Is it possible to fit a 350mm rotor on the front of a 928?
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From: Helsinki, Finland
Modified 928 GT hub, 996 GT2 6 caliper monoblock front brake, Cayenne 350mm disk and TSW 18" wheel. Trial fitment on workbench to see if hub modification is successful mod. Works fine.
Nordschleife Master
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From: theporscheconnection.com
Fabio:
Yes, it is possible, but there are other fitments issues to resolve.
Usually, with the 350/355mm rotors, you need to run a true 18" wheel to clear the caliper. Given the 928 front spindle, I also suspect that the caliper shape and how it protrudes forward is another wheel fitment challenge.
FWIW, I am in the process of upgrading the brakes on my GTS. I will be using Alcon rotors upfront using aluminum mounting hats being clamped with Ferrari F50 calipers. In the rear, I am using the 965 (3.6T) rotors with 993RS calipers. As soon as the rear rotors arrive, this setup will be installed.
As a suggestion, make sure you are confident with why you want to alter the rotor diameter / caliper specs. Be sure to know the hydraulic changes that come with the caliper you are considering and how both the change in mechanical torque and hydraulic clamping affects the bias. If you make these changes without considering the affects, you can box yourself into a bias scenario that is VERY unpleasant to drive !
$0.02
Yes, it is possible, but there are other fitments issues to resolve.
Usually, with the 350/355mm rotors, you need to run a true 18" wheel to clear the caliper. Given the 928 front spindle, I also suspect that the caliper shape and how it protrudes forward is another wheel fitment challenge.
FWIW, I am in the process of upgrading the brakes on my GTS. I will be using Alcon rotors upfront using aluminum mounting hats being clamped with Ferrari F50 calipers. In the rear, I am using the 965 (3.6T) rotors with 993RS calipers. As soon as the rear rotors arrive, this setup will be installed.
As a suggestion, make sure you are confident with why you want to alter the rotor diameter / caliper specs. Be sure to know the hydraulic changes that come with the caliper you are considering and how both the change in mechanical torque and hydraulic clamping affects the bias. If you make these changes without considering the affects, you can box yourself into a bias scenario that is VERY unpleasant to drive !
$0.02
Any update on your setup? I would love to see what you ended up doing with your brakes.
Nordschleife Master
Joined: Apr 2003
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From: Abbotsford B.C.
Ryan if you look at the pictures the two "ears" which the caliper bolts to were welded on there and machined.
I would be leary about having a welded part there, but havent inspected the material enough. I thought it was cast though.
I would be leary about having a welded part there, but havent inspected the material enough. I thought it was cast though.
Nordschleife Master
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From: theporscheconnection.com
yeah your absolutely right, not someplace i want or need to go.
Great idea though
I need to figure out which 322mm rotors to put on my car now. 965 cast hole, 928 GTS, or 993 TT with aluminum hats? Any suggestions? Price is a concern.
I priced out the 993TT idea to about $650 with the hats not including shipping from 2 different places.
I dont know what the cost is for the 965 rotors yet. Will know tomorrow. Same story for the GTS rotors.
I am thinking that if the 965 rotors can be had for around $400 for the pair I will just do that.
Apparently the 993 compound rotors (which would be my top pic) have an offset difference of 6mm. I thought of maybe using a 6mm spacer but that seems too simple, it must be 6mm of offset in the opposite direction in which case the hub would have to be taller and would be the only way to solve the alignment problem.
Maybe i am missing something here though. Anyone else been here, done this with 322mm rotors? Are there any other options that i am missing or not aware of?
Great idea though
I need to figure out which 322mm rotors to put on my car now. 965 cast hole, 928 GTS, or 993 TT with aluminum hats? Any suggestions? Price is a concern.
I priced out the 993TT idea to about $650 with the hats not including shipping from 2 different places.
I dont know what the cost is for the 965 rotors yet. Will know tomorrow. Same story for the GTS rotors.
I am thinking that if the 965 rotors can be had for around $400 for the pair I will just do that.
Apparently the 993 compound rotors (which would be my top pic) have an offset difference of 6mm. I thought of maybe using a 6mm spacer but that seems too simple, it must be 6mm of offset in the opposite direction in which case the hub would have to be taller and would be the only way to solve the alignment problem.
Maybe i am missing something here though. Anyone else been here, done this with 322mm rotors? Are there any other options that i am missing or not aware of?
Track Day
Joined: Jul 2006
Posts: 15
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From: Hellsinki
I had also 6-piston Cayenne calipers to fit on my GT. Using a 350mm rotor it is close to impossible(GT2 or Cayenne) to machine an adapter for it. With a 380mm rotor there might be a chance but I'd still go for a GT2 caliper as it enables more clearance between the caliper and attachment surface. Eventually as I get the GT moving I'll have a few tough braking sessions( 160Mph->0) to make sure nothing will fly through the fender when the going gets rough.
Three Wheelin'
Joined: Nov 2003
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From: Doylestown, PA
I would be leary about having a welded part there, but havent inspected the material enough. I thought it was cast though.
Spindles are forgings not castings certainly OK to weld. I imagine the bolts that mount the calipers run thru the spacer that has been welded on into the original spindle metal so that the welded spacer would not be bearing the load of the bolt .
Spindles are forgings not castings certainly OK to weld. I imagine the bolts that mount the calipers run thru the spacer that has been welded on into the original spindle metal so that the welded spacer would not be bearing the load of the bolt .
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Three Wheelin'
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I would be leary about having a welded part there, but havent inspected the material enough. I thought it was cast though.
Spindles are forgings not castings certainly OK to weld. I imagine the bolts that mount the calipers run thru the spacer that has been welded on into the original spindle metal so that the welded spacer would not be bearing the load of the bolt .
Spindles are forgings not castings certainly OK to weld. I imagine the bolts that mount the calipers run thru the spacer that has been welded on into the original spindle metal so that the welded spacer would not be bearing the load of the bolt .
Correct me if I'm wrong, but aren't the spindles and arms (for attaching tie rod, lower/upper ball joints, and brake calipers) one piece?
I haven't looked at one lately (I probably should), but using your example, the whole piece would then be either cast or forged....?
[correction: the tie rod arm is bolt on]--rhj
--Russ
Race Car
Joined: Jun 2001
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From: Finland
Somehow i got the impression that guys were able to produce an adapter for that GT. I have also studied this issue because we wanted to develope an adapter for six pot GT2 caliper for 951 S spindle (same as S4, GT,GTS etc.).
We have already kit for 951 spindle. At least here in Finland that welded spindle is illegal.... I suppose Erkka & friends are familiar that. Here's our 951 "kit" we had manufactured:
Caliper under my friends 951
We have already kit for 951 spindle. At least here in Finland that welded spindle is illegal.... I suppose Erkka & friends are familiar that. Here's our 951 "kit" we had manufactured:
Caliper under my friends 951
Race Car
Joined: Jun 2001
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From: Finland
Yes we can use ceramic discs as well. Pictured disk is 996 Turbo unit. It's a direct bolt on unit to 951. Our cars are not M030 cars, so spindle has axial caliper mounting holes. We have not yet managed to fabricate adapter for 951S model, because it has radial type of attacment to the spindle, just like most 928's have. Newer monoblocks has 11mm difference what comes to distance of bolt mounting holes compared to old school calipers. I suppose it is easier use Cayenne calipers, because they have axial attchment to the spindle, so fabricating adapter is easier to do.
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Its virtually impossible to make adapter to fit GT2 or GT3 front brakes into "S4" front suspension. With 380 mm disk maybe but with 350 mm no way it will fit properly. If one wants to make it easy its better to change '84-85 front suspension from M593 ABS option car and use later ABS teeth ring. I'm not sure if all '84-85 spindles have mounting point for ABS sensor or not. If you want GT2 brakes Nick go this route.
Cayenne calipers are way to go if one wants to use "S4" hubs. Adapter for those is "easy" to do.
PS. Olli. we know. Mod is so well done that its virtually impossible to say its not stock once its painted. Guy who did it knows what he's doing. He's puting GT2 brakes into his old Saab.
Cayenne calipers are way to go if one wants to use "S4" hubs. Adapter for those is "easy" to do.
PS. Olli. we know. Mod is so well done that its virtually impossible to say its not stock once its painted. Guy who did it knows what he's doing. He's puting GT2 brakes into his old Saab.
Drifting
Joined: May 2002
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From: New Zealand
mmm... is the stock 951 mounting the same as the 928 'S' or the earlier 928? does this expand the range of brake upgrades accesable to the earlier cars? im thinking of my 79 which already has 'S' brakes but for which i am wanting more braking but also to keep the stock phonedials.
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From: Finland
If early 928 use the same "baby" 4-piston Brembo as 951, then it might be possible. What comes to disks, i suppose using some other (two piece disk) than OEM disk gives more possibilities especially if you are using custom made center section.
Erkka, i thought you sold your old "warrior"
PS. Olli. we know. Mod is so well done that its virtually impossible to say its not stock once its painted. Guy who did it knows what he's doing. He's puting GT2 brakes into his old Saab
Erkka, i thought you sold your old "warrior"