tbennett017

Sent the Dosh.

Thanks!

Goughary

Pm sent

Flashtv

Hi 9M, and all the gang on here, wondering if the kits are still available? And can post to Toronto canada? I may order a few sets since they are rare. So thrilled to find you here on Renn.
Also love to hear from anyone who has installed and using.
Cheers
Geoff.

Goughary

I have installed them. Very happy. Easy to do and was very necessary in my case. Thanks to 9m for providing.

Flashtv

Fantastic! Thank you or the feedback, I've ordered them this morning and now we wait...

-nick

A bump for this old thread. Colin got a seal kit to me very quickly early this year. I discovered that my longitudinal lock was leaking badly when I pulled the tunnel underbody cover off. The new seals fixed a lot of odd PDAS behavior- lights and buzzer were going off when the longitudinal lock was being activated but wasn't holding hydraulic pressure. I had the lights&buzzer happen randomly on big potholes, during autocross (obviously, not during a good lap!), and snowy surfaces. Now I understand why the lights went off and I had a hard time getting up my steep street in the snow last year- the lock was trying to give more power to the front wheels but it was just squirting fluid.

A few tips to help the seal replacement-

1. After you stretch the center seal over the piston, let it sit for ~1 hour and it will shrink back down. Then you can press the piston into the cylinder much more easily.
2. Similar with the seals that wrap around the piston. wrap them around the piston and then wrap them with cling wrap for an hour so that they hold their bend when you slip the piston into the cylinder.

3. My light bulb moment: Replace the original bleeders in the cylinders with SB6100 Speed Bleeders (M6x1.0mm size). Open the speed bleeders slightly, then sit in the car with the ignition on and click the PDAS switch on/off. Every time you engage the locks, the PDAS control will shoot a nice squirt of hydraulic fluid through them both. The speed bleeders make this annoying job easy as pie No hammer, Bosch or otherwise, needed.

http://www.speedbleeder.com/



And a big for Colin and 9m!

Goughary

Rock on Nick. I need to do that. And I still need to replace the seals in the front diff lock. Which is that? The one in the back by the right rear wheel was way easier to get to. That diff lock had long ago seized. So no clue what I will find in the other.

-nick

Rear lock is the transverse. Front is the longitudinal. All kinds of gnarly gunk came out of the cylinders!

alexjc4

Good tip on the speed bleeders for the locks, just ordered some

I bought Colin's seal kit a while back and it looks like I may need to fit it some time soon - the rear transverse lock is starting to drip fluid.

NineMeister

Great feedback Nick. Your findings are spot on, so as soon as I get the chance I will update the instructions with this new information. It's also reassuring to know that in our own little way we are helping to keep our 964 C4's on the road and running properly. The seals are still available at the intro price to all Rennlist members, just follow the purchasing instructions at the start of the thread.

Goughary

My transverse lock has a small weep since the install of the new seals. Any idea what one could do wrong with the simple kit install?

-nick

Full disclosure time- My future wife came out to the garage to join in the fun of rebuilding the longitudinal slave cylinder. Unfortunately, big gloves + small hands = dropped the delicate tin piston on the concrete floor! I thought that I straightened the bend out of the top corner of the piston well enough, but the first time that I tried to bleed it under pressure, it leaked. I took it apart again and found that the top seal was still slightly pinched by the bend. Straightened it again, this time the seal was free to rotate, and no leaks at all now. Whew!

I have faith that you didn't put the center seal in backwards, right?

Those are, at least, free fixes to try/check if it's still leaky.

Assuming that it isn't a scored or pitted cylinder bore... Even still, a machine shop might be able to hone it smooth if it isn't too bad. Not sure if these things can be sleeved? At the replacement prices, it's worth checking. Rob- here's hoping it's the easy fix!

Colin- Feel free to mail out one of your billet heads for this service announcement!

Goughary

I didn't know there was a backward and forward. So I have a 50 50 shot that I did it right...

I think maybe your honing idea is the right one. Maybe the bore is rough from corrosion.

All that means that I need another new seal Colin, for when I take this apart again...ugh.

pi5tolpete

What a great idea with the speed bleeder idea. Just ordered mine. Here's hoping for a clean extraction of the 25-year old ones...

Goughary

bumping to ask a question abt how the dif locks actually work -

the spring is in the back of the diff lock - so does the hydraulic fluid suck the pin back into the lock? and then press it into the differential when it needs to lock the diff? or is it the other way around? what is actually going on in the trans-axle? a curiosity really...