Re: Source for 83/4 Sure Grip Gears

Removing the thrust blocks or buttons as Randy's Ring & Pinion Tech Support calls them I found is not the best way. First of all the thrust block stops the inward movement of the axle so the thrust clearance on the axle end play can be set. Second it would increase lateral movement and stress the axle bearings with street driving. I'll quote from the Chrysler Axle Guide that us 62-63 tapered axle guys have to keep in mind.

"There was a difference in thrust blocks prior to 1964 that make center section interchange, as well as axle interchange problematic. The thrust block, or axle shaft thrust spacer is the block that both left and right axle butt up against inside the center of the differential. Prior to 1964, all open differentials used a thrust block that was approximately 1/8" to 1/4" thicker than units made after 1964, however, was identical to all 1964 and later Sure Grips and open differentials. In 1964, the thrust block width was changed to match the Sure Grip thrust block width."

"This difference in thrust blocks between Sure Grip differentials and open differentials required that two different axles be produced for each 8 3/4" housing manufactured. This is true of all 1959-1963 cars with 8 3/4"s."

"A 1964 and later differential, or any Sure Grip differential, cannot be used with 1959-1963 rear ends and axles originally equipped with an open differential. The original axles must be machined or original Sure Grip length axles must be used." Shorten each axle 1/16" solves the problem.

Nick T.

From: "Bill Parker" <hemirr@xxxxxxxxx>

Subject: Re: Source for 83/4 Sure Grip Gears

I thought you could just leave the thrust block out of the newer unit, which gives room for the slightly longer axles, since the tapered axles are not dependent on the thrust block to set end play. Of course I may be all wet with 90w40. Haven't done this change myself.

On Oct 14, 2016, at 11:38 AM, furyus63@xxxxxxxxxxx wrote:

The 742 SG unit with 3.55 gear is easy to find, again just have to shorted the axles 1/16", or find for sale a complete drum to drum newer post '65 unit without tapered axles.

Nick

From: "hmsevans via The 1962 to 1965 Mopar Mail List Clubhouse" <1962to1965mopars@xxxxxxxxxxxxxxxx>

Subject: Re: Source for 83/4 Sure Grip Gears

Nick,
I will call and find out if they make a 741 unit
If not ,I will have to fine a 742 ,
Any other Idea's how I could go to a 3.55 sure grip?

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I purchased my 742 3.55 SG unit from Randy's, when I could not reinstall my axles their tech support could not help. I wrote a tech article years ago to the 62-65 site with this info. I do not believe any of the rear gear outlets have ready made 741 units any longer, mostly 742 or 489. I have never found documentation on the axle length for a 741 SG unit.

Nick T.

From: "hmsevans via The 1962 to 1965 Mopar Mail List Clubhouse" <1962to1965mopars@xxxxxxxxxxxxxxxx>

Subject: Re: Source for 83/4 Sure Grip Gears

Nick

What about buying a new 741 New unit from Dr Diff or Randy's Ring and Pinion ,Will they work in the stock unit if I shorten the axles ?

A 741 carrier with 3.55 Sure Grip is difficult to find now a days, but there are some out there. The most common upgrade I know of is to replace the 741 non-Sure Grip with a 742 Sure Grip unit which is more than for your street use only.

The problem is axle length with your '62 tapered axle 8 3/4 unit. Both axles must be shortened 1/16" to be able to obtain the .013 to .023 inch axle shaft end play which is required.

Axle length 2070573 741 case w/o SG 30 1/2"
Axle length 2404050 742 case w/SG 30 7/16"

The axle for a SG unit is 1/16" shorter than the non-SG unit. It took about 45 minutes each to grind down and dress the axle end.

Nick T.

From: "hmsevans via The 1962 to 1965 Mopar Mail List Clubhouse" <1962to1965mopars@xxxxxxxxxxxxxxxx>

Subject: Re: Source for 83/4 Sure Grip Gears

Nick
That is exactly want I want to do, Its a 741
Thanks

Mark,

I've done this conversion before. Most likely the gear in the carrier is a 8 3/4 2.76 non-Sure Grip and you're wanting to replace it with a 8 3/4 3.55 Sure Grip. The important question is what carrier do you have, a 741 or 742. There may be a slight modification for you to make which I can explain later.

Nick Tiberio
FuryUs63

From: "hmsevans via The 1962 to 1965 Mopar Mail List Clubhouse" <1962to1965mopars@xxxxxxxxxxxxxxxx>

Subject: Source for 83/4 Sure Grip Gears

Starting to rebuild the components for my 62 Plymouth,413,auto
I have the rear end disassembled and cleaned.I have 2.73 std gears .I want to replace with a 3.54 sure grip for the street use only.
I plan to use the stock axles and 14" drums brakes on the rear, but use the drum conversion kit.
What is the most reliable New Gear sure grip set package that I use?
Mark

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