Measuring for new driveshaft - not fully loaded car (rolling chassis only)

Jack Parmentier · Jan 4, 2021

Restoring my '69 Charger from scratch... I have only the rolling chassis on the ground ( 440 engine, 727 trans, ESPO XD suspension, 8 3/4 rear-axle installed -- no doors, hood, trunk, glass, etc.. ) and wanting to measure for a new Strange U1699 3" driveshaft (1350 U-joints)

But from what I am told, I need to have a fully loaded car before I can make this measurement. All weight added... As you can see, the rear end of car is off the ground quite a bit now. ( Note -- the lift is not holding up the car )

Anyway I can cheat and load the car somehow with weight to measure ? I'm wanting to get the driveshaft installed so I can put in my TTI exhaust ... seems you need the driveshaft installed first before putting in the exhaust, to make sure no interference issues.

Any hints / ideas... ?

Thanks,
Jack

6PKRTSE · Jan 4, 2021

Not easily. I know my car came down 2-1/2"-3" while assembling it and and weight.

sam dupont · Jan 4, 2021

Five or six garbage cans filled with water?

1 Wild R/T · Jan 4, 2021

If the 440 is mounted in the stock location, the 727 has the standard 18 1/2" tailshaft & the 8 3/4 is mounted with stock springs in the stock location.... The stock drive shaft measurement should be fine.... That is 52.07....

Kern Dog · Jan 4, 2021

This issue comes up occasionally.
For years, I was confident that at ride height with the shaft in place, the yoke should stick out of the transmission by about an inch. About a year ago, someone else posted about this topic and somebody made the claim that as the axle droops, the drive shaft needs to be shorter. He said this because when the axle moves down in extension, it also moves forward due to the leaf springs being hinged at the front and shackled at the rear.
I do wonder how much different the lengths really are though between full extension and compression. How much can it change?

1 Wild R/T · Jan 4, 2021

Kern Dog said:
This issue comes up occasionally.
For years, I was confident that at ride height with the shaft in place, the yoke should stick out of the transmission by about an inch. About a year ago, someone else posted about this topic and somebody made the claim that as the axle droops, the drive shaft needs to be shorter. He said this because when the axle moves down in extension, it also moves forward due to the leaf springs being hinged at the front and shackled at the rear.
I do wonder how much different the lengths really are though between full extension and compression. How much can it change?

Put your car up on a lift & try it.... Use your trans jack to raise the axle & se what happens... I have, the driveshaft definitely pulls out as the axle rises....

Kern Dog · Jan 4, 2021

1 Wild R/T said:
The shaft definitely pulls out ....

Jack Parmentier · Jan 5, 2021

1 Wild R/T said:
Put your car up on a lift & try it.... Use your trans jack to raise the axle & se what happens... I have, the driveshaft definitely pulls out as the axle rises....

I did notice that the driveshaft shaft distance increased about 1/4" when I went from no load to letting the tires down on the ground.

Jack Parmentier · Jan 5, 2021

I talked with Strange Engineering this morning & they provided me with no help as to whether the distance increased or decreased with a fully loaded car.... they just said it "changes based on weight."

watermelon · Jan 5, 2021

i did a driveshaft measurement for my tko500 installation on my 66 and the instructions do say to have all the weight in the car as it will be driven

see Step 1 for reference:

https://shiftsst.com/pub/media/wysi...00100_Driveshaft_Measuring_Procedure_RevB.pdf

watermelon

tonysrt · Jan 5, 2021

A 71 Duster with 340- 727 & 83/4 rear calls for a 44.99" driveshaft from C/L of yokes. If I make it 45" will I have a problem? Is this called cutting hairs and how big or small is .01 when measuring 45". Most guys know that size but I'll leave it to your imagination. Don't want to offend anybody, Amen or is it Awomen now?

Don Frelier · Jan 5, 2021

tonysrt said:
Amen or is it Awomen now?

I think it's APART right now.

Jack Parmentier · Jan 6, 2021

tonysrt said:
A 71 Duster with 340- 727 & 83/4 rear calls for a 44.99" driveshaft from C/L of yokes. If I make it 45" will I have a problem? Is this called cutting hairs and how big or small is .01 when measuring 45". Most guys know that size but I'll leave it to your imagination. Don't want to offend anybody, Amen or is it Awomen now?

Well, actually the issue is that I don't want to tear apart hundreds of hours of work and money as this is not a factory setup, since I have moved to larger 1350 U-joints, so I can't just put in any driveshaft that might work.... 500+ HP on the wrong driveshaft setup can ruin a good day. So I fail to see the humor....

Jack Parmentier · Jan 6, 2021

watermelon said:
i did a driveshaft measurement for my tko500 installation on my 66 and the instructions do say to have all the weight in the car as it will be driven

see Step 1 for reference:

https://shiftsst.com/pub/media/wysi...00100_Driveshaft_Measuring_Procedure_RevB.pdf

watermelon

Thanks.... that matches up with the information from Strange.

So guess I need to get going on finishing the car & adding the body panels, doors etc. so I can get the driveshaft & exhaust installed !

tonysrt · Jan 6, 2021

The only problem with all the weight in the car is how can you get under it to measure what length you need. Unless you have a 4 post lift and weigh about 100lbs. your not getting under that baby to measure anything. And if you get under might not be able to get out.

66Satellite47 · Jan 7, 2021

I think Wild RT nailed it, if you have the motor in stock location, stock position of the rear axel, a normal car 727, the OEM length driveshaft is fine. Doesn't matter if you've gone to the 1350 U joints. It's U joint CC dimension that counts.

Fran Blacker · Jan 7, 2021

I used an OEM driveshaft in my 65 Dodge it was to short. (1330 ujoint) So I added 1.5" C to C ordered a d shaft with 1350 ujoint. It was almost to long because the yoke was thicker from ujoint forward.

Jesse6869 · Jan 7, 2021

Stock dimensions stock components all should be the same, as long as u use center to center of u joints. Don’t over think it.

66Satellite47 · Jan 7, 2021

Fran Blacker said:
I used an OEM driveshaft in my 65 Dodge it was to short. (1330 ujoint) So I added 1.5" C to C ordered a d shaft with 1350 ujoint. It was almost to long because the yoke was thicker from ujoint forward.

Center to center is the dimension you need to use. The 1350 U joint is only slightly larger than a 1330. Won't change the CC dimension much.

Fran Blacker · Jan 7, 2021

66Satellite47 said:
Center to center is the dimension you need to use. The 1350 U joint is only slightly larger than a 1330. Won't change the CC dimension much.

True that cup diameter makes little difference. What I'm trying to get across is don't order a d shaft C to C unless you have the yoke your using. On my d shaft he yoke forward to where the hub starts was at least a 1/2 to 5/8 in longer than the one that I had. If I had a picture it would be plain as day.

Measuring for new driveshaft - not fully loaded car (rolling chassis only)

Active Member

Well-Known Member

Well-Known Member

FBBO Gold Member

Life is full of turns. Build your car to handle.

FBBO Gold Member

Life is full of turns. Build your car to handle.

Active Member

Active Member

Well-Known Member

Well-Known Member

FBBO Gold Member

Active Member

Active Member

Well-Known Member

Well-Known Member

FBBO Gold Member

Well-Known Member

Well-Known Member

FBBO Gold Member

Similar threads