearbox? I already intend to get the flywheel balanced and lightened

[Ess_Three]

Glen, how difficult is it to fit a 3.94FD? Is it something average tools and knowledge can change?

If you know how to re-build a gearbox and have a manual, it's not too hard.
You'd need the correct tools of course...You'd need to shim the diff using the correct shims (after measuring) and you'd be as well changing the synchros and bearings whilst you are in there...but with the right tools and a manual it's do-able.

Drilling the old diff rivets off is probably the hardest job...the rest is using hand tools.

Personally, I don't bother...I'd use my mate Hotgolf...he can build them with his eyes shut...so I'd rather let him do it.

[thai-wronghorse]

What donor box did you use?

I didn't...
I bought a new FD when they were approx £200.
Then I bought a 4.2 at £280ish...any by the time I was doing my VW Motorsport 6 speed 'box, they were up to £400+. Gulp.

I believe the Passat AGC or AYH gearboxes have the 3.94 FDs in.

I might be able to get my hands on a Corrado 1.8 16v AGC gearbox cheap, could it not just be exchanged for the CDA in my 16v or are the ratios completely wrong apart from the 3.94 FD?

[VW BUSH]

AGC
FD= 3.94, 1=3.78, 2=2.11, 3=1.35, 4=.97, 5=.78 (AYH 5=0.83)

CDA
FD= 3.68 1=3.30, 2=1.94, 3=1.31, 4=1.03, 5=.84

AGC is lower through the range, you will lose top speed over greater acceleration.
Probably find you spin up a bit more in the wet or cold as well.
AYH is slightly lower in 5th and appears to be the shortest box VW have.
Cant see it being an issue if you want acceleration, but top speed and overall mpg will be affected.

I have a 3.94 on an my 8v since I had the bx rebuilt, why VW rivet the FD on is beyond me and is the weak spot on the transmission.....
Anyway it makes it a much better car, not sure where peak bhp is now though but 2nd and 3rd is awesome with little or no bogging down.
MPG is awful if It gets ragged but hey you win some you lose some

[Len]

Cant say that I have ever been really specific about what cost/power estimates I have been given but hear goes.

£5k should get you to around 200/220 bhp depending on which cams you use.

£8k can get to approx 240 bhp

Anymore than that and its more like £12k as the 100mm crank alone is £1,400.

This ONLY for engine work, so it you want an LSD, new ARB's and powerflex bushes.
I am assuming folk have already done coilovers/SS exhaust and all the "standard mods"