Printable Version of Topic
Click here to view this topic in its original format
914World.com _ 914World Garage _ CV Bolt Replacement
Posted by: Nogoodwithusernames Jul 2 2020, 10:07 PM
Was going to take the 914 out for a spin tonight 
and two streets from the house *POP* and engine free revs... Figured I broke an axle or something along those lines and sure enough drive side axle is no longer connected to the trans. Haven't dug in to find out if the bolts sheared or backed out but it needs fixing.
I'm planning on replacing all the CV bolts with the safety wire versions from 914 rubber and obviously safety wiring them. But should I locktite them? Antisieze? Neither? Figure I'd clean them and repack the grease, anything else while I'm under there? Might finally put the new shifter bushings I've had sitting around for eons...
(Also how many are there? I think VW has 6 bolts per CV, same for our little NARP? *EDIT* 914 rubber says it right on their site, 16 total.)
Posted by: JamesM Jul 3 2020, 02:08 AM
4 bolts + 2 roll pins per CV joint.
Make sure you have the roll pins, I have found them missing on cars before
Posted by: wndsrfr Jul 3 2020, 06:09 AM
4 bolts + 2 roll pins per CV joint.
Make sure you have the roll pins, I have found them missing on cars before
No loctite needed if you safety wire....
Posted by: 914Sixer Jul 3 2020, 06:49 AM
Run the 12.9 bolts instead of the stock ones. Use new Schoor washers every time for a better bite. 4 bolts per CV= 16 total. If you torque them properly no safety wire need.
Posted by: roblav1 Jul 3 2020, 07:36 AM
If you're running the early 911 CV's with 2 pins and 4 bolts each, Schoor washers for the CVs on a Hummer are better and cheaper.
Posted by: cuddy_k Jul 3 2020, 07:37 AM
Like many things on our cars, it all works as a system. New bolts and schnoor washers should be fine. No loctite or anything else needed. I’ve never had any back out. The safety wire is great for extra peace of mind.
Posted by: Bartlett 914 Jul 3 2020, 07:49 AM
I too have been through this. I discovered the main culprit causing the CV's to work loose it the output flange on the transmission. What happens is when the CV works loose, the bolts pull on the threaded portion of the output flange. This makes the threaded spots higher than the rest of the flange. It may seem that the CV and the output flange are sitting flat to each other but they are not. If you remove the flange and chuck it in a lathe and make a "clean up" cut you will see the high spots are at the thread holes. Once this is clean and flat, screws and new Schorr washers are all that is needed. I use standard socked head cap screws
Posted by: bdstone914 Jul 3 2020, 07:50 AM
Clean the holes for the CV bolts. Grease affects the torque value.
If you dont use safety wire put a dot of bright paint on the bottom of the bolt and flange. Check occasionally to see if the dots do not align and they are beginning to back out.
Posted by: cary Jul 3 2020, 08:04 AM
My only addition. If you damage the hex socket in anyway. Change out the bolt.
Posted by: ClayPerrine Jul 3 2020, 08:21 AM
Run the 12.9 bolts instead of the stock ones. Use new Schoor washers every time for a better bite. 4 bolts per CV= 16 total. If you torque them properly no safety wire need.
Also, break out your torque wrench, and properly torque the bolts. Done correctly, you won't have any issues with them backing out.
Posted by: Mikey914 Jul 3 2020, 09:49 AM
We stock the safety wire version and the Schoor washers you can start with the new bolts
The wire will definitely hold them, But you can even cheat and go every other if you want to save a buck.
Posted by: IronHillRestorations Jul 3 2020, 11:19 AM
As long as you use new Schnorr washers, make sure the treads are free from grease, and torque to spec, you’ll be good. Schnorr washers are one and done, and 100% not reusable. That’s where people have trouble
Posted by: michael7810 Jul 3 2020, 11:36 AM
I think it’s a good idea to recheck the torque after 500-ish miles as the gaskets can settle a bit. After the retorque I’ve never had one loosen and I don’t use safety wire.
Posted by: mepstein Jul 3 2020, 11:45 AM
I think it’s a good idea to recheck the torque after 500-ish miles as the gaskets can settle a bit. After the retorque I’ve never had one loosen and I don’t use safety wire.
The question comes up all the time on Pelican. Porsche doesn't safety wire the cv bolts on their passenger cars. The answer is to follow the correct procedure for install and they will stay tight.
Posted by: preach Jul 3 2020, 01:39 PM
Clean the holes for the CV bolts. Grease affects the torque value.
If you dont use safety wire put a dot of bright paint on the bottom of the bolt and flange. Check occasionally to see if the dots do not align and they are beginning to back out.
I thought that true about grease on fasteners for most of my life.
For the last 13 years I have worked as a mechanic and we are required to lubricate fasteners unless we are required to loctite them. Most of the time it is Molykote P-37, but often it is system oil and in some systems another type of lube.
The engineering thought behind this is that a fastener can have small imperfections that can bind and distort the real torque value. The lubrication prevents this as well as minimizes the chance of the fastener to gall.
The majority of the fasteners I deal with have some sort of locking device, wire or locking elements/anaerobic fluid. Additionally many of them are not ferrous metal and will gall pretty easy.
In my shop at home I tend to use a lubricant on all fasteners except for lug nuts.
Not arguing the point just putting up my experience.
Posted by: mepstein Jul 3 2020, 01:54 PM
Clean the holes for the CV bolts. Grease affects the torque value.
If you dont use safety wire put a dot of bright paint on the bottom of the bolt and flange. Check occasionally to see if the dots do not align and they are beginning to back out.
I thought that true about grease on fasteners for most of my life.
For the last 13 years I have worked as a mechanic and we are required to lubricate fasteners unless we are required to loctite them. Most of the time it is Molykote P-37, but often it is system oil and in some systems another type of lube.
The engineering thought behind this is that a fastener can have small imperfections that can bind and distort the real torque value. The lubrication prevents this as well as minimizes the chance of the fastener to gall.
The majority of the fasteners I deal with have some sort of locking device, wire or locking elements/anaerobic fluid. Additionally many of them are not ferrous metal and will gall pretty easy.
In my shop at home I tend to use a lubricant on all fasteners except for lug nuts.
Not arguing the point just putting up my experience.
Makes sense but in the case of cv bolts, you want them bone dry and clean.
Posted by: ericoneal Jul 3 2020, 03:20 PM
How much torque?
Run the 12.9 bolts instead of the stock ones. Use new Schoor washers every time for a better bite. 4 bolts per CV= 16 total. If you torque them properly no safety wire need.
Also, break out your torque wrench, and properly torque the bolts. Done correctly, you won't have any issues with them backing out.
Posted by: 76-914 Jul 3 2020, 04:18 PM
Clean the holes for the CV bolts. Grease affects the torque value.
If you dont use safety wire put a dot of bright paint on the bottom of the bolt and flange. Check occasionally to see if the dots do not align and they are beginning to back out.
I thought that true about grease on fasteners for most of my life.
For the last 13 years I have worked as a mechanic and we are required to lubricate fasteners unless we are required to loctite them. Most of the time it is Molykote P-37, but often it is system oil and in some systems another type of lube.
The engineering thought behind this is that a fastener can have small imperfections that can bind and distort the real torque value. The lubrication prevents this as well as minimizes the chance of the fastener to gall.
The majority of the fasteners I deal with have some sort of locking device, wire or locking elements/anaerobic fluid. Additionally many of them are not ferrous metal and will gall pretty easy.
In my shop at home I tend to use a lubricant on all fasteners except for lug nuts.
Not arguing the point just putting up my experience.
Makes sense but in the case of cv bolts, you want them bone dry and clean.
I have to agree with Preach here. Unless specified all torque values are not for dry fit. Usually a drop of oil on the 3 starting threads is recommended. Besides, the area is never clean unless you've rebuilt that entire CV and corresponding hub. You're a sharp cookie Mark so I'd like to see where you've read that. For my own enlightenment anyway. I could probably win a bar bet with that knowledge. To the OP. Do not try to loosen the bolts, or tighten for that matter, unless the Allen socket is clean and the 4 square wrench bottoms out completely.
Posted by: 76-914 Jul 3 2020, 04:20 PM
How much torque?
Run the 12.9 bolts instead of the stock ones. Use new Schoor washers every time for a better bite. 4 bolts per CV= 16 total. If you torque them properly no safety wire need.
Also, break out your torque wrench, and properly torque the bolts. Done correctly, you won't have any issues with them backing out.
37 ft lbs IIRC. I wrote it on my 3/8 torque wrench box so I wouldn't have to look it up every time. Did the same for the lug nuts on my 1/2" TW box.
Posted by: 914_teener Jul 4 2020, 05:39 PM
Clean the holes for the CV bolts. Grease affects the torque value.
If you dont use safety wire put a dot of bright paint on the bottom of the bolt and flange. Check occasionally to see if the dots do not align and they are beginning to back out.
I thought that true about grease on fasteners for most of my life.
For the last 13 years I have worked as a mechanic and we are required to lubricate fasteners unless we are required to loctite them. Most of the time it is Molykote P-37, but often it is system oil and in some systems another type of lube.
The engineering thought behind this is that a fastener can have small imperfections that can bind and distort the real torque value. The lubrication prevents this as well as minimizes the chance of the fastener to gall.
The majority of the fasteners I deal with have some sort of locking device, wire or locking elements/anaerobic fluid. Additionally many of them are not ferrous metal and will gall pretty easy.
In my shop at home I tend to use a lubricant on all fasteners except for lug nuts.
Not arguing the point just putting up my experience.
Makes sense but in the case of cv bolts, you want them bone dry and clean.
I have to agree with Preach here. Unless specified all torque values are not for dry fit. Usually a drop of oil on the 3 starting threads is recommended. Besides, the area is never clean unless you've rebuilt that entire CV and corresponding hub. You're a sharp cookie Mark so I'd like to see where you've read that. For my own enlightenment anyway. I could probably win a bar bet with that knowledge. To the OP. Do not try to loosen the bolts, or tighten for that matter, unless the Allen socket is clean and the 4 square wrench bottoms out completely.
Wait.....check to see if it IS a triple square or a socket head cap screw (allen). 4 square is a kids game. If it.s a triple square and it.s dirty it.s hard to tell. Clean everything there first and make sure. If you strip one of those that be a no fun zone. Take the triple square bit and seat it with a rap with a small hard mallet.
Also...if you use a cv with no recess for a gasket don.t use a gasket.
BTDT.
Posted by: 76-914 Jul 4 2020, 07:01 PM
@914teener 
I don't know if that was a result of fat fingers or just a plain old Brain Fart!
Posted by: Nogoodwithusernames Sep 27 2020, 02:37 PM
Alright folks, I finally got around to getting the 914 up on stands and slid under the car to start seeing what was what. I promptly discovered this is a larger task than I initially expected after reading through the procedure in a few of the manuals... I also discovered some additional damage... (output flange and CV, see below)
I'm contemplating just pulling the engine and trans, then pulling the axles.
This would:
1- Avoid having to screw around with the HE's and risk one not sealing up properly upon re-install.
2- Make it much easier to drain and refill the transmission fluid (the output flange on the side that came loose was damaged on one of the locating dowel holes 
and no dowel pins left on that flange)
3- Make installing shifter bushings easier?
4- General clean up and inspection of drivetrain and engine compartment would be nice.
Another issue I saw while under the car, the CV that came loose had broken a piece off the cage that holds the ball bearings in place... Can I get just a new cage or do I need a new complete CV joint?
Anyone up in Nor-Cal (I'm in Yuba City) be willing to meet up for a Saturday and help make sure I don't make any costly mistakes? It's nice having an extra set of eyes and hands from someone with a bit more experience than myself. I'd be more than willing to compensate your time. (An extra floor jack and an impact gun would be nice, but I can borrow an impact gun from my FIL if needed.)
Posted by: Mikey914 Sep 27 2020, 05:21 PM
You don’t have to pull it all, but if you are thinking of doing anything else, you might as well, as I’m sure you will see a few other things to do also.
Posted by: Ansbacher Sep 27 2020, 06:16 PM
When dropping my engine recently I found my CV bolts ridiculously loose. Am I just lucky nothing broke loose prior, or has this problem been blown out of proportion???
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)