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Broken driveshaft-hoping to learn a lot from repair


RebekahsZ

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I broke my driveshaft last week at the track by twisting off the slip yoke.  The driveshaft was made by JCIs driveshaft builder.  It was made with what looks like zerk-ed spicer u-joints and a 5-1/2" standard 27 spline slip yoke.  This is the second driveshaft I have gotten from them, as the paint was cracking at the junction between the tube and the weld-on yoke on the first driveshaft.  JCI has been super nice and sold me the second driveshaft for only $100 in order to try to stand by the product.  Basically, I think we should consider the standard JCI driveshaft as good driveshafts for daily driver putting around, but not for sticky-tire repeated high rpm clutch dumping.  I have ordered a replacement yoke from Speedway motors just to get the car back on the road and ready for an autocross, but I am also working on having a custom "nitrous ready" driveshaft made by The Driveshaft Shop.  I hope to re-build my broken driveshaft with stronger u-joints and yokes to serve as a spare ( I'll probably  break a driveshaft again).

 

Some questions for the smart and experienced guys:

 

1) What are the relative strengths of some of the special yokes that are available:  chrome moly, "hardened", nitrited, forged?

 

2)  Should I be concerned that my u-joint caps seem to have rotated (spun) inside the holes in the driveshaft and in the yokes?  I originally thought my diff flange yoke was damaged because the paint is scratched on the u-joint cap, but when I look closer, the cap has rotated and so have the c-clips that hold them in place.

 

3) Is an aluminum shaft stronger than a steel one of the same diameter?

 

4) Are there any issues with the "quick release" style yokes that have bolt-on saddles for the u-joint on the slip yoke?

 

5) Where might I find a high strength yoke for the differential end of the shaft that will be compatable with the R200?

 

I have a HF press, so making some changes is no problem.

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I have an answer for question 5. Driveline service of Atlanta sold me a yoke for $50 and installed and balanced the shaft. It needed a combo U joint. It was just a camaro shaft that was shortened, then the rear joint was the combo joint with the beefed up flange installed. Their number is 678-813-1190 The guy I spoke to was very knowledgeable and had done this several times.

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There are at least three diff/pinion flanges for the R200. I have all three. The smallest one uses 5/16 bolts (that's what is on car now); the other two use 3/8 bolts. I put the two that use 3/8 bolts in a box with all my specs and measurements in a box to be mailed to The Driveshaft Shop tomorrow. I'll let them pick from thosr two flanges. Point of contact there is Frank. Will probably modify crossmember to make it easier to get a wrench on the driveshaft bolts.

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There are at least three diff/pinion flanges for the R200. I have all three. The smallest one uses 5/16 bolts (that's what is on car now); the other two use 3/8 bolts. I put the two that use 3/8 bolts in a box with all my specs and measurements in a box to be mailed to The Driveshaft Shop tomorrow. I'll let them pick from thosr two flanges. Point of contact there is Frank. Will probably modify crossmember to make it easier to get a wrench on the driveshaft bolts.

 

 

Re: Driveshaft bolt access

 

Try socket shoulder bolts (allen head) instead of threaded  bolts.  The socket shoulder bolts I use have long non-threaded shoulders so there are no threads between the mating surfaces of the flanges. I install them so that the head faces to the rear and the threaded part and nuts face the front of the car.  Much easier to access the head with an allen wrench in a tight space than common bolt heads. The  non-threaded shoulder part of the bolt handles shear loads better than a threaded bolt. Use with nylock nuts.

 

See picture of socket shoulder bolt. As can be seen the threaded part of the bolt is not subject to shearing where the flanges bolt together (the shoulder length is equal to the width of the two flanges when mated). There have been some discussions on this subject in the drivetrain forum etc..

post-178-0-16730600-1374514688_thumb.png

Edited by Miles
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There are at least three diff/pinion flanges for the R200. I have all three. The smallest one uses 5/16 bolts (that's what is on car now); the other two use 3/8 bolts.

Might not matter, but that would be 8 mm and 10 mm, most likely. 

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Yes, that is right. I can't tell an appreciable difference between 8mm and 5/16", and 10mm and 3/8" accept price and availability. I will look at the Allen head option. I just don't know how to put a torque wrench on a Allen wrench. What I COULD use is a box-end crows foot type socket.

 

QUESTION: are the flange junctions held together by the bolts in shear, or by the clamping force on the flanges achieved by the axial loading of the bolts? If it is the axial clamping force, then it is really only the axial strength of the fastener that matters....I'm thinking out loud, hoping for either confirmation or opposition trying to learn.

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Here is the link about using cap/shoulder bolts:  http://forums.hybridz.org/topic/81101-driveshaft-bolt-size/

 

Also, the JTR manual recommends using socket head bolts 8mm x 30mm long with self locking nuts because it is difficult to get a box wrench around hex head bolts. If you are not sure about the length, just mate the flanges together and measure the thickness across both flanges at the bolt holes. That will be the required length of the shoulder portion of the bolt.

 

Notice that all of the stock driveshaft and half-shaft bolts are soulder bolts.

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Make sure you get at least grade 8/10.9.  There has been debate over too hard being more susceptible to cracking. We have turnstiles at work that use grade 12.9 of these bolts that that shoulder is around 5/8" or so and the threaded parts is slightly smaller, maybe like 1/2" I have to easy out about 2-4 a year because they snap off at the transition.

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" I will look at the Allen head option. I just don't know how to put a torque wrench on a Allen wrench. What I COULD use is a box-end crows foot type socket."

 

 

Are you just overlooking a hex (Allen) bit socket?

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I'm out of town, but I will check the Allen socket option when I get home. In my feeble memory, I don't think there is room for a socket and a ratchet in there between either the flange/u-joint or the flange/diff. I will be using 10mm bolts since I will be using the larger flange. So far, I can only find bolts for which the shank is either too long or too short. If anybody else has a source, sound off.

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Do you have a link for a supplier that provides the shank (shoulder) length for their bolts? I haven't. I got my sat set from bolt depot-by trial and error (and lots of shipping charges) I found some 8mms that were perfect, but when I reordered in bulk (so I can do scheduled replacement), they had changed suppliers and while the bolts were the same diameter and length, the shoulder length had changed!

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I bought mine from Rainbow Fasteners in Sacramento.

 

Website: http://www.rainbowfasteners.com/search/

 

They had to special order  the bolts from Rainbow Fasteners as the  required shoulder length was not common. They  also supplied the nyloc nuts.

 

Before you order, carefully measure the width of the two flanges together to get the optimal length shoulder.

 

The bolts I  received had the threaded portion run out of threads just before they reached full torque so put a washer under the head and all was well (see threads pictured in above post).  That was four years ago and no problems have come up. 

 

There may be other fastener suppliers closer to you. I chose Rainbow because they were the only local supplier that could get the bolts with the correct shoulder length. As I recall I also researched MacMaster Carr and Grainger, but they could not supply the bolts.

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I'm out of town, but I will check the Allen socket option when I get home. In my feeble memory, I don't think there is room for a socket and a ratchet in there between either the flange/u-joint or the flange/diff. I will be using 10mm bolts since I will be using the larger flange. So far, I can only find bolts for which the shank is either too long or too short. If anybody else has a source, sound off.

 

Just hold the head with an Allen wrench while tightening the nut. Lots of room.

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OR, you could go to Courtesy Nissan and get the proper fasteners (bolts, nuts, washers) for your flange.  They used to be able to source them, at least.

 

Properly tightened, a bolted joint (like your driveshaft flange) should load the bolt in tension, not shear.  If your bolts are getting loaded in shear then the joint is either loose or is going to be shortly.  That said, the bolt in this case needs to be strong enough to survive the eventuality of a loose joint, at least for a while...

Edited by TimZ
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