Main Steering Shaft Failure

Technical and Repair Discussions

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PostPosted: Mon Jul 09, 2018 9:26 am
We were at a race this weekend in Colorado, where the main steering shaft of one of the cars failed.We have never expeirienced this on our cars, but this an item that we routinely replace before it breaks. Every race car has points of weekness and this is one of them. You don't want this to happen to you. The point of contention is where the short steering shaft is attached to the main long shaft with two bolts.

The main longer shaft cracks at that point. If you are lucky to notice it before it fails is one thing, but that doesn't happen in most cases. Pay the extra 100 bucks or so to avoid a much bigger problem. Very easy to replace and the peice of mind is worth the price. It's not easy to detect before it is too late.


Pat
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PostPosted: Tue Jul 10, 2018 4:45 pm
I believe there is a new, longer main steering shaft (the solid one that connects to the steering rack) that may help. Most of the failures we've seen have been in the hollow side (steering wheel end), but given the age of the some the cars it may not be a bad idea to replace both, especially if there's been any significant front end crashes that could put significant torque on the steering shaft components.
Bob Breton - SRF 51 - San Francisco Region

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PostPosted: Wed Jul 11, 2018 11:41 am
The last one I replaced is considerably long. They impounded all the cars after the failure. The main longer shaft, which fits into the rack itself, failed in the hollow upper section where it is hollow and the steering wheel shaft fits inside of. The failure was between the two bolts that attach the shorter steering shaft to the main longer shaft. There are several adjustment holes in the main shaft, but the failure was of course, where the bolts attach the shafts together. The main long shaft it hollow om my car as was on the others I looked at.


Pat
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PostPosted: Wed Jul 11, 2018 10:05 pm
I think the spot you’re describing takes the brunt of the torque in the shaft assembly upon any sideways or wheel-to-wheel impact. I got hit in the front wheel at low speed after spinning in the rain and the whole shaft twisted, but the worst of it was around the bolts. Definitely something to look at after any hit to the front wheels (also check the rack mounts in a moderate+ impact).
____________
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PostPosted: Thu Jul 12, 2018 4:08 pm
Good points Denny

I am wondering if we won't see more unusual failures with the increase in grip with our tires? It would seem likely. Steering and suspension parts could be victims. For years, I use to replace regularly the lower studs that had the full circular notched slotted grooves. Once they changed this to a single groove, I haven't been doing that. Has anyone ever seen these new studs fail?

The only time I have replaced these now, is if there was a hit directly to the wheel.


Got to thinking about how they checked the shaft at impound. They only looked at the top of the shaft and not the bottom.

Pat
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PostPosted: Fri Jul 13, 2018 1:24 am
I think the long shaft Pat is referring to is the lower part of that goes from the bearing to the rack. The long shaft Bob is referring to the the one that the steering wheel attaches to. I'm told there is a newer (long) version of the upper shaft.
When a driver likes the wheel in his chest, the original upper shaft ends up with bolts through the upper two holes on the lower shaft.
I think having the bolts too close together concentrates all the force is too small an area on the lower (hollow) shaft. If you can spread the bolts more (using a longer upper shaft), spreads it out more.
Dave Harriman
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PostPosted: Thu Jul 19, 2018 1:40 pm
just a note.

It may be worth the time to cover the bolt area of the shaft with some impact resistant material. I received a wound on my leg that required 4 stitches from hitting one of those bolts.

Good news, your leg breaks the shaft before the shaft breaks your leg.

I don't want to talk about how I know this! :roll:
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PostPosted: Mon Jul 23, 2018 4:15 am
There are two versions of the upper steering wheel shaft, old and new. The older version is about 16” long and can crack and fail. The upper shaft that connects to the steering wheel is short and doesn’t go very deep into the lower tube. After time the lower tube can crack and loss of steering control can result. The new upper steering shaft is longer, about 23” and goes deep into the tube eliminating the possibility of failure. It isn’t fun if the steering wheel comes loose while on track as it did to one our drivers going into turn 9 at Laguna Seca. If you have the older short upper shaft you should consider replacing it with the new one that is longer. If you don’t replace it at least check for cracks regularly. Bruce @ AccelRaceTek
Attachments
Photo Steering Shafts LR.jpg
Old and New Shaft
Photo Steering Shafts LR.jpg (47.5 KiB) Viewed 483 times
Photo Steering crack 2018-04-128.jpg
Crack in Lower Shaft
Photo Steering crack 2018-04-128.jpg (63.84 KiB) Viewed 483 times
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PostPosted: Mon Jul 23, 2018 9:19 pm
Thanks for that info Bruce. I must have missed that item in our monthly email update newsletter from Enterprises... :roll:
Mark Fick
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PostPosted: Wed Jul 25, 2018 4:35 pm
Thanks for the heads up and the photos.
Les Kurz
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