The 914 5-Lug Guide
So you want to go 5-Lug on your 914...
We literally wrote the book on 5-lug conversions so, sit back and enjoy the ride errrrr... read.
It’s quite obvious that the classic Fuchs 5x130 wheel is a desirable option for us teeners. Be it polished paddles, or full painted centers, a nice set of Fuchs (or, a wide variety of modestly priced Fachs) can really make a 914 stand out in a crowd… wide body or not. The factory 914-6 had them. The GT’s had them. They offer wider and taller wheel choices and frankly, they just scream “Porsche”. For these reasons, many 914 owners embark upon the quest to install the coveted 5-Lug Fuchs wheel on their 914.
There are about as many ways to go about the process as there are days in the month which is why and when the questions begin to flow. Having gone through this process a number of times for not only ourselves but, for countless customers, we’ve honed in on a process which involves a bit more than throwing some money at wheels, tires and suspension goodies (more on that money aspect in a minute).
First, let’s ask a few questions that the Internet generally won't ask:
1. Wide Body (914-6/GT flares, etc.) or Narrow body (stock)?
2. How much power do you have or do you plan have?
3. What is your driving style?
4. How many miles will you put on your car in a year?
You see… it’s more than just one extra lug nut and some expensive wheels we’re looking at here. With 911 suspensions come 911 brakes and torsion bars. With 911 brakes come larger pistons and some have a much larger pad contact patch. Nice huh? Until you find your brake bias is thrown off –or– “Gee… my 914 use to be fun to drive around town, now I dread every bump in the road. Maybe this boy-racer stuff isn’t all it was made out to be.”
So… before you get stuck with a mismatched system that cost you double what it should or, you wind up with a bone jarring ride you wish you never had, let’s take a look at the options.
Many "Narrow Bodied" cars simply need the 5-Lug rotors. There's only so much tire you can fit under one of these cars and, going "big-brake crazy" may simply be a "big-waste-o-money". Likewise, stock motors will do just fine with stock CV joints (you'll see how they play into this as we progress). This can save you a ton of money that you can now spend on killer shocks and tires.
"Wide Bodied" cars can have a much larger tire contact patch. This can easily overstress a stock caliper setup so your decision to step up in terms of struts and calipers should be carefully thought out. Your horsepower can also come into play (again... with the aforementioned CV's). If it's a full on competition car then you may want to go in one direction vs. a lazy Sunday drive that may never get over 50mph. As you read on, think clearly about how you intend to build and use the car. Some of you may be planning for a larger powerplant in the future (once young Hans and Gretel have graduated college), in that case we tend to recommend you do this job once and get the system you will need for the future. There's no sense in spending good money on a system you'll have to scrap in the future.
Away we go...
Starting with the “Front-End” and going from least expensive to, the most comprehensive it looks like this:
Option #1. Drilled 914 Front Rotors – First a little information on the 914 rotor/hub system. The 914 front rotor is a different animal than that of its 911 brethren. The 914 rotor has the hub system literally built into the rotor. This can make a 914 rotor more expensive than the 911 unit in a few ways. First off; the rotor itself is more expensive. Second; you’ll need to replace the bearings on a 914 rotor each time you get new rotors. If you’re an aggressive AXer, you could easily cook your rotors before your bearings are due. If you’re a daily driver or a summer sunny day driver, this is probably OK. That said; a 911 system has a rotor that is separate from the hub. If you cook a rotor you simply unbolt it from the hub and bolt on a new rotor. Another difference is the spindle. The 911 has a beefier spindle than a 914 so… (to answer another common question) no, 911 hubs won’t bolt on 914 struts/spindles.
All this to preface the fact that you can drill a 914 front rotor to a 5x130mm pattern. A common way to do this is to machine the hubs from the backside and press in studs, in doing so; you will have to machine through the webbing that strengthens the rotor. You'll also be pressing a hardened steel stud into a cast rotor body. This is why this is no longer our choice anymore. Our preference in doing this now would be to machine the rotors from the front and use screw in 14x1.5mm studs (yes, we can hear a few screaming in horror as we type this). IF DONE PROPERLY this would be our preferred method. First off; it will not cut into the webbing on the backside. Secondly; the factory drilled into the face of the cast rotor; why can't you? And finally, to do it properly would require Loctite “Red”… the permanent stuff. This is, after all, a permanent application. Late model rotors will need the centering ring machined off to work with Fuchs. This requires a bit more time and money at the machine shop but, a fairly common and easy practice. Below is a machined Late 914-4 front rotor (notice the machining marks around the hub where the centering ring was machined off).
Pros – This is the cheap way and, last we checked, 914’s seem to have a way of attracting the "cheap-elite." It’s good for a daily driver that won’t be raced. It’s good for that weekend, top off, summer cruiser. It’s good for the narrow bodied cars. It retains all of your current suspension and brake bits which will save you a ton of dough.
Cons – If you need new rotors, you’ll need to do it all over again. You can salvage your studs with a MAPP torch but, all of that machine work will go in the scrap heap. Even with the Loctite Red, I’d make it a habit of checking them every-so-often. 911 struts offer a factory bolt on option for more up-front money.
This May Be For You If – You have a narrow bodied car. You are a daily driver. You are a weekend sunny-day driver. You don’t plan any engine upgrades beyond 140hp. You’re perfectly happy with your 914 the way it is now… you just want 5-Lug Fuchs.
Option #2. 911T Struts or 914-6 Struts (only) – OK, we’ll come right out and say it; this is one of our favorite options for 5-Lug on a 914. The factory thought so too… it’s what they used on the 914-6 to give it its 5-Lug suspension. Actually, the factory used 911 A-Arms and had a special t-bar made up in the 914 size with the 911 spline count (figure that one out for us). We’ve seen factory assembly videos and, we're guessing it was easier for them to sub out the units as a whole as the entire front suspension is installed at one time.
914-6 Struts are simply 911T struts in all measures. The odd thing is they come with a 914 part number. That said, don't be confused; the 914-4 strut is quite different. One clue is a straight steering arm on the 914-4 version. Another is the smaller spindle. Yet another is the 16mm "coarse" thread (16x1.5) rotors attachment nut vs. a 16mm "fine" thread (16x1) attachment nut for the 914-6 and 911 versions. If the odd chance (they're not that common) you have 914-6 struts, you're good to go. Part number for the -6 struts is 914 341 091 00 and 914 341 092 00. Again, they are otherwise identical to the 911 version. Again, a "guess" would have it that these had to have 914 part numbers to be assembled as a complete unit into a 914-6. That "unit" (which would consist of the strut, inserts, hubs, rotors, backing plates, balljoints, a-arms, etc...) would basically have no other part numbers on it. Having the 914.341.xxx.xx number would signify that that "unit" had the proper 914-6 17mm torsion bars with the 911 spline count.
There are two basic versions of the 911 strut; early ball joint and late ball joint. We prefer the late ball joint style as its wedge pin was an improvement over the pinch style older ball joints that have been known to oval the hole in the bottom of the strut. That said, this is a “rare” occurrence and we wouldn’t pass up a set of pinch style struts if the price was right. Just make sure the holes are true on the bottom. Even if the holes are wallowed out, a good welder can cut the base off a late 914-4 strut with the wedge pin and weld it onto these struts. Then you can smile as you saved a set of cool old struts. These struts are made by Boge. The Boge manufacture means you can have your choice of inserts (Boge, Bilstein or Koni). They have a 3” caliper mounting ear spacing. The mounting is common for the 911 M-Caliper that, again, was used on the 914-6. You can also upgrade the calipers to our ultra-lightweight AM aluminum 3” calipers which have roughly the same pad area as the 911 S-Caliper or the 911 A-Caliper (both of with require the 3.5” struts… more on those to come). For rotors, these take the uber-common 20mm rotor used on such Porsche icons as the 914-6, 914-6/GT, 911RS, 911ST and 76 930 through the 911SC range (ending in 1983). You can find these struts for anywhere from $300 - $700 for a pair in all of the usual places (eBay, etc.). You’ll want to make sure the struts come with hubs and preferably calipers. Hubs are the most important item as they can vary from year to year (to clearance various calipers) and, they can be expensive at around $250-400 per pair. The rest we consider throw away or expendable items. Inserts – You’ll want new ones unless you can prove they are fairly new and have low miles. Rotors – Ditto. Calipers – Most we’ve seen on these bargain struts need a full restoration. Bearings – you get the picture. The M-Caliper or Brembo and the vented rotor are more than enough brake to handle any tire or braking situation you can throw under a narrow bodied car. Yes, it is our opinion that anything more than this on a narrow car is either Internet bragging rights or… a waste of money.
Let’s talk about the “Struts Only” comment. we're a fan of keeping the 914 spring rate on 90% of these cars. Again, look at the initial questions and ask yourself; “Do I really want to mess with the stock suspension geometry all that much?” A well set up 914 with stock t-bars and awesome strut inserts and modern rubber can be a dream to drive (or a nightmare… you decide). These struts will bolt on to your existing arms and utilize your existing spring rates etc. This will generally save you money and dentist bills. You’ll have a 914 that not only looks great but still drives great.
If you are building a wide-body or a narrow road-racer, you may want to opt for the entire 911 suspension as their torsion bars are easier to find in the various larger sizes. If you’re on the path to tune your suspension, make your choices wisely.
If you’ve made it this far, your probably starting to get the picture that it’s not only about the wheels, It’s literally an entirely new suspension for your car.
Pros – These can be fairly inexpensive and plentiful. A lot of 911T owners have moved to a 3.5” strut for S-Calipers or A-Calipers or even Turbo calipers. We’d be willing to bet there are quite a few of these in piles in the backrooms of many race-shops. They are a neat and clean “factory” bolt on option (wanna do it the way the good Dr. did it?). They offer a vented rotor option for your 914. Inserts are plentiful and it’s “drivers choice” Bilstein, Koni and Boge all fit and are excellent choices depending on your driving style. With the discovery of the new AM Aluminum 3” caliper, brake upgrades no longer necessitate a change to the more expensive 3.5” struts.
Cons – Price may be the only obstacle we can think of. If you’re a member of the cheap-elite, these may leave you with an empty feeling in the pit of your wallet. Sure, you can get them fairly inexpensively but, don’t forget; inserts, calipers, bearings, rotors etc. That said, going 5-lug is rarely a “cheap” excursion.
This May Be For You If – You have a narrow bodied car. You are a daily driver. You are a weekend sunny-day driver. You insist on doing it the way the factory did it. You have a wide bodied car and have decided to go with our AM Aluminum caliper upgrade (this is the lightest caliper we’ve found). AXer, road-course racing… all good with this set-up.
Option #3. The Myriad of 3.5” Strut Options – Be careful here… we're equally as biased and hopefully you’ll see why. There are many choices and some are quite plentiful. There are advantages and pitfalls to each. Let’s start by listing the struts:
Koni – As the Boge 911T option above these came in both the early pinch style and later wedge pin. These will only accept Koni inserts and it can be difficult to do any custom modifications (raising the spindles, etc.) Calipers that will work are (in order of preference) S-Calipers, Turbo Calipers, A-Calipers and Wide A-Calipers (Carrera Calipers). These struts are orange in appearance from the factory.
Bilstein – These also came in early and late configurations. These will only accept Bilstein inserts (starting to see some pitfalls here?) The straight tubes allow for spindle modifications. Calipers are the same as above. These struts are green in appearance from the factory.
911SC Boge – These only came in the later ball joint configuration. As a Boge strut, inserts from all manufacturers have been made to fit, so… these are a bit more attractive for that versatility alone. Calipers are as above. These struts are black.
For calipers alone, we are extremely cautious on this setup for a 914. You have two basic choices; the S-Caliper or the A-Caliper. You also have the Turbo calipers but a good set is roughly the cost of a really nice 914 for a full set. The A-Caliper and its derivative the Wide A-Caliper both weigh over 9lbs. EACH! If you go Carrera (Wide A) you’ll add an additional 10lbs. of brake rotor to the equation. Compared to a Brembo caliper on a 20mm rotor, you’ll be adding over 20lbs. of un-sprung weight to your lightweight sports car with no additional stopping power (remember, the factory won Le Mans on a 20mm rotor). Our favorite for this set-up is the S-Caliper but… they ain’t cheap. You can find them for $300-400 a pair but they will need “extensive” work. All of those calipers will need new pistons and probably new compensating lines. And… “should” have the factory anodizing re-done. Plan on spending another $800.00 on your bargain calipers.
All that said; there’s plenty of 5-Lug 914’s driving around out there with A-Calipers and Wide A-Calipers. It’s a fine setup that will offer dependable braking day after day. A pair of 911SC Boge struts would be a very competent system for a wide body or higher horse power 914. We would caution against Wide A-Calipers and the 24mm rotors (Carrera suspension). While it sounds all dreamy on the outside, this is an option that only adds weight with zero gain over the standard SC A-Caliper system. Those thicker rotors were designed for a much heavier 911 Carrera that needed to scrub off speed and shed heat a bit differently than our light weight 914’s. Porsche used the S-Caliper/Rear M-Caliper combination on the 911RS and first 930 with power in the 220hp to 240hp range.
Pros – You’ll have a larger choice of Porsche’s bigger calipers available “if you need them.” Because of the popularity of the 911SC these struts are fairly plentiful. Boge versions allow a wide variety of insert options.
Cons – The best calipers can be expensive. The cheapest calipers are the heaviest we’ve weighed for a 911 or a 914 (that’s a lot of un-sprung weight to add). A full set of Turbo calipers for these inserts can cost more than a great 914. Koni and Bilstein versions are usually expensive and limited to their proprietary brand inserts.
This May Be For You If – You have a wide-body car. You have 150hp or more. You want factory brake options. You’re building a GT replica and you want the exact set-up the factory cars had. You’re an S-Caliper fan. A buddy is offering you a set of SC struts complete for $300.00. You have gobs of horse power and don’t care how much your suspension components weigh.
With all of the above strut options you can opt to bolt on the entire 911 front end with the A-Arms and all. These do bolt right up (another common question). This will “generally” be more money and you will have the 911 T-Bars to add to your suspension geometry equation. You decide if you want/need a harsher ride or not… drivers choice.
Also with the above (with the exception of the drilled 914 rotors) you’ll have 48mm pistons in your front calipers. This can throw off your braking bias. This is especially true with the Aluminum AM, S-Caliper and A-Caliper options as they all have larger pads as well (M-Calipers have the same size pad as a 914). You may want to look into a solution for the rear such as the expensive 914-6 caliper, modified Ferrari calipers, or 911 Rear M-Calipers and a handbrake solution (it adds up fast). Don’t forget a 19 or a 23mm Master Cylinder.
Speaking of adding up fast; have you checked Fuchs wheel prices these days?
A final note on custom solutions… you can add almost “any” brake caliper you’d like to these struts. We won’t delve into all of the custom applications and adapters. Suffice to say… “It can be done” if you feel the need.
On to the Rear Hubs and Rotors:
This is a system that you will have to ask yourself; “how much power and torque do/will I have?” Torque kills, and in this case you are limited by your CV joints “not” your hubs.
Again, we’ll try to go through the options starting with the least expensive and going through to a more thorough high horse power solution. First, a little education on the nomenclature of the bits and pieces required. Starting at the outside of the car and moving inward toward the transmission:
1. The Hub – This is the round device our rotors sit on which is pulled into the control arm bearing.
2. The Stub Axle – This small piece slides through the center of the hub and is fixed by the splines in the hub and the large 30mm nut and cotter pin. It determines what CV you will use as it bolts to the CV moving inward.
3. The CV Joint – 914 and 914-6 CV joints are dimensionally the same as the VW Beetle CV joint.
4. The Axle – 914 Axles are 28mm longer than 911 axles.
5. Another CV.
6. The Axle Flange or Final Drive Flange – This, like the stub axles on the other end, bolts the driveline up to the transmission.
As mentioned earlier, the hub component is not a problem area with 5-lug conversions. The problems begin when you have higher horse power and want a beefier CV. The 914 hubs have a different spline count than the 911 hubs so… they can only mate to 914 stub axles (more on that as we delve into this section). On the transmission side, the 914 transmission is basically an early 911 901 gearbox with a different nose cone and a flipped R&P so… an upgraded flange can be plentiful. With that bit of information in hand, let’s take a look at the options.
Option #1. Re-drilled 914 Hubs – There are a couple ways to go about this so we’ll explain the process. Most are machined from the backside and a flat surface is “spot-faced” on to the rear of the hub for the studs to mount flush against. Then 911 studs are pressed in. There’s a slight problem we’ve found when doing this; once you’ve spot-faced the hub to accept the 911 stud you only have 3mm of stud engagement left in the hub. This means you’ll only have 3mm of hub material for the stud to press through and bite into. Factory hubs have roughly 8-10mm of hub engagement. We don’t feel this is a strength issue (as we’ve never seen a properly drilled hub fail) as much as it is an issue with the studs eventually working their way loose from the hub. We had originally eliminated this problem by spot facing a larger area and literally welding on a ring boss to our hubs bringing the engagement back up to the factory 10mm depth but that proved to be a lengthy, timely and costly process that didn't really net the best results. Now we simply drill and tap them. As mentioned with the front 914 drilled rotors, if you drill the hubs to a 5x130mm pattern and use the screw in studs and Loctite Red all of your engagement issues basically go away. There is no need for spot-facing the hubs. Again, this will prove to be controversial to some but we feel it's the best option overall. The factory hub is hardened and we've literally have never seen a failure in 20 plus years of doing this. Again... the factory dilled and tapped the hub, so can you.
This picture shows how thin the hub can be if it's just spot-faced:
Here's a picture of our old 914 hub with stud bosses prior to welding
Early 914 hubs (1970 only) had extra bosses for stud engagement. In reviewing 914-6 hubs from a very early car (Bob Burton’s #41) it appears a similar pattern was used on that hub as well. This is odd because that hub had a 911 spline count in the center so… it is unclear if the 914 hub was going to win or the 911 hub was in the works for both 4 and 5-lug applications. In the end the factory decided upon two different hubs. These early 914 hubs have been coveted for their extra bosses that are in place for the use of 5x130 studs. You would simply drill them to the pattern, spot face them a little and press in the studs. The only issue we see there is, these bosses are only 5mm tall so, it really isn’t that beefy but again, this isn’t a real problem area.
Here's an early 914 hub with the factory bosses that we drilled to 5x130mm.
If you decide to go with a 914 re-drilled hub you will be stuck with 914 CV joints. We say this because; if you plan to go to a higher horse power motor you may want to review this application. We’d rate these good for 140-150hp with a mature driver at the helm (no wheelies). Remember, 914 hubs only accept 914 stub axles. 914 stub axles only accept the smaller 914 CV’s “This” becomes your limiting factor when choosing a 5-lug system for your car... not the hub.
That said, this can save you a ton of money in CV’s and custom axle applications. This is literally a bolt on application that will require new rear bearings and a 914-6 rear rotor or a 914 rear rotor drilled to the 5x130 pattern to match the hub. You'll have to mill 4mm off the diameter of the 914-6 rotor and they're kindof expensive. At this point, we'd go with a drilled 914-4 rotor for this application. Once this set-up is in your control arm, you simply bolt your 914 stub axle/CV/Axle assembly back in place and you’re good to go.
Pros – This is a very cost effective solution for the 914 owner that will stay under 140hp. It’s attractive to the cheap-elite as there are no further costs or modifications associated with the set-up. It uses all of your stock components. These do not fail. They are extremely durable and reliable for normal street and even race work.
Cons – The system itself limits you to the use of 914 CV joints.
This May Be For You If – You have a narrow bodied car and it’s a daily or a sunny day driver. You plan to stay under 140hp. You’re happy with your 914 just the way it is, you just want 5-lug wheels. This is also good for autocross or road race cars that are under the 140-150hp limit… more if you think you know how to be kind to your CV joints.
Option #2. The 911 Hub and a 914-6 Stub Axle – This will allow you to use the exact set-up that the factory used on a 914-6. We are “not” fans of this set-up for practical applications for the following reasons. First off, 914-6 stub axles are stupid expensive. Secondly, they have the same spline count as the 911 hub which (obviously) allows the use of the 911 hub which is great BUT… they go back and bolt to the 914 CV which, once again, will be your weakest link.
The way overpriced 914-6 Stub Axle (this is a stock one):
Pros – You can do it like the 914-6. No machine work to be done. Bolt on application. It slides into a 911 hub.
Cons – 914-6 stub axles are way too much money. This, again, limits you to the use of 914 CV’s.
This May Be For You If – You didn’t read anything above?? You for some reason think that re-drilled 914 hubs are not a good idea. Our advice, if you’re OK with 914 CV’s is to avoid the 911 hub and 914-6 stub axle combo and save yourself $8-900.00
Option #3. 944 CV’s and 911 Hub/Stub Axle/Flange Conversion - 944 CV’s have the same spline count as a 914 axle and will “almost” slide on. You’ll have to machine 4mm off your 914 axles where the bottom of the CV’s mounts up as the 944 CV’s are 4mm deeper than a 914 CV. The 944 CV at 100mm is slightly smaller than the 911 108mm but should be more than capable of handling extra power associated with engine conversions. While the fasteners are smaller (M8 vs. M10 in the next example) there are more of them, six vs. 4 and two pins.
Here's a picture of the 914 axles with the needed modification:
Here's the fairly rare 6 bolt coarse splined flange and 6 bolt stub axle:
Pros – CV’s are common and available. Only a slight amount of machining needed to your 914 axles. Handles higher horse power applications. Concise system that, machining withstanding, uses bolt up stock components. Depending on the cost of machining and 944 components, this may be less expensive than the next system.
Cons – Coarse spline 6 bolt flanges have been harder to find (limited to a few years before the splines were changed). You’ll have to machine your 914 axles to make this work. 100mm CV’s are slightly smaller than the 911/930 108mm variety. Uses smaller M8 hardware to fasten CV’s (the last two are probably not issues AT ALL with this set-up). You don't have the advantage of the free floating axle as seen in the next set up.
This May Be For You If – You’re looking to install a big six. You’re installing a V8 or other high horse power conversion motor. You want an extremely clean “set-it and forget-it” combo. You have a wide body car with as much rubber and power you can humanly muster into a 914. You have access to a machine shop that is capable.
Option #4. The 911 “System” with Custom Length Axles – For higher horse power applications, this is our favorite. You simply use all of the 911 components and slip in a custom length axle shaft from “Sway-A-Way”.
What’s nice about this system is, it all bolts together with no extra machining and, you get an axle upgrade with the Sway-A-Way or EMPI units. These axles allow for a free floating CV which will find natural center and allow for better handling of torque. This has long been a known upgrade in the VW off-road racing community and, for $325.00 a pair of these axles can make their way onto your car. The 911 components (read: CV joints) can easily handle upwards of 300hp without failure. 911 stub axles slide into 911 hubs and early coarse splined flanges bolt right on to our versions of the 901 transmission.
A shot of the custom length Sway-A-Way free floating axle next to the 911 counterpart. Note the 914 length:
Here's a shot of the 108mm 911 stub axle and CV on the custom axle:
Pros – Bolt together application. Handles gobs of horse power. Free floating axles handle torque better than stock.
Cons – Can be pricey for some. Expect to pay over $900.00 for a finished system using used 911 parts found cheap. Overkill for a standard 914 with under 150hp. 108mm CV’s no longer exist BUT you can purchase them as complete axle assemblies. 930 units can also be modified for the dual pin conversion.
This May Be For You If – You’re looking to install a big six. You’re installing a V8 or other high horse power conversion motor. You want an extremely clean “set-it and forget-it” combo. You have a wide body car with as much rubber and power you can humanly muster into a 914.
There you have it. At close to 4,500 words, you can see that the options and issues are vast. All of our 5-Lug recommendations come after answering all the questions our customers have asked over the years. Everything depends on your driving style and overall intentions for your vehicle. While we did touch on calipers, we didn’t go into detail rear caliper solutions to retain proper brake bias. Suffice to say this can be accomplished with 914-6 calipers or modified Ferrari calipers or, 911 Rear M-Caliper solutions as mentioned previously. Again, with a handbrake modification, virtually any caliper combination can be achieved with these systems. All it takes is cubic dollars.
Speaking of which; a good 5-Lug system can run you $3,000 to $4,000 dollars, wheels, tires and all. You now transverse the slippery slope. Enjoy the ride.