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When I was replacing my center support bearing i noticed that the splines on the transmission side are showing some wear.  The differential side doesn't look as bad but i haven't taken one apart in years.  I can't feel any slop when the two are mated.

 

Do I need to worry about the condition of the two splined parts?  Is there anything I can do to help make up for the wear of the splines?

DriveShaft Splines 5-speed (2).jpg

DriveShaft Splines 5-speed (5).jpg

DriveShaft Splines 5-speed (6).jpg

Edited by halboyles

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Hmmm- did you ever notice any noises transitioning on or off- throttle?

 

I had one chew itself up that way, but the nut was finger- tight when I took it apart.

It had been making a <ping> for a while, and I was lazy about checking it.....

 

If it was mine, I'd be tempted to put it all back together, torque the ever- lovin' snot out of it,

and then check it every so often to make sure it stayed tight.

You could TRY some loctite sleeve retainer on the splines, but don't get it on the threads-

it holds so well that you won't be able to tell when the nut is losing clamp on the u- joint flange,

and then it'll chow itself up.

 

Do make sure the nut's not close to bottoming out on the root of the threads- it needs to be

able to really clamp the u- joint flange.

 

hth

t

 

Edited by TobyB

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There really wasn't any noises during throttle transition.  And i can't make the joint move when holding the front end in a vise.  If i hadn't been replacing the CSB i wouldn't have found the damage.

 

i will take your advice and torque "the ever-lovin' snot out of it" (that's about exactly the length of the wrench plus a three foot pipe right?)  I think i will put some Loctite 660 on just for some extra insurance.  Thanks for the tip about not getting it on the nut threads.

 

By the way,  to get that kind of torque how do you recommend holding the DS in the vise:  by the input flange, on the DS just behind the flange, asking your friendly WWF wrestler to hold on to it, ...

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Yours look good compared to the splines on my 235 CR 5-speed, but they can be repaired...

 

Mark92131

IMG_0896.JPG

IMG_1091.JPG

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10 minutes ago, halboyles said:

Yikes!  How did you have those splines repaired?  They look like they are new.

 

There are several ways, (spray welding), but basically they are re-welded and re-cut.

 

Mark92131

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As to holding it for torquing, I have a 2' section of pipe welded to a flat plate that I've drilled a bunch of holes in.

 

I get someone to stand on the driveshaft with that 'universal wrench' bolted to the end, and then torque

against them.  Hopefully, they are very, very large.  Usually, we end up balancing against each other, which

amounts to at least 3-400 ft- lbs.  

 

Looking at those splines again, they don't look so bad.  They are formed by distorting the bar stock, not by grinding

(like Mark's are) so they, by nature, look very odd.  It makes them very strong, though.  I think you'll be OK if you get them

nice and tight.

 

hth

t

 

 

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42 minutes ago, TobyB said:

They are formed by distorting the bar stock, not by grinding

 

damn... that wold be some TOUGH tooling.

 

or is it formed hot? ...probably so

Edited by zinz

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So its the Sumo wrestler method rather than the WWF wrestler method that does the trick.  Luckily i do know some Sumo wrestlers so i am going to fabricate your clever flange wrench tool and invite a jonokuchi (lowest level Sumo) over for some yakimeshi and torquing.

 

Thanks Toby for looking at the splines again.  We will be driving this '76 out to the O'fest next month and I feel much better about our 4000 mile trip now.

 

Also, i have to agree with "zinz" about the spline forming technique.  But now I see how the splines would normally looked a little "smashed" during the process.  I found a rather good description and video on the process and it is indeed amazing:   http://www.ernst-grob.com/en/processes/cold-forming-solid-materials/index.html

 

 

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Yeah, they'd be done cold.  But pre heat- treat.

The BMW driveshaft changed a LOT from 1972 to 1982...  and got super high- tech.  And failed a LOT less by the end of it!

 

The yokes are spin- welded on, too.

 

Hal, you have tons of spline left- even if it DID start moving around, I suspect you'd get much farther than 4k miles on that, if you keep an eye on it.

 

And again, keep the loctite OFF the nut- you want to be able to tell if it loosens.  Loctite isn't going to keep it from wearing itself loose, which is the (very low) danger here.

 

hth

 

t

 

Edited by TobyB

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Toby,  thank you for your time and expertise.  We'll torque eternally-devoted mucous out of the drive shaft nut, keep an eye on it, and be sure to stay below the speed limit during the Laguna Seca Driving School.

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