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Joined: Jan 2004
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Okay, sitting in the bed of my 55.1 I have a 1977 posi 3:42 rear end.

As much as I think about putting that in, I am very tempted to just call Patrick's and get the 2:38 gears.

I like the fact that I have a stock rear end and stock front end.

I need your input, what would you do? Change the gears or swap the rear end?

Thanks,
Chris


Chris 1955FirstSeries
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Bolter
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what ratio are you running now,, and what would be cost between the two, I would rather have the 3 plus gearing then the 2 plus but I do have 2;73 in mine and it does ok as compared to the patricks 3:55 that I use to have in it,, patricks was a lot quicker but then the rpm's was much greater,, at 60 it was about 3000 and now it is about 1600 and twice the gas mileage,,,regards..Fred


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Whooooo, Brain Fart, I meant 3:38 gears from Patrick not the 2:38, my fault.

I figure it will cost me $400 to do the rear plust $350 for disc conversion plus $300 for dual master cylinder plus lines totaling $1000+ bucks.

The 3:38 gears would run me $750.


Chris 1955FirstSeries
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Bolter
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tough shot to call, either way seems ok,,but I always try to reduce my cost as long as I think that I will be ok with the end results..IN about 3 and half my grandson will be driving, I plan on letting him have mine,, may up date to 350, clip, and all that , I hate to as it is very dependable as it and runs well, I know the update would be easier for him to drive,,, take care,,,Fred


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Cruising in the Passing Lane
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If you spend $750 for the gears are you still going to want to update to disk brakes, new lines and a dual master? If so, the budget comparison is faulty.

I don't think you'd ever notice the difference between 3.38 and 3.42, but posi can be real nice if you ever find yourself on a slick surface.

If it were me I'd swap rears, but maybe not put disks on the new rear. Actually, I did swap rears, and put disks on the front but not the rear.


1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
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So if I go with the rear swap and disc brakes on the front, do I have to put the dual master in? Or can I survive till I can generate more funds and do the dual master later?

Thanks,
Chris


Chris 1955FirstSeries
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i have a nova rear with 2.73 gears have had for 21 yrs, not the best choice.will swap for 3.11 late with a ford 9". drove my 54-3100 21 yrs with single master no problems now have adual master. go to randy's ring&pinion and play with calculator before you decide. besides it fun to play with tire sizes and gears. at 35 mph and the 2.73 only doing 1000 rpm to low. lugs at the slighest up hill and i live in flat indiana. hope this helps. ron


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Quote
Originally posted by Chris55.1:
So if I go with the rear swap and disc brakes on the front, do I have to put the dual master in? Or can I survive till I can generate more funds and do the dual master later?

Thanks,
Chris
I swapped rears installing one with 3.08 gears and drum brakes and 5-lug hubs. I had to buy new wheels and I did the rear brakes as part of that project. When I saw your $400 figure at first I wondered what you were spending it all on, but I think I spent in that neighborhood on mine. For a while I ran with 6-lug wheels in the front and 5-lug in the rear.

Then some months later I had trouble with the front brakes and decided to upgrade to disk rather than repair. I bought a kit that used disks and calipers from the same car my rear had come from. I installed the disk kit and first time I applied the brakes the fronts froze and wouldn't turn.

Turns out I had a 10 lb residual valve built into the existing master and that was enough to prevent me from turning the disks by hand. I solved the problem by switching to a dual master and replumbing the entire system with the appropriate residual valves for front and rear.

If I were doing it again and wished to do it one piece at a time, I'd install the dual master (use a disk brake type) and replumb before installing the disk brakes.

If you stay with drums on the rear, I don't think it would matter what order you do that part in.

If you hunt around on my web site (www.OldSub.com) the whole story with more details are posted there. I've been driving mine for a couple years now with the new brakes and stuff and mostly I'm happy with it.


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I have your same model truck and am going through this same scenario, I think I am going to try to find a 60 through 66 complete rear end with 3.08 gear. I have been told I should be able to find one for $100 to $150. my stock rear shoes have less than 7,000 miles since the drums were turned and new shoes were installed so I'll keep them. Changing over the newer housing with spring perches should cost less than $100. Hopefully I'll have less than $300 total and will get that 70 mph cruising speed at 2600 rpm.
As always, suggestions or comments are welcome.


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You will never notice the difference between 3.42s and 3.38s.Whichever is cheapest and easiest.

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I believe I am going to swap the rear end. Drive the truck with 6 lugs up front and 5 in the back for a while.

Eventually probably the following year swap to front disc and 5 lug and put in the dual master and booster at the same time.

Thanks for all the input.

Chris


Chris 1955FirstSeries

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