DPI Platinum LSD unit (streetable?) other ?'s also.... - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 10 Old 02-03-2011, 09:34 PM Thread Starter
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DPI Platinum LSD unit (streetable?) other ?'s also....

I am building a 2600lb (goal) road race oriented LS2 (GM) powered turbocharged '93 Mazda RX-7 with Fbody T56 and Cobra 8.8" IRS diff out back running DriveShaftShop 300M custom Pro Level axles (31 spline Porsche CV style inners, 33 spline HD outers). Power output will be in the 700-900rwhp range with a boost/gear/speed controller. Running the new Holley Dominator EFI system.

Just bought a DPI LSD unit to put in the pumpkin with 3.31 gears and dedicated diff cooler. Car has 315/30/18 fronts and 335/30/18 Hoosiers out back to put the power down and Penske double adj coilovers with other goodies. Fully stripped/full cage/aero tricks etc race car.

A few questions:
1) is this streetable as I want to take the car out for limited street adventures
2) how will this LSD unit take hard launches. ie drag strip launches

Anything else to note ie maintenance, broken/worn parts you have noticed with yours, feedback etc? Fluid preferences/break in procedure?

Thanks for any info. I did a search; however the last topic about the DPI units was years old. The Plantinum unit wasn't even available at that time.

The car I'm building isn't in my sig. It is the New New Project


'93 RX7, 2800lbs, LS7/T56Magnum/Cobra 8.8" [email protected]
'93 RX7, 2900lbs, LS9 88mm turbo/T56 Magnum, solid 8.8" ran [email protected] on 11psi
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Car: '93 RX7, 2470lbs wet, 438ci LS7, Gforce GSR dogbox, 8.8" IRS diff, JRZ's *SOLD*

Last edited by gnx7; 02-03-2011 at 09:38 PM.
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post #2 of 10 Old 02-04-2011, 11:21 AM
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I use the platinum track in my racecar. Back when the car was streetable I never had an issue with the diff. It occasionally pops when making u turns but that is normal. I would not make hard launches on drag slicks with this diff. The cases are not bullet proof, Griggs racing strongly advised against using drag slicks but said drag radials would be ok, but my car has 1/3 the power you are looking to make so I would be very careful in your case. Autocrossers that run big slicks, ie CP class tend to blow up the cases as well. I think it has to do with the tighter turns and the fact that autocrossers are a little more violent with throttle application than road racers. You're on the right track with the diff cooler, it will definitely extend the life of the unit. At some point I'd like to install one in my car. Change the oil regularly if you race. I change my oil every other event per Randy's (DPI owner) recommendation and I use 3 quarts instead of 2. I burned up my unit two seasons ago because I was only running 2 quarts and I didn't change the oil at all during the season. An internal part critical to the unit wore out and it cost me nearly $500 to have Randy rebuild it. I won't be making that mistake again. I use the Joe Gibbs 75/140 when available, but the Redline 75/140 and Royal Purple 75/140 are also recommended by Randy and they can be bought at any decent auto store.

I noticed you are building an LS2. I'm not knocking the motor but I hope you are addressing the oiling issues that motor has. I've seen a few of them blow up at the track in the last couple of years. Good luck with the build sounds like a very quick machine.


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post #3 of 10 Old 02-04-2011, 07:06 PM Thread Starter
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Thank you for the feedback!

Any other input?

Diff cooler is 100% on the to do list. In the directions it was saying to change the fluid every 250 laps.... which I would translate into 500-1000miles.

I have addressed the oiling issues. Dailey billet dry sump system




Guess for drag racing I'll have to install another diff with a spool.

Some pics of the DIFF setup:


DSS Axle kit:



And what the car should look similar to when completed (my street RX-7). This project car is very close to being finished. This month I hope.


Last edited by gnx7; 02-04-2011 at 07:14 PM.
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post #4 of 10 Old 02-04-2011, 07:53 PM
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I've had similar experiences. I use Royal Purple 75/140 with DPI's friction modifier for fluid. I don't have a diff cooler, but run an overflow tank. A hose runs up from the breather fitting into the trunk area to the bottom on the tank. The top of the tank is vented to the back of the car. I keep at least 3 qts in the rear axle maybe more as I fill it from the overflow tank.

My car is not streetable but would not expect any problems. I don't drag race and that differential is just too much money to risk breaking. When it was new, it sounded pretty bad. Lots of noise but it worn off after a few track days. I think mine is about due for a rebuild. The car does not seem to pull out of a turn as strong as it used to.

Overall I think it's a great unit. Definitely a wow factor after swapping out the stock Ford differential.

Last edited by SteveL1994; 02-04-2011 at 07:56 PM.
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post #5 of 10 Old 02-08-2011, 04:24 PM Thread Starter
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Thanks for sharing. After reading some of the issues with the T2-R LSD unit I opted for this one. Plus they are local so I can pester them if need be

3 quarts of fluid.... hmmm. Maybe I'll do an overflow, plus pump, plus cooler setup. The goal is to take the car to the Silver State Challenge and really see what it can do.

'93 RX7, 2800lbs, LS7/T56Magnum/Cobra 8.8" [email protected]
'93 RX7, 2900lbs, LS9 88mm turbo/T56 Magnum, solid 8.8" ran [email protected] on 11psi
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Car: '93 RX7, 2470lbs wet, 438ci LS7, Gforce GSR dogbox, 8.8" IRS diff, JRZ's *SOLD*
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post #6 of 10 Old 02-10-2011, 02:48 PM
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Holy CRAP! That car is going to be crazy.

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post #7 of 10 Old 02-14-2011, 09:18 PM
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Quote:
Originally Posted by dpspeed View Post
Holy CRAP! That car is going to be crazy.
Kinda what I was thinking too.

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post #8 of 10 Old 02-23-2011, 05:37 PM
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Do you have a build thread anywhere for that car? I would love to read up on it.

92 Limited Edition Vert HodgePodge MM , Cobra Brakes, Roll Bar, Auborn Pro, 31 spline Mosers, 3.73's
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post #9 of 10 Old 02-28-2011, 02:58 PM Thread Starter
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I'm shipping the car to TN to my buddy in March that owns a fab/race shop to have pretty much all the work performed. Once it gets rolling I'll make a build thread.

Goal is to take it to Road Atlanta to shake down the car in the summer and then ship it back out to CA to do some road racing and then Mojave Mile 1 mile shootout in the Fall. Want to break a top speed record out there.

'93 RX7, 2800lbs, LS7/T56Magnum/Cobra 8.8" [email protected]
'93 RX7, 2900lbs, LS9 88mm turbo/T56 Magnum, solid 8.8" ran [email protected] on 11psi
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Car: '93 RX7, 2470lbs wet, 438ci LS7, Gforce GSR dogbox, 8.8" IRS diff, JRZ's *SOLD*
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post #10 of 10 Old 10-15-2012, 04:51 AM
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any update? I am looking at a DPI unit for my 89 vert. 500rwhp road race. I would like to know what you think of the unit? Everything else that is out there is rated up to 500hp max. After that, you are looking at a DPI.

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