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4.083 Gears & Overheating?

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Old 04-15-2011, 10:33 PM
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Question 4.083 Gears & Overheating?

So I'm pretty much halfway into re-gearing my differential to a 4.083 FD on my 2006 5AT Coupe and I know running at higher speeds in top gear the RPM difference compared to the normal final drive is higher.

Now, about once a month I do a 140 mile, 2-and-a-half-hour commute and use the interstate and I can easily find myself doing 80 to 90 mph (I know, I speed, I'm sorry, its an addiction) for a lengthy portion of the trip which means I'm definitely going to be increasing the RPM's the engine sees constantly for those 2 and a 1/2 hours.

So my question to you guys is, do I need to get any sort of additional cooling mods (automatic transmission cooler, bigger radiator, both) to prevent damage, or do you think the stock cooling system will suffice for this kind of use? That commute is pretty much the longest trip the car will see, but like I said, I do it pretty much every month.

Thanks for your help!
 
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Old 04-16-2011, 03:32 PM
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Originally Posted by 35Alive
So I'm pretty much halfway into re-gearing my differential to a 4.083 FD on my 2006 5AT Coupe and I know running at higher speeds in top gear the RPM difference compared to the normal final drive is higher.

Now, about once a month I do a 140 mile, 2-and-a-half-hour commute and use the interstate and I can easily find myself doing 80 to 90 mph (I know, I speed, I'm sorry, its an addiction) for a lengthy portion of the trip which means I'm definitely going to be increasing the RPM's the engine sees constantly for those 2 and a 1/2 hours.

So my question to you guys is, do I need to get any sort of additional cooling mods (automatic transmission cooler, bigger radiator, both) to prevent damage, or do you think the stock cooling system will suffice for this kind of use? That commute is pretty much the longest trip the car will see, but like I said, I do it pretty much every month.

Thanks for your help!
I don't think so. While the rpms will be elevated a bit, I don't think they'll be elevated enough to cause any issues. The torque converter should be locked at speed which greatly reduces ATF temps.

BTW, those gears are absolutely overkill for a bolt-on VQ35DE. In the 1/4 mile, you'll be slower. Consider a set of 3.54s or 3.69s instead.
 
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Old 04-16-2011, 05:40 PM
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Originally Posted by DaveB
I don't think so. While the rpms will be elevated a bit, I don't think they'll be elevated enough to cause any issues. The torque converter should be locked at speed which greatly reduces ATF temps.

BTW, those gears are absolutely overkill for a bolt-on VQ35DE. In the 1/4 mile, you'll be slower. Consider a set of 3.54s or 3.69s instead.
Good to know, thanks for the reply. And I'll lose 1/4 mile time because of the top end loss associated with shorter gearing I assume you're refering to? How much slower are we talking? I'm more about 0-60 than anything, that's what I want to improve the most by re-gearing.
 
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Old 04-17-2011, 01:13 AM
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For the simplicity of it I would get a complete pumpkin from a 6mt G35(3.5fd) or from a G37(3.69fd) it would be cheaper and much simpler than buying and installing an aftermarket 4.08 gear set the performance difference would be small. IMO
 
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Old 04-17-2011, 01:57 PM
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Originally Posted by Sylvan lake V35
For the simplicity of it I would get a complete pumpkin from a 6mt G35(3.5fd) or from a G37(3.69fd) it would be cheaper and much simpler than buying and installing an aftermarket 4.08 gear set the performance difference would be small. IMO
Well, I already have the 6MT diff. housing (minus the ring and pinion), so simplicity is already out the window lol. And since I'm going to have to rebuild it I was thinking might as well go with the R&P of my own picking. Thanks for the input though man, always appreciate your expertise.
 
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