C30 heavy duty rear axle top speed

[Steeveedee]

Originally Posted by Aruba1

This is Mexico, lol. https://www.youtube.com/watch?v=hxXJ5wyZ4gY

Put a 409 in it, too! I don't know that I would really want to drive a loaded dump truck 88 MPH!

[Sheepdip]

The Gear Vendors OD's (I have 2-- one behind a TH350 and one behind a SM465) uses a speed signal generator inline with the speedo cable to create a voltage signal to the little computer brain as to when you are going fast enough to kick in the planetary gear OD which is about +/- 45 mph minimum, so that is something to keep in mind with the GV verses a manual OD.

[Aruba1]

Originally Posted by Steeveedee

Put a 409 in it, too! I don't know that I would really want to drive a loaded dump truck 88 MPH!

That night she topped 105.

[allchevy58]

On my 1964 C30, it had 5:14. I bought a Dana 70HD, with sway bar out of a 77 Chevy C30 dually, installed 4:10 with posi. Bolted right in, welded some shock mounts and shortened or lengthened the drive line, can't remember. 65 mph at 3,000 rpm. Had a ratio adapter built for the speedometer so speedo is right on.

[Aruba1]

This is the exact same setup as mine... 70HD, shorted drive shaft, welded suspension brackets and repositioned leaf brackets. I like the leaf springs setup. What stock with the truck or it came from the donor? Did you had to reposition the rear leaf brackets or was it a bolt-on?

Originally Posted by allchevy58

On my 1964 C30, it had 5:14. I bought a Dana 70HD, with sway bar out of a 77 Chevy C30 dually, installed 4:10 with posi. Bolted right in, welded some shock mounts and shortened or lengthened the drive line, can't remember. 65 mph at 3,000 rpm. Had a ratio adapter built for the speedometer so speedo is right on.

[allchevy58]

Originally Posted by Aruba1

This is the exact same setup as mine... 70HD, shorted drive shaft, welded suspension brackets and repositioned leaf brackets. I like the leaf springs setup. What stock with the truck or it came from the donor? Did you had to reposition the rear leaf brackets or was it a bolt-on?

Bolted right in, 64 springs and block, pads on the rearend were in the right place. I did need longer u-bolts due to the 70HD being 4" and the sway bar bracket.

[special-K]

I would leave that original rear in place and add an auxiliary transmission. You would not have to alter your PTO set-up, you would be leaving that truck as the cool not too common 11k# axle option that it is, and be doing what an innovative minded truck owner might have done back in the day. There was a company called Brownie that made units for this application and I know of guys doing their own engineering to install back to back transmissions. Twin sticking is just too dang cool and a totally vintage truckin' way to go. These days you could simply (other than the $1,600 cost) install an Advance Adapters Ranger 2spd. With an auxiliary transmission you will also have the ability to split shift, but would not have to if you didn't want. I believe you will gain a higher speed overdrive over using an overdrive transmission.

https://www.advanceadapters.com/cate...-splitter/236/