GermanLook Forums  

Go Back   GermanLook Forums > Technical Section > Brakes

Reply
 
Thread Tools Display Modes
  #1  
Old November 11th 2009, 22:29
vdubfund's Avatar
vdubfund vdubfund is offline
Registered User
 
Join Date: Sep 2007
Location: Osaka,Japan
Posts: 67
996 // 986 calipers Dimensions

Hey everyone
This may have been cover before, if so apologies.....
Are the 996 caliper dimensionally the same as a 986 caliper.
Am wanting to use either 993/996 rear discs with 996 calipers with 16" fuchs.
Does anyone know if they`ll fit ( 993 disc is 299 x24mm) Where as 944na rear discs are 289 x 20mm , fronts will either been boxters S discs or 996......

I know the 986 caliper will be fine in the fuchs , but if the 996 caliper is larger will it foul the wheel??? Trying not to use spacers in the rear trying to keep everything under stock fenders. If 16 x 7" dont fit then it`ll have to be 16 x 6" all round.

This will all go on a 64 bug / short S/A with 924S caliper brackets.

993 calipers in the rear would be OK, but I figured there the same as a 944T caliper. And I believe they require spacers with 16" fuchs.

As for the fronts any advise is much appreciated, still undecided.
I have 944 spindles that I was thinking of having cut down and welded to the link spindle....

Cheers
Dean
Reply With Quote
  #2  
Old November 12th 2009, 08:45
evilC's Avatar
evilC evilC is offline
Registered User
 
Join Date: Jun 2008
Location: UK Where Leics is more
Posts: 644
The 944T discs are 299x24 (IIRC) so will fit to the 968 calipers. I used 928S4 calipers on mine.
Reply With Quote
  #3  
Old November 12th 2009, 20:53
flat flat is offline
Moderator
 
Join Date: Dec 2002
Posts: 664
Hi,

The 996 and 986s (boxster S) are the same caliper, except the 996 comes black and 986S comes in red. The regular boxster (986) is a unique caliper and is smaller than the 996.

Use the 996 rear rotors because the 993 are a little short and the brake shoe will overhang the braking surface on the rotor. This can be corrected by machining the hub a little to get the 993 rotor to sit right. You'll need a radial to axial adapter to use the 996 calipers with your 924s backplates.

The 16" fuchs will fit if they have a 951 part number and not the 911 part number (slight difference in the spoke design to accomodate 4 piston brembo's).

I'd stay away from welding on the spindle....

Lanner
__________________
www.vdubengineering.com
Toronto (Mississauga), Canada
Reply With Quote
  #4  
Old November 12th 2009, 22:37
vdubfund's Avatar
vdubfund vdubfund is offline
Registered User
 
Join Date: Sep 2007
Location: Osaka,Japan
Posts: 67
Cheers for the in info.
I thought the welding would be fine, I thought that what these bus guys were doing on there lowered spindles.... since the beetle isn`t very heavy.

Lanner whats the cost on your radial mounts?
Lanner do you know the height difference of the 996 and 993 rear rotor?( 75mm???) The 996 must be the same a 944T rotor?? By going with the 993 rotor it would help tuck the wheels a little more no?
Thanks again
Dean
Reply With Quote
  #5  
Old November 14th 2009, 09:09
flat flat is offline
Moderator
 
Join Date: Dec 2002
Posts: 664
I think if there are more sophisticated ways of doing things (ie machining), then the welded style seems a little barbaric to me. But I do agree with you about the bus spindles, I even had a set of Nate's on my last bus. All government auto inspections will not pass a welded spindle.

The overall height of the rotors will not make a difference in track, because at the hub mounting face they are all 6mm. IIRC the overall heights for the rear rotors are 65mm (993/964), 67mm (996) and 71mm (86 944T). My radial mounts for the rear are $C160pr with all required hardware. On IRS cars the 944T cover the brake shoes completely, the 996's just (ie shoe is axially flush with drum surface in rotor) and the 993's will have the shoes overhang the drum surface. With swingaxle it's a different story because depending on the end castings (short vs long) the outer bearing is in a different position axially from IRS, so the hub and rotor would move in/out when compared to IRS.

Long story short for your swingaxle car is that you can make the 993 rotors work and engage the brake shoes correctly, but you will have to machine/space the hub relative to the caliper backingplate.

Cheers,
Lanner
__________________
www.vdubengineering.com
Toronto (Mississauga), Canada
Reply With Quote
  #6  
Old October 2nd 2015, 14:40
proudbugowner proudbugowner is offline
Registered User
 
Join Date: Apr 2015
Location: Greece
Posts: 17
I saw today that the 996 rear rotor is 75mm height and the 986 rear rotor is 67mm height, just to add the info...

I also tried the boxster (not S) rear caliper to the 944NA rear rotors but the brake pads overhang about 2.7mm on the outside, is this known and acceptable?

Last edited by proudbugowner; October 2nd 2015 at 15:13.
Reply With Quote
  #7  
Old October 6th 2015, 03:50
kai4130 kai4130 is offline
Registered User
 
Join Date: May 2006
Posts: 63
Quote:
Originally Posted by proudbugowner View Post
I saw today that the 996 rear rotor is 75mm height and the 986 rear rotor is 67mm height, just to add the info...

I also tried the boxster (not S) rear caliper to the 944NA rear rotors but the brake pads overhang about 2.7mm on the outside, is this known and acceptable?
I hope not!!! Ive just ordered some 944 NA disc's 289x20.4mm. I've also got some 987 (non S) calipers to fit also. so same as yours

Lanner is sending me some of his brackets and this is the combination he recommends when fitting a 986 rear caliper to the 944 NA setup.



FYI the 986 ( Non S )rear disc is available in 292x20.4mm and 299x20.4MM, which could help solve your issue.

How is your caliper mounted?


NO that is not acceptable to have the pad over hanging the disc.
Reply With Quote
  #8  
Old October 6th 2015, 07:56
effvee effvee is offline
Registered User
 
Join Date: Aug 2002
Location: California
Posts: 639
Any pictures
Reply With Quote
  #9  
Old October 6th 2015, 10:30
kai4130 kai4130 is offline
Registered User
 
Join Date: May 2006
Posts: 63
Will show and tell in a few weeks. My car has gone away for a short while... Its a big secret
Reply With Quote
  #10  
Old October 6th 2015, 15:23
proudbugowner proudbugowner is offline
Registered User
 
Join Date: Apr 2015
Location: Greece
Posts: 17
Maybe Lanner (flat) is referring to the 87+ rotors (the ones with the 100mm hat height) that have 50mm pad area height even though they are 20.5mm width - I am told this, did not measure myself.

The 289x20.5x71mm rotors have about 46mm pad area height. The 986 rear pad has a height of about 48.5mm so it overhangs a bit.
effvee I uploaded some photos.

My calipers are not yet attached. I put them on just to see but for the rears there is no room for the whole brake pad.

Front:


Back:


Top (see the overhang, about 2.5mm):


kai4130 please report back.

addition: The Boxster rear rotor will not clear the handbrake shoes and hub and the Boxster S rear rotor has a bore of 98mm instead of 103mm that we need, so it requires some machining there. xD It also has a height of 67mm instead of 71mm.

Last edited by proudbugowner; October 6th 2015 at 15:33.
Reply With Quote
  #11  
Old October 6th 2015, 17:58
kai4130 kai4130 is offline
Registered User
 
Join Date: May 2006
Posts: 63
I had some issues getting the correct information from Lanner but he definitely confirmed its the earlier disc.

"Rear rotors are stock 83-85 944 NA, 289x20.4mm."

Hence why I've now bought these. I still have my original 986 disc. I've ordered new NA 944 rear disc and my the originals ones are here also. I expect Lanner has posted me my brackets now which will take up to 10 days to arrive. By then my car should have made its way back to me and I can confirm what I've got.



I've bought my disc from this place and they have all the information required regarding the disc.

http://www.mtecbrakes.com/brake-discs/porsche.html

proudbugowner is indeed correct about the Centerbores sizes being different for the 986 and 944.
Reply With Quote
  #12  
Old October 6th 2015, 18:05
kai4130 kai4130 is offline
Registered User
 
Join Date: May 2006
Posts: 63
I've just been looking at my suppliers site again and you are that correct the 87> disc has a larger hat height. Incidentally out of the possibilities this is the most expensive disc available. I've got a feeling that I'll be sending my new discs back then and going for the 87> disc. But I'll wait until I have everything here and can check it all.
Reply With Quote
  #13  
Old October 6th 2015, 19:14
proudbugowner proudbugowner is offline
Registered User
 
Join Date: Apr 2015
Location: Greece
Posts: 17
To fit an 87- rotor to a -87 arm I think you need the stub axle and the hub (have no idea if they fit) or maybe use a 29mm spacer on the inside along with longer studs (also no idea)? Theoretically they should not fit because - if what I was told is true - the 87+ rotor has the same outside diameter (289mm) plus a larger pad area height (about 50mm) and as a result the center should be smaller by about 10mm in diameter.

I am aiming for the 24mm width '86 turbo rotor (299x24x71mm) and will mackine the calipers to accept it, inevitably.

Dat Porsche world, where everything looks as if it fits, but it doesn't. xD
Reply With Quote
  #14  
Old October 7th 2015, 02:08
flat flat is offline
Moderator
 
Join Date: Dec 2002
Posts: 664
Dont overthink it gents.

On beetle IRS/ swing axle (ie early 944 setup): For 986 caliper use the 83-85 944 rotor 289x20.4. Test fit the loaded caliper with radial adapter without rotor, you will have to grind the inner pad slightly so pad doesnt interfere with radial adapter or 944 backingplate. You are grinding the metal support plate of the pad, and not the actual friction material. Now assemble again with rotor and grind same on outboard pad to just clear rotor. Its a small amount...2-3mm.

The 986 rotor is useless. Using the late rotor on early setup doesnt work, late rotor hat is too big. Late 944 (alum arms) has no cross compatibility with early 944 (steel arms)...its completely different the way the hub mounts in arm. About the only things that work between early vs late are na calipers and ebrake hardware.

For 996 or 986S rear caliper, use 944 86T rear rotor 299x24.

Advantage of using the 986 caliper with 944na rotor and slightly clearanced pads is that 15" wheels fit. With 986S caliper and bigger rotor you will need 16" wheels.

Clear as mud?
__________________
www.vdubengineering.com
Toronto (Mississauga), Canada
Reply With Quote
  #15  
Old October 7th 2015, 08:54
proudbugowner proudbugowner is offline
Registered User
 
Join Date: Apr 2015
Location: Greece
Posts: 17
Thank you Lanner, your input is always helpful and decisive.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 04:43.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
© www.GermanLook.net 2002-2017. All Rights Reserved