Jump to content

964kg Porsche 964 - Road Spec.


World Citizen

Recommended Posts

  • Replies 603
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

  • 3 weeks later...
All good stuff! The PCCB discs are usually sold on an exchange basis so not all that common second hand but I'll have an ask around for you.

 

Damn and double damn, spotted a set of Boxter S PCCB rear discs with bells last night on Ebay. 2 days to go, so this afternoon I went to phone the seller ony to find they had been withdrawn as someone had made him an offer he couldn't refuse. Sold for £250, aaarrrrhhhh! :banghead:

 

I'm also looking at alternative conventional floating cast-iron vented discs from either Brembo, Alcan, AP Racing and Wilwood, anyone have any good or bad experiences they can share with regards to these makes?

Edited by World Citizen
Link to comment
Share on other sites

Trackday buddy of mine drives an Impreza fitted with AP 6 pot up front and 4 pot on the rear. With those humungous things on the front, the rears could be just two pot and the thing would still stand on a sixpence. When he first tried it the brake balance was a little awry and the rear kept trying to overtake into corners! I can't remember the pads he was using possibly Pagid? Anyway, there were three sections to each rear pad seperated with what I can only presume were ventilation slots. Simple solution until brake bias controller could be fitted was to chop outside sections of the pad leaving a surface area of about 25cm square acting on each face of the rear discs. Once this was done, he let me loose in it for 6 laps on the Nordschliefe. As the top programmer for a respected specialist in Motorsport ECU design, this car was properly sorted on the mechanical side, putting out about 350 conservative horses. It was barking stark staring mad bonkers with extra chilli. I was giggling like a girl everytime a corner came and went. There has never been anything yet I have driven to match the retardation that thing could manage. So, a big thumbs up for AP there. Wish I could tell you what that's like compared to ceramic but the only car I have driven in anger with that fitted was an S8. 2 tonne versus 1100kg. That's not a fair comparison really.

Link to comment
Share on other sites

Good story Tank, only as I understand it, reducing the pad size doesn't have any significant effect on bias - it just means the pad wears out faster. The bias is basically 3 things -

 

1. the hydraulic ratio as determined by the piston sizes front and rear

2. the torque applied as determined by the disc diameter and the distance of the pad from the axle centreline

3. the torque applied as determined by the friction co-ef of the pads

 

The pad size discussion has been totally done to death on Pelican and Bill V, Steve W and other brake gurus have been correcting folks for years on this one.

Link to comment
Share on other sites

Thanks for that Tankman.

 

Richard is right friction is not relative to area as the smaller the area the higher the contact pressure so they end up cancelling each other out. Or so I have been told by someone that knows.

 

Bias is also effected by another ratio, master cylinder size to caliper piston size.

 

The more and more I find out about ceramic dics compared to cast iron the more I want them. That's if I can find some at a reasonable price and I can get them to fit in a 16" wheel. The smallest Porsche size I've found is dia. 350mm as most cars fitted with them run 19" wheel but I could really do with a dia. 330mm.

Link to comment
Share on other sites

A while ago i looked into having some made to fit my car. These guys seemed to be the place to go;

 

http://www.movitbrakes.com/en/produkte/keramik/

 

Thanks for that Tankman.

 

Richard is right friction is not relative to area as the smaller the area the higher the contact pressure so they end up cancelling each other out. Or so I have been told by someone that knows.

 

Bias is also effected by another ratio, master cylinder size to caliper piston size.

 

The more and more I find out about ceramic dics compared to cast iron the more I want them. That's if I can find some at a reasonable price and I can get them to fit in a 16" wheel. The smallest Porsche size I've found is dia. 350mm as most cars fitted with them run 19" wheel but I could really do with a dia. 330mm.

Edited by marquee
Link to comment
Share on other sites

  • 5 months later...

About time I did an update, so here goes, sorry but no pictures yet

 

Over the last few months I've been doing research, research and more research as my project is going to be a real bitza.

 

As my hot rod is going to be one big fabrication and carbon fibre moulding project I've got the added complication that I don't have to be confined by one particular model of 911 as a starting point so my options for various parts is wide open. This may sound like fun having a clean sheet of paper to start from but it does cause headaches when trying to choose the best individual Porsche parts for my needs.

 

To start being able to layout everything on CAD I first needed to know what wheel and tyre size I could use and then once I've fixed my wheel size then begin to workout what to use for wheel hubs, axles, brake calipers and discs etc.

 

No update on the gearbox sequential shift, this can wait until later. I have managed to find out one section of a 4WD 6-speed gearbox will bolt directly on to mine which will allow me to shorten the length of the box by quite a bit and fit a machined cross member for bolting to the chassis. Just got to find one now!

 

Choosing a wheel diameter wasn't too hard as anything other than a 15" Fuchs would be giving the game away long before anyone gets up close for a proper look. Choosing what width for the wheels was a little harder as tyre choice really dictates what are the best widths to go for. At the moment I think it will either be 8's or 9's up front or 9's or 10's at the back, 10's would have to use Michelin TB15's as there doesn't seem to be any other rubber this wide for a 15" diameter wheel. With the weight distribution I hoping to have I don't think I will need to run a 2" width stagger front to back and shouldn't need to go as wide as 11's as if the car is light as I hope it will be I can't see these getting up to temperature. I have bought a set of April 72 date matched Flat 6's which have enough room for large brake callipers but I still need to look into the inner shape of a deep 6 or 7's and 8's. It looks like the best way of widening whichever Fuchs wheel I go with will be by cutting and shutting and welding a widening band, all the widening will be done on the inside half to keep the outside looking stock.

 

For brakes I've looked at all the usual suspects such as Porsche 930, Porsche 964, the aluminium billet callipers sold by Early 911, Tuthill's, Kroggers etc. I think the aluminium billet callipers are a great upgrade and would be my first choice but I wanted a brake calliper that was a little bit more in keeping with theme of my hot rod, something less modern looking. The Porsche 930 callipers are again a good upgrade but heavy in comparison to more modern competition type callipers and expensive for what you get. When choosing a brake system for a car you start off working out the biggest diameter disc you have room for and then using the biggest pad area that will fit. The reasons for this are the further away from the axle centreline you can apply the brake pad the greater the stopping torque can be applied, also the bigger the disc pad size the lower the running temperature and when used with a 6 pot calliper the more even the pressure over the whole pad area (obviously brake cooling, pad compound helps too). In the end I am pretty sure I will go for either AP Racing or Alcon using a 315mm X 32mm disc and 6-pot calliper on the front and a 305mm x 28mm disc and 4-pot calliper on the rear. I have a super whizzy spread sheet that will help me choose a balanced setup once I have a few more accurate figures for F/R weight distribution, centre of gravity height etc. I am also making sure I can easily change to machined down PCCB discs at a later date as and when I can find some as there is a huge weight benefit with these.

 

For the front hubs I've gone for late Porsche 944 Turbo parts as these have integral toothed wheel for the ABS system and their shape will hopefully allow me to use the same cutom made brake disc bells front and rear which will save on machining costs. I won't use the toothed wheel for an ABS system but it will give me the option to use it as an input for a traction control system. I'm hoping to come up with a neat way of doing the brake cooling, more of that later.

 

For the rear wheel hubs and outboard stub axle I wanted 930 parts but managed to find another option for about the 10th of the price that 930 parts go for. I need to run 930 CV joints as these take a large angle of driveshaft sweep which I need to get the engine in. My 6 speed gearbox stub axles have the same PCD and bolt size as a 930 CV joint so the inboard end was sorted, the outboard end has taken a lot more effort to solve. In the end I found out that an early 928S use a CV joint with the same PCD and bolt size as the 930 CV joint, so the rear wheel hubs and stub axles are going to be from an early 928S, I eventually found a pair from a Porsche breaker advertising on ebay.

 

As my car has to be road legal, it has to have a mechanically activated handbrake system. I've looked at a few different handbrake callipers from Brembo, Wilwood, AP Racing but none of them appealed for one reason ar another. I like the brake shoe in the disc bell system the 911's use but as I will use aluminium disc bells I end up with a smaller inner diameter so I can't use Porsche 180mm dia. sized ones. A quick look on the EBC motorbike/scooter catologue and there is plenty of choice for lightweight aluminium shoes suitable for my smaller 160mm dia. handbrake (Vespa ones are looking like my favourite choice). I will also need to fit a thin walled steel sleeve inside my aluminium disc bell to give a hard enough surface for them to rub against.

 

That briefly covers where I'm up to now, so what's next?

 

Now I have my 930 and recent Porsche part purchases back here with me from England I was going to take a lot of measurements of my 930 body shell and plumb bob the floor pan silhouette on to my garage floor which will give me a basic plan view profile to design my space frame around. I also need to measure and model all the bits I've bought which will allow my to start designing the suspension uprights, from here I can start working out suspension geometry. As I've said before this is going to be a super duper long term project.

Link to comment
Share on other sites

  • 1 month later...

Another jigsaw piece :yahoo: needs a little bit of work before I can use it but there won't be any welding involved

 

5224318001_082501b1ee_b.jpg

 

Big shout out to Mr. P. for taking a look at it for me and not taking the mickey, thanks :ani_clapping:

Edited by World Citizen
Link to comment
Share on other sites

With my limited knowledge of brakes and the fact that you have narrowed your choice down to Alcon and AP, I am loathe to make this suggestion, but are you aware of Endless? Olaf Manthey uses these on the 997RSR 24H Nürburgring winning car. See their site and see what you think.

Endless Brakes

Link to comment
Share on other sites

Tankman, fantastic find with the Endless brakes, the monoblock calipers look sweet, thanks for shouting as they weren't on my radar

 

Another little purchase for my project,

post-3031-1291675996_thumb.jpg

It's the rear active spoiler motor assembly from a Porsche Cayman that lifts the flush spoiler above the rear bodywork. Both the active spoiler on the Boxter and Cayman work by not increasing down force on the rear but by breaking up the airflow before it rolls under the rear of the car which in turn reduces rear lift.

 

I'm going for a clean narrow bodied look, no duck tail or whale tail just a flat lid for me. I'm going to bastardise the assy and somehow build it into the rear engine lid to lift up a hidden active rear spoiler so that when lowered fits flush with the engine lid keeping the clean original lines of the car.

 

Sort of like this but not as tall and without being bullet proof ;)

post-3031-1291676667_thumb.jpg

Edited by World Citizen
Link to comment
Share on other sites

Tankman, fantastic find with the Endless brakes, the monoblock calipers look sweet, thanks for shouting as they weren't on my radar

 

Another little purchase for my project,

post-3031-1291675996_thumb.jpg

It's the rear active spoiler motor assembly from a Porsche Cayman that lifts the flush spoiler above the rear bodywork. Both the active spoiler on the Boxter and Cayman work by not increasing down force on the rear but by breaking up the airflow before it rolls under the rear of the car which in turn reduces rear lift.

 

I'm going for a clean narrow bodied look, no duck tail or whale tail just a flat lid for me. I'm going to bastardise the assy and somehow build it into the rear engine lid to lift up a hidden active rear spoiler so that when lowered fits flush with the engine lid keeping the clean original lines of the car.

 

Sort of like this but not as tall and without being bullet proof ;)

post-3031-1291676667_thumb.jpg

 

Why not get a 964 lid and remould the protruding plastic lip so its flush? Paul Stephens does something similar.

I have a 964 lid on my semi retro 3.2 and it does make a big difference in stability on freeways/motorways.

post-3723-1291727201_thumb.jpg

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...