Measuring for a new driveshaft - does this make sense? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RedRider · 01-05-2018, 04:44 PM

Just finished a lwb to swb conversion and I'm looking to replace my two piece driveshaft with a one piece. I need a measurement for the driveline shop.

A couple questions for the drive shaft pros here:

To get the best measurement, I was hoping to measure from u-joint to u-joint. I pulled the slip yolk off the old shaft and pressed it all the way into the transmission. Then I slid a rigid piece of cardboard through the middle of front yolk:

Moving back to the rear, I made a measurement from the base where the u-joint rides (bottom of the laser measure):

Three measurements from three spots on the cardboard were all the same; about 60 inches:

Does this approach makes sense? Is there a better way to measure what I need?

Second question, how does this measurement compare to those running a 1-piece drive shaft? This is a 1970 C-10 w/ a 350 and 350 tranny. Also, what diameter shaft should I expect?

geezer#99 · 01-05-2018, 05:01 PM

You need to pull the slip yoke out of the tranny about 1 inch and then measure from Center to Center on the u-joints.
You should also have your pinion angle set correctly to get an accurate measurement.

WB72 · 01-05-2018, 05:43 PM

agreed with the 1" slip yolk measurement. my driveshaft place told me 3/4", but what is 1/4" between friends?

bs46488 · 01-05-2018, 05:57 PM

My shop said pull the yoke out 3/4"

If I remember correctly it was around 58 3/4", but I have a TH400 trans in mine.

Rufas · 01-05-2018, 11:06 PM

Just ask the shop that is going to shorten your driveshaft and use their directions. Don't try to second guess.

boynton · 01-05-2018, 11:42 PM

Quote:

Originally Posted by WB72

agreed with the 1" slip yolk measurement. my driveshaft place told me 3/4", but what is 1/4" between friends?

2nd

NoNeck · 01-06-2018, 12:33 AM

3/4" works well. Make sure the measurements are taken at ride height.

POP

Jrainman · 01-06-2018, 11:41 AM

Quote:

Originally Posted by Rufas

Just ask the shop that is going to shorten your driveshaft and use their directions. Don't try to second guess.

Agree ask your drive line shop they all have there own beliefs, my shop uses 5/8 as play , And remember as No neck stated Take mesurement at ride height , My drive line shop tells me this is the Number one mistake made , you can not take your mesurement with the truck on jack stands it MUST BE ON THE GROUND . and the 60'' sounds to long , TH 350 and th 400 and 200 4 r trans from my experience were all under 60 inches.

RedRider · 01-06-2018, 01:58 PM

Quote:

Originally Posted by NoNeck

3/4" works well. Make sure the measurements are taken at ride height.

How about ride weight? Should I wait until the bed is on before I take measurements?

RedRider · 01-06-2018, 02:05 PM

Quote:

Originally Posted by NoNeck

3/4" works well. Make sure the measurements are taken at ride height.

How about ride weight? Should I wait until the bed is on before I take measurements?

geezer#99 · 01-06-2018, 03:47 PM

Quote:

Originally Posted by RedRider

How about ride weight? Should I wait until the bed is on before I take measurements?

Yes. Or add the same amount of weight over the axle. Barbell weights work good.

spoon3210 · 01-06-2018, 04:09 PM

I pulled my yoke out 3/4 measured from center of u joint to center of u joint and went to the wrecking yard. They usually have a huge pile of drive shafts. I found one in excellent condition. I painted it and put new u joints in it and for 80 bucks I was back in business. There is a u joint that uses early model chevy caps and later model chevy caps so everything fits perfectly. The newer caps are a little bigger.

Lee H · 01-06-2018, 07:11 PM

Most drive line shops have a tutorial on how to measure with a downloadable form to put all the measurements on.

Keith Seymore · 01-06-2018, 08:12 PM

Quote:

Originally Posted by Rufas

Just ask the shop that is going to shorten your driveshaft and use their directions. Don't try to second guess.

Quote:

Originally Posted by Jrainman

Agree ask your drive line shop they all have there own beliefs,

This.

I was a driveline development engineer for GM Truck, and my shop still sent me back to do the measurements "their way".

K

**70STOVEBOLT** · 01-06-2018, 09:08 PM

59.5 for my 70 C/10 with 402/TH400

Kuzican · 01-08-2018, 02:40 PM

https://www.southwestspeed.com/?sec=...hafts&ssub=!!2 1/2" Steel Driveshafts

RedRider · 01-08-2018, 03:37 PM

Quote:

Originally Posted by Kuzican

https://www.southwestspeed.com/?sec=...hafts&ssub=!!2 1/2" Steel Driveshafts

Cool! That's a lot cheaper than the $350 I was quoted. It seems like I'm doing all the technical work and carrying all the liability for a wrong measurement, so why not get one off the internet?

bs46488 · 01-08-2018, 06:13 PM

I bought my driveshaft from Tatton's in Utah off the internet.

Great customer service, fast turnaround and I think I paid around $250 for it to be shipped to my door.

RedRider · 02-01-2018, 04:09 PM

Quote:

Originally Posted by Kuzican

https://www.southwestspeed.com/?sec=...hafts&ssub=!!2 1/2" Steel Driveshafts

Had an interesting discussion with Southwest Speed trying to order my driveshaft. Nice guys but communication was sort of a challenge. Nevertheless, I gave them a rear pinion flange to transmission seal measurement (62") and they're sending me at 3" diameter, 59" driveshaft.

So if I was measuring 60" u-joint to u-joint and they're accounting for 1" of slip, then 59" should be correct right???

Kuzican · 02-01-2018, 04:29 PM

That's how I measured to, don't remember the numbers, didn't even ask them what size they were sending me, guess I trust people to much, it fit perfect.

RedRider · 02-01-2018, 05:11 PM

Quote:

Originally Posted by Kuzican

That's how I measured to, don't remember the numbers, didn't even ask them what size they were sending me, guess I trust people to much, it fit perfect.

That’s reassuring, fingers crossed.

fotyfobravo · 02-01-2018, 07:03 PM

My 70 GMC short bed had the 2 piece with a bearing at the joint. I replaced with a well balanced one piece and it made a huge difference. Much smoother.

**truckdude239** · 02-03-2018, 09:58 AM

When i had mine cut down i was told from the hard part of the seal to the center of the ujoint

Sleipnir · 02-05-2018, 10:46 AM

Guys I have a question about the Southwest speed drive shafts. Could I buy two of them to make a two piece drive shaft? The size I would need for a one piece is about 69 inches long and they dont make one that long.

RedRider · 02-05-2018, 12:43 PM

Quote:

Originally Posted by Sleipnir

Guys I have a question about the Southwest speed drive shafts. Could I buy two of them to make a two piece drive shaft? The size I would need for a one piece is about 69 inches long and they dont make one that long.

They can build whatever you want but they're only responsible for the build, not the application.

01-05-2018, 04:44 PM	#1
RedRider Registered User Join Date: Jan 2016 Location: Poway, CA Posts: 356	Measuring for a new driveshaft - does this make sense? Just finished a lwb to swb conversion and I'm looking to replace my two piece driveshaft with a one piece. I need a measurement for the driveline shop. A couple questions for the drive shaft pros here: To get the best measurement, I was hoping to measure from u-joint to u-joint. I pulled the slip yolk off the old shaft and pressed it all the way into the transmission. Then I slid a rigid piece of cardboard through the middle of front yolk: Moving back to the rear, I made a measurement from the base where the u-joint rides (bottom of the laser measure): Three measurements from three spots on the cardboard were all the same; about 60 inches: Does this approach makes sense? Is there a better way to measure what I need? Second question, how does this measurement compare to those running a 1-piece drive shaft? This is a 1970 C-10 w/ a 350 and 350 tranny. Also, what diameter shaft should I expect? __________________ 1970 C-10 "Old Yeller"

01-05-2018, 05:01 PM	#2
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,655	Re: Measuring for a new driveshaft - does this make sense? You need to pull the slip yoke out of the tranny about 1 inch and then measure from Center to Center on the u-joints. You should also have your pinion angle set correctly to get an accurate measurement.

01-05-2018, 05:43 PM	#3
WB72 Before and After Join Date: Feb 2000 Location: Leduc, Alberta CANADA Posts: 632	Re: Measuring for a new driveshaft - does this make sense? agreed with the 1" slip yolk measurement. my driveshaft place told me 3/4", but what is 1/4" between friends? __________________ Not Grandpa's C-20 anymore... 383 Stroker 425HP, 485Ft/Lbs Lowered 3.5" Front / 5" Rear 66,000 miles. Alberta, CANADA

01-05-2018, 05:57 PM	#4
bs46488 Registered User Join Date: May 2014 Location: San Diego, CA Posts: 547	Re: Measuring for a new driveshaft - does this make sense? My shop said pull the yoke out 3/4" If I remember correctly it was around 58 3/4", but I have a TH400 trans in mine. __________________ Project Engine Stand 1972 SWB conversion: http://67-72chevytrucks.com/vboard/s...d.php?t=673914 1970 Nova: http://67-72chevytrucks.com/vboard/s...d.php?t=708161

01-05-2018, 11:06 PM	#5
Rufas Registered User Join Date: May 2016 Location: Fort Mohave, AZ Posts: 367	Re: Measuring for a new driveshaft - does this make sense? Just ask the shop that is going to shorten your driveshaft and use their directions. Don't try to second guess. __________________ 1970 GMC 2500 700R Trans RideTech 4 link rear suspension - Air Bagged on all four corners 350 SBC 300hp Weiand Supercharger FiTech EFI

01-06-2018, 12:33 AM	#7
NoNeck Registered User Join Date: Jan 2011 Location: Chattanooga, TN Posts: 1,108	Re: Measuring for a new driveshaft - does this make sense? 3/4" works well. Make sure the measurements are taken at ride height. POP __________________ 2016 RAM Laramie HEMI 1966 Fairlane GT/A, 390/335 HP If it costs you a dollar to make a friend, KEEP THE DOLLAR. If it costs you a friend to make a dollar, KEEP THE FRIEND.

01-06-2018, 04:09 PM	#12
spoon3210 Registered User Join Date: Oct 2016 Location: fort worth texas Posts: 30	Re: Measuring for a new driveshaft - does this make sense? I pulled my yoke out 3/4 measured from center of u joint to center of u joint and went to the wrecking yard. They usually have a huge pile of drive shafts. I found one in excellent condition. I painted it and put new u joints in it and for 80 bucks I was back in business. There is a u joint that uses early model chevy caps and later model chevy caps so everything fits perfectly. The newer caps are a little bigger.

01-06-2018, 07:11 PM	#13
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,148	Re: Measuring for a new driveshaft - does this make sense? Most drive line shops have a tutorial on how to measure with a downloadable form to put all the measurements on. __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

01-06-2018, 09:08 PM	#15
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,307	Re: Measuring for a new driveshaft - does this make sense? 59.5 for my 70 C/10 with 402/TH400 __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Power windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear

01-08-2018, 02:40 PM	#16
Kuzican Registered User Join Date: Oct 2016 Location: Louisiana Posts: 37	Re: Measuring for a new driveshaft - does this make sense? https://www.southwestspeed.com/?sec=...hafts&ssub=!!2 1/2" Steel Driveshafts __________________ :

01-08-2018, 06:13 PM	#18
bs46488 Registered User Join Date: May 2014 Location: San Diego, CA Posts: 547	Re: Measuring for a new driveshaft - does this make sense? I bought my driveshaft from Tatton's in Utah off the internet. Great customer service, fast turnaround and I think I paid around $250 for it to be shipped to my door. __________________ Project Engine Stand 1972 SWB conversion: http://67-72chevytrucks.com/vboard/s...d.php?t=673914 1970 Nova: http://67-72chevytrucks.com/vboard/s...d.php?t=708161

02-01-2018, 04:29 PM	#20
Kuzican Registered User Join Date: Oct 2016 Location: Louisiana Posts: 37	Re: Measuring for a new driveshaft - does this make sense? That's how I measured to, don't remember the numbers, didn't even ask them what size they were sending me, guess I trust people to much, it fit perfect. __________________ :

02-01-2018, 07:03 PM	#22
fotyfobravo Registered User Join Date: Aug 2007 Location: Waleska, Ga Posts: 20	Re: Measuring for a new driveshaft - does this make sense? My 70 GMC short bed had the 2 piece with a bearing at the joint. I replaced with a well balanced one piece and it made a huge difference. Much smoother.

02-03-2018, 09:58 AM	#23
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,234	Re: Measuring for a new driveshaft - does this make sense? When i had mine cut down i was told from the hard part of the seal to the center of the ujoint __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

02-05-2018, 10:46 AM	#24
Sleipnir Registered User Join Date: Oct 2017 Location: Seguin, TX Posts: 89	Re: Measuring for a new driveshaft - does this make sense? Guys I have a question about the Southwest speed drive shafts. Could I buy two of them to make a two piece drive shaft? The size I would need for a one piece is about 69 inches long and they dont make one that long. __________________ 67 C10 "Big Red"



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