Hydraulic Servo Laid Bare!

[jade]

Does anyone know whether Audi made an uprated version of the servo which provides more assistance, possibly used by their motorsport folk?

There a thread on this, Using the larger servo and the newer R8 rs6 Master cylinder

[Rusty]

Sounds interesting, link?

[jade]

http://www.s2forum.com/forum/showthr...t=larger+servo

Sounds interesting, link?

[Rusty]

Thanks for the link.

I think vacuum servo is the way to go, as parts are readily available and the lack of service kit means that the existing worn servo moving parts cannot be replaced without manufacturing them, even if the o rings and seals could be.

[jade]

Thanks for the link.

I think vacuum servo is the way to go, as parts are readily available and the lack of service kit means that the existing worn servo moving parts cannot be replaced without manufacturing them, even if the o rings and seals could be.

Yes, I have a vacuum set up ready to go on, But I would like to see if it is possible to fit the 26.99mm from the later models with a adapter of some sorts

[Rusty]

Need to compare the nose and fixings but perhaps that's best on another thread, so it doesn't get lost

[popdemonic]

I was searching ebay and found one version of the audi brake servo(blk finished) for sale.the listing shows
The item for sale including with the rebuild kits for 800usd.i remember the brake servo is non serviceable
Parts.i'm wondering where did the seller sort the rebuild kits for the brake aervo.i never seen one for
our brake servo version(rs2 s2 urs4/s6).if we can sort one from the manufacturer(Ate).that would be a good news
for anyone who's running the brake servo.i recently converted the single diaphragm vacuum brake booster
Back to hydro system.i might be getting the dual diaphragm brake booster from A8 in the future.
Personally i dont like the too stiff pedal for single diaphragm vacuum booster from A6 C4.i have seen
The C4 with 2.7tt motor with dual type booster from A8.the parts is identical on C4 chassis.
Almost pluh and play.moding or triming the chassis or firewall is not required.

[Jimmaey]

does anyone know where to get the seals to revise the brake servo? My one was leaking into the cabin side with sticky pedals and spongy brake as a result. im hoping i can get it fixed like this instead of buying another second hand unit that could break aswell.

[Rusty]

All the info I've found suggest this is not a serviceable part but error404 may be able to shed some light, or dave (urs4boy) or ZF themselves.

[veneto rs2]

All the info I've found suggest this is not a serviceable part but error404 may be able to shed some light, or dave (urs4boy) or ZF themselves.

Rusty this forum member does supply the serviceable parts and also he does the work of repairing them.
I'm already in contact with him and we'll definetely ship few boosters from RS2s and Urquattros to service for few italians.

http://www.s2forum.com/forum/showthread.php?t=80364

Above the thread where he present his work.

[master6]

Booster DIY repair kits, and a repair service too.

Hi Rusty,


I am new to your Audi Forum, having just joined.

I have recently posted repair and rebuild information on ATe Hydraulic Brake Boosters.

I liked your information on this new style Audi ATe booster. It does look as it is rebuildable.

But caution should be used on the light blue o-rings, these rings are probably made of nylon and when they are removed from the piston they will stretch, and not return back to the original size. This nylon materal is quite hard in comparison to the rubber o-rings.
I have found that they do not ware out. The lubrication of the ATF makes it almost a frictionless piston, and replacing them is not worth the hassle.
And because of the stretching, and they do not like to go back inside the booster without damage.
Maybe ATe found a new material that returns back to its old size, after being stretched to install onto the internal piston.

In the older BMW's ATe had white nylon square cut rings, with a rubber o-ring underneath the white nylon, 2 (one on each end of the internal piston).
I used to supply new nylon rings but mine were a grey color, as mine were impregnated with Graphite. I stopped selling them as they were not 100% for the DIY market.
Just as you show, the light blue ones, in your photos.

Veneto rs2 post #25 above,
He posted my Booster website on the S2 Forum.
EDIT : it has been changed, this is the new link, please use this one below.

https://photos.google.com/share/AF1Q...NpZDRQVHlGal9n

Cheers,

Jay

Please note:- The only thing that keeps this complicated piece of kit lubricated is the PAS fluid. Incorrect or dirty fluid will lead to premature wear, a £600 bill for a new servo and about 2 hours' labour! That's assuming that failure doesn't result in brake failure... you have been warned

Decided to see how easy this 'non serviceable item' was to disassemble... turns out that with nothing more than a pair of pliers, small screwdriver and a small punch, I took it apart in my kitchen

Here are some pictures showing all the bits and bobs. There is only one bit I didn't take apart - the inboard shaft, which is held together with a roll pin.

Approximate parts list

1. Body
2. Outboard seal
3. Outboard shaft with hardened tip
4. Plastic bush / cover (blue)
5. O ring seal (black)
6. Retaining Cap /
7. Washer
8. Spring
9. O ring seal
10. Inboard shaft (2 part) + joint + 270deg restrictor
11. Ballbearing (possibly used as a valve or between the shaft and Retaining cap)
12. Piston + split pin
13. Retaining pin + seal
14. Plastic bush / cover (blue)
15. O ring seal (black)
16. Retaining collar + seal
17. Circlip
18. Dust seal
19. Locking nut
20. Clevis
21. Clevis pin

[John.]

After deciding it'll be quicker to bleed my brakes by just pumping the pedal instead of using easy-bleed kit........I now have the green fluid dripping out the small hole on the bottom of the servo ............engine NOT started.
I'm assuming that because the piston has moved way further than normal that a seal has turned or got torn........is it worth a strip-down??

Anyone have a working spare they're willing to sell?

[master6]

Servo Repair Service

Hi John,

What type of servo do you have?
I have a servo repair service.
The link below has two types of servos, one has 4 studs and the other has 3 studs.

here is a link, https://goo.gl/photos/QCcFGTqdeeGDSgC48
Please follow the instructions on page 2,3,4 to view the Captions (info panel)

Best,

[John.]

Hi John,

What type of servo do you have?
I have a servo repair service.
The link below has two types of servos, one has 4 studs and the other has 3 studs.

here is a link, https://goo.gl/photos/QCcFGTqdeeGDSgC48
Please follow the instructions on page 2,3,4 to view the Captions (info panel)

Best,

Mine has 4 studs, what money and turn-around-time are we looking at? Please note I'm not on your shores! If you'd rather send me a PM.
Regards,
John.