Information on 5:12 Differential Ratio
#1
Rotary Freak
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Information on 5:12 Differential Ratio
Looking for any help anyone can provide on acquiring, installing, maintaining and benefits of a 5:12 diff ratio for a second gen. On another website I read that the improved acceleration capability may be worth up to 2 seconds a lap. I am concerned about cost, durability, temp rise (in diff) and availability.
How is this achieved? I have read that it is a first gen diff with a welded on extension to the pinion shaft. This sounds a little scary to me. I am running the car as a cross between EP and a World Challange spec and my longest races are 3 hours. Thanks in advance for the help.
How is this achieved? I have read that it is a first gen diff with a welded on extension to the pinion shaft. This sounds a little scary to me. I am running the car as a cross between EP and a World Challange spec and my longest races are 3 hours. Thanks in advance for the help.
#2
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it is a modified 1st gen piece as you described and most EP cars I have seen use a cooler to help it last. as for performance it is likely to make your car faster.
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most IT cars can't suck enough air to make use of the 5.12, they simply can't rev fast enough.
At least that's what I've heard from other IT racers.
But one thing I didn't hear is, how the heck do you run a cooler for a differential?
At least that's what I've heard from other IT racers.
But one thing I didn't hear is, how the heck do you run a cooler for a differential?
#4
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Originally posted by Barwick
most IT cars can't suck enough air to make use of the 5.12, they simply can't rev fast enough.
At least that's what I've heard from other IT racers.
most IT cars can't suck enough air to make use of the 5.12, they simply can't rev fast enough.
At least that's what I've heard from other IT racers.
But one thing I didn't hear is, how the heck do you run a cooler for a differential?
Disclaimer: The above modification has been deemed illegal for IT-rules competition. Your situation may vary.
#5
Rotary Freak
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2nd Gen Differential Oil Cooler
Simply plumbed it is as follows:
1) out from drain plug at bottom of diff.
2) through filter element
3) through pump, has to be able to handle gear lube and temperatures up to 300 F.
4) through cooler element
5) back in through filler plug hole
Will need to add fittings and hoses. Doubt that diff cooler liquid to air rad can be plumbed on to a street car as no place will be out of the way and have air flow. I will mount mine drawing air through rear plexi window and exiting through screen in place of license plate mount.
Concern over diff temp with new gear, is that even with stock diff I have seen over 200 F temps.
1) out from drain plug at bottom of diff.
2) through filter element
3) through pump, has to be able to handle gear lube and temperatures up to 300 F.
4) through cooler element
5) back in through filler plug hole
Will need to add fittings and hoses. Doubt that diff cooler liquid to air rad can be plumbed on to a street car as no place will be out of the way and have air flow. I will mount mine drawing air through rear plexi window and exiting through screen in place of license plate mount.
Concern over diff temp with new gear, is that even with stock diff I have seen over 200 F temps.
#6
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Re: Information on 5:12 Differential Ratio
Originally posted by 23Racer
I am concerned about cost, durability, temp rise (in diff) and availability.
I am concerned about cost, durability, temp rise (in diff) and availability.
Durability - have yet to see a 5.12 gearset fail. Ever.
Temp rise - not a concern if you change your fluid regularly (1-2 weekends).
Availability - The gearset is readily available, but the machine work is hard to come by. The only sources I know of are SpeedSource (941-578-7071, www.speedsourceinc.com ) and ISC Racing (863-324-4539, www.iscracing.net ). Both are in Florida.
#7
Rotary Freak
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Thanks
Thanks Chris for the information. I will contact Speedsource and ISC on Monday. I will tell them you gave me the lead and maybe they will give you a break someday.
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I should note though that I have the 5.12 rear in my race car (although I haven't driven it yet). I think the guy's reasoning for giving me that tip is because I race at Waterford Hills www.waterfordhills.com and it's a very tight track, so that the engine needs to rev like crap at the low speeds (average speed for the track record in IT7 (12A first gen with ITA rules) is 68 mph or so). So at those low speeds the 5.12 might not be the best. Check out the track, there's only one real straight. It's so tight that really that back straight is the only place you can check your guages.
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