turbos/A4 and rear gears
02-22-2010, 02:24 PM
#1
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turbos/A4 and rear gears Let's try this again. You guys with turbochargers and automatics what rear gears are you running? How do you like them and what gears would you run if you where to make a change.
02-22-2010, 04:55 PM
#4
Again, since you seemed to miss them in the othe thread: how tall is your rear tire you race on? how fast will your car approximatly go in the 1/4 mile? How high are you comfortable spinning your motor?
I'm tryin to help ya man, relax.
02-22-2010, 05:35 PM
#6
There's tons of factors that will help you determine what gear to run. Is it a street car or a track car? What will it make peak power at RPM wise? What size tires are you planning on running? How heavy is the car? What cam are you going to run/where does the car make power?
In my 3600lb '98 z28 making 500/550rw I ran 3.42s and 26" MT radials and had plenty of room to grow. Boost came on at a good rate - wasn't too fast where the tires would just boil and was fast enough where it would build boost and be manageable on the street - and the car ran well with them.
This car I have now is about the same weight, and is in the middle of a M6 to 4L80 swap and 3.73 to 3.23 gear swap.... but its making about 125 more hp than the last one, and I intend to make more in the future. It's a street car so I want the power to come on like the last car - not too fast and rip thru the tires and not really be 'in boost', but steady to build boost from the load of the motor on the 3.23s and make the power much more manageable on a 295/45/17 MT radial.
In my 3600lb '98 z28 making 500/550rw I ran 3.42s and 26" MT radials and had plenty of room to grow. Boost came on at a good rate - wasn't too fast where the tires would just boil and was fast enough where it would build boost and be manageable on the street - and the car ran well with them.
This car I have now is about the same weight, and is in the middle of a M6 to 4L80 swap and 3.73 to 3.23 gear swap.... but its making about 125 more hp than the last one, and I intend to make more in the future. It's a street car so I want the power to come on like the last car - not too fast and rip thru the tires and not really be 'in boost', but steady to build boost from the load of the motor on the 3.23s and make the power much more manageable on a 295/45/17 MT radial.
02-22-2010, 06:37 PM
#7
Yeah there is not 100% perfect ratio as most people have different ideas about what they like for gearing and different needs.
I see a lot of guys liking the really low numerical gears like 2.73,3.08 type of thing on turbo auto builds. I drive mostly city and mostly off boost and personally don't like the feel of the car which is pretty darn heavy with that type of gear. I went to 3.54 as that is only choice the Dana gives for low numerical gear. I do plan to run 295/45/17 at track and sometimes street and think they are bit taller than my regular street tires so they will knock the gear down a bit. I think would have likely gone 3.42 if it was offered and possibly 3.23 lowest.
I have had a few other auto cars that were not turbo but they both were converted to 3.42 and with reasonable stall they seemed to be nice combos. One of them was turbo 400 in a 400 cube built a bit 80 TA. The other car is wifes 96z with 2800 vig and 3.42s getting fairly modded.
But again turbos are a bit different. But of course off boost they aren't really.
Lower numerical gears can help the turbo cars get and keep traction and some seem to feel maybe justifiably that they can help load the turbos to give quicker spool up.
I have no complaints with spool up on my 3.54s. But traction is not that easy to come by. But am looking at other options like ramping the boost in by rpm,time ,gear.
As said I don't like the feeling of 3.00 or lower gears when driving around off boost.
Also most guys are going to set up the gears so you have enough mph without having to go to overdrive at the track. If they care about getting best 1/4 mile times.Not everyone does.
I see a lot of guys liking the really low numerical gears like 2.73,3.08 type of thing on turbo auto builds. I drive mostly city and mostly off boost and personally don't like the feel of the car which is pretty darn heavy with that type of gear. I went to 3.54 as that is only choice the Dana gives for low numerical gear. I do plan to run 295/45/17 at track and sometimes street and think they are bit taller than my regular street tires so they will knock the gear down a bit. I think would have likely gone 3.42 if it was offered and possibly 3.23 lowest.
I have had a few other auto cars that were not turbo but they both were converted to 3.42 and with reasonable stall they seemed to be nice combos. One of them was turbo 400 in a 400 cube built a bit 80 TA. The other car is wifes 96z with 2800 vig and 3.42s getting fairly modded.
But again turbos are a bit different. But of course off boost they aren't really.
Lower numerical gears can help the turbo cars get and keep traction and some seem to feel maybe justifiably that they can help load the turbos to give quicker spool up.
I have no complaints with spool up on my 3.54s. But traction is not that easy to come by. But am looking at other options like ramping the boost in by rpm,time ,gear.
As said I don't like the feeling of 3.00 or lower gears when driving around off boost.
Also most guys are going to set up the gears so you have enough mph without having to go to overdrive at the track. If they care about getting best 1/4 mile times.Not everyone does.
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02-22-2010, 08:06 PM
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5.3 truck block, 383, ported LQ9 heads, 224/228 cam
TC76 w/.96 A/R. 3500 stall.
I presently have 3.73's but now that I'm installing a 9" I'm thinking of going with 3.00. Car is only a weekend car, so I'm not to concerned about the tall gearing in town type stuff.
Right now with the 3.73's it just spins in first, shifts to 2nd and starts pulling hard, 3rd the gearing is to short. It's like the motor needs to be geared to make it work harder to accelerate the car.
TC76 w/.96 A/R. 3500 stall.
I presently have 3.73's but now that I'm installing a 9" I'm thinking of going with 3.00. Car is only a weekend car, so I'm not to concerned about the tall gearing in town type stuff.
Right now with the 3.73's it just spins in first, shifts to 2nd and starts pulling hard, 3rd the gearing is to short. It's like the motor needs to be geared to make it work harder to accelerate the car.
02-23-2010, 09:05 AM
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I didn't say anything about a TH400. Maybe someone else did. I asked you a few very specific questions that will determine the best gear for YOUR car.
Again, since you seemed to miss them in the othe thread: how tall is your rear tire you race on? how fast will your car approximatly go in the 1/4 mile? How high are you comfortable spinning your motor?
I'm tryin to help ya man, relax.
Again, since you seemed to miss them in the othe thread: how tall is your rear tire you race on? how fast will your car approximatly go in the 1/4 mile? How high are you comfortable spinning your motor?
I'm tryin to help ya man, relax.
I dont know.........I use a 2.48 first gear, for several reasons, your not interested in.