Drive shaft question

[Automan]

Hi Everyone: I am about to go to the suspension company and order my driveshaft. Now the yoke at the end of the transmission (Toploader). How far out should i position the yoke to get my measurement. I understand that it can't sit all the way in because of bumps on the road would cause some unwanted attention. Is 1.5 inches too much? Whats your advice?


Thankyou in advance
Automan

[ZOERA-SC7XX]

I have the original driveshaft in my garage along with the original toploader that came out of a '66 Galaxie...the yoke sat halfway into the housing.

[Clois Harlan]

Automan,

I think that is a pretty good measurement. Remember, you have to be able to move your driveshaft forward to install or remove it from the rear pinion.

Clois

[trularin]

Take your yoke, push it all the way into the transmission with evenything else in the position you are going to be driving.

Place a scale next to it and pull it out 1 inch. Measure between the center of the U joint to the center of the U joint.

Tell the man you want 'X' and you measured center of U joint to center of U joint.

I just had one done after I swaped transmissions and that was how they said to measure it.

Hope this helps.

[Roger Bolick]

Several driveshaft places all quoted me 3/4" out, i.e. push the yoke in all the way, mark it, measure 3/4" more, place it at this mark, then measure the Center Line of the U-joint to the Center Line of the rear U-joint at ride height. If there is a flange at the rear, use the face. (FYI, it does take most of the 3/4" slide to remove the rear caps, so a 1" gap might work better if you're not accurate in your measurements)

One place said the splines had to be engaged at least 2/3 of their length at level to allow for the rearward movement.... which I'd guess means at least 1/2 of the splines need to be engaged at worse case to avoid any issues. (toploader yoke has 5" of splines for a thin wall tube 1.6825 OD, 50% would be 2 1/2" of spline engagement minimum, seems reasonable)

In an IRS car, both the trans and diff are mounted solid to the frame, so the only movement is the bending of the frame and movement of the diff in its mounts and the engine rotation, so I have trouble envisoning this being more than 1/8" total. The 3/4" will allow movement to remove the rear caps. Based on the above numbers, even a 2 1/2" gap would allow the minimum of engagement! All this work and you end up with 12" between U-joint centerlines, best to verify this due to all different combos.

[Roscoe]

http://www.dennysdriveshaft.com/

[Automan]

Thanks everyone. I have given the information to the manufacturer and i should have a brand new driveshaft on Friday.

Automan

[Ant]

I am about to get my driveshaft done by a very good shop and they have in 3" diameter tube to fit my 1350 weld on flanges etc, varying thicknesses of tube going from 0.065" to 0.250" so I have a choice, and would assume the 0.250" (1/4") tube is far to heavy, they have 1/8" tube, I would appreciate knowing what others use, bearing in mind I have 566ftIbs torque and 675bhp, running on slicks at times, so it will probably need to be heavier than 0.065"

[Juggernaut]

I haven't heard anybody mention getting a used drive shaft that is compatible with the tranny & rear end, then have it cut & balanced to fit your individual car?

I did that years ago when I put a small block in a Vega & it worked well.

Thats what I was going to do, is there any problems with doing it this way? Should I just get a new one made?

Thanks,
Randy

[Roscoe]

My opinion? Call Denny and get a nice new one.

Roscoe

[jerry w]

I agree.......Check Denny's Driveshafts. Great service and he backs up what he makes.

Regards

[Juggernaut]

I think I'll call Denny's.

Thanks,
Randy