I've been searching and reading as much as possible and though I've seen references to 911 front suspesion conversions I haven't found any specifics on what year models are good, better, best and why. Does anyone have or know where on the internet it may already be? I'd like to find details as to what years, models, options, how to identify, and pros and cons of each one.

Thanks,

Greg

I would go for the later years for the 3.5" brake spacing. Mine has a Carerra front end from an 80's 911 with the A calipers. My last one I went with an early model from the early 70's and the ball joints were different and the brake spacing was only 3" which limits the size of brakes you can run. They all work though, so it's just a matter of what you can find and what you want.

It would probably be best to stick with 1974 and up (not sure how far, maybe 89). The very early ones up to 1968 can have pretty funky parts. From 1969 the 911 mostly had vented rotors with either 3.0" or 3.5" caliper bolt spacing. Avoid the 911E with the hydro-pneumatic struts (no torsion bars in A arms). So look for the 911S with the 3.5" spacing. The struts with the pinch bolt for the ball joint are not as desirable either, so that means about 1973 up. 1974 were almost all 911S (3.5") with the better ball joint. Try to get the whole front suspension (struts, brakes, A-arms, cross member, pan; steering rack optional and nothing after the rack itself is useful). Aluminum "S" or iron "A" calipers can be used, but the "A" is much less expensive. Early Turbo is essentially 911"S". From 1978 they get kind of funky with the super expensive 4 piston calipers. Early front vented rotors are 20mm thick, and the Carrera got the 24mm thick that can aid heat dissipation but would reduce acceleration in a low HP car. It also depends on the type of car you are building; built for street, autocross, track and what HP.

Ok, depending on what I find it looks like the perfered choices are `74 and up. And from `78 up they could have either style calipers?
What year and model did the Aluminum crossmember start?

I still have to dismantle the recently accuired `74 I have to see how good the tub really is. Depending on what I find, the street project and the autocrosser project could end up swaping tubs.

The street project plans are for a DD that will see ocasional autocross and maybe possibly a little track time for fun. It will be 2.0 turbo subaru powered with either a subie trans or one of the late 915's I have.
The autocrosser will not be street legal but a dedicated autocrosser that may see some track time too. Current plans for power are a mildly built 5.0L Ford V8 at ~400HP, lots of tubing and hiem joints and 1850 to 1900 lbs w/driver.

Its really really difficult to get anything but a -4 to 1850
in fact its difficult to get a -4 to 1850

I'm at 1837 and it took 2 years of weekends to achieve that... a coupl of thousands of hours.

there are a bunch of threads out there about the front suspension
it was actually 1972 when they changed the ball joints, so your ok with going 72 and later.

its a bit about money
with small brakes you can probably do a full front end for 500
with the later bigger brakes it's closer to 1000
for the 500 difference you get marginally bigger calipers and an aluminum crossbar that is only marginally lighter (and some claim it flexes and actually deteriorates the handling) I personally don't buy into the flex arguement, but the point is that 500$ buys nothing you can feel seat of the pants.

of course to actually reach 1850 your going to need every pound you can get

I am converting my 75 over to a /6 useing a 3.0 911 engine. I searched for a 911 front end and came across a 1972 that included strut housings,struts,calipers,rotors,hubs for 300.00 so I jumped on it. Yes it uses the 3 inch brake caliper spacing but my intent is street rocket, autocross monster and maybe a DE or two per year. The rotors are 20mm thick vented which are the same size as my 83SC and I have no problems with heat or fade on the heavier SC. Granted the SC has larger 3.5 inch calipers but still the same rotor. I think with todays brake pad technology and cooling setups I don't anticipate any problems with my setup. I am also going to use the 3 inch M calipers on the rear with a adjustable proportioning valve so I'll be able to take advantage of the M calipers all the way around. As stated earlier one advantage to the 1978-1989 strut assemblies is that you can use the 24mm thick Carrera rotors which give better thermal mass for cooling, the downside being they are heavier.

I guess it's a good thing both projects are still in the planning stages.

Looks like the smaller 911 brake stuff will be great for the street project car but I may have to rethink some more things with the autocrosser project. Since in SCCA EM I'll have an 1850 lb minimum W/driver and in XP about 2300 lbs Without driver when using a 5.0L engine.

EMROADSTER,

Brant is correct about the price of the front ends. In general the smaller setups run around $500 or so whereas the large brake setups tend to run around $1,000. The other thing to keep in mind, and this is advice that was given to me by Eric Shea, the resident brake guru, you can buy just the struts for around $150 if you are patient. You don't necessarily need the entire front end. That was what I had intended to do until . . .

I happened to find a complete late 80's Carrera front end with the struts, calipers, rotors, aluminum cross member, sway bar and steering rack for $400 from a member here. I then found the matching rear calipers from an 86 Carrera with all new seals and brake pads on ebay for $150 along with the matching 86 Carrera master cylinder for $35. A set of rear rotors and Eric Shea's rear 5 lug converted trailing arms and I will be good to go. Moral of the story, if you are patient and a little lucky you can put together a nice setup for not a lot of $$$.

Oh yeah, this is all intended for my '73 2.0 turbocharged subie project.

Greg,

One thing I like to look at is the body, hence, what size tire can you fit. There comes a point where your tires and HP will overcome the potential of the brakes:

Narrow Body - Basic M-Caliper struts from 69-73 MY 911T's. They have M-Calipers, vented rotors and can handle a plethora of replacement strut inserts. This is exactly what the factory 914-6 came with and is more than adequate in braking capabilities. These can be fairly easily coupled with the stock rears. A basic 1970 911T strut is my favorite for this conversion.

Wide Body - Early Koni, Bilstein or later SC struts with 3.5" spacing. This will allow S-Caliper, A-Caliper, Early Turbo Caliper, Carerra-Caliper (A-Caliper with larger spacers) These brakes all have the same piston size as the M-Caliper however the pad area is larger. These should be paired with 914-6 rears or Ferrari rears for street use (handbrake) or 911 rear M-Calipers for track use. A basic 911SC strut is my favorite for this conversion (allows more insert capabilities).

The later SC (Boge) struts with the 3.5" spacing should be a little more flexible with regard to inserts whereas Koni struts will only take Koni inserts and Bilstein struts will only take Bilstein inserts.

I use Koni's on my cars but they are a little difficult to do any spindle mods on them (I'm testament that it can be done however). I like the trunk knob adjustability of a Koni.

Bilsteins are easier to perform spindle mods on but you are set with the insert you get... it is however, one hell of an insert.

I have an earlier 911 front end for my 76 914 , I want to use the 5 lug hubs and the ventilated rotors and the Bilstiens . The 911 calipers are toast but my 914 calipers are excellent it appears to me that the only difference in the two calipers are the little spacers used to spread them to fit the larger ventilated rotor. Could I rebuild my 914 calipers with these spacers and have them fit the 911 rotors ?

I prefer later model 911 BOGE struts.

There is a larger selection of inserts available for use with them. In fact, I believe that some 914 inserts can be made to work with them.

I also prefer the later SC or later struts. They are newer and have the 3.5" bolt spacing for the larger calipers.

Like most everything else, buy the latest struts in the best condition that you can afford.



If you are on a budget and building a street car, some of the best deals can be found on the older 3" bolt spacing struts and calipers as most people want the 3.5" spacing.

Here's what $450 on ebay got me. 3.5in A calipers, struts, A arms, torsion bars, aluminum crossmember with horn attached, steering rack, underbody swaybar, 4-to-5 lug converted rear end (poorly done; hubs replaced by Eric Shea's nice ones), half shafts with CVs, and rear calipers.

Be patient and you will find a good deal on a 911 front end.

Spoke

No. Not the same size spacers. You could probably use the rear m-caliper spacers but you'd have to mill 3mm off them. Just get the 911 M-Calipers rebuilt. They have a slightly larger piston and should be perfect with the vented rotors.

3" is perfect for a narrow car.
3.5" is best for a flared car.

anyone ever look at a 944 front end? It looks like more of them are available in junk yards... I saw at least 3 over the weekend...

They're wethless unless it is a turbo. N/A 944's have a single piston, floating caliper like most passenger cars, and light trucks. They do O.K. for a stock 944, but I personally HATE floating calipers.

John,
What do you consider to be late model?
How would I tell the difference between a Boge, Bilstien and a Koni?
Is it simply stamped on the outside of the strut housing?

Sorry for the confusion.

My own personal thoughts of 911's ends with the 1989 model year. I know the air cooled cars continued on, but the suspension parts on the late 1989+ cars no longer bolt directly to our beloved 914's.

So, I consider 79-89 late® model 911's (I know I am stuck living in the past, but I do drive a 914.)

You can tell Bilstein struts because they are green (at least from the factory) The KONI struts were red/orange, and the BOGE struts were black.

Yes they are stamped right on the strut.

My street car uses Bilstein struts. They are a bit odd in the fact that the shock is upside down and the rod is pinned to the bottom of the strut. They are John Deere Green, and they are a bit bouncy, but they do seem to work.

Our track car uses BOGE struts from a 930 and can use a variety of inserts (KONI, Bilstein, etc.) I believe we have adjustable KONI inserts in them and they work well.

Eric,

Regarding A-Caliper spacers. What variations are there and why? I assume it is for different rotor widths. I initially thought that there would be a version with no spacer and a later version with a spacer. But with you mentioned above that the Carerra version of the A-Caliper has a larger spacer, that implies that other versions exist with smaller spacers. If they all have spacers is it that the caliper was an off the shelf ATE item and each customer (such as Porsche) would just use an appropriate spacer depending upon the rotor width?

So what is the scoop? And what different spacer sizes are in use? I am personally interested as I just aquired some A-calipers and realize that I don't know which rotor they would match up with and maybe I can figure this out via the spacer size in the caliper.

Richard

Pretty much.

I'm not sure if they're called A-Calipers but various BMW calipers are virtually identical with the A-Caliper castings except they are on a 3" spacing. They have the widows peak down the backside of the caliper which leads to a fluid inlet. The only difference I've seen on the BMW calipers is the fluid inlet is on one side of the peak or the other (depending, left or right) where the Porsche version of the A-Caliper has the fluid inlet at the bottom of the peak. There are some misc. casting differences but they look a lot alike. The BMW caliper does not use a spacer and can be bolted to a 914 (not a great idea but done widely). It has a 48mm piston and the same pad size as the A and S-Calipers.

I'm not certain of the spacer sizes but the first one which is commonly referred to as the A-Caliper is for the basic 911SC and runs on the standard 20mm vented front rotor (the same rotor that came on a 914-6). The later A-Caliper, which some call the Carrera caliper, is the exact same caliper with a larger spacer to fit on the 24mm Carrera rotor.

You should be able to tell what you have based upon the width of the rotor gap... standard A-Caliper should be 24mm

Here's a thread with some pictures of various BMW and A-Calipers"

Click Here

I chose the 3.5" spaced front struts as the Boxter caliper is a direct bolt up. Rich has a very nice kit that adapts the rear boxter caliper to the 914 trailing arm to complete the set up.

Personally, I too like the door knob adjustability of the KONI...but Bilstien is an excellent quality product. (I went with KONI)

Lastly... I have a set of 944 Turbo calipers (F+R) if anyone wants to fool around with them...

Cheers,

S.

Thanks everyone for the input, this was more of the kind of detail I was looking for.

A friend just gave me a book writen by Bruce Anderson called "Porsche 911 Performance Handbook" published in 1987. Looks to have some good detailed info also. As I read it I'll post some of the details here to help this thread along for others that are looking for the same kind of info that I am.

Thanks,

Ok, here is what I've found about brakes in the "911 Performance Handbook" by Bruce Anderson.

Brakes, page 187
"As the 911S and the 911 derivatives have continued to go faster and faster, an improvement in brakes was needed to keep pace. The first change was in 1967 when the vented rotors were introduced on all four corners of the new 911S model. The next significant change was for the model year 1968, when all models received dual master cylinders. For model year 1969, the front calipers were increased in size and made of aluminum for the 911S model. Also in 1969, the rear calipers for all models were replaced with the larger M-caliper, which was the caliper that had been used as the front caliper on all 911S.
When used as front calipers they used the larger 48 mm pistons, and when used in the rear they used 38 mm pistons. However, because the M-calipers were used front and rear, the same size pads were used front and rear for the 911T and E models. The 911T's had solid rotors, while the 911E and S had the vented rotors. Of course, with their larger aluminum front calipers the S models used even larger front pads. In 1970 the 2.2 911T's also received the vented rotors.
When the 1973 2.7 Carrera RS was introduced, it received the 911S brakes along with it's aluminum front calipers. The 3.0 Carrera RS for 1974 had the brakes from the 917 race car, the first four-piston calipers installed on a production model 911. The 1974 3.0 Carrera RS was a very limited series, with a little over one hundred being built, and then most of those were made into the Carrera RSR race cars.
In 1975 the 911 Turbo (930) had the same combination of brakes that had been used first on the 2.0 liter 911S in 1969. In 1976 the new A-series caliper was introduced, installed on the 911S and Carreras, while the 911 Turbo continued to use the aluminum S-calipers.
The new A-caliper was an existing model that ATE made for Alfa Romeo. They were the same size as the aluminum S-caliper and used brake pads of the same area. The A-caliper is a little narrower so that instead of using brake pads that are 13 mm thick, like the S-caliper, they used a thinner 10 mm brake pad.
In 1978 some of the 911SC's continued to use the aluminum S-caliper in front and the M-caliper in the rear, but in 1979 all SC's used the A-caliper, and the S-caliper was gone forever.
The brakes were revised again for the 3.2 Carrera in 1984, when the Carrera was introduced. The brake system had the following changes in 1984: Brake-disc thickness front and rear was increased from 20 to 24 mm. Brake calipers adapted to thicker disc with spacers. The A and M-caliper designs were still used for the 1984 models. The brake caliper piston diameter for the rear brakes was increased from 38 to 42 mm. The M-caliper design was still retained for the rear--Porsche just installed larger pistons. The pistons for the front calipers remained 48 mm, the same as they had been since 1969 with the aluminum S-calipers."

Wrong. Totally different casting more akin to the early 914 front caliper (nose 1/2 is identical in fact, with the exception of the larger 43mm piston in the teener front). Fluid inlets were on the ends vs. on the sides as the (physically) much larger "front" M-Caliper has. But... they still refer to it as an M-Caliper for some reason... "rear" M-Caliper but M-Caliper nonetheless.



And Mercedes and BMW and... and... and... economies of scale crept in here.



This is important because those considering putting the early front 914 calipers on the rear should note that this size piston (the 914 is actually 43mm so it's even larger than a rear Carrera caliper) was never on a 911 until 84 and, what is omited here is; the 911 got it's first proportioning valve at that time as well. The backs were a great deal larger than their predecessors so the p-valve was needed.



The same as it's been since the very first 911 left the line in 1965 actually.

As always, good info from Bruce... Thanks for posting Greg. I like to use the relative power of each individual vehicle to help draft brake systems for our cars (which are slightly better balanced and weigh less.) Note the first 930 with 240hp recieved S-Calipers and rear M-Calipers. Tires on it were very similar to our wide body cars. I also like to keep our proportioning valves in place and adjust as needed.