need trans advice on motor pull 1985 Jetta 1.6TD

[btrapr]

I am getting ready to pull the motor and transmission out of an 85 Jetta due to a weaping head gasket. I have a rebuilt Turbo Hydraulic shortblock I am going to go back with, ARP, 1.9 metal head gasket BUT I found out this vehicle has a GASSER TRANS. I had a 1.9 cam plate put into the IP and plan on running 2.5" exhaust.

BAD news I think? I noticed that the transmission is a 5speed AUG which appears to be a gas model according this site CAN I USE THIS?
http://www.a2resource.com/eandt/ratios.html
This site is showing this transmission in use in a 1989-1992 1.8 8v___ "AUG" 1st_3.46 2nd_1.94 3rd__1.44 4th__1.13 5th__0.89 Final__3.67 Red (15 tooth) 100mm

I do have an "FO" 5 speed but it shows having 90mm flanges so I would have to buy axles or sink money into switching the flanges out SINCE I dont know how.
The site shows my other transmission was in use from 11/78-5/79 "FO" 1st__3.46 2nd__1.94 3rd__1.29 4th__0.97 5th__0.76 Final__3.89 5687.62 White (16 tooth) Flanges 90mm

I also noticed that this site was showing a 1.9TD transmission that isn't to far off my gear ration in the AUG BUT I am not sure how much different the power band and RPM range is between a 1.6TD and a 1.9TD????
CHD,DFP,ATH 1st__3.45 2nd__1.94 3rd__1.28 4th__0.91 5th__0.75 FINAL__3.67 From '93 1.9L TD 75hp

****I am not sure what to do NOW? I am planning on making this my daily driver which means periodic trip to the mountains?

PLEASE help me figure out my best solution____UPDATE Figured out its not that hard to change flanges...if I need to to get the FO trans in

thanks

[bscutt]

The FO ratio is good for a 1.6na and would be fine for your 1.9. If I read this correctly the gasser transmission will have you a higher in the revs at highway speeds (I could be wrong here, see note below)

Best to look at one of the on line calculators to see where your rpms will be at a few combinations. I was doing math in my head and I'm tired so better to rely on some real calculators.

[TylerDurden]

I don't think the FO case will have the mount-points for the MK2 shift linkage.

The AUG doesn't look that bad to me... I've got a 1.6TD with AGS (3.94 r&p) and wish it had more gear for highway.

With stock tires, I hit 67mph @ 3000rpm. I'll probably just get taller tires to bring down the revs.

[Fatmobile]

I wonder if the 5th from the FO (because it lacks mounting points for a MK2 or later)
can be used in the AUG,
because it has the 3.67 ring gear for better highway RPMs.

[btrapr]

Thanks for the input.

I believe I will put the AUG back in it. The guy I got the car from used it as a long distance daily HWY commuter car, but did not go up and down hills to get there. Then the head started leaking so he went and bought a TDI (lucky him).

Fatmobile- There are a few local guys I could ask about the 5th gear swap, but not sure if I mind a little higher RPM's with the mods I'm doing to the engine.

FYI___ The motor is a 1.6TD hydro head, I am putting a 1OVER rebuilt shortblock, mildy ported (gasket match and bowl blended) hydro head on it, IC install, and I am having a 10mm head and 1.9 cam plate put in it, and 2.5" exhaust. I am looking for improved power as well as decent economy

[bscutt]

Now that I am more awake, I went here for a rpm vs speed calculator http://www.spiretech.net/~vw6spd/tech.html

for a 3.67 final drive and .89 5th gear I see 3393 rpm at 70 mph
for a 3.89 final drive and .76 5th gear I see 3071 rpm at 70 mph

did this for 175.70 r13 tires

so about 300 rpm difference at 70 which is not a huge difference but is about 10%
MPG wise probably would not be much and the AUG might be better on the hills

[82vdub]

And as Tylerdurden mentioned, using a taller tire will lower the highway RPM's, if they are a problem too.

[btrapr]

awesome! I feel more confident now that I see some numbers.


thanks