240 Steady bearing mod

Welp... on the long list of vibration chasing I landed on modifying the prop shaft steady bearing.

After changing the final drive from 3.73 to 3.31 the increased torque demand required to spin the rear wheels is causing the centre u-join to bang on the tunnel. The rubber bushing was worn-out so I changed it and Ricky Martin is still singing.

I'm considering a 740 centre support mod. I would go beamer style but the drive shaft is still a tad out of alignment. With a fabricated mount I cab slot the holes to shim it or move it left or right for fine adjustment.

MY car has the 1.75" spline so I'll have to go with the smaller size for the 740.

Before I go ahead with fabricating a bracket with the 740 style bushing support. Can it handle the torqe from a 5.0? Or... is there another centre support design I can use from a different car?

Suggestions???

NOTE: I know most would recommend "just" upgrading the driveshaft to the 2" spline, unfortunately that will require an other custom hybrid T-5 to M46 shaft to be built.

Here is a heavy duty driveshaft support. https://www.stsmachininginc.com/col...aring-for-240-1974-1993?variant=7918985740324 But it probably is only for the larger 240 driveshaft.

dl242gt said:

Here is a heavy duty driveshaft support. https://www.stsmachininginc.com/col...aring-for-240-1974-1993?variant=7918985740324 But it probably is only for the larger 240 driveshaft.

Click to expand...

That's what I told him in his last driveshaft thread.

Also good lord V8 power through 140 sized U joints?

dl242gt said:

Here is a heavy duty driveshaft support. https://www.stsmachininginc.com/col...aring-for-240-1974-1993?variant=7918985740324 But it probably is only for the larger 240 driveshaft.

Click to expand...

Yeah, won’t fit as offered. Can probably find a bearing that will work in that case I only need the rubber. Only knock against it is I can’t really adjust it.

Redwood Chair said:

That's what I told him in his last driveshaft thread.

Also good lord V8 power through 140 sized U joints?

Click to expand...

Yeah, no. I’m not going to modify or make a new driveshaft to fit a support. I’d rather make a support to fit my driveshaft.

It worked that way for the last 20 years and 25,000 miles until I got it and changed the final gear ratio. The u-joints looked like they held-up when I changed them… only the rear one was toasted and it was the original. lol.

At this point in the game it just needs to work.

When I put the 350 Chevy in my wagon, Power Glide trans, I used a drive shaft from a '62 Caddy. I cut it down +4 feet. Still in the car 325K miles later.

Making a new shaft just isn’t in the cards…

Sig

You could get a sleeve made to adapt the small center support bearing to the STS bearing.

This was about 45 minutes of work with the drill and the angle grinder. Once installed with the 740 bearing, I had room to move it around to align the shaft.

It’s handled just about everything I’ve thrown at it.

740atl said:

This was about 45 minutes of work with the drill and the angle grinder. Once installed with the 740 bearing, I had room to move it around to align the shaft.

It’s handled just about everything I’ve thrown at it.

Click to expand...

~300 ft/lbs of torque, 3.31 final with a TrueTrac?

Going with the smaller 740 steady bearing or something generic.

A fabricated mount is the way to go in my case. Been having driveshaft alignment problems from day one.