Can you go single driveline on 720 ext cab

[MF720]

Since my carrier bearing looks like it has been put through a meat grinder I was going to straighten out a few things. Bearing is bad due to bad pinion angle from non angle drop blocks being used. So i got new 4* angle drop blocks and was about to order up a new bearing when a friend told me he has a drive shaft laying around that he believes is long enough to convert to over to a single. Is there any good reason to do this? If so does anyone know where I should get the shaft length measurements from. Plan is to fix this in 2 weeks so I need to make a decesion.

[izzo]

Weird, my 80 720 had a single piece drive line. But it was single cab. yes you can go with a single drive line, not sure if theres another one out there you can just throw in or if you have to get a custom one. You should replace those drop blocks with some angled ones, or be ready to do u joints every so often...

 

You can get just angled drop blocks without the whole kit for pretty cheap.

[ggzilla]

Carrier bearing is not very expensive. If the rubber and bracket are chewed up too, those are additional parts.

[MF720]

Carrier bearing is not very expensive. If the rubber and bracket are chewed up too, those are additional parts.

 

 

That was the plan just do the bearing but along came a buddy with his free offering to go single but I don't want to bother if there will be no improvement.

[mikec]

where can i get proper angled drop blocks? i'm just running regular 2" blocks and my csb took a dump.

[albyneau]

While I'm not familiar with the belly side of a 720 regarding clearances, I can tell you this as related by my driveline guy (who's had my business since the 70's)~

 

The practical limit on DL length for a lower RPM street vehicle is 60". Higher revs and/or serious power output should be limited to 48".

 

Yes, there's longer ones out there~ but for the most part they've lived sedentary lives under American land-yachts and rarely spun over 3000 RPMs

[datasour14]

i have 4' blocks that are angled in my 80 720 but when i got my new center bearing it had seemed to move the bearing forward a few in. so i would watch for that but its not anything mr drill bit cant take care of. theres a little room on the x-member. pinion angle is a little off but i cant feel anything bad under there and the l block isnt exactly making joint splitting torque either. just food for thought ey good luck.

[flatcat19]

This goes to both of you running 4" blocks...MF720 and datasour14

 

Did you shim up the center bearing?

 

Find some 1" square tubing, and place between carrier bearing and crossmember.

 

See if that helps the positioning.

It will help take care of a lot of NVH you might be experiencing...if not at least save some wear on the bearing and u-joints.

[wayno]

The longer the driveshaft, the bigger round it needs to be. This driveshaft is 70 to 75 inches long, it's hard to measure as this 1947 chevy truck is so low, it has a 350/350 with a performance manifold and carb. The driveline is 4 inches round/across, they told me that it had to be that big, that there is a ratio that is used.

[datasour14]

This goes to both of you running 4" blocks...MF720 and datasour14

 

Did you shim up the center bearing?

 

Find some 1" square tubing, and place between carrier bearing and crossmember.

 

See if that helps the positioning.

It will help take care of a lot of NVH you might be experiencing...if not at least save some wear on the bearing and u-joints.

 

i didnt but that sounds like it should work out nicely. i have a faint vibration when im releasing the clutch in 3rd and 4th. ill get under there and see about getting it a little higher. planning on mono leafing it soon anyway so i know its going to need the help.