If you are planning on replacing all four CV joints, itís cheaper to purchase a complete axle
Replace your rear wheel bearings
This article is one in a series that have been released in conjunction with Wayne's
book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything
from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive
step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website
for more details.
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One of the most common suspension items to replace or service on the 911 is the constant velocity, or CV joints that connect the wheels to the transmission. These bearings, packed in grease, get a tremendous amount of mileage through the years, and thus have a tendency to wear out after about 100,000 miles or so. One of the clear signs that the joints need replacing is the distinct sound of a clunk, clunk, clunk coming from the rear axle when the car is in motion.
In some cases, the boots that cover and protect the CV joints will be torn and need replacing. The procedure for replacing the boots is very similar to the procedure for replacing the entire joint. New boots should be installed each time a new CV joint is installed.
If you are planning on replacing both the inner and outer joints, then you should probably purchase a brand new axle. The new Lobro axle contains both the inner and outer CV joints, as well as the boots that cover and protect them. In addition, the complete axle is usually about the same cost as if you purchased just the CV joints and the boots. Plus, the entire assembly ships with everything installed. All you need to do is to bolt it up to the car.
The complete axle is also a good option for replacing the CV joints on the late model 911 1984-89 Carreras. The inner CV joints are an integrated part of the stub axle, and are not available separately. The Carrera axle ships with the two CV joints and the stub axle as a simple replacement unit.
The first step is to jack up and raise the car off of the ground (see Project 1 for details). You donít need to remove the road wheels, although it is recommended that you do so in order to gain yourself some more working room. The next step is to start removing the bolts from the CV joints. Start by making sure that you have the correct tool. On some early 911s, the bolts need a six-point star pattern removal tool to loosen them up. On some others, the bolts used only a standard Allen hex pattern. Either way, you must have the correct tool for the removal task, or you might strip out the CV bolts. If you do strip out the bolts, the only way to remove the bolts is to grind them off, which is not a fun task. Sometimes on the early cars, the bolts have been replaced with ones that are easier to remove. For instance, itís common to find that the bolts on the early cars have been replaced with ones similar to the simpler hex pattern. Either way, itís recommended that you use a socket tool to remove the bolts and reinstall the bolts, since you will have to torque them with a torque wrench when you are finished.
In order to gain access to the CV bolts, rotate the wheel of the car until you can clearly get your socket wrench on the bolts. Then, pull the emergency brake and place the transmission into first gear. This will allow you to loosen the bolts without having the axle spin. When you have removed all the bolts that you can from this angle, release the brake, take the car out of gear, and rotate the wheel until you can reach the next set of bolts. If you are planning on removing the whole axle by removing both the inner and outer joints, then work on the bolts on both the inner and outer joints at the same time.
Once you have the CV bolts disconnected, itís now time to separate them from the transmission or the stub axle. On the early cars, there are roll pins that help align the CV joints with the flange. Using a small screwdriver, poke into the CV joint seal that is located between the CV joint and the transmission. With the emergency brake released and the car out of gear, rotate the wheel around as you gently pry the two apart. On the later cars, there is no pin holding the joint and the flange together, so they should simply come apart. Make sure that you wear safety glasses when working underneath the car. You would hate to have an axle fall on your face.
If you are replacing the entire axle, or the boots on both sides, simply remove the axle and take it over to your workbench. If you are only replacing one boot or one CV joint, you will have to continue to work underneath the car. The CV joints are held onto the axles using a large circlip. Remove this circlip, and the joints should come right off. In general, itís a really bad sign if large balls from the bearing start falling out. Thatís a clear indicator that you need to replace the joints. If you are reusing the joints again, make sure that you carefully place them in a plastic bag, and avoid getting any dirt or grime in them. Even a crystal of sand or two accidentally placed in the joints can help them wear out prematurely.
Once you have removed the joints, then the replacement of the boots should be easy. Simply disconnect the small clips that hold the boot to the shaft and slide it off. The new ones are simply installed in a reverse manner.
When installing the new CV joints, make sure that you pack them with plenty of CV joint grease before you install them on the car. Also make sure that you place plenty of grease in and around the boot. Move the joint in and out as you insert the grease to make sure that you get it well lubricated, as the new CV joints do not come pre-greased. When ready, place the new boot on the axle and then place the CV joint on the axle. Reattach the circlip so that the joint is attached to the axle.
Now, insert the CV joint back into either the stub axle flange or the transmission flange, making sure that you donít forget to install the CV joint gasket. Pack a little more grease into the recesses of the flange before you remate the joints together. Finally insert the bolts, and tighten them up. Using a torque wrench, tighten up the bolts to 83 N-m 61 ft-lb for cars with four M10 bolts on the flanges, and 47 N-m 34 ft-lb for cars with six M8 bolts on the flanges. For 1965-68 911s, tighten them up to 47 N-m if you have the Nadella axles M10 bolts, or 43 N-m if you have the early Loebro CV joints M8 bolts. You may need to drop the car down onto the ground in order to tighten to this spec without turning the wheels.
Once you have the entire assembly back together, take the car out for a drive, and check the rear for noises. All should be smooth and quiet, and the boots should no longer leak.
Shown here is a complete axle for a late model 911 Carrera (1985-89), a CV joint for the 911SC, and a CV boot for an early 911. On these later cars, the outer CV joint is not available separately, but must be purchased as a complete axle. This is because the joint is integrated into the stub axle and cannot be separated. If the boots are damaged and leaking, then you should replace them, because dirt and debris can find their way inside.
The four CV joints are located in the rear of the car, attached to both the transmission flanges and the stub axles on the trailing arms. Itís recommended to replace the joints in pairs: either both of the inside ones or both of the outside ones. Chances are if one of the joints is showing signs of wear and deterioration, then the other three will not be far behind.
Comments: Thank you for the article it was very helpful. I am reassembling the rear left outside CV joint for a 1973 914 Porsche half axel. Can you help me with the details on how to reassemble this rear left outside CV joint?
April 2, 2015
Followup from the Pelican Staff: Can you share some photos of the axle end and pod? I may be able to give you some advice.
We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.
I would grab a repair manual. It will have the procedure, special tools and torque specs.
Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
Comments: hi what CV boot do I use for a 930 CV joint. I took measurement of the CV boot I have and it likes the axle side is about 1.12 inches the flange side is about 2.50 and the height is 3.50
August 13, 2014
Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
Comments: we are on our 2nd set of axles in just a few years on our 79 930 TT. This is a track only race car. Is there another, more durable, bolt-on alternative to the axles from the older 911s - or is this just another "cost" of racing? Thank you and please excuse my lack of knowledge.
June 27, 2014
Followup from the Pelican Staff: There may be an aftermarket option for beefy axles. I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
Comments: my name is Kirby Gentry I own a 1977 Porsche 911 s I recently replaced both rear wheel bearings upon reassembly I noticed that the passenger side stub axle does not extend through the hub as far as it previously did I am also experiencing a rotation that is not smooth throughout its 360-degrees the wheel actually stops while you are pushing it around its full rotation, also there is a slight clicking coming from what I am sure is the CV axle i intend to remove the CV axle and use a drift to remove the stub axle from the hub and make sure that it is seated properly hoping this will remove that bind I apparently have put the CV axle n just a note it was working perfectly before I disassembled it. I would appreciate anyone's thoughts or comments on this, as my project to rectify my mistake begins for first thing in the morning..
May 10, 2014
Followup from the Pelican Staff: Sounds to me like the bearing is either wrong (too big) or it came apart during installation, preventing the axle from fitting. - Nick at Pelican Parts
Comments: Great article, can you confirm whether it is the inner or outer cv that are not available as it says the 'inner CV joints are an integrated part of the stub axle, and are not available separately'.
Comments: I Have two torn inner-rear boot covers on a 1991 Carrera4. Do I have to replace the whole axels, or just the inner covers?
January 28, 2014
Followup from the Pelican Staff: You can do it either way. If the axles are noisy, I would replace the entire unit. - Nick at Pelican Parts
Comments: Hello, I have a build going that will use a '76 930 transaxle to a modified Corvette C5 hub 930 pattern. Since I must spec axles regardless, I'd like to know if I should use the '85-'89 911 or the Turbo CV's for best strength. It looks like only the width changes. Thanks.
August 6, 2013
Followup from the Pelican Staff: The turbo axles would be the stronger design - Kerry at Pelican Parts
Comments: Hi, can you please clarify, I am working with a 1987 SC that needs a new outer CV boot, can it be done in car, do I need to remove/rebuild the whole axle, or do I need to buy a new axle. Thanks. There are three conflicting statements in this page. 1. The original article says "the inner CV joints are an integrated part of the stub axle, and are not available separately. 2. Then in one of the pictures it says "On these later cars, the outer CV joint is not available separately, but must be purchased as a complete axle. This is because the joint is integrated into the stub axle and cannot be separated." 3. Then in one of the comments it says "the article says the outer boot is not available because it is attached to the entire shaft. The whole axle should be replaced at this point."
edit to previous comment, it's an inner boot that is leaking, not an outer boot, but same confusion persists. Can I just pull the axle, pull the outer cv joint and boot, then replace the inner boot and reassemble? Thanks.
June 22, 2013
Followup from the Pelican Staff: I would suggest removing it from the vehicle. You will have a much easier time reassembling it.
As far as rebuilding it. It depends on what you find when you open it up.- Nick at Pelican Parts
Comments: Incorrect Torque Specs: Using a torque wrench, tighten up the bolts to 83 N-m 61 ft-lb for cars with four M10 bolts on the flanges, and 47 N-m 34 ft-lb for cars with six M8 bolts on the flanges. For 1965-68 911s, tighten them up to 47 N-m if you have the Nadella axles M10 bolts, or 43 N-m if you have the early Loebro CV joints M8 bolts.
Followup from the Pelican Staff: Thanks for the information on the earlier 911, we have updated the article to make sure it's correct. - Nick at Pelican Parts
nick @ pelican parts
Comments: How much wood could a woodchuck chuck if a woodchuck chucked wood in a 911 while working on the CV Joints
May 28, 2013
Followup from the Pelican Staff: Just enough wood would get chucked, no more and no less - Nick at Pelican Parts
Comments: article says inner is not available. inner is avialable.
February 13, 2013
Followup from the Pelican Staff: I believe the article says the outer boot is not available because it is attached to the entire shaft. The whole axle should be replaced at this point. - Nick at Pelican Parts
Comments: Can you install complete new half-shafts on a 71 914 without having to pull the stub axels out ? Axel end of half-shaft sets in quite deep into trailing arm. Have 5 lug hubs. Looks like original half-shafts mounted to 350 SBC. Thinking of upgrading to Renegade Hybrids shafts but not sure of "fitment" problems; like spline or shaft length issues. I know the passengers rear cv joint is "clunking" loudly. Wondering if it would be worth the the cost of replacing both shafts or just fixing the one cv joint. Thanks for any advice !!!
December 16, 2012
Followup from the Pelican Staff: Our High Performance 914 Axle Upgrade Kit is exactly what you are looking for. - Nick at Pelican Parts
Comments: HI. Umm, there is no way you are going to be able to torque an 8mm allen socket head bolt to 61 ft lbs... I think this value has been posted in error- my book says 31 or 34 ft lbs for 8mm bolts, and the much higher value is for the CV joints with the larger, 10mm bolts.
August 26, 2012
Followup from the Pelican Staff: 60 ft/lbs (83NM) is the correct spec for this application as they use hardened higher grade bolts. - Nick at Pelican Parts
Comments: Re: Previous message torn boot, can't find clip. I found the clip! Thanks for any time you gave. I had expected to find it on the axle side of the cv joint. I didn't realize the cap on the cv housing was removable & the clip was accessed from there.
February 12, 2012
Followup from the Pelican Staff: Great, I hope everything worked out for you - Nick at Pelican Parts
Comments: I have a torn ,Lt. rear,outer, cv boot I'd like to replace on my '92 C4. I expected to find a clip that would allow removal of the joint to the axle. Am I heading the right direction?or are there special circumstances with '92 C4s. I have "101 Projects", "Bentley's-Without guesswork" & "Enthusiast's Companion".Dempsey's book is strong 'till '89. The others are vague. Any ideas would help- I'm not finding a clip.
February 10, 2012
Followup from the Pelican Staff: The clip is on the inner side of the CV joint - Nick at Pelican Parts
Check out some other sample projects
from the book: