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Getting the 5.125 rear end should I also replace the lsd

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Old 12-22-2014, 04:45 PM
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Getting the 5.125 rear end should I also replace the lsd
The 5.125 is already pricey enough, but would it be worth while to get the os giken lsd and be done with the diff?
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Old 12-22-2014, 05:02 PM
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What type of racing do you do?
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Old 12-22-2014, 05:35 PM
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Track days with the local group not scca or nasa.
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Old 12-23-2014, 01:48 PM
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I got the tomei 2way lsd and its awesome! Highly recommend it.
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Old 12-23-2014, 09:41 PM
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Not much help from me, but I'll be interested to see what you decide to go with. I'm in the same boat.

What's the best price you've found on the OS-Giken unit?
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Old 12-24-2014, 01:45 AM
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Don't put a 2 way diff in a road course car you'll understeer like mad...
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Old 12-24-2014, 05:46 AM
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You're better off to go with a fresh OEM LSD if you feel yours is beat up. Especially if you will still be street driving the car
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Old 12-24-2014, 07:56 AM
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someone on here did a review on a 2way and went back to stock. try searching for it

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Old 12-24-2014, 10:52 AM
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hopefully you are also installing an electric gear oil pump, oil cooler, and oil lines tapped into the rear diff cover to keep it from overheating
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Old 12-24-2014, 07:52 PM
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Originally Posted by TeamRX8
hopefully you are also installing an electric gear oil pump, oil cooler, and oil lines tapped into the rear diff cover to keep it from overheating
Great idea!
Last edited by rustrocket; 12-25-2014 at 07:32 PM.
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Old 12-24-2014, 10:03 PM
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In all fairness, some tracks will heat up diffs quicker than others but I don't know of many people who can run upwards of 20min with the 5.12's and not overheat to some extent
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Old 12-25-2014, 06:31 PM
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Originally Posted by TeamRX8
perhaps you should try searching before posting ...
You're right. I'm sorry. It won't happen again.
Last edited by rustrocket; 12-25-2014 at 07:32 PM.
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Old 12-25-2014, 08:28 PM
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It's not that big if a deal. I was just pointing out that over 10 years of information and experiences are documented here if you take the time to look for it ...



.
Last edited by TeamRX8; 12-25-2014 at 08:32 PM.
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Old 12-25-2014, 10:42 PM
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That will be part of the plan. Thank you.
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Old 12-29-2014, 11:01 PM
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Are you doing it on your own? Esther way make sure you get some set up info on the backlash. You do not want to run the stock recommendation. I can get specs if you need them. Replace the seals and such while your at it, that stuff is cheap considering your probably sending a solid 2k on this...

Stephen
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Old 01-04-2015, 09:35 AM
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I'll be having a shop to put it together.
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Old 01-04-2015, 03:37 PM
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Why not posted up the specs for everyone to see them? Figuring it needs to be looser to accounts for the heat load ...
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Old 01-04-2015, 11:16 PM
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I will be installing a 5.12 on my car in the next couple of days. Using the factory LSD. I'm not planning on oil cooling just yet. I won't be doing sessions longer than 20 mins.

I don't have the specs as I bought the whole pumpkin off of a race car.

I will report any weirdness I run into.
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Old 01-05-2015, 04:34 PM
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A diff cooler is always a good idea... that being said I've run my 5.12 diff in my car for three seasons now with no cooler and no problems. It does get hot and sometimes spit oil out of the vent on top... but it has held up so far. Most races are 25 minute sprint races but I've done some 45 minute races as well.
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Old 01-05-2015, 08:29 PM
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say again ... ?

https://www.rx8club.com/rx-8-racing-...advice-224093/

pretty sure you won't stay anywhere near 200*F without a cooler setup
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Old 01-06-2015, 09:52 AM
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You are like the search master... or you have a postographic memory! lol

It turned out that diff was built incorrectly. The problems I was having that I talk about in that post were not due to the gear ratio but due to incorrect assembly/setup. After that race I had the diff redone by a more knowledgeable shop and since then no problems.

I'm not saying a differential cooler isn't a good idea. It definately is - the rear end gets really really hot. I'm just saying that you might be able to get away without one... at least for a while... who knows... mine is probably a ticking time bomb!

Originally Posted by TeamRX8
say again ... ?

https://www.rx8club.com/rx-8-racing-...advice-224093/

pretty sure you won't stay anywhere near 200*F without a cooler setup
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Old 01-22-2015, 10:16 PM
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Originally Posted by ScubaSteve8
You're better off to go with a fresh OEM LSD if you feel yours is beat up. Especially if you will still be street driving the car
For that cost you might as well get an OS Giken LSD. Maybe I'm the only one here who has one?


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Old 01-23-2015, 10:03 AM
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I'm using the factory LSD.
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Old 01-23-2015, 02:57 PM
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Mazda only sells it as a complete assy; $640 + shipping from Motorsports. Might as well buy a tunable aftermarket LSD instead of ever replacing it.

my low mileage OE LSD is sitting in a box waiting for a new home if anyone ever needs one (approx. 5000 miles combined street/autox use)
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Old 01-24-2015, 10:16 AM
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Installation note: easier to pull the end links off from the inside (pulling the bolts off) than pulling the ball joints - you will need to realign the rear anyway. Check the diff mounts when you do so. Buy extra half shaft clips.

I can say it is amazing on track.
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