The Porsche 924 Owners Club

Drive shaft bolts and retainers - New Product!
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Author:  DrJohn [ Mon Jun 01, 2020 8:41 pm ]
Post subject:  Drive shaft bolts and retainers - New Product!

Hi all.
In brief: I'm going to start selling driveshaft bolt kits for the 924, 944 and 968, together with retaining clips to prevent them working loose with time. I will sell them here 30% off at £20 per set inc UK postage, but on ebay they will be £30 due to fee's etc (plus a small profit hopefully to contribute towards ongoing car upgrades!)

The problem and explanation:

Having just swapped my gearbox I came across the standard problem of soft headed drive shaft bolts. Even with the correct tool (a snap-on no less so can't blame the tool shape!) a few rounded in the heads an necessitated driving a large torx bit into them to get them out. Not a big deal on the ramp, but on axle stands it's a real pain! I looked into replacement bolts and they are surprisingly expensive. There are 24 of them between both shafts (6/CV) and at almost £3 each it soon mounts up.

I tracked down some alternatives in 12.9 grade, with black oxide finish and a more commonly available 6mm allen hex head. These fit perfectly, look the part, and are easier to work with for most folk.

The next problem I read about on researching these bolts is them coming loose and owners not noticing them. Even reports of driveshafts coming adrift after having work done at reputable garages. Locktite isn't an option without a lot of hassle, since there is inevitably grease in the holes. Some owners go to the hassle of drilling the heads and wire-locking them in place, but that risks weakening the head and drilling 24 bolts at 12.9 grade isn't a quick job.

The clips I've designed hold the bolts relative to it's adjacent partner, so neither can unwind and loosen in time. The clips are easily removed and can be reused time and time again. If you were to break one on fitting or removal, there will spares included in the kit which eases fitting and takes away the stress - although they are tough clips and should resist 'reasonable' force during fitting and removal. No possibility of the clips getting stuck permanently due to galvanic corrosion etc, as a last resort they can be simply melted away with direct heat from an open flame or soldering iron.

Any questions please ask. I am yet to stock pile the parts required but I expect to have them delivered within 7-10 days of ordering.

Ps: Classic example of these bolts coming loose! ... -spec.html


Author:  Targa924 [ Mon Jun 01, 2020 10:07 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Hi John, sounds like a great idea. I’d like a set please, as driveshafts refurb is on my to-do list.

I’m not in a rush as I think the drivetrain refresh will be a winter job, but PM me when you’re ready for payments and I’ll add them to the new parts pile :beer:

Author:  green_ghost [ Mon Jun 01, 2020 10:51 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Hi John,
Great idea - I was not aware of this problem, and still to refurb this part of the car, so please put me down for a set?

Author:  dd924 [ Tue Jun 02, 2020 12:09 am ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Good idea, but I would still re-torque the bolts after a couple of hundred miles.

The spreading bars reduce pressure (PSI) on the bellows plate which doesn't sit properly on the CV (bellows plate has rounded corners, CV has sharper), after time it settles in and reduces tension on the bolts - they need re-torquing but any sort of lock stops the problem exacerbating.

Author:  MartinT [ Tue Jun 02, 2020 10:58 am ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Hi John, I'll have a set please

Author:  DrJohn [ Tue Jun 02, 2020 3:46 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Thanks for the replies everyone. Andy, completely agree about re-torquing the bolts if you’ve fitted new components - for example new boots etc, but when reusing existing components I don’t think re-torquing is quite so important.

In response to knowing this is a problem, the soft heads with annoying tri-square or (I forget the other name for the spline tool A- something I think!) is a well documented problem. Shafts and bolts coming loose is less frequently discussed on here - but since the bits I’ve put together upgrade the bolts (to atleast an easier to use head and equivalent if not higher tensile strength) the retainers are maybe just added belt and braces.

Just bare in mind that looking at some Cv boot kits online you might get bolts included. I’m not sure of the type or quality etc but just have a look before ordering mine - seems a shame to pay twice for them!

Pic attached of retainer clip in place on my car. The astute might realise the Allen head socket must be rotated correctly to allow fitment. Whilst true, and a small amount of increased tightening torque might be needed, I’ll supply 3 versions of the retainer clips in the pack so you can choose the correct orientation for each pair of bolts. Confused? Don’t worry, I’ll include full instructions and it’s really very simple! :smile:

I’ll order the parts now and get the instructions typed up hoping to ship by the end of the week or Monday latest. I’ll let you know about paypal once it’s all here and ready to go.


D04751C9-B3FB-471E-8FC2-CF0B3E300E3B.jpeg [ 2.42 MiB | Viewed 999 times ]

Author:  Nige [ Tue Jun 02, 2020 4:21 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Are they normally a Torx headed bolt?

I think I'll take a set for my S please John. I'll need to drop my transmission at some time so I may as well give it some DrJohn treatment :beer:

Author:  Lesworth [ Tue Jun 02, 2020 4:46 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

I used schnorr washers over the moon plates to help prevent the bolts coming loose, with paint marks to provide visible evidence of movement.

This looks like a neat solution!

Author:  DrJohn [ Tue Jun 02, 2020 7:28 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!

Hi Nige. No, Torx in this size are much too course (ie fewer teeth). Standard are 12point x 8mm ‘triple square’ but there is also a 3 letter name given to them. Something like AMZ or something but I drew a blank on eBay. I’ve only read one person recently mention that name. Most refer to them as triple square. I’ll have a look what’s written on my snap on tool.

Schnorr washers - never heard of them but just googled and what a cool thing they are! Do you need a certain torque on the bolt to get them to bite or is that not quoted? Either way they look like a nice item to have on the shelf for a few jobs.

What I haven’t been able to do with my clips is validate they do what they should! I’m not trying to fleece anyone, but logic would suggest they will resist any backing out since the force promoting that is minimal. I assume they work loose as a function of loading and unloading, heat cycling and vibration. But others on here with engineering backgrounds might know otherwise? I’m quite happy to receive constructive feedback if anyone thinks the clips could be improved. The better the final product the better it is for all of us!


Author:  dd924 [ Tue Jun 02, 2020 10:06 pm ]
Post subject:  Re: Drive shaft bolts and retainers - New Product!


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