There I was, ready to leave work after a long day of none sense. The car was warmed up, the parking lot was clear and I decided I wanted to get on it a little bit. Well, big mistake. I guess the stock diff wasnt a big fan of that because as soon as I started to launch the tires bit hard and then a horrific grinding noise that sounded like gears were shredding. I immediately pushed the clutch in and rolled into a parking spot all the while trailing 90W behind my vehicle. I got a quick look at the puddle of growing oil and got disheartened. I had to gather my things and get a ride from a friend before I could get a good look at what happened.

So I have been doing some searching since I got home and it is obviously a fairly common problem with higher horsepower applications. I ran 353rwhp on a mustang dyno, Its not that high but apparently high enough. I thought I had pillow ball issues but it seems perhaps that maybe I had some serious backlash issues instead. Or both? I will continue to read up on the subject but in the mean time I was wondering if anyone had any advice as to what I should specifically look for tomorrow when I get a chance to get under the car. As well as any good solutions to fix this issue with some type of relative quickness. Any advice is appreciated.

Thank you,

Brian

 

what year is your 7?

 

repalce the complete diff

 

Its a 94.

I just got pricing on a kaaz unit from the shop that built my engine, 900 bucks. Does that sound about right?

I am so tired of things breaking on this car right before I get out of the military and eating up my savings. Im to the point that I would almost rather sell it.

 

well you know what they say, it's called an fd (financial disaster) for a reason. im suprised it broke, i always thought it was alot stronger then that.

 

Just replace the complete diff. I have a few low mile stock diffs complete..

less than 30,000 miles
Bolt it in and go..

They are $350.00 plus shipping

 

If I blew one stock diff then another one is bound to go. Though it may be cheaper that way to just slap one in and sell it which I had planned on doing anyway.

 

T2 diff is stronger and cheaper than a Kaaz...

 

YES , and the Cobra cradles are the way to go if you're going to do burnouts , Drift , or go in a straight line (Drag) ... aftermarket (Fighters-Garage) toe links and trailing arms , and soild Diff bushings will prevent wheel hop , which is most likely what destroyed your Diff ... stock FD Diff can handle some HP , but hard launches and wheel hop will destroy a stock FD Diff

 

3 things:
Replace broken diff Assembly ( the whole pumpkin complete)
New diff mount bushings
Aftermarket diff brace ( Chris @ Banzai has his brace on special right now!!)
link:
https://www.rx7club.com/showthread.p...02#post8766902

The end..

 

you should just get a cobra cradle and diff . handle tons of power and have infinate gear ratios u can chose from.

 

u figure most of the high hp v8 rx7 run im sure u would be much happier at the end .

 

I've never broken a TII diff but did break plenty of output shafts (tulips/axlecups/whatever you call them)

Your diff itself is probably fine. I bet you broke the case.

 

No he probably took the diff with it. If the case fails everything caves in. I'm tryin to decide if i'm going to invest in a Pineapple brace or save up for a Cobra diff.

 

Wheel Hop FTL

 

Thank Jebus I'm putting in a T2 diff. as "preventative maintenance".

 

I have a nice new Samberg cradle for installing the Cobra diff in the FD presently advertised in the clasified section. It is brand new, never installed, already painted and will save you over $150 from buying direct. Plus I can ship it right away - no waiting for another group buy from Justin.

 

I also have a clutch type TII diff unit for $175 plus shipping just in case you want to just beef up your present set up and keep the car. The TII unit is definitely more robust than the stock FD part and bolts into the FD case. As you can see, I was preparing for diff upgrades until financial issues slammed the door on my FD project. I hope I can help you out.

 

the stock FD limited slip is a Torsen which has small spider gears that BREAK. it is designed for max grip while road racing. it doesn't work for drag starts and takes the rear gears with it.

all you need to do is jump on the T2 diff offered above, buy the Banzai Racing support and get a set of solid diff bushings. there is a set offered in the classifieds somewhere for $25... generally they are around 50.

you are then good to go.

howard coleman

 

How does that work with the cobra diff (which eliminates the Power plant frame) and no tranny mount? The rotary doesn't have a tranny mount, that was the purpose of the PPF...

I have Justin Samberg's Mazda diff cradle, which for the LS1 swap keeps the Mazda diff, which is great for road course stuff and not so great for drag lanches, but you need a tranny mount to triangulate the transmission and engine mounts. Most swap kits include the tranny mount for the LS1 but I am unaware of a mount for the rotary... Are they out there?

If they are, you could even go with a stock diff and Justin's Mazda cradle, which is $550 IIRC.