Ebslinger

Tried to do a search, but to no success... was way overwhelmed.

I am sure this question has been asked a thousand times, but...

Does anyone know if some one makes different final drive gear ratios? Currently running 3.88 in a 86 944 N/A (I believe).

Would like to drop that down to about 4.11 or 4.13...

Any Ideas?

Thank you.

Dougs951S

There are some audi gear sets that fit, be prepared to open your wallet. I had a 4.11 set in an old N/A car I had. I believe it came from an early 90's audi 5000/200tq. You'll turn ~3500 rpm at 75 mph with a 4.11 gear set and stock size tires. By the way, numerically higher ratio differential gears are weaker because the teeth are finer, and I eventually broke that differential with stock 150 hp when I spun taking off from a light, and then dead hooked with only 215 tires.

Ebslinger

I'm OK with the lose of top speed... doubt the car will ever see speeds above 50 - 60 Mph. Do you remember the parts number and any issues with installation?>

Dougs951S

Don't have the part number off hand, but any late 80's/early 90's manual audi 5000/200 will have a type 016 gearbox basically identical to ours (except it is a FWD tranny with a rear PTO intended for AWD use) with a swappable 4.11 R&P. Good luck finding one though.

one more note, you wont find that short gears in a turbo car, they were in the N/A inline 5 powered cars. The main issue as noted above, is breakage since the 4.11 gear set was never intended to sit behind an engine as "powerful" as the 944's.

one more note, it isnt a dramatic difference, the 4.11 set is less than 6% shorter than the stock gearing so you don't lose much, but you dont gain much either. It isnt nearly as dramatic as say, putting an S2 R&P into a 951 trans. You have to decide if the money (seriously, it isnt a cheap or easy swap unless you know how to replace the R&P and shim it yourself, which requires special tools) if worth it for what is really a mild performance increase. If your car is stock, rogue's N/A tune is a better bang for your buck overall in terms of perceived performance gain (you'll gain more than 6% for sure) as well as throttle response and overall driveability. Definitely cheaper too if you are paying a shop to swap the R&P.

Last note, I swear!: The 30v 3.0 V6 powered manual audi A4's from early 2000's also have a type of 016 gearbox and a 4.375 final drive. That is the shortest I am aware of in the 016 family. I do not know if it can be placed into a 944 box. If it was possible, it would probably survive just fine in an N/A since the engine it ran behind put out stock 951 power levels. With stock size tires it'd put you at ~3650 rpm at 75 mph.

odonnell

When I asked about an Audi 4000cs trans swappability, a lot of people had great info to share:

https://rennlist.com/forums/924-931-...rbo-forum.html

TL;DR you're going to make the (already relatively vulnerable) ring and pinion even more vulnerable. The 924 2.0 transmissions had them I think, they are already machined to fit the 016 transaxle. The AWD Audi trans I posted about has a physically larger pinion shaft and is probably not worthwhile to adapt. So if you're going to use it, start with a 924 trans you can confirm has a 4.11

acorad

Read through this: http://944hybrids.forumotion.com/t11...r-options-audi

It's been several years now and the 0.68 Audi 5th gear is still something I appreciate every day.

Andy

Ebslinger

This is all great information. Thank you. It will give me some initial food for thought.

I wonder if the failure of the lower ring and pinion is caused by case deformation in high torque situations? hum...

V2Rocket

the shorter the ratio the smaller the pinion gear has to get to make the desired ratio (since the ring gear doesn't change diameter much if at all)

smaller = weaker as far as metal is concerned.

odonnell

I think it's simply failure due to shear stress and fatigue. I remember someone posting (I think it was either Kevin Gross or Dimi) that a lot of failures were because of the pinion bearings.

In my trans, teeth from the pinion and the spider gears in the diff were just hanging out in the bottom of the diff chamber.
Pics.