6061-T6 Gear Shift Tubing

[Rick Iverson]

Strong enough?

[BLS]

Well, size matters

I think this has been discussed in the past. IIRC, the reason you might go to aluminum is weight savings, and that savings over CM tube is negligible if any. 6 ft of 4130 at 5/8 od with 049 wall is less than 2 pounds.

YMMV

[stownsen914]

I have a vintage Porsche racecar that has an aluminum shift rod - something like 3/4" or 7/8" OD .125" wall. Seems to work fine, though that's probably thicker than it needs to be. I dealt with some ovaling of the holes where the U joint bolts to it. I wondered if the softer aluminum made it more susceptible to this, but a thinner wall steel tube might have a similar result. If the holes are sized correctly in the first place and everything is kept tight, it probably shouldn't have been an issue in the first place.

[DaveW]

Either steel or AL will work, but it's a matter of which is more important to you - weight or compact size. As stated above, the weight savings is negligible, and alloy steel will be more robust, especially at the fasteners.

[problemchild]

I will take CM in the biggest diameter that will fit in my application (and which I can afford the joints).

[Rick Iverson]

Fellas;

So here’s the deal. I fell into a terrific bargain on some MS Apex joints, and thought replacing the OEM shift rods (serious overkill, and hefty in weight) with CrMo 0.50” OD tubing (that I bought). The problem is the tubing is within the +/- specs, but the OD dimension is greater than the precision of the ID of the bearing.

My thought was to switch to Al tubing with a closer tolerance. Thoughts?

[DaveW]

Fellas;

So here’s the deal. I fell into a terrific bargain on some MS Apex joints, and thought replacing the OEM shift rods (serious overkill, and hefty in weight) with CrMo 0.50” OD tubing (that I bought). The problem is the tubing is within the +/- specs, but the OD dimension is. greater than the precision of the ID of the bearing.

My thought was to switch to Al tubing with a closer tolerance. Thoughts?

IMO, any 1/2" OD aluminum tubing will likely have issues with yielding, especially at the fastener locations. If you are certain you want aluminum, I'd go with solid 7075 (73 ksi yield) rod like this at McMaster-Carr: https://www.mcmaster.com/90465K73 .

Even that may have wear issues where it rides inside the guides and with that small diameter, yield and create rotational play at the fasteners.

[jrh3]

Fellas;

So here’s the deal. I fell into a terrific bargain on some MS Apex joints, and thought replacing the OEM shift rods (serious overkill, and hefty in weight) with CrMo 0.50” OD tubing (that I bought). The problem is the tubing is within the +/- specs, but the OD dimension is. greater than the precision of the ID of the bearing.

My thought was to switch to Al tubing with a closer tolerance. Thoughts?

Use CrMo, run a solid or heavy wall plug into the tube end. Turn the tube down to fit the Apex ID and bolt through.
Might be good to braze the plug in place

[tlracer]

Fellas;

So here’s the deal. I fell into a terrific bargain on some MS Apex joints, and thought replacing the OEM shift rods (serious overkill, and hefty in weight) with CrMo 0.50” OD tubing (that I bought). The problem is the tubing is within the +/- specs, but the OD dimension is. greater than the precision of the ID of the bearing.

My thought was to switch to Al tubing with a closer tolerance. Thoughts?

How far out is the mismatch between the CrMo tube and joints? If that's too great to 'fettle' a fit, then I'd go with jrh3's suggestion of using thick-wall tube stubs as adaptors.

[DaveW]

Use CrMo, run a solid or heavy wall plug into the tube end. Turn the tube down to fit the Apex ID and bolt through.
Might be good to braze the plug in place

Rick said the tube was too big for the (support?) BEARINGS, not the U-joints. If that's the case then he'd have to turn a lot of the tubing to get it to fit. I thought he meant that literally, so I didn't suggest turning down the ends.

[Rick Iverson]

How far out is the mismatch between the CrMo tube and joints? If that's too great to 'fettle' a fit, then I'd go with jrh3's suggestion of using thick-wall tube stubs as adaptors.

0.003. +

[Rick Iverson]

Rick said the tube was too big for the (support?) BEARINGS, not the U-joints. If that's the case then he'd have to turn a lot of the tubing to get it to fit. I thought he meant that literally, so I didn't suggest turning down the ends.

Dave, you are precisely correct Bud

[tlracer]

Rick said the tube was too big for the (support?) BEARINGS, not the U-joints. If that's the case then he'd have to turn a lot of the tubing to get it to fit. I thought he meant that literally, so I didn't suggest turning down the ends.

Thanks for the correction DaveW! Like others I misunderstood that it was the tube & joints that didn't work together...

Depends on where the joints are in relation to the support bearings though: If joints are immediately next to the bearings, then using short stubs machined to suit the latter, with CrMo for the long straight runs should be possible.

[BLS]

Are the support bearings bushing types?

Sandpaper will knock 3 thou out real quick....
Even better, a small hone if you have it.

[BeerBudgetRacing]

Are the support bearings bushing types?

Sandpaper will knock 3 thou out real quick....
Even better, a small hone if you have it.

The VD use swivel joint/spherical bearings like this: https://www.mcmaster.com/63195K16/
Most of the action is sliding.
I replaced some once in my 94/95 and it was easy to fit them with some sandpaper and polished both the rod and the bearing.

[Rick Iverson]

Most of the action is sliding.

How about a brake hone to ream the inner ring ID of the bearing?

[DaveW]

How about a brake hone to ream the inner ring ID of the bearing?

Would likely work if you can find one small enough to fit.

[BLS]

How about a brake hone to ream the inner ring ID of the bearing?

Sure, but I've knocked 3 thou off with sandpaper many times to fit something and it's really not that difficult. Roll the paper up to several thicknesses, insert into the bushing and work it a bit in several directions. Use a 150 and then finish it with something like 220.

[jrh3]

How about a brake hone to ream the inner ring ID of the bearing?

Maybe : small cartridge roll; slot mandrel (homemade or buy) aluminum oxide roll; or small standing drum

[DaveW]

Opening up the bearings sure sounds like the way to go. Much easier and less expensive to do than tubing diameter reductions.

[Rick Iverson]

Opening up the bearings sure sounds like the way to go. Much easier and less expensive to do than tubing diameter reductions.

Right as rain. NAPA tomorrow

[BLS]

"or small standing drum"

Very good idea.