Front Drive Shaft grrrrrrrrr findings so far. . (1 Viewer)

concretejungle

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Had time to take my driveshaft to the local driveshaft shop. Pretty cool that as i walked in, there was a cruiserhead that i had wheeled with in Daton several years ago. Anyways, back on track. . . so the shop owner came out and rolled under my truck, measured the distance from my output flange on the diff to the output flange on my center diff. Then he measured my drive shaft length while it was fully compressed. Then he said "well, your problem is that you are driving around on a fully compressed drive shaft" :confused: He said he will shorten my driveshaft by 1 inch, balance it and then it should be fine. So, i'll let you know when i go and pick it up and put it in if that was the fix.

I was trying to figure out what would cause this distance to shorten?
 

sleeoffroad

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Uhm, did you have those measurements? I can not see how that distance can get shorter with a 2.5" lift. I am trying to see if the caster plates would do that, but I can not see that either.
 

concretejungle

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sleeoffroad said:
Uhm, did you have those measurements? I can not see how that distance can get shorter with a 2.5" lift. I am trying to see if the caster plates would do that, but I can not see that either.

I was wondering the same damn thing! I asked him that same question, then he asked me what did i do for my castor angle after the lift, i pointed at the plates and he said that could have done it.

I do not have the measurements. If i remember correctly he measured 30 1/8 inches flange to flange, then stood my driveshaft up on the concrete, compressed it and then measured it. I think it said it was 30 inches.
 

sleeoffroad

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Are you sure that you did not have too much grease in the shaft and when you compressed it, it bottomed out on the grease and not the shaft itself?
 

concretejungle

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sleeoffroad said:
Are you sure that you did not have too much grease in the shaft and when you compressed it, it bottomed out on the grease and not the shaft itself?

Really sure. He showed me and i pressed it also. You could feel it hit, not squish. Then we pulled it out to make sure it wasn't packed with grease, and it wasn't.
 
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That's damn near impossible, unless your transfer moved forward or your axle moved back, or you have the rear driveshaft installed in the front. I'd make double sure of that, then stick a long *something* in the slip yoke and make absolutely sure it's not grease in there. The thing didn't grow longer.
Cutting it seems like supreme folly.

-Spike
 

concretejungle

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Spike, i was dumbfounded when he said that. I kinda looked at him puzzled. He measured 3 times, because i asked if he was positive. I felt a little comforted when the fella cruiserhead was there and he assured me the guy knows his stuff. I guess we'll see.
 
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I've got the GRRRRR too, and I pulled the shaft and ordered new u-joints last week. I'll give you a report asap if that fixes it. Hopefully in time to save your driveshaft.

I'd definitely get a second opinion before I let somebody cut MY shaft if it's not too late.
 
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Before he cuts that thing, check this: I just installed Slee's 6" lift, which gave me a new front drive shaft. I just looked at my old shaft. It measures approximately 30.5 inches compressed. I noticed that when fully compressed, the slip yoke seal (female side) pretty much bottoms out on the collar of the male u-joint end, meaning that cutting the splined shaft will not shorten the overall compressed length of the driveshaft. If your mechanic is suggesting cutting the splined shaft, you should stop him. Make sure the seal collar is bottomed out on the u-joint collar, if it's not, your slip joint is not fully compressed- for whatever reason. I'd still suspect grease packed in there- with a good tight fit, it will feel like trying to compress steel.

-Spike

P.S. As I'm sure you know, raising the vehicle should have lengthened the distance between the t-case and the axle flange, even considering correction for caster. Something ain't right in Denmark.

-S.
 

concretejungle

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Spike, i'm totally feelin' what you are saying. He is a driveshaft guy, that's all he does, so he should know the right way to shorten one. He has thousands of driveshafts laying in the shop. Couple of big-rig driveshafts laying there. I couldn't even pick those bad boys up.

He called today and said it was ready. So, when i get it tomorrow, i'm going to have him put it in and put my truck on the lift that way i will know that when the truck suspension is sagging the shaft aint coming apart and pogo-sticking into my T-case. Then i'll drive it and see if it's cured.

I'll post back.
 
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30 1/8"? Mine measures 31 3/4" inches flange to flange, that's a lot of movement, something is wrong. With the radius arms the flange to flange measurement stays relatively constant with lift and the Slee brackets use the stock rear bushing bolt location. I don't see how your setup can account for that much movement? Are the motor mounts broken? Axle, arms, something bent? What is the rear shaft flange to flange measurement? Mine is 37 3/4".
 

Onur

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CJ--

Cutting drive shafts seems like some thing you should get a second (or a third, fourth, fifth and sixth opinion on).

You're riding on OEM shafts, right?

Very puzzling...

Let us know what happens...
Good luck.
-onur
 
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Sorry to hear you've already done u-joints. I was hoping that was the fix for sure. Remove the grease fitting on shaft itself if you're not sure if it's compressed all the way or not. Just measured mine... it's about 30.6 fully compressed. The distance from flange to flange (with 850's and an ARB) is about 31.6 (shaft not installed).

Hope that works for you... sort of.
 

Romer

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Try loosening the zirc on the driveshaft and then fully compress it. I did this after I cleaned the crap out and it made a bif difference and then I tightned it back up. Kind of like bleeding the air pockets out.
 
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Hmmm... I haven't mapped out the geometry of it, but could raising the rear more than the front (no spacers, right?) shorten the flange to flange distance in the front?
 

concretejungle

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I don't see how raising the truck could make the distance shorter, period. I'm going over today at lunch to get it. I'll post back up this evening with results.
 

sleeoffroad

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If you look at the arc that the drive shaft travels, vs the arc that the front axle travels you will see how that works. As the axle compresses it moves forward, and the transfercase stays stationary, so the driveshaft has to expand when the truck is compressed.

Something does not make sense. I measured a truck with 2.5" of lift. The bottom flange to flange measurement (weight of the truck on the wheels) are 31.75" and the measurement top to top of flange is 32.75". That with a shaft that should be in the 30/30.5" range compressed works fine. I can not see how adding the caster plates can rotate the pinion back that far? My gut feeling is still that the shaft is not fully compressed when you measured it.

The ring (with the wiper/seal) on the sleeve will bottom out on the flange on the yoke side. Normally since the drivehaft has about 1" of exposed slip joint all the time, this area builds up withe crud and rust and it is possible that the wiper/seal did not want to move past this point, unless you took some emery cloth and cleaned up that area.
 

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