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Engine Specific Info and Questions => IDI Engine => Topic started by: 54321chris on January 30, 2010, 07:23:22 pm
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Sorry if this has been covered before, but I didn't see it in the search. I have an ATA 02a transmission, 5th gear .795, R&P 3.684. My tach isn't working, but I'm guessing by the noise under the hood that revs in fifth gear are way too high. Now for the questions:
1. Can I swap fifth gear from an 02j transmission?
2. What kind of drop will I see from using a .744 fifth gear from a EUH transmission? Is this a decent drop, or should I shoot for one of the .681 or .658 gearsets for the tdis?
My car is a 1990 Corrado with a 1.6, T3, in the middle of turning up the juice.
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Found a gearing calculator. Apparently the swap would drop the rpms from 3024 to 2834 at 70 mph. Good enough? I'm trying to get a good cruising rpm out of this.
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the .681 would give me rpm of 2593 at 70, which is really close to the standard passat tdi gearing. Still wondering if the 02j gears can be used.
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the 02J gears can be used.
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I don't know exactly what you mean by "turning up the juice" but I would advise you to be careful not to overgear the car. I believe the torque curve of the stock motor stays pretty flat until 3K rpm, so there is not much reason to go lower than that for your cruising speed. If your motor is making gobs more power than stock -AT 2600 RPM- then you might get away with the .681. I would not do it until I had verified the engine output at that RPM on a chassis dyno.
In answer to your "good enough" question in your second post, it would be for me but then 3Krpm at 70mph would be good enough for me too. My engine is still reasonably quiet at that RPM.
-David
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From my understanding, 3k is quite a bit higher than stock gearing would be for a diesel, and I don't want to punish myself unnecessarily on my daily 80 miles of freeway driving.
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i don't think you will be punishing yourself.. the stock td makes its torque at 2800 rpm(??) so 3000 cruising rpm would be a very efficient and powerful spot to cruise in. You will have to drop a gear and give it if you go with too low of gearing, where you would be cruising at 25-2600rpm...
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i like a fifth gear that i can drive all the way to town and not have to shift 4th. and my car right now, you gotta shift it. but thats from lack of torque (gasser) oh, wait, it doesnt have torque. thats right.
from my experience, in a light VW, with a fairly powerful diesel, you can get away with 3.67 gears and a .75 od just fine. it works out good. im at about 2700 rpms at 70 mph with my stock ACN.
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I have a CHD with a .71 from a FF trans
It's a 020 with a peloquin, 100 mm inners with 90 mm outer's
There is a ebay seller that sells ohc units, his shop is located in the NW area
Ebay Item:160384615155
Good luck
G.B.