Rear End Question
11-10-08, 02:33 PM
#1
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Rear End Question
Hi, so I'm just wondering if there is any way to get a lower Rear end gear ratio? Can i swap the gears out of a Mazda truck or something else? The car i have is a 87 Base model N/A
Thanks
Matt
Thanks
Matt
11-10-08, 03:27 PM
#2
You've got a 3.9 rear end already, which is the lowest ratio of any FC rear end. There's not going to be any bolt-in rear end w/ lower ratio that wouldn't require a custom driveshaft, mounts, etc...
Why would you want a lower ratio anyway? You'd be trading acceleration for top speed, which means nothing since an NA motor will never run out of gearing.
Why would you want a lower ratio anyway? You'd be trading acceleration for top speed, which means nothing since an NA motor will never run out of gearing.
11-10-08, 04:28 PM
#3
You've got a 3.9 rear end already, which is the lowest ratio of any FC rear end. There's not going to be any bolt-in rear end w/ lower ratio that wouldn't require a custom driveshaft, mounts, etc...
Why would you want a lower ratio anyway? You'd be trading acceleration for top speed, which means nothing since an NA motor will never run out of gearing.
Why would you want a lower ratio anyway? You'd be trading acceleration for top speed, which means nothing since an NA motor will never run out of gearing.
A GTU-s would have a 4.3 ratio, other than that, Mazdatrix sells 4.3 R&P for around $600. Pretty steep for the amount of performance improvement.
11-11-08, 12:40 AM
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You've got a 3.9 rear end already, which is the lowest ratio of any FC rear end. There's not going to be any bolt-in rear end w/ lower ratio that wouldn't require a custom driveshaft, mounts, etc...
Why would you want a lower ratio anyway? You'd be trading acceleration for top speed, which means nothing since an NA motor will never run out of gearing.
Why would you want a lower ratio anyway? You'd be trading acceleration for top speed, which means nothing since an NA motor will never run out of gearing.
Matt
11-11-08, 01:56 AM
#6
Well, I'm 0 for 2 unless you have an automatic, which did have a 3.9. With a manual trans, you'll have a 4.1 open diff stock. There's a sticky thread at the top of this section that lists all standard features by year/model.
I take it you actually would prefer the 3.9 since it would reduce cruising RPMs and save fuel? If that's the case, '88 convertibles and NA automatics had them.
I take it you actually would prefer the 3.9 since it would reduce cruising RPMs and save fuel? If that's the case, '88 convertibles and NA automatics had them.
11-11-08, 02:35 AM
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Well, I'm 0 for 2 unless you have an automatic, which did have a 3.9. With a manual trans, you'll have a 4.1 open diff stock. There's a sticky thread at the top of this section that lists all standard features by year/model.
I take it you actually would prefer the 3.9 since it would reduce cruising RPMs and save fuel? If that's the case, '88 convertibles and NA automatics had them.
I take it you actually would prefer the 3.9 since it would reduce cruising RPMs and save fuel? If that's the case, '88 convertibles and NA automatics had them.
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11-11-08, 04:52 AM
#8
Well, if you think changing from a 4.1 to 3.9, which is actually higher gearing, will be a fuel saver, it will only drop the RPM .048%. If you're spinning at 2500 changing from a 4.1 to a 3.9 will save you about 147 RPM and that small of a change won't do anything that is noticeable for putting money in your pocket. Also the small block certainly likes the lower gearing.
11-11-08, 07:16 AM
#10
53.6%/46.4% - Crap!
I think you will definitely want a transmission with overdrive or your motor will be turning at a high RPM on the highway.
I would suggest a T-56 if you can find/afford one. I *think* an LT1-style T-56 works with an older SBC. If you can find a T-56 with a 0.50 6th gear you will be turning at about 1800 RPM at 65 mph, even with 4.10 rear gears.
If you want to look into using something like that I would suggest checking out www.v8rx7forum.com. They will be able to give you some other good ideas. I have an LT1/T-56, but I don't know what the SBC guys usually run.
I would suggest a T-56 if you can find/afford one. I *think* an LT1-style T-56 works with an older SBC. If you can find a T-56 with a 0.50 6th gear you will be turning at about 1800 RPM at 65 mph, even with 4.10 rear gears.
If you want to look into using something like that I would suggest checking out www.v8rx7forum.com. They will be able to give you some other good ideas. I have an LT1/T-56, but I don't know what the SBC guys usually run.
