Steering Shaft U-Joint Freeplay?

[OK-944]

I’m in a bit of a sticky-wicket with a Porsche specialist repair shop - which has refused to do a four-wheel alignment based on the small amount of freeplay exhibited by the lower u-joint of my car’s steering shaft. The tech explained that the needle bearings within the joint had likely worn, which could create a potentially dangerous (even catastrophic) situation.

So…I purchased another (used) steering shaft - which also exhibits basically the same amount of freeplay in the same (lower) u-joint, plus a bit of the same in the upper joint as well.

Thing is, the actual freeplay is present as a slight “up and down” or “sliding” motion along the long orientations of each of the small shafts within these u-joints, while no amount of back and forth, rotational force causes any freeplay whatsoever.

Thinking about this further, I’d guess that a certain amount of u-joint freeplay, so long as this is only exhibited along the same orientation as the needle bearings themselves, would either need to be spec’d in during manufacture, and/or as a maximum allowable tolerance over time, and that so long as no freeplay exists axially to the orientation of the needle bearings (which would manifest as rotational freeplay), these joints would remain perfectly functional and safe.

My cynical self is feeling a bit put off by the Porsche repair technician - as he had a few bigger fish (newer/fancier P-cars with more lucrative issues) to fry, lined up that morning - and possibly used his “discovery” of my supposed steering shaft issue as an excuse to blow me off. My problem now is finding another shop within any sort of reasonable driving distance which is actually equipped to align my wheels.

At any rate…any further thoughts about the above? Thanks!

[walfreyydo]

Get another u-joint without freeplay, Im sure there are still used ones out there that are in good condition - contact plyhammers and Im sure he will get you one that is solid... dont buy from ebay or untrusted parts reseller.

The freeplay in the u-joint will make it difficult/impossible to align (also a safety issue). This is probably why you are getting a cold shoulder from the shop. Its a liability thing and they cant align the car if your steering components are worn anyways because the laser reading will shift due to the slight play in your steering.

The tricky thing with doing alignment on these cars is the rear toe and camber need to be set together, with a special tool (although cheap). I wouldnt say it *must* be aligned by a shop familiar with 944's but it probably doesn't hurt. I would recommend that you purchase the tool (https://www.pelicanparts.com/More_Info/RENS98051P.htm?pn=REN-S-98051P&bc=c&SVSVSI=0763) if you dont have it already and make sure the shop doing the alignment has the tool and knows how to use it. This might be another reason why you are getting weird vibes from the shop-rear alignment on these cars can be a pain in the ass (although not a valid reason to refuse work).

I get mine aligned at a small town local non-porsche shop, and I showed the tech the tool, explained how the rear alignment works (how toe and camber need to be adjusted together) and he was easily able to figure it out and get it aligned. They even set my alignment per the specs I wanted (increased negative camber) for autox/track driving. These types of places are great to work with if you build a relationship with them.

Having some knowledge yourself on some of the tricks on these cars can go a long way to getting it done right, especially if the person working on it might be somewhat unfamilar to the specific suspension geometry.

[Monkey Wrench]

some shops employ a service manager who tends to stand between the customer and the mechanic, so the problems get reported to him by you and then relayed to the mechanic with potential loss of detail, opportunity for questions , or decision making ability. Its so you arent; slowing down the mechanic with conversation. a smaller shop might be easier to communicate directly with than a dealership. I'd prefer that if you can find it. maybe a specialized alignment shop would be more knowledgeable on allotment than a general mechanic?

[Monkey Wrench]

Ive seen the needle bearing all fall out of badly abused Uoints, not on the steering column and from what Ive seen it did not became detached , but of course had a ton of freeplay.

perhaps if the part is expensive or scarce you could find one at a wrecker that would work? if the shaft is splined then the splines must fit of course. any car has them so perhaps there are other cars that use the same part?

I once had a VW bug and the steering shook like crazy , the whole front end had been seriously abused. i attempted to adjust the freeplay in the steering box and thought I had it ok..

later on, The ( ball bearings) in the steering box fell out of their cage resulting in the worm gear coming detached. I was on a bridge that had a curve in it on the inside lane. my steering locked, good thing no one was in the outside lane, but I was scared that I would then go into oncoming traffic. My steering wheel would not turn at all ..
what I did was turn slightly TOWARDS the oncoming lane and then back and luckily a bearing moved, dislodged from its stuck position, and the box unlocked somewhat. by the time I got off the bridge I could spin the steering wheel , it had become completely detached. that could easily have killed me.

I'd correct this because it will be annoying and you want to remove that freeplay.
if you look closely at the bearing cage you might find bearing numbers stamped in. If you find that you can go to a bearing retailer ( or online search engine) with the bearing number and perhaps just get a new needle bearing. You may need a special puller or access to a hydraulic press of some sort to extract it. If stuck it may be possible to use a dremil to cut the bearing up and remove it in pieces, then install a new one.

i dont know if that needle bearing is specific to Porsche but in general machine or car makers buy standardized bearings from bearing companies. Actually making bearings requires very specific machinery.
OT , but Volvo means " I roll " in Swedish , they started as a bearing manufacturer.

I have a tool that I made somewhere and it is for removing a needle bearing from a blind hole, its like bolt with a tapered end and the rest is split so it can expand. it fits inside the bore. wen you turn the bolt it expands and grabs the bearing and the bolt reaches the bottom of the blind hole and then it presses the bearing out as you continue turning. you might try snap-on for a tool like that. i copied someone else's tool and made my own.

It would be standard process to just change the U joint and that may come along with the aluminum casting. , like a U joint in a driveshaft the X shaped part has ends that are fitted to the bearing and it is an assembly. those pins are hardened steel and precision fitted. you may have ridges and roughness on that if it's far gone.

someone with one of those out of the car might look for a bearing number? Most will suggest replacing it as a unit. I'd check the price and try to replace it as an assembly ( as normal) if you can.


some mechanics may try such a repair but most will just replace the part and the part may not be worth time messing about.


any grit in those bearings will kill them in short order, I dont think they see the sort of wear a U joint in a drive train does. If you ever disassemble one be careful about keeping things clean. I thinkits unlikely anyone will take their steering columb apart to clean and re-grease them unless they are really into a serious restoration. likely they get dry of lube and then fail in time.

sometimes you can spot problems like that visually, like if you notice some rust near it, this is caused by tiny fragments of metal about the area. even on indoor machines that never see the weather or humidity I'll sometimes spot bad bearings like that by rust debris that is nearby. Just a thing to watch for. i always thought it unusual that the rust would appear from the fragments , even though there is no water or other rust evidence nearby.

my 66 Volvo has a rubber doughnut that is bolted to both portions instead of a U-joint. I think the idea is that the rubber can break in a crash.

[OK-944]

What I'm saying is that the U-joint in question is actually fine...and that the nature of the freeplay is analogous to runout (back and forth movement) in a driveshaft - a specified amount of which is actually essential to the health of our engines.

It is the presence of freeplay which is lateral to the orientation of the shaft (which in an engines driveshaft would indicate bearing wear) which can be lethal.

My understanding about the needle bearing races in U-joints is that these are capped at each end at the factory and thus these are sealed bearings and cannot be serviced (although I've heard something about folks rebuilding them?), and that over time these caps can become compromised and leak - which can facilitate corrosion of the needle bearings, possibly leading to a catastrophic failure of the entire joint.

But again, in the case of the steering shaft U-joints on my car, they're giving no indication that their U-joints are anything but functional and safe. Still, I'm curious if Porsche has specified a maximum allowable amount of the "good" freeplay in these joints, just as they specify a maximum amount of end-play for the engine's drive-shaft.

[OK-944]

(double-post)

[944 Ecology]

https://www.jmgshop.com/steering-shaft-rebuild-service-422-p.asp

[jcommin]

I have an 83 with manual steering. Several years ago I needed to replace the steering shaft. The technician showed me the play from t he bearings. The OE manual shaft is is very difficult to get, so the options are re-build or get an aftermarket shaft. I chose the later because I didn't trust the quality of the needle bearings used.

I know this shaft is pricey, but the shaft lasted well over 30 yrs before I replaced it. The new shaft will outlast me.

[Monkey Wrench]

drivetrain U joints used in other cars so sometimes have a grease nipple, Ive noticed on newer ones there is a lump in the casting where the nipple would go but it's not drilled and no nipple. by the time you take apart a U joint to fix it you might as well renew, they usually are not that expensive.

since this is a little U joint, not a drive train one, you might consider using a small U joint that would be used to couple a smaller motor in machinery. here's some examples . keep in mind it may be designed to let the steering column move or shorten in an accident so you dont want to eliminate that safety feature.

https://www.mcmaster.com/products/u-joints/u-joint-type~single/

there are also spider couplings, which are somewhat similar but no bearings, just a rubber piece between.
https://www.mcmaster.com/products/spider-couplings/

common to use such a coupling between a motor and driven part to make alignment of the shaft less critical. on a big motor that alignment is set up with face and rim procedures using dial indicators to adjust alignment so the drive line is in near perfect alignment. some of those couplings allow some tolerance but some may not be designed to flex very much. There are a lot of different ones for different applications.

of course you dont wan to mess with geometry and safety but perhaps some of the small U-joints would have the same dimension U joint and hence be a parts source.

some of the newer cars use a servo motor and that replaces a hydraulic system for power steering. I had a demo from a guy that converted a Volvo P1800 using such parts from a newer vehicle. he had a knob to adjust the amount of "help" that the servo motor gives the driver in turning the steering wheel. I like the simplicity of manual steering but he wanted to add power steering and fit it in quite well so nothing odd was visible. the steering is still mechanically coupled in case of failure of the motor. I thought t was kind of a slick idea, but I prefer the old armstrong system myself.