[Dimma]

Since none of you guys ( noone here, nor on the R.L. forum ) join me in getting the Turbo R&P from Albins I think I've found another route :



Virtually shopping around in the Audi transmission warehouse I found a set of gears which should give me a topspeed with which I should be able to signal the GT2 guys from the left lane on the Autobahn <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" /> Still there will be not too big a gap between the gears when I look at my attached gearchart :



I think this is a winner ! what do you guys think ?

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[DaveN]

Ouch! That set puts you back to a 5 speed - almost a 4 speed. Sixth is useless without a whole lot of Veyron torque <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

I have had my car to 262+ and I was only at 6K so the ratio to power seems almost right with the stock gearing. A few hundred less in 6th would be nice on the freewayto get you into the late 2000's though.

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[flash]

i just went through this. i have bad news for you.



our box is NOT a standard 01E audi box. the case and some of the internals are, but other parts are not.



there are 2 different 5th/6th shaft diameters for audi. the one for the diesels is NOT the same as the one for the other cars. unfortunately, we have the one for the diesels, so none of the ratios below .6 will work in our box. all of the ratios for the other audis use the wrong shaft for us. that is why i paused on the project, as i now have to make custom gears. i have not done it yet because i really need to line up a few people first.



also, .56 is REALLY tall. remember where your peak torque point is, and the redline. to achieve maximum top speed, you need to set your target rpm at the given speed well above your peak torque point. for example, if your peak torque point is 4k rpm, your top speed should be achieved no lower than 5k rpm. otherwise, you will actually go faster in 5th than in 6th.



my plan is to leave 1-4 alone, and only change out 5th and 6th to .857 5th and either .73 or .71 6th. that would give me a theoretical top end of between 180 and 185 with a 7k redline, which is as fast as this car will go without extreme aerodynamic work anyway.

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[Dimma]

Thanks for the info flash but I'm confused now : all the ratios i've chosen come from a Audi 01e diesel transmission so I should be Ok, or ?



Well, I have the Audi box here so I'll take it apart one of these days and have a look myself ; that has always been the best way to convince me <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />



My peak torque point is 440 Nm @ 3500 rpm, and is currently over 400 Nm from 2750-6500 rpm. When I run high boost I expect something like 600 Nm+ for the same rpm-range .... so I expect to be Ok with this gearset. If not I'll can change it back to whatever seems right to me by that time ....



Thanks for your input !



[quote name='flash' timestamp='1341763274' post='129003']

unfortunately, we have the one for the diesels, [/quote]

Thinking about this some more I do not understand that we're unlucky with this ... the diesel tranny has taller gears then the petrol ones, since these petrol cars run higher revs and so will have shorter ratio's then the diesel boys. So I think we're lucky to have the Diesel shaft so we can mount taller gears allowing higher top speeds ....



Do I miss the point here or am I totally nuts ( no need to answer this question extensively <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

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[flash]

i think .56 is going to be way too tall to do anything other than be an overdrive for fuel economy, and i think it is too tall for that, because you will be way below your torque peak, and off boost.



i also think you're going to lose some of the fun in the middle gears. the 2-3-4 spacing is what makes the car so fun. stretching 3 and 4 out is going to seriously change the way that feels. typically you push gears closer together for performance, not spread them out. for anything other than track, i think you are going to hate the spacing.



5th gear will be your top speed gear.



this one is hard. like i said, i just went through this. i could not come up with a set that worked. i'm also currently running about 400Nm in the same range, and will be up around 450 in about 2 weeks. i can tell you right now that even going to .71 6th was going to be dicey. .73 is likely a better match.



a high boost engine is going to have a tougher time down low in the rpm band. i think i would be looking for something about .68 for 6th at 600Nm. the problem with that is the rest of the gears would all have to change.



all in all i think you are better off with your original plan of a ring and pinion change, and likely to spend less money getting there too.



good luck

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[Dubai944]

Ahhh.. finally a real case for the V8 swap? Tree stump pulling torque to turn mega tall ratios so you can flash GT2s out of the fast lane on the Autobahn ... Now it all makes sense <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />

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[flash]

lol - don't get me started. that's a HUGE undertaking. it's a LOT more complicated to put a V8 in the 968 than it is in a 944.



drove one - not impressed - the owner, who spent a small fortune trying to do it, for reasons i will let him elaborate on, is removing the V8 and putting a D1R supercharged 3.0 back in the car.

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[Rap]

Google Hooked on Driving. The owners name is Joe Mills. He put a Vette engine in his 968. Talk to him about this, although he has some issues he seemed pleased!

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[Cloud9...68]

[quote name='Rap' timestamp='1341799294' post='129015']

Google Hooked on Driving. The owners name is Joe Mills. He put a Vette engine in his 968. Talk to him about this, although he has some issues he seemed pleased!

[/quote]

Sigh...Here we go again... Somebody needs to explain to me why anyone would do this, versus just buying a Corvette. Novelty, I guess. Can't think of any other reason.

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[flash]

lol - welcome to the club - jackets on the way.

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[tamathumper]

Vive la difference?

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[RS Barn]

Joe's car is a pumped up fire breathing V-8. All cammy and stuff. Lots of elaborate adaptations for cooling, exhaust, stand alone ignition, 951 tranny.They get hot!!!

Plus eat off clean.

Bunch of time and money in that car.

Looks great too

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[Dimma]

After extensive research I finally made up my mind about the gears. I know it's not ideal, but I'm going to give it a try.



I leave my first and 2nd gear unchanged and take 3rd to 6th from several Audi A8 diesel(s) , being 1,32, 0,97 0,73 and 0,60. I used the 996 Gt2 gearchart to compare and I'm actually not dramatically far off from that gearset. 3rd has an 4,8 overall ratio in the Gt2, 4,9 in mine ; 4th 3,8 against my 3,6, 5th is 3,2 against my 2,7 and 6th is 2,6 against my 2,3. I know 5th and 6th are just a bit too far away to be perfect but I just couldn't find any gears closer than this ... and believe me, I've searched ... on the other hand the 0,6 6th will bring me a theoratical topspeed of 350 km/h @ 6600 Rpm ... it's worth a try, I think. Now searching for the selected Audi gearboxes ... located 1 in Germany, the second one not yet ..



With this gearset the car will run 130 Km/h ( which is max highway speed over here ) @ 2500 Rpm in 6th ( 370 Nm at that Rpm in the current low boost setup ) and 3000 Rpm ( 420 Nm at that Rpm ) in 5th ; that's eco friendly, isn't it ? <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />

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[flash]

i would check the shaft diameters before ordering the gears. this box is a weird amalgamation of parts. i just ate a bunch of money in shipping and restocking fees returning gears that did not fit our shaft diameters, which are different than the O1E. so far, i have only been able to find 6th that crosses over, and only in .6 and .56 ratios. i'm not sure 3-5 cross over.

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[Dimma]

Thanks for the tip ! I learned the Quattro boxes are useless ( both Petrol and Diesel ), because 3rd and 4th are firm on the shaft ( which is thicker there than ours ) and it's a 'double shaft' because of the rear drive of the 4 wheel drive. Did you order gears for 2 Wd diesel Audi's or ?



Thanks !

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[flash]

i would have to go back and check what the fitment was. i ordered by part number, based on the ratio, only to find out they did not fit our shaft diameters.

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[Dimma]

Thank you but don't bother ; I have a Diesel gearbox here ( not the right ratio's though ) which I can dismantle and check measurments.

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[Dimma]

Good news : finally found the time to take the 2Wd A8 diesel gearbox I bought in Germany apart and, as I expected, the gears do fit our gearbox. I will take 4th, 5th and 6th from that gearbox and 3th out of a different model.



First and second stay as they are, 3th will be a 1.32 ratio, 4th 0.97, 5th 0.73 and 6th 0.60.



Now ordering the bearings and all other stuff to rebuild the box. A lot of cleaning up to do .....

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[flash]

best of luck. i don't think you are going to be able to go nearly as fast as you think, and i think 5th will be your top speed gear, not 6th. i'm not sure you'll have enough torque in 6th to cruise either. you may find yourself having to downshift to accelerate.



i'm afraid of the same problem, which is exactly why i have not done this yet.

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[flash]

to clarify my thinking about acceleration, let me explain:



in a stock car, at 3400 in 6th gear you are doing 80mph. to accelerate at that point, you really need to downshift to 5th, so you can hit the peak torque point of 4200 rpm. even so, the acceleration is not particularly great.



with the gearing you are setting up, you will need to be making 180 ft/lb at the wheels at about 2200rpm to be able to accelerate as fast.



as an example, with my kit, i am making that at about 2600 rpm, but it isn't until about 3400 rpm that i feel like i am making enough torque to accelerate without downshifting, and i am making about 230 ft/lb at the wheels at that point. it still isn't rocket fast, but it's comfortable.



i would look closely at your dyno charts and see how much torque you have at a given rpm, then look at how you drive and what you want.



i just went through this. that's how i came to the conclusion that, even after bumping up power in my kit to a peak torque of 275 ft/lbs at the wheels, i won't be able to turn a 6th gear any taller than .7 without giving up top speed in that gear

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