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373 v 411's ?
Hey Guys,
I'm thinking about changing the differential ratio in my car and I'm wondering how much difference it would make. Here are the specs on my car. 351 Ford crate advertised at 362hp at fly wheel Tremec 5 speed 8.8 axle with 373 gears. The car is not a racer. I'm just looking for some more 0-60 acceleration. MPH is not a factor. If it was I'd buy a Prius. Also, how difficult is it to change rear end gears? |
If 3:73s aren't enough to convert your tires to smoke with that engine, you must have something wrong that lower gears aren't going to fix. I've got 3:75s and 1st gear is pretty close to useless already.
Pete |
The difference you will notice is: an even more useless first gear.
Honestly, with a Tremec a 3.27 gear is better. |
I have the Tremec z in my Classic Roadster with the 3.27 rear and you still
have to be careful in 1st or all you do is spin the tires. |
If you put in 4.11s, first gear becomes useless and 2nd would become your first gear. I have 3.73s with 25.5 tall tires and only use first for crawling in traffic or for steep hills starts. Depending on your overdrive ratio, the 4.11s may make highway riding lousy.
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Ok, you're looking for opinions, correct? 4.11's won't do anything for you except replacing rear tires more often.
I've got a FE in mine w/3.27's. My opinion, big blocks (FE's or 385-series) work best with 3.27's or 3.07's in our light cars. I've ridden in many, many small block replica's, with all different rear ratios; in my opinion, depending on build level/cu. in., small blocks work best w/3.27's or 3.55's. Obviously, 1st gear ratio of many differenent trannies come into play too. |
3.73 is about as low as i would go. the engine is pretty strong with the svo block. it probably has a vic jr intake, you can replace that with a rpm air gap and that will give it some zip. the cam is probably retarded, advance about 4 degrees and that will help. change heads will help little. i did a write up on doing this if you search. getting rid of the heavy 40 pound flywheel/clutch for a lighter unit will help quite a bit.
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Hold on now Turbos!! If you haven’t run 4.10s maybe you should hold your comments.
I run several different ratios 3.27, 3.73 and 4.10s. I think they are great, maybe the best ratio for the typical street cobra application with one caveat: you need to run a sticky tire. You guys should all know by now, this game is all about the tire! If you run T/A radial (or similar rubber ilk), it doesn’t matter what gear or how much HP you have, you can incinerate them in 1st and 2nd gear. Climb out of the automotive dark ages and get some capable tires. But I digress.. Roger, 4.10s will provide slightly better acceleration over 3.73s. You will pick up 200-300 rpm on the highway @ 65-70mph depending on the 5th gear ratio you have. Changing gears in an 8.8 isn’t hard but it does require the tools and knowledge to set the thing up correctly. Unless you are going to do many, take it to a local shop and have it done. The last one I had done (here in LA) ran me about $200+ parts with the center section out of the car. Jason |
FFR, fuel injection 302, mild.
I like the 4.11, I drive mostly on two lane roads and I like to hear the pipes. I have 3.07 rear end and I end up driving around in 3rd gear at 55mph. I don't like to go much over 55mph, I know the cops are watching. If the pipes growl at 55mph, that is fine for me. I like to wind her out until 55 and then I back off. I like to go to 55 fast but I have no desire to push 100mph in this car. |
4.10s are perfect for that, especially when you’re not making a ton of HP. It will feel snappy and pull strong compared to the 3.07s. If you not looking to go over 100mph, I would consider a set of 4.30’s. Get a used set on Ebay for cheap and give them a try!!
Jason |
Hey Guys,
Thanks for all the great information. Vector1 ... thanks for the tip on the flywheel ... I going to think about that one. I know I could do it myself as I put the clutch in myself when I built the car. My instruction sheet that came with the engine recommends a 1" carb spacer. Would that really do anything for me? Thanks again, Roger |
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Pete |
Roger,
You probably wont notice that much of a differenc between 3:73 and 4:10's. I switched from a 3.27 to 3.73, some difference but not huge. I will second what D cell said about considering 4:30's. The flywheel will help some, I swithced from a 14 pound aluminum one to a steel. The steel is much easier to slip and drive. |
The more I think on this the more i'm inclined to leave well enough alone.
For a street cruser the car is fine the way it is. If I decided a need more performance I'll just go with a 460 :) .... won't happen ... I'm broke. So goes retirement, so much time, so little money. |
Roger I changed from a 3.5:1 to a 3.89:1 with a TKO600 transmission. 347 engine. I changed ratio because the 0.64 5th gear ratio would not play nice with my cam at 55-60 mph. Seat of the pants, not that much difference.
Pick up a part time or seasonal job that you enjoy. You should be able to make an easy $3K over a winter (or summer if your in a desert). Get with KC on a set of heads, intake, and cam. That is a change you will feel in the seat of your pants! |
I use 3.7's with 17 x 12 on a 315 Nittro 555r's. (25 1/4" tall tire) Tremec R600 w/ .82 final. Thats the ticket for me. The motor's a 460 by New Generation Engine. She turns 2300 at 100 klms in fifth. Dyno says 750 hp at 5800. Torque is 610 ft pds from 1400 to 4200, on a flat line. With the 3.7's The car is most manageable in traffic. 3.55's at idle produce too much head snap for my liking.
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I have 466 stroker pushing 700 plus HP. Tremec 600/ 5 speed/ 0.82 fifth. I have 3.08's in a 9 inch Currie, with an Aurburn Ratchet spool. My RPM is 2100 at 63 MPH in 5th. I don't allow the engine to go past 4200. No need to thrash the motor. The 3.08 will give me 22 MPH in first @ 2500. I get 37 MPH at 4200 in first. With 680 ft/p torque at 1400, I have to be careful not to destroy my M/T's and have the wife *itch at me.
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Load in your specifics and see what you get with this calculator Gear Calculator I opted for a 3.27 rearend with TKO600 (.82) just because I don't want a useless 1st gear as some here have stated. Also opens up 5th for some nice gas friendly cruising at a good clip.
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Nothing like bolting in a clutch. |
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