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Wheel Broke off while driving, trying to figure out what went wrong and how to fix it
Hey y'all,
I've had my 944 for about two years now and done a substantial amount of work on the car. I was not expecting the wheel hub and brake assembly to break off mid driving however. I had extra bearings and planned on replacing them anyhow but the process has now been expedited. This was what was left on the car side. It snapped the caliper in half as well. For reference this is the Front Driver Side on a 1984 944. My main question is, is there supposed to be threads here? Do I need to replace anything on the car side of things? Does anybody have a good video for this? Thank you!
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This is a well known weak point on the early 944's. The speedometer is cable driven off the left front wheel and that spindlle is hollow to allow the cable through. You will need a new spindle.
Also my speedometer stopped working a couple hours of driving before the wheel broke off, was that a warning sign? Also when I go to fix everything how do I hook up the speedo cable again?
Thank you! As a follow up to this question are 924/late 944 spindles compatible with the 84'
Late 944 are not compatible, compatible 944 is 83-early 85. Not sure on 944.
Purchasing a used '83 with hole drilled for speedometer cable could lead to same failure.
On my race car, I replaced my '83 left front spindle with a solid one without the center hole.
Someone must have come up with how to integrate an electric speedometer with a transmission that originally was not set up for electric speedometer.,Contact dcAuto Porsche, might have used components.
As noted, this is a classic weak point and failure mode. To get technical, it is a fatigue failure, which means that a lot of small shock loads (millions of them really) add up to one big failure.
Your cheapest solution will to be to find OEM donor parts, used. At a minimum, take the axle stub to a machine shop and have them test it for cracks. This will either be magnflux or dye penetrant.
If you can swing it, buy a new axle from Porsche. With the fresh metal, it will probably outlive the car.
Or upgrade to the later parts. There are multiple things that you have to change, including the wheels, so that is going to be expensive.
From the PET, plate 401-05, the part you need to buy (if you stay stock) is the steering knuckle 477 407 311 L
You might search Ebaymotors with that part number. Leave out the spaces.
I did like Tom with my race car and upgraded to a solid spindle, it also came with Rennline aluminium hubs as part of the package , don't remember
if all this was part of a later car ... my race car is an 83 but all the suspension bits are from later cars except for the front control arms.
I saw quite a few cars lose a wheel due to the infamous hollow spindle !
Thats scary!! All things considered it could have been worse. Take advice and take your time. I agree with Harvey if you buy used have it inspected by a reputable machine shop that can actually magflux Etc.
Late 944 are not compatible, compatible 944 is 83-early 85. Not sure on 944.
Purchasing a used '83 with hole drilled for speedometer cable could lead to same failure.
On my race car, I replaced my '83 left front spindle with a solid one without the center hole.
Someone must have come up with how to integrate an electric speedometer with a transmission that originally was not set up for electric speedometer.,Contact dcAuto Porsche, might have used components.
They make solid versions for Early set up?? Im concerned with this on my 931, so I have to stay with the early offset. and would rather not change to late struts.
They make solid versions for Early set up?? Im concerned with this on my 931, so I have to stay with the early offset. and would rather not change to late struts.
The solid left front spindle is sourced from a series 2 944 with the early offset, namely the 85/2 and 96 944 cars. Part number is 477 407 311 N
As you go through your options, keep in mind that the basic design is not flawed. It does represent the weakest link. The hollow nature of the axle is not a primary cause. The strength of a shaft in bending is most strongly determined by the material out on the outer circumference. The material at the middle of the shaft contributes almost nothing. The main culprets are high mileage on the car (and thus many millions of cycles of very low stress bending) and maybe damage to the face of the shaft, such as a nick or corrosion, which is where the crack initiates. If you can find a used part and get it crack checked, I would buy it and proceed with confidence.
The racers of course want to rule out anything that will bring their expensive track weekend to a premature conclusion so everything, including the hollow stub axle, gets upgraded. Racers don't even use their speedo
02-10-2022, 04:52 PM
Wheel Broke off while driving, trying to figure out what went wrong and how to fix it
