18" and Big Reds on an 86?

[Mike the mechanic]

Hey guys, I have this vision of what my car will look like in the future and it includes Big reds and 3.6 turbo 964 18" wheels. Before I let this vision take over my life, I need to know a few things:
Firstly, if I get a set of big reds from a wrecking yard, assuming the discs and calipers are in good shape, aside from pads, what else will I need to make them fit? do I need the spindle or anything like that?
Secondly, who sells the adapters for this?
Thirdly, does anyone know if 18x10 and 18x8.5 wheels with 265-35's and 225-40's fit on my car (narrow body 86)? Now I have C-2 turbo 17x9 and 17x7,5 wheels with 255-40's and 225-45's and absolutely no rubbing.
Help me make my dream come true.


Mike
86 Carrera t

Tire rack has tire specs for the rim size and tire size you listed.
17x9 255-40 section width 10.2"
17x7.5 225-45 section width 8.8"

18x10 265-35 section width 10.5"
18x8.5 225-40 section width 8.9"
The spec chart gives all the information you would need including rev's per mile so you can see how much your speedo will be off if any.

this is for michelin pilot sports, but they should have specs for the tire you would be using.
www.tirerack.com
As far as the big reds go I just bought the kit from PP.
The difference is the calipers bolt onto the spindle in a up/down manner instead of the left to right fashion. So you will need adapters for the front and rear. The rear rotors are stock items off of a (I dont know have to check the numbers)
The fronts use a specail hat rotor combination.
The combination fits with 17x7.5 BBS LM's plenty of clearance between the rim and caliper. The rears should clear the rims the same. Though I can't say for sure(can only afford the fronts this month).
Good luck though with your dream

[Steve W]

I have 18x9.5 rears 3 piece with 265-35s Yokohama A008P and 18x8 fronts with 225-40s under my standard body '84. These will be the absolute largest you will be able to fit in your car. This is pretty much the stock spec of the wheels for the '94 Turbo 3.6 except it's rear rims are 10" wide Speedlines. My fender lips front and rear are rolled to barely clear the tires. You cannot fit any wider rims under those fenders without rubbing something. My rears clear the bolt on my trailing arms by 4 mm and if the fronts were any wider they will rub the steering arms on full lock position. The car has a very tough and aggressive look with the wheels right to the edge of the fenders. If I get a chance, I can upload a pic later.

BTW, Andial found that after testing and evaluating virtually every different performance tire available on the 911, the Bridgestone SO2 turned out to be the best street tire.

Steve

[Bill Verburg]

Any of the late Brembos will require CNC maching of the caliper to adapt to the front struts of a 911. The CNC programs are proprietary in nature so you must get it done by someone with specific expertise in that particular mod. Those folks are in the business of selling their own product , they are thus loath to do similar work cheaply. Bite the bullit and buy a properly engineered kit, which will include the machined calipers, caliper adaptors rotors, rotor adaptors, pads and hard lines(often flex lines as well). Do the front and rear at the same time THEY MUST BE MATCHED for proper reliable service. You risk major brake imbalance otherwise, they may seem fine 99% of the time but unless you try panic stops you won't know what will happen at the extreme limits.

The rear rotors are generally oem Zimmerman 78-89 930 309x28 mm rotors.

I am using 17x8 and 17x9.5 Kinesis rims. I priced the 18" equivalents and discussed the cost/benefits with my race car prep shop. Their feeling was that the sweet spot was with the 17s. One of the reasons was the lack of variety of 18" tires at the time, that has since changed of course. The 235/45 and 275/40 tires in 17" which I use are physicaly larger(wxh) than the proposed 18s so they can be made to fit as long as rim offsets are right. As Steve pointed out the clearance at the trailing arm bolts is very tight and the front lips will need to be shaved to non-existance, the rear lips will also need a little work.

Pics of all of the above are posted at my websites

[diverdan]

It will look awesome,,,,,,but you may not like the steering. Heavy!

[5axis]

Originally posted by Bill Verburg
Any of the late Brembos will require CNC maching of the caliper to adapt to the front struts of a 911. The CNC programs are proprietary in nature so you must get it done by someone with specific expertise in that particular mod. Those folks are in the business of selling their own product , they are thus loath to do similar work cheaply.

Bill what's the big deal with the programs? I crank out piles of one off paths for prototype work.. the output is sort of machine specific but other than M codes the XYZ's are mostly the same. (canned cycles vary) If it isn't some 3D funky nurb or other spline derived surface I could probably just do it in a bridgeport. A tool maker with a compound sineplate and a cross slide rotary table can do some impressive things. Given a good print, 3d surface, solid ,or wire frame and any decent toolie should be able make the part you want. If you RE a converted part anybody else should be able to make one for you.

The cheap part: Bill is probably right, it will likely be more cost efficent to buy the package. I don't work cheap, I got to pay for boats, bikes,and a turbo cab.
david 89 turbo cab

[Bill Verburg]

5axis,
How many sets of calipers do you have to experiment with? Do you know the precise XYZs for the cuts? Do you know exactly how deep to drill for the new bolts? etc. The adapters are easy just copy a set. But without access to the engineering drawings for the calipers everything will be trial and error. Everything is easy once you've done it once, that first time is the trick. When you buy a kit you are paying for the parts and the vendors hard earned experience/expertise. If you think it's so easy , set up a business to accomodate the countless tinkerers out there who want to put $3000 brakes on their cars for $500 and a few hours of sweat. Don't forget to add in the overhead for things like liability ins. in case there is a problem.

[Jim Smolka]

I am not sure, but I believe there was a note put out stating that 18" wheels were not recommended for '89 and earlier cars....
Does anyone have record of this???

[pbs911]

I have also read that Porsche put out a bulletin blacklisting 18" wheels on the 911. After conducting numerous tests, it was determined the suspension components are prone to failure with the 18" wheels.

[targa88]

Mike,
Sounds like an awesome project, if not a costly one. I know that you do most of your work yourself - but still.
I remember seeing a site ( in the US) that sold these kits ready made. I will try to retrieve.
Personally, I can't see/understand the advantage of going to the 18" wheels (unsprung weight, etc.), coupled with the current car and future engine it is going to be a behemoth.
You should come out to the track with us next season, and get some hands on experience, not to mention a bunch of free advice from those who have modified....

[Mike the mechanic]

Thank you all for your informative replies!!! Cwood, thank you very much, I didnt realise the Tire rack had these features on their website, that really helps me out. Steve, I would love to see what your car looks like, maybe you can email moe a picture???? I haven't seen a narrow body with 18" yet so it would be really helpfull to me. Bill, I guess you are right, I should buy a ready-made kit. Buying the parts from a wrecking yard and paying someone to redrill the calipers will surely cost more than a kit. It's just that I don't have that kind of budget just yet. I wonder, if 930 brakes will bolt on my car... Jim, pbs, any plus sizing of a wheel/tire combo will put extra starin on your ball-joints. tie-rods, shocks, etc, but they look REALLY good. I dont expect to get much better handling either, the 17s are really good. Hey targa88, how are ya? The 18" wheels will decrease my ride comfort ( I know the 17s have also) amd increase my unsprung weight, but I dont race the car on a track, and even if I start, I am not experienced enough on the track to be able to notice the difference. I would love to come to the track next year. I wanted to come this year but I was out of town for most of the events. Besides, I fear my years of "fast street driving" must have corrupted my potential for learning "real fast driving".
We'll see next year. Hey targa, did you store your car yet?

Mike
86 Carrera t