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Trans Build: Need FWD Education

Old Jan 25, 2020 | 09:08 PM
  #1  
JackDW - 852's Avatar
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Question Need FWD Education

I have always owned RWD performance vehicles. The 2004 SS I recently purchased is the first FWD vehicle I have fooled with. One of the items I don't like is it is fairly weak at the bottom end. In the case of RWD, I would just add a better gear. Love the 4:10 but the 3:90 or 3:73 is probably a better all around gear.

Based upon some initial research, it does not seem that the final drive ratio work the same in FWD,

I keep seeing where people want to up the 2:93 final to something higher like the 2:70s What is this all about. I need more guts at the bottom end. I don't care what the top end is. I will not be using that top end, just want to get there faster. My experience (at least in my area) is the lower gear (3:73 or lower) results in better mileage for me. I DON'T drive much open flat roads so the extra torque provided by the gears allows me to use less throttle when pulling out. I can climb hills without increasing throttle and by using less throttle, I get better gas mileage. So don't jump into how the lower gears hurt my mileage. IT DOES NOT, at least in my case.

So can someone explain how FWD final drive ratio works and how to improve my low end torque. The engine seems to produce good power just slow at the start.

Thanks for pointing me the right direction. I hope to have this discussion with a local performance shop but would like some knowledge before I go there.
 
Old Jan 26, 2020 | 01:08 PM
  #2  
Jeffs02rwdSS's Avatar
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individual gear ratios in the 440-T4 are as follows: 1st-2.921, 2nd-1.568, 3rd-1.000, 4th-0.705, Reverse-2.385. The TH350 has a case length of 21.50" long and the gear ratio's are 1st 2.52:1, 2nd 1.52:1, 3rd 1:1. I believe you are getting final drive and transmission gearing confused. As you can see the T440/ 4T60E has better low gearing than a comparable TH350 . High gear in the TH350 is the Same as 3rd gear in the 4T60E.. I hope this explains a little.
 
Old Jan 26, 2020 | 02:22 PM
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bumpin96monte's Avatar
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Originally Posted by JackDW - 852
So can someone explain how FWD final drive ratio works and how to improve my low end torque. The engine seems to produce good power just slow at the start.
The most common way to adjust this ratio is to swap out the drive chain (connects the input shaft to all the junk leading to the output shaft) and sprockets. Most common options are 2.93, 3.29, and 3.69 (assuming starting with a 3.29 diff). Unfortunately it's pretty labor intensive as you've got to pull the side case cover off the trans. May also consider a looser converter if you want stronger takeoff.

TBH, the reason not a lot of people go that route (besides the expense) is that on modded FWD 3800s (especially supercharged setups), its usually a struggle to put the power down from a dig. So besides all out drag cars running slicks and hardcore suspension setups, people generally lean towards numerically lower setups.
 

Last edited by bumpin96monte; Jan 26, 2020 at 07:35 PM.
Old Jan 30, 2020 | 09:58 AM
  #4  
JackDW - 852's Avatar
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Thanks Jeffs02rwdSS and bumpin96monte. Yep, I have a lot to learn regarding the FWD. Following your response and doing some research, I now realize that the FWD systems do not use the old Ring and Pinion setup but uses a gear and chain setup. Very much like a system in a 4-wheel drive transfer case.

The more I lean about these systems, the less I like them. GM must have saved a lot of money to put such a "clunky" system in these cars. The older RWD systems had become almost "bulletproof". Love the looks of the 04 Monte but that drive train..... well this can be a family forum so I will not express my initial opinion of the FWD systems. Hopefully, I will eventually find something positive to say about it in the future (but I am not holding my breath).
 
Old Jan 30, 2020 | 02:19 PM
  #5  
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To be honest there's a lot of great things that came from FWD. I appreciate both older and newer car's for different reasons. Even though the driveline changed the car's became faster with the same or less power because of rotating mass. The cars are 2000-2007 are basically the same weight as 1978-88 model's except a little bigger (2000 +) and are running the same engine's. But dramaticly faster and get better fuel mileage. I'm not trying to change your mind on how a RWD car isn't better or worse . Both have things that make them special.
 
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