Changing Rear Diff on a MY99 STi5
 

Hiya,

I need to Change my Rear Diff on a MY99 STi5.
I have a R180 diff and just need help in replacing.

I have a few questions as well.

1. Do I need to renew the driveshaft oil seals?
2. What do I need to slacken before I get the shaft out?
3. How do I get the shaft out? do I need a tool?

Any help or guides, much appreciated.
Obviously I will put new oil in.
Cheers, Ricky.

Are you changing the diff for one the same, or a different type,... ie, 160-180? cos i think the shafts are different depending on which one you have!

Ron is dead right!
The R180 needs different shafts and hubs too I think.
To answer your questions (as I have just done this job for the 4th time)

Oil seals are ok if they are in good condition
You need to remove the long through bolt that passes through the 4 lower lateral arms/hubs.
To remove the shafts from the diff you need to pull VERY hard and above all SHARPLY on the hub as if you are trying to pull the hub off the car sideways. This will dislodge the small snap-ring on the half shafts which can get stuck in the diff! Quite a violent action.
Alternativly, if you have a good pry-bar, that will need a sharp snatch to do the same job, kinder on the CV's.

The shaft's 'stub shaft' is quite long (80mm ish) and you can JUST clear the diff oil seals (be carefull!)

The diff itself is a big unbolt job and is heavier than you think when it comes free.

If you need the driveshafts/hubs, call David at Welcome to the API website
Tell him '911' sent you.

Graham
:D

Cheers for the replies, yes the diff is an R180 in the car and the replacement is a R180.

Easy life then!
Graham :D

R180's can be 3.9 ratio or 3.54, or 4.4, Make sure you change like for like or there will be BIG problems. If in doubt take out the filler plug, paint mark a tooth and count the ring gear teeth.

3.9 will have 39 - JDM 01 on, these usually have a temperature sender in the plug.

4.4 will have 40 - STi vers 3 / 4 / 5 /6 coupe.

3.54 will be something else :D I forget what . - UK 01 on STi

David APi

PS, just thought;

No hassle to fit at all if like for like. EXCEPT that the drive shafts vary depending upon whether plated or viscous diff [ or open ].

Probably best, if not sure, to take the back cover off and see if the actual differential is the same shape / style / etc - as the wrong shafts will not engage in the diff and you'll have more problems.

Good luck.

Hiya,

---

My Transmission code on my Type RA according to the VIN plate is:
TY754VB1EA

The diff I have bought is from a Type R and I have removed the top plug and counted the teeth, there are 40.

---

Does this seem OK?
How can I tell if the new Type R rear diff is plated?
How can I tell if my original one is a R180 and the Type R one I have is an R180?

---
Cheers, Ricky.

That box should be a 4:444 final drive.
Thus, from David's info the diff is a 4:444 too, so perfect.

I think all Type R's were plated and R180.
I've had a painful time with rear diffs, and have learnt to only trust what you see when you take the alloy diff cover off and an EXPERT like David above see's it.

Been there and done that!

Cheers, you have been very helpful, I'm either going to attempt it myself or get Subaru4You to do the job.
However I am sure that some time in the future I will going to see David at API and getting a monster 6 speed setup..

Can I tell from the splines if it is a R180?

Regards, Ricky.

No.
The R180 is physically larger in width especially, and uses the rare shorter drive shafts etc to fit to a classic.

Unless you are used to seeing both sizes, it is very hard to tell which is which (unless side-by-side.)

Hiya, so if I measure the width for the one in the car and the new one they should be the same. How much wider are the RA R180 diffs over the 'normal' R160 diffs? Are we talking a few inches or mm here? Cheers, Ricky.

At a guess about 20 to 25mm across the alloy flanges where the driveshafts go in.
A 160 measures:170mm across the alloy side plates (just been and measured mine)
The R 180 will be about 200mm

Graham

The R180 is quite a bigger all over than the R160 if they look and measure about the same then they are the same. It is more centimetres than millimeters.

As for the driveshaft fitting, there are 2 choices; best is take the back cover off and look see, OR; look through the drivesahft holes and see if what you see in the donor is the same as the replacement. IE all the way through no obstruction, a shaft crossing over the middlemaking a blockage but still able to see round it, or no hole at all.

Good luck David

But definitely a 4.4 as Graham says above.

PPS got that shaft out yet Graham ??

Yep, a bloody big lump hammer, a 1/2 socket set extension as a drift and an almight thwack sent it flying out. good rustic engineering!
Shattered the C cilp in the diff...which I've fished out with a magnet!

I've machined a new groove in the CV stub now to position the clip correctly.
On the other side I took the diff side CV off the saft I had off you and installed to the original Sti shaft and the fit is perfect.(new shaft was too short, so maybe it was a R180 shaft?)
By the weekend I might actually have it all back in the car (I'm getting good at rear diff changing now) and the car moving on the road!

What a game!

Graham
:D

Hiya,

Both diffs measure the same at just over 180mm to the outside edge of the flange each side.
So good news is that both are the same size and definately are bigger than an R160.

Maybe I have an R170 then ?? :lol1: :wonder:

Nope, an R180 I recon!

The bottom 2 bolts on the rear diff plate are 60mm apart on an R160 and 80mm apart on an R180. An R180 is from memory 210mm high vs 200mm for the R160.

Paul

Hiya,

Thanks all, diff fitted today and all went well.
Seems tighter but it appears my 'diff noise' is a wheel bearing doh!

So I have an R180 diff for sale, 49K miles.

How do I tell if it is an LSD or plated?