S4 Caliper refinish and re-build: What to (and what not to) do:
01-07-2009, 04:02 PM
#16
Race Car
I can do it. However, i need to do it with at least 10 folks.
A group buy for the kit would be $700 (rotors, race pads, spacers, GTS bolts, and instructions on the light dremel work)
Let me know if you guys are interested. Its a great modification. one of the cheapest and most effective Ive done in a long time!
Think about it. Basically, GTS brakes for $700!! (and no disconnecting your S4 calipers or any mess!)
mk
A group buy for the kit would be $700 (rotors, race pads, spacers, GTS bolts, and instructions on the light dremel work)
Let me know if you guys are interested. Its a great modification. one of the cheapest and most effective Ive done in a long time!
Think about it. Basically, GTS brakes for $700!! (and no disconnecting your S4 calipers or any mess!)
mk
Dan
'91 928GT S/C
475hp/460lb.ft
01-08-2009, 12:55 AM
#18
Nordschleife Master
I do know the GTS's calipers (at least the fronts) are i assume pwder oated or painted with that very heavy paint.
When used though the faded finishes on the S4 and GTS calipers do appear to different.
07-01-2009, 01:24 AM
#19
I just had to rebuild the driver's front caliper on my wife's '91 S4. The outside pistons had froze up.
I also wanted to try the Hawk Ceramic pads on her car & I got them for front & rear for her '91 for about $255 shipped from the Tire Rack.
Soooooo, I had to figure out what my best options were with time & money. Thoughts of spending $500+ for a new caliper, or $1400+ for upgrading to the GTS setup didn't sit so well with my current auto repair budget, since I've been in "Car Repair Hell" the past couple of months with one car after another needing something thats never cheap. I ended up deciding to do the rebuild mainly based upon reading & seeing your detailed info in this thread Rob, so a very big THANK YOU, to You, for taking the time to write it up & especially to put in the pics. That always makes the difference for me. My brake guy said there was no reason to rebuild the others now if they were working ok & he gave me some good tips too.
I was able to locate the correct brass fittings at Lowes in the plumbing dept. so I could connect my compressor to the caliper. It took just two fittings to get it connected up. The stuck pistons came right out with one blast from the compressor, 100psi is way too much btw, they sounded like a gun shot when they hit the wood shims from just 1/2" away! 50psi makes more sense & when reading again tonite I saw your recommendation for that.
The only snag was in getting the dust boots out, but again, that was only due to my ignorance in never having done this before. I thought they were all rubber, including the edge that fits into the caliper. It wasn't until I finally wised up & looked at the new ones that I saw they were a metal ring that I realized your method with the screw driver was to wedge between the ring & the caliper to ease it up a little at a time. Once I got past that & with a stubborn piston or two in getting them to go back in, it wasn't bad at all. Of course, I just did the one, I imagine all four would become tedious.
I also want to say a special Thank You to both Roger T. & Mark A. for both taking much time out of their day to explain to me my options. Roger also for letting me interrupt his vacation, & Mark also for reminding me about Rob's thread explaining how to do the rebuild. I apologize to you both that neither of you made any money this time, but I assure you that the time you both spend helping answer questions & helping solve problems for us 928ers does not go unappreciated or unrepayed.
For me this time, since everyone would have to order them, I ended up getting the kits from Brumos Porsche since they are local & near to me, took a couple days to get them. They gave me a good price on them too, the small piston kit was $19.61 ea. and the larger ones were $23.20 ea. So the cost was less than $100. One odd thing, the Hawk pads had dampers with the front pad set, but not the rear. So I included those when I got the rebuild kits.
I also wanted to try the Hawk Ceramic pads on her car & I got them for front & rear for her '91 for about $255 shipped from the Tire Rack.
Soooooo, I had to figure out what my best options were with time & money. Thoughts of spending $500+ for a new caliper, or $1400+ for upgrading to the GTS setup didn't sit so well with my current auto repair budget, since I've been in "Car Repair Hell" the past couple of months with one car after another needing something thats never cheap. I ended up deciding to do the rebuild mainly based upon reading & seeing your detailed info in this thread Rob, so a very big THANK YOU, to You, for taking the time to write it up & especially to put in the pics. That always makes the difference for me. My brake guy said there was no reason to rebuild the others now if they were working ok & he gave me some good tips too.
I was able to locate the correct brass fittings at Lowes in the plumbing dept. so I could connect my compressor to the caliper. It took just two fittings to get it connected up. The stuck pistons came right out with one blast from the compressor, 100psi is way too much btw, they sounded like a gun shot when they hit the wood shims from just 1/2" away! 50psi makes more sense & when reading again tonite I saw your recommendation for that.
The only snag was in getting the dust boots out, but again, that was only due to my ignorance in never having done this before. I thought they were all rubber, including the edge that fits into the caliper. It wasn't until I finally wised up & looked at the new ones that I saw they were a metal ring that I realized your method with the screw driver was to wedge between the ring & the caliper to ease it up a little at a time. Once I got past that & with a stubborn piston or two in getting them to go back in, it wasn't bad at all. Of course, I just did the one, I imagine all four would become tedious.
I also want to say a special Thank You to both Roger T. & Mark A. for both taking much time out of their day to explain to me my options. Roger also for letting me interrupt his vacation, & Mark also for reminding me about Rob's thread explaining how to do the rebuild. I apologize to you both that neither of you made any money this time, but I assure you that the time you both spend helping answer questions & helping solve problems for us 928ers does not go unappreciated or unrepayed.
For me this time, since everyone would have to order them, I ended up getting the kits from Brumos Porsche since they are local & near to me, took a couple days to get them. They gave me a good price on them too, the small piston kit was $19.61 ea. and the larger ones were $23.20 ea. So the cost was less than $100. One odd thing, the Hawk pads had dampers with the front pad set, but not the rear. So I included those when I got the rebuild kits.
07-01-2009, 01:40 AM
#20
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Ryan-
Believe me, I am with you 110% on the finish, I don't like it either. I'm mad at myself for not just stopping and coming up with a better solution before just slopping on the G2 epoxy paint and moving on (the holidays were coming to a close and January is super busy for me). And I should point out that I'm not disparaging the G2 paint or even Preval sprayers, I just didn't figure out how to use them properly. I probably shouldn't even post such hideous pictures, but hell, sometimes you have to post the negative data with the positive data. Brendan's powdercoating looks like the best solution to me right now, though maybe if I had any painting skills at all I could have done a better job with what I had.
You may be right on the GTS calipers, but the total cost for all 16 caliper kits and 4 pairs of bleeders was $318. Mostly the benefit is the experience of doing it and knowing that all the bits are renewed. (Though like I said at the top, they probably would have been fine for a long time more without the rebuild- the brake hose re-fresh is probably the only thing that was really necessary....)
StratfordShark:
The extractors are from a set of Snap-On extractors I got off of Ebay. I've posted these pics in another thread somewhere on here. They just chock up in a 1/2" socket and you turn out the stripped bolt. For that brake caliper bolt I think I got it started by using the impact wrench on it, just to get a good bite on the bolt. That sucker was on there TIGHT....
If you're going to go to the trouble of re-doing the calipers, i would definitely do all four brake hoses, the rears aren't THAT bad. Clearance is tight, but dropping the heat shields an inch and using an 11 mm stubby on the fitting will work. The e-brake cable can be pushed out of the way without too much difficulty. Like so many things on this car, you just need to find the little pocket of space that just barely allows you to turn the wrench on whatever you're trying to remove.
Believe me, I am with you 110% on the finish, I don't like it either. I'm mad at myself for not just stopping and coming up with a better solution before just slopping on the G2 epoxy paint and moving on (the holidays were coming to a close and January is super busy for me). And I should point out that I'm not disparaging the G2 paint or even Preval sprayers, I just didn't figure out how to use them properly. I probably shouldn't even post such hideous pictures, but hell, sometimes you have to post the negative data with the positive data. Brendan's powdercoating looks like the best solution to me right now, though maybe if I had any painting skills at all I could have done a better job with what I had.
You may be right on the GTS calipers, but the total cost for all 16 caliper kits and 4 pairs of bleeders was $318. Mostly the benefit is the experience of doing it and knowing that all the bits are renewed. (Though like I said at the top, they probably would have been fine for a long time more without the rebuild- the brake hose re-fresh is probably the only thing that was really necessary....)
StratfordShark:
The extractors are from a set of Snap-On extractors I got off of Ebay. I've posted these pics in another thread somewhere on here. They just chock up in a 1/2" socket and you turn out the stripped bolt. For that brake caliper bolt I think I got it started by using the impact wrench on it, just to get a good bite on the bolt. That sucker was on there TIGHT....
If you're going to go to the trouble of re-doing the calipers, i would definitely do all four brake hoses, the rears aren't THAT bad. Clearance is tight, but dropping the heat shields an inch and using an 11 mm stubby on the fitting will work. The e-brake cable can be pushed out of the way without too much difficulty. Like so many things on this car, you just need to find the little pocket of space that just barely allows you to turn the wrench on whatever you're trying to remove.
07-01-2009, 01:45 AM
#21
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Greg-
That was a good Ebay find, I think they were about $60. A lot, but even so they have saved me at least $60 of hassle already.
Mel- Glad the writeup worked for you!
That was a good Ebay find, I think they were about $60. A lot, but even so they have saved me at least $60 of hassle already.
Mel- Glad the writeup worked for you!
07-01-2009, 02:17 AM
#22
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I will say that is a good deal if you paid 60 bucks for them.
I also hope you do not get scars from the burns when using them.
I do have one question, why did you not powder coat them?
I also hope you do not get scars from the burns when using them.
I do have one question, why did you not powder coat them?
07-01-2009, 02:33 AM
#23
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The calipers? Because, quite literally, I am an idiot. I had seen Brendan's pics before, but then got all caught up in spraying them with G2 caliper paint in Preval sprayers. I gleefully collected all the stuff together, spent hours stripping and prepping, and then proceeded to spatter (poorly) the first caliper. At that point I should have re-stripped and sent them out to be PC'ed, they weren't yet rebuilt. However, the car had been down for a while and it was nearing the end of the holiday break. So I hurriedly did a crap job painting them and then rebuilt them. I have since gotten more comfortable with havinng 928's around that don't move under their own power......
07-01-2009, 02:41 AM
#25
Three Wheelin'
this is a good post.
dont worry about the finish no one is going to stick their head throught the spokes to look at the finish on those calipers they look better than what they were.
good job
dont worry about the finish no one is going to stick their head throught the spokes to look at the finish on those calipers they look better than what they were.
good job
07-01-2009, 05:31 AM
#26
Not the sharpest tool in the shed
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Okay I'm interested but I'm not sure how these parts turn the S4 brakes into GTS brakes. What is the difference between the stock S4 and GTS systems? Is it only the rotors (are they larger diameter, thicker, both)? Why are the spacers needed and what sort of dremel work is required. Do you have a previous write up of this?
Thanks
Thanks
I can do it. However, i need to do it with at least 10 folks.
A group buy for the kit would be $700 (rotors, race pads, spacers, GTS bolts, and instructions on the light dremel work)
Let me know if you guys are interested. Its a great modification. one of the cheapest and most effective Ive done in a long time!
Think about it. Basically, GTS brakes for $700!! (and no disconnecting your S4 calipers or any mess!)
mk
A group buy for the kit would be $700 (rotors, race pads, spacers, GTS bolts, and instructions on the light dremel work)
Let me know if you guys are interested. Its a great modification. one of the cheapest and most effective Ive done in a long time!
Think about it. Basically, GTS brakes for $700!! (and no disconnecting your S4 calipers or any mess!)
mk
07-01-2009, 08:58 AM
#27
One other thing I forgot to mention, regarding getting the inner seals out. I was petrified with the thought of using a metal pick for the risk of scarring the inner wall of the cylinders. Especially not knowing how stubborn they would be. Everyone I spoke to cautioned not to scar the aluminum. So instead, I used a wooden toothpick & it worked very easily, they came right out & no risk of scratching the cylinders.
07-01-2009, 05:06 PM
#28
Been following this thread with interest, as I was planning on a rebuild myself over the holiday weekend.
I had everything I needed ( ordered from Roger Tyson ) except seals and boots. I ended up ordering them from Zeckhausen:
http://www.zeckhausen.com/Brembo/Con...es.htm#Rebuild
Spent about 1/2 hour on the phone with Dave. He was knowledgeable and helpful.
No connection or affiliation, just passing along a positive experience.
-Ken
I had everything I needed ( ordered from Roger Tyson ) except seals and boots. I ended up ordering them from Zeckhausen:
http://www.zeckhausen.com/Brembo/Con...es.htm#Rebuild
Spent about 1/2 hour on the phone with Dave. He was knowledgeable and helpful.
No connection or affiliation, just passing along a positive experience.
-Ken
Last edited by KenRudd; 07-01-2009 at 05:13 PM. Reason: typo
07-01-2009, 06:06 PM
#29
Rennlist Member
simple dremel work on the calipers ends, GTS rotors and the spacers I mention. (basically machined washers that are near 3/8" thick)
the only difference in the end is caliper size, and that is not a big deal at all and has no bearing on braking force.
do a search on the S4 to GTS brake conversion.
mk
the only difference in the end is caliper size, and that is not a big deal at all and has no bearing on braking force.
do a search on the S4 to GTS brake conversion.
mk
Okay I'm interested but I'm not sure how these parts turn the S4 brakes into GTS brakes. What is the difference between the stock S4 and GTS systems? Is it only the rotors (are they larger diameter, thicker, both)? Why are the spacers needed and what sort of dremel work is required. Do you have a previous write up of this?
Thanks
Thanks
07-03-2009, 05:57 PM
#30
Per my post above, I began a rebuild today.
When I got my calipers off and popped my pistons, the piston and the dust boot looked nothing like the pictures on this thread and a won't fit the dust boots I ordered.
I anticipated that there may be either 42mm or 44mm pistons on the front, and ordered accordingly, but my pistons do not have any grooves for dust boots and the caliper itself has no provisions for dust boots. As indicated in my signature line, this is an '88 S4. The build date on my vehicle is October 1987, making it an early '88.
So, I looked closer at page 47-04 and particularly 47-05 of the WSM. (hindsight being better than no sight at all) It appears my car has the "Previous Version" of the brakes (Modification I). The pistons are certainly 44MM but it seems my '88 has the scraper ring style, and Porsche went to dust boots ( "protective cap") in 1989.
Soooooo...are replacement scraper rings still available? If so, how are the old ones removed? They don't seem as straight foward as dust boots.
-Ken
When I got my calipers off and popped my pistons, the piston and the dust boot looked nothing like the pictures on this thread and a won't fit the dust boots I ordered.
I anticipated that there may be either 42mm or 44mm pistons on the front, and ordered accordingly, but my pistons do not have any grooves for dust boots and the caliper itself has no provisions for dust boots. As indicated in my signature line, this is an '88 S4. The build date on my vehicle is October 1987, making it an early '88.
So, I looked closer at page 47-04 and particularly 47-05 of the WSM. (hindsight being better than no sight at all) It appears my car has the "Previous Version" of the brakes (Modification I). The pistons are certainly 44MM but it seems my '88 has the scraper ring style, and Porsche went to dust boots ( "protective cap") in 1989.
Soooooo...are replacement scraper rings still available? If so, how are the old ones removed? They don't seem as straight foward as dust boots.
-Ken