Should I Use a Splined or DD Shaft?

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LIME TWIST DART

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What considerations are there in deciding on a splined steering shaft or a DD shaft?
Pros, Cons? Tips, Safety?

Need to mate up my Flaming River Column and Flaming River manual box. It will be a two joint system. I believe the original setup had the column and box near perfectly inline. I have the new column mocked up with a bit more deflection (up and down @ about 10 degrees). I believe this will be easily managed by the two joints. I did this for 3 reasons. 1) To get the column snug to the opening in the dash. 2) There is no real collapsable component, so the angle could possibly help prevent significant movement of the column into the compartment in case of a collision. 3) To create more room around the headers. The shaft will be about 6" after considering the length of the joints. Total gap from column to box is about 9". 3/4" 36 spline on box and 1" DD on column.

Would like to decide on the shaft type so I can buy and finish mocking everything up before fabing the floor mount.

Thoughts?
 

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Either works well. Pick one.

I am probably going to end up using a combination of both on my rat truck.
 
Hi,
I used a splined end on my steering box. Then double d were used on the rest of the assembly. Additionally you may want to pin and weld all the joints used. I used two bearing supports, mocked it all up to insure it turned well without binding, then finished the welding , etc. the bearings i used also have zerk fittings for the occasional shot of grease.
(This set up is being used to fit an early hemi into a 40s plymouth. Still working well for at least 6 years now without problems)
Russ
 
I am a fan of DD.....

biggest reason is cut to length with less waste....plus no additional splines showing because the spline ends only come in 2" segments.

it gets to be a PIA to line up the safety notch on the spline especially in a hard to see tight spot

You can use your factory shaft by simply machining flat sides (DD) on the end.....no adapter needed. Once done the install and any future removal /install is a breeze.

Actually, I can not think of one advantage to a spline over DD.....if you ever pull your factory shaft apart, you will find the safety collapsible part is ....DD (3/4" into 1")

JMHO
 
I used all unisteer joints on mine with flaming river column...Although not a A-body car, the concept is the same......one had splines on one end for the rack and the other end was DD...then went DD shaft up to another joint with 2 DD's....then another piece of DD shaft through support Heim joint up to another joint with 2 DD's and connected to the column....I have some pics below.....Also, a little tip; it helps to mach it up with wooden dowels ahead of time and get your lengths, angles, and support weld area marked and chosen as a wooden dowel is about 3 bucks if you screw it up.....Instead of cutting DD shaft wrong length....Especially polished stainless steel like I used....I think it was 100 bucks or so for 24 inches of it

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I also prefer DD but if I can get one splined end in there it really helps if you need to change the "clock" of the steering wheel a few degrees. With the DD you can only change the clock position 180 degrees at a time.
Both are extremely reliable and if you happen to need to change the clock position a few degrees you're going to wish that you had used at least one splined joint. The DD has really gone down in price on ebay!!

http://www.ebay.com/itm/161809134815?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT

http://www.ebay.com/itm/161811618894?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Treblig
 
Everything in my setup is DD except the spline on the steering box. that way as stated above, you can still clock the steering wheel, However as denny points out, you can cut DD to any lenth, and you can assemble and disassemble at will. just remember to dimple, and set screw the shafts at your joints... i had one pull out at the drag strip when an alignment shop loosened it, and forgot to re tighten it... Denny was there! lol thank god it was in the pits.
 
johnnymac2k6 said:
Everything in my setup is DD except the spline on the steering box. that way as stated above, you can still clock the steering wheel, However as denny points out, you can cut DD to any lenth, and you can assemble and disassemble at will. just remember to dimple, and set screw the shafts at your joints... i had one pull out at the drag strip when an alignment shop loosened it, and forgot to re tighten it... Denny was there! lol thank god it was in the pits.
Click to expand...

Yes, if you have splines at the steering box then no need for splines in the steering shaft!!!
I have built two hot rods for my kids (may others for other people) and I also worry about the joints/shafts separating so I always try to use the split type u-joint. It's a little more trouble because once you get it cut to length you have to file/grind a slot for the bolt to pass through but once that's done (and little lock tight) you have a joint that can't hardly ever come apart unless you put a wrench on it!! Even the factory used this type of split, splined joint on some of the steering box joints, I guess they had the same concern.
Split joints cost a little more but when safety is concerned, who cares!! Besides...the cost of the shafts have gone down to where you have extra money for good joints!! They are sometimes a little more bulky but again...SAFETY FIRST!!

http://www.ebay.com/itm/Unisteer-80...ash=item58c3ee66ac:g:8C8AAOSwHnFVv9qM&vxp=mtr

http://www.ebay.com/itm/Unisteer-Pe...ash=item4d2b24afe2:g:qogAAOSwBLlVAIOC&vxp=mtr

Treblig
 
Thanks for all the input. Looks like DD is the way to go for me. The box is splined, so I can clock the setup there.
 
Treblig said:
Yes, if you have splines at the steering box then no need for splines in the steering shaft!!!
I have built two hot rods for my kids (may others for other people) and I also worry about the joints/shafts separating so I always try to use the split type u-joint. It's a little more trouble because once you get it cut to length you have to file/grind a slot for the bolt to pass through but once that's done (and little lock tight) you have a joint that can't hardly ever come apart unless you put a wrench on it!! Even the factory used this type of split, splined joint on some of the steering box joints, I guess they had the same concern.
Split joints cost a little more but when safety is concerned, who cares!! Besides...the cost of the shafts have gone down to where you have extra money for good joints!! They are sometimes a little more bulky but again...SAFETY FIRST!!

http://www.ebay.com/itm/Unisteer-80...ash=item58c3ee66ac:g:8C8AAOSwHnFVv9qM&vxp=mtr

http://www.ebay.com/itm/Unisteer-Pe...ash=item4d2b24afe2:g:qogAAOSwBLlVAIOC&vxp=mtr

Treblig
Click to expand...


Yes, these are the joints I used also.....As mentioned you have to file/grind a recess half moon in your shaft to get the bolt from the joint through but this prevents the shaft from falling out should the bolt ever loosen up......Kind of a safeguard....Also, I want to mention that you have to really really tighten the allen bolts on the unisteer u-joints to get them to cinch....I believe they say 75 foot lbs. on their instructions....
 
bbrroowwnn said:
Yes, these are the joints I used also.....As mentioned you have to file/grind a recess half moon in your shaft to get the bolt from the joint through but this prevents the shaft from falling out should the bolt ever loosen up......Kind of a safeguard....Also, I want to mention that you have to really really tighten the allen bolts on the unisteer u-joints to get them to cinch....I believe they say 75 foot lbs. on their instructions....
Click to expand...

Yes, everyone has to realize that the bolt doesn't just tighten into the threads like a normal bolt installation...it has to squeeze the split joint to make solid contact with the shaft splines/DD. So in essence your tightening the bolt and compressing the split joint. I try and get some vice grips or a small clamp to squeeze the split joint tight so the bolt gets to torque properly in the threads without having to also squeeze the joint together. It's not a deal breaker, just something I do to ensure that the split joint is "clamping" good up against the splines/DD shaft so that the torque is not fighting the split joint as you torque the bolt.

treblig
 
Treblig said:
Yes, everyone has to realize that the bolt doesn't just tighten into the threads like a normal bolt installation...it has to squeeze the split joint to make solid contact with the shaft splines/DD. So in essence your tightening the bolt and compressing the split joint. I try and get some vice grips or a small clamp to squeeze the split joint tight so the bolt gets to torque properly in the threads without having to also squeeze the joint together. It's not a deal breaker, just something I do to ensure that the split joint is "clamping" good up against the splines/DD shaft so that the torque is not fighting the split joint as you torque the bolt.

treblig
Click to expand...

Good tip. Thanks
 
What is a split joint?

With DD or spline , all I ever did was add a small notch (machined) for the extra /safety set allen. No need to drill thru the shaft. IMHO ...that would provide a weak point in the shaft.

Maybe I am missing something.

I would suggest incorporating a vibration dampener ...whether you are keeping the stock box or changing to a rack and pinion. Usually on a HDK install,coming off the rack, a combination vibration dampener /universal with a DD end is used.
 
HemiDenny said:
What is a split joint?

With DD or spline , all I ever did was add a small notch (machined) for the extra /safety set allen. No need to drill thru the shaft. IMHO ...that would provide a weak point in the shaft.

Maybe I am missing something.

I would suggest incorporating a vibration dampener ...whether you are keeping the stock box or changing to a rack and pinion. Usually on a HDK install,coming off the rack, a combination vibration dampener /universal with a DD end is used.
Click to expand...


Re-read post #11. I posted two sites (addresses) showing the split joint u-joints. You don't drill through the shaft (that would not be good). You simply file a slot on the outside of the shaft for the bolt to lock the shaft onto the u-joint. Like I wrote earlier, factory cars came with the split joint and the factory splined shaft had a slot/groove machined all the way around the shaft so you can "clock" the steering shaft wherever you like. The bolt passes through this slot/groove, in our case you only need a slot on the side the bolt passes through and not all the way around so it's actually stronger than factory!! Hole DOES NOT THROUGH THE SHAFT but on the outside.

Factory type example:

http://www.cjponyparts.com/borgeson...7/?year=2002&gclid=CPvPxv-VwMoCFQ8uaQodHHAEzg


Treblig
 
I see....just a little different from the Flaming River / Borgason joints I am used to.

Nice.
 
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