Driveshaft length question.

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cudaspaz

cudaspaz

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I got my driveshaft back from the shop.

When I initially called them they wanted such and such measurements.
I gave them the measurements they wanted but then when I got there they wanted to know how much of the splined output shaft stuck out of the rear of the case.

I remembered it was about 1/2 inch to 1 inch.

Okay cool he says.

When I installed the shaft the front yoke bottomed out into the output shaft and I barely had enough room to squeeze the rear U-joint onto the rear yoke.

I really had to fight it and hold my tounge just right to get enough room to get the surfaces lined up but I got it in just barely.

My question is: Is my driveshaft too long, and will it bump up against the tranny when the rear settles/jounces during driving and suspension movement?

It seems like I should have more play than that.

I also have the front seal of the input shaft leaking, could this be that when I drove the car I heard a tapping sound when I let off the gas.

It could be unrelated but I have this scenario going on in my head because i did hear a strange noise the first time i drove it, but not the second time.

keep in mind both trips were only about 1/4 mile each.
 
According to a book I have here your driveshaft length should be 48.6 from center to center of u-joints. That`s for a small block 4spd. with 8.75 rear end in Mopar A-bodies with 109 wheelbase.
 
Spaz........ Don't drive it like that..........

You need at least 1" from the edge of the tailshaft housing for that thing to have enough play in it when you torque or move the driveline angles due to various driving conditions..........it has to have some play.......

I just did one that had too much sticking out of the tailshaft housing......Had about 2-1/4........REALLY sloppy, and it played into ruining the u-joints and tail bearing........I had it shortened, and it now has a full 1" out of the tail......Could have had an inch and a quarter to half, BUT the inch is good.......

If yours is as tight as you say, there's gonna be trouble at some point......you're gonna need some surplus for normal play and it's gonna jam that tail.....Lord only knows what could be the result if it's not corrected.

Be careful............Just my 4 cents. 8)
 
I intend to take it to the driveshaft shop and have it shortened.

I wonder if that expained the tapping noise I heard during a very short test drive from the rear when I let off the gas in third gear.

It did not do it the second short test drive but I did not get into third gear the second time.

Thanks for the info guys!!!!!!!!
 
Shove the front u joint into the rear of the tranny and measure from the center of the u joint at the rear of the tranny to the center of the rear u joint on the rear end and subtract .75 and your good to go. Sounds like your too tight.
 
Yep.

I disconnected the rear of the shaft while the wheels were on the ground and pushed the yoke forward.
It only traveled about a half inch.

My driveshaft is exactly 49 inches from center u-joint to center u- joint.

I think my slip yoke is too long.

The yoke has 5" of useable surface area before it bevels into the rear of the yoke.

I have about 1-3/4" of yoke sticking out while the wheels are on the ground.

I now have a driveshaft that is too long because the driveshaft shop asked for specific measurements that were given to them, now I have fluid leaking from the front of the transmission, not to mention the paranoia that I may have really fokked something up because I again, listened to a professional that's supposed to know what the hell they are doing.

I swear, I can't freaking win sometimes.

I'm just in a sour mood about the car and my Daughter pulled a stupid *** stunt tonight so I 'm even more pissed off.
 
From my own past observations, the engine and/or tranny mounts take a beating and worst case it could potentially shove things around inside the tranny itself. The shop owner and I almost came to blows on that one, but he was signing the paychecks.
 
it sounds like the driveshaft shop didnt give you what you asked for. If so, they can pay for the fix. I agree with above, shove the yoke in the tranny all the way then pull out about an inch to 1.5 and measure from there. I had an engine shop do some work on a block I didnt ask for, irritated the crap out of me.
 
So.....Smallblock says .75" to take out and Baxter61 says 1.5" to take out. Which would it be?
I have to shorten mine also. Gotta 440 and 8 3/4 in a 69 Cuda.
 
Okay guys, just to clear things up.

I have not posted my results, but I did have my driveshaft shortened another 1.5 inches.
This does the trick and I will have plenty of forward freeplay.

The main problem was the initial measurements were correct but another, longer front slip yoke was put on thus throwing the initial measurements out the window.
The driveshaft shop did not take the longer yoke into consideration and the end result was the driveshaft was too long now, but it's fine now since they shortened it again.

I was told that with the car on the ground you should have 1.5 to 2" of forward play with the slip yoke going into the tranny before it bottoms out in the tailshaft.
 
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