Goughary

Front diff axle flange seals went in today. I know I wrote about this in the past, but I'll go over it again here since its an easy job and all of us need new axle flange seals after 25 years and few of us ever bother to do them. If you look at your front diff or rear transaxle, and you have black crud surrounding them, then the likelihood is that over the years, this is the spray or diff fluid that is slowly seeping out when your car is hot and you are driving it hard. Cold diff fluid won't weep out of these seals unless they are blown, and they typically don't blow out. They just get worn and hard and don't seal as well as they used to...and if you are following some old school method or timeline that says trans fluid should be done every 20-30-40k miles...you, in some cases, prior to doing these seals, likely don't even have all your fluid still in the trans or diff and that's just not fun. I'm on the "it should last forever" plan, and not the "this car I'm paying payments on needs to get me through the next 38 months", plan....so for me, I do diff and trans every 10k. And motor oil every 3k. And I fully flush and bleed the hydraulic fluid twice a year. A good shop guy once told me "your car will never hate you for feeding it fresh fluids". Truer words never spoken. If we took care of airplane motors the way most people take care of their car motors, we'd have planes falling out of the sky all the time...

Fresh fluids all the time, and a car engine will almost literally last forever. Sort of...but you get the point.

Onward- step one, drain diff fluid. Crack the drain plug. Crack the fill plug. I use, now, a 10 mm Blackhawk 1/2 drive impact Allen socket on a breaker bar. Never use a cheep alternative, at least not on a car that hasn't been having regular fluid changes, by you, where you know they haven't been over tightened and if they've been off, you know you won't have issues. We had on that require so much force that we broke a 10mm Allen socket. Bent it into a pretzel. Tells you how long some diffs go without fluid changes. Plus there are manuals out there that state 52 ft/lbs of torque when you tighten them back up. Correct torque is 35 ft/lbs. I use 38...



Next, get out your impact gun and a 17mm socket. Hit the axle bolt with the impact gun- ONLY for taking it off. Do not use an impact gun to put it back on. Tightening torque putting it back on is 32 ft/lb. so not go higher. There is a thread somewhere recently that will make you believe this would be a very bad idea...

Once the bolt is out, the flange just comes straight out. Clean it with wd40 and a brass brush. You don't want grit to go into your diff. So cleaner is safer.

Get a seal pick. I've don't these with a pair of channel lock pliers. Ripping them out, but there is a steal ring inside the seal, so honestly, a seal pick is just easier. You only want to hook the seal pick into the steal portion of the seal. Any farther and you will be booking the inner lip of the diff and when you pry the seal out you will scratch the seat. So think 6-7mm in is where you want to be booking the seal. Pry it out. It's hard, but it comes.



Clean the area careful to not get grit inside.
Grease up the new seal, and then take a 74mm flat bearing press tool or something wide and flat like that and tap in the new seal. You only go flush to the case. No deeper. And make sure it's equal depth all around. Use a plastic hammer and tap it evenly into place - LOW force. You don't have to hit it hard. Don't bend the steal in the new seal. This is very easy if you are easy. If you are a monkey...or a gorilla...it's not going to be a good day and you'll have to pry it out and use another seal.



Slide the flange back in. Screw the flange bolt back in finger tight.

Screw a bolt into the flange on one of the six axle bolt holes so that the flange can't rotate. To bolt will be using the diff case to stop the flange from turning. Torque the flange bolt to 32 ft/lbs



And done. On to the next.

Then refill the diff. Use new crush washers. Put the drain plug in first. Make sure you wet the crush washer with diff fluid first. Torque to 38 ft /lbs. Then using a pump, fill the diff till the fluid is running out the filler hole and screw the filler plug in. Torque to 38 ft/lbs and your job is done.



On to the rear. Pretty much all Porsche's from the era have the same seals. So now you can do 944, 951, 968, 928, and 911 flange seals. Lol.

A shop will charge you huge money for this job. But if your axles are out anyway...it's an hours worth of time...so worth doing and in this case, they wont hopefully add too much to the bill. Or as a diy, the seals are 17 dollars and the fluid is fifty. And you are good for another 20 years...

ffc

When you replace your PDAS cylinders do you do have to do anything to prevent hydraulic fluid loss? In other words when you disconnect the units does fluid go everywhere? I ask because I have this job lined up for the weekend with Colins seals and want to get my prep right.

Nash_TDI

WOW.

Just read the entire thread today. Some in detail some scanning pictures. Amazing work can't wait to apply some of it to my 993 project/basketcase. Took many of notes and copied some of the useful links.

Also preordered a "awesome" T.

Clint

Goughary

Pump the brake pedal tillers rock hard. This will release all the pressure from the system. Then put a drip pan under the hard line. It'll drip but nothing to worry about.

You need to have some way of bleeding the locks after, so I hope you have a pdt999...doing it with the central dash control sucks. And it's a long process

Goughary

Nice. Way to go Clint. Last the only one was pre ordered, it was made and shipped. So let's see...unless there are two other guys wanting to buy a couple dbfd tshirts that are listening...


I actually need to get back on the shirts. I have a few almost done, but I have no time for graphic design anymore...but they are coming

HalV

Any opportunity to put the "Make Awesome Happen" slogan on the back of the "drive break fix drive" T-shirt?

ffc

Thanks for this. I have the PDT999 and have been waiting for this opportunity to use it.

Goughary

It's common to drain the battery too much while bleeding. Especially if you are going slow and doing a real fluid flush. Also good to have a battery jumper on hand, you plug it onto the battery and turn it on and use it as an extended battery, which will then allow the pdt to read and work the locks.

ffc

Good to know, thank you very much.

deadendd9009

Thought I'd ask but could you take the flange to drive the seal in place, or at least get it started square? Seems the flange has a nice flat lip.

And how are you liking that Delvac transmission oil?

Goughary

You can't use the flange to get t started. But you also don't need to. You just tap it in with a seal press tool. Easy enough.

Delvac seems to be the chosen fluid. I've always used redline. But making the switch. So I'll know more later on that one.

deadendd9009

It may be very obvious when I see it, but can you show me what that tool looks like?

Your thread, by the way, is a gold mine. Thank you so, so much for it!

Goughary

I went on eBay and bought this kit a while back. It's been invaluable...there are lots of different kinds, but this works for a lot of basic stuff. You don't want to use these for pressing bushings, or any very high pressure pressing...but do small bearings, seals, wheel studs, all the basic stuff, works great.

To be honest, I prefer higher quality. But we unfortunately live in a world today where minimal quality is the norm and the only thing affordable.

Side note- I was at a Sears the other day..can't believe how far down the ladder craftsman tools have fallen. Talk about a good company gone bad. What I do now is each time I break or ruin a craftsman tool, I just replace it with snap on, blue point, sk, or some other higher quality brand. Crazy.

Goughary

Forgot the picture...:

JasonAndreas

Not so much for winter driving in New England.