I have recently faced this problem in the restoration of my 3/4 ton GMC with
a 4.57 ratio. For the 3/4 ton you just can't buy a higher speed ring gear
and pinion. My options included replacing the "pumpkin" with a chevy/gmc
rearend from an automatic transmission truck up to 1972, but the highest
gear ratio available would be 4.11. I opted to get a later model rear (75
Suburban) end with a 3.43 ratio. The problem was that the width was too
wide from wheel mount to wheel mount. Had a local shop cut (very
accurately) 5.75" out of the new rear end axel housing. Also had to remount
the leaf spring mounts. My new rear end had different length axles
originally, and had to use 2 short axels. After grinding and paint, can't
tell any difference, and when done she'll go down the road without any
problem. This worked out well for me.
Jon
49 GMC 3/4 ton...completely disassembled and harmless
----- Original Message -----
From: dpewter <dpewter@msn.com>
To: AKBurke <ajkburke@msn.com>; 50chevy <50chevy@iwon.com>; OleTrucks List
<oletrucks@autox.team.net>
Sent: Sunday, September 16, 2001 3:58 AM
Subject: Re: [oletrucks] Cutting down those high RPM's
> FYI: The 3.55 rears from the cars (that had automatic trannies) will NOT
fit
> inside of the truck pumpkin. I don't know what ratio the trucks with
> automatic trannies had, but most of them would have been open driveshafts
&
> I don't know if the internals on the differential are interchangeable with
> the closed type (aside from AD trucks with automatic trannies being pretty
> rare to begin with).
>
> Regards,
> Doug Pewterbaugh
> dpewter@msn.com
> Denton, TX
> 49 3104 216 5-window
>
> ----- Original Message -----
> From: "AKBurke" <ajkburke@msn.com>
> To: "50chevy" <50chevy@iwon.com>; "OleTrucks List"
> <oletrucks@autox.team.net>
> Sent: Saturday, September 15, 2001 10:53 PM
> Subject: RE: [oletrucks] Cutting down those high RPM's
>
>
> > >> I think the easiest and cheapest alternative
> > >> is to just change out the 4.11 gear for a 3.55
> > >> (or or other) from a salvage yard.
> >
> > I must be missing something....since Patrick's wants $275 and Carter's
> > wants $400 for the 3.55 ring and pinion. From what salvage vehicle
> > are you (and then me) going to find these parts?
> >
> > -A
> > oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|