Driveshaft too short after lift?

Daveid01 · Sep 7, 2024

My son has a 1973 k2500 truck that he just added a 4" lift kit to. Afterwards we noticed a drip coming from the driveshaft. Is this driveshaft now too short due to the lift kit? If so, do I need a need driveshaft or can it be modified?

Thank you in advance for the help

Rusty Nail · Sep 7, 2024

Lol wouldnt think it would start leaking while shading the lawn though.
But yeap. 4 inch is sometimes too much without supporting mods.
I've got nothing further to add.
Bet somebody else will.

PrairieDrifter · Sep 7, 2024

It'll work for the meantime. But if you don't want a huge hole in your floor, and the wiring and brake lines all mangled. I would suggest lengthening it. Probably about an inch and half, but you'll need to measure.

Front driveshafts are more forgiving, because you aren't driving highway in 4wd. It looks like your splines are just about to start showing. So any kind of jumping action could pull it apart, even the right axle droop and driveshaft rpm.

When those style shafts slip apart they like to ruin the transfer case and rear end too. As well as the other stuff mentioned before.

A driveshaft shop can lengthen that no problem. The splines may need rebuilt too.

Zelph · Sep 7, 2024

Use this chart and instructions. Take it to your local drive line shop and have them lengthen and balance.

Dennys Driveshaft How to Measure Correctly Diagram B

Dennys Driveshaft has the best measuring diagrams in the business. It easy to get a driveshaft that fits perfectly. Printable sheets for a variety of auto and truck applications.

www.dennysdriveshaft.com

Grit dog · Sep 8, 2024

Agree with above, although 4” lift and K20 “should” be ok as is. At least comparing to my truck.
But your pic, it appears you’re focusing on the grease splatter where the 2 halves connect? That can’t drip (oil).

Rickf · Sep 8, 2024

Before you have the driveshaft lengthened take the cap off the end of the yoke and check the condition of the seal/packing. If needed change the seal/packing clean the old grease out and pump some new grease in until it leaks out the weep hole near the u-joint. Then have the driveshaft lengthened.

bucket · Sep 8, 2024

Grit dog said:
Agree with above, although 4” lift and K20 “should” be ok as is. At least comparing to my truck.
But your pic, it appears you’re focusing on the grease splatter where the 2 halves connect? That can’t drip (oil).

That's what I'm seeing too. The slip portion of the shaft is now extended further than it was, which exposed an area that was coated in grease. After being driven, the grease of course was flung from the shaft.

I'd pull the shaft, with the rear axle hanging, to check for sufficient spline engagement.

Daveid01 · Sep 8, 2024

Thank you guys for all the info and help. I noticed that it couldn't drip after I posted but my son kept talking about it dripping. (The drip is from the transfer case)
Sounds like I know how to move forward on this. Much appreciated! It wasn't something we thought about until after the lift kit was installed.
Thanks again!

Dixie Pride · Sep 9, 2024

Have a 1985 3/4 ton longbed with a 5" front lift for 40 years,it has been airborn before and no issues.Most folks agree if you see no spline you are ok .

Grit dog · Sep 9, 2024

Dixie Pride said:
Have a 1985 3/4 ton longbed with a 5" front lift for 40 years,it has been airborn before and no issues.Most folks agree if you see no spline you are ok .

Good to know. Since I’ve put another 1” of lift under the K20 (5” total lift) I’ve wondered how close it is or if the front ds is too short. We just stuck the 2 halves back together after slapping in the 1” zero rates.

Driveshaft too short after lift?

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