Changing ring and pinion gears?

[zieg85]

After "carefully" reading the following article: 

http://pirate4x4.com/tech/billavista/PR-ARB/articles/14b_Gear_Setup/

I have decided to seek out an expert.  Having access to tools is not like having them yourself.  Those special clam shell bearing removers are slick... I'll just have to do my homework on finding a reputable shop and hope for the best.

Thanks guys for giving me some direction and the drive to research it a little.  The truck is going to be stored in its resting place this winter in the next week or two so I have about 4 months to find a shop.

[Stewart G Griffin]

Besides the obvious of not having to crawl around on the ground, are there any other significant advantages and reasons why you should do this with the axle out of the car?

(i'm trying to determine the feasibility of doing it in car)

[Irish_Alley]

cause then gravity will not be fighting you it all falls in place when its out of the truck

[VileZambonie]

So Zieg, why do you want to change gear ratio's? What made you not want to tackle this now?

[zieg85]

So Zieg, why do you want to change gear ratio's? What made you not want to tackle this now?

First part of the question is the 4.56 in my C30 makes it not fun to drive, at all.  I want to be able to run it down the highway at the 70 mph speed limit and not be afraid of spinning a bearing because of the high rpm.  I want a nice highway gear in it and if I can find a 3.21 I would be elated.  Seems the aftermarket offerings only goes as high as a 3.42 which may be the way I have to go. 

Second part is while I have access to a press, it is just a press and it is 47 miles away from where the truck is.  I am confident I could pull it off and I will attempt it when I have my own shop in the near future with all the proper tools to do the swap including a lift.   My shop will have a spray booth and alignment rack in it as well.  Just need to wait until spring rolls around to break ground...   

[VileZambonie]

Nice! What trans do you have?

[zieg85]

Nice! What trans do you have?

TH400.

[VileZambonie]

Have you considered a 700R4 or 4L80E instead?

[zieg85]

Have you considered a 700R4 or 4L80E instead?

Actually I have a 700R4 of unknown condition, it came in my 1986 C10 parts truck, all that I know is it went right into drive and reverse without any problems but... the TV cable was never hooked up to the late 70's 350 2bbl that was the heart of the beast.  I haven't eyeballed the carb on my C30 so I don't know if it has the set up to operate the 700R4 TV cable and I am afraid the cost of everything properly set up would far exceed a ring and pinion change to pretty much accomplish the same end result, 3.32 final drive with the 700R4 versus whatever I end up with a 3.21 or 3.42 with the rear end gear change.  I have read they can be made very robust but in this truck old school is fine with me.  I like the ratio drops between the TH400 much better than the 700R4.  This truck will only tow if the C20 is down for some reason.  I have to watch my spending as I am balancing 2 trucks taking some sizable coin plus hopefully the shop build this spring.

[bake74]

     You defiantly need to start a shop, everyone deserves a shop of their own.   

[VileZambonie]

Agreed and what better way to waste money, time, oxygen and beer than in your garage? 

I would personally build the trans over the rear end and leave what you have. With those gears and a rebuilt 700R4 or 4L80E you can tow just fine.

[Stewart G Griffin]

1) Suggestions on how to find a good shop that does this kind of thing?


2) Are there any calculators that determine rpm at any given speed if you know tire diameter, gear ratio etc.?

[Stewart G Griffin]

Nevermind; Here's a good calculator:

http://www.ringpinion.com/Calculators/Calc_RPM.aspx

[Stewart G Griffin]

Here's a good write-up on changing gears:  Yes, it's harder than it looks!   i'm thinking of just getting a new engine----or a new truck!

http://pirate4x4.com/tech/billavista/Gear_Setup/

[Jason S]

For Stewie's '87, to do things right, you'd have two gear sets to swap out and get set correctly.

You could try to find a matching set of axles from a 3/4 or 1-ton truck with a 4.10 ratio and swap them in.  A 3/4 ton truck would still be 10-bolt front, but 14-bolt rear... The only drawback is that you could wind up with axles needing a new ring and pinion and bearings...

I'm not a master mechanic, but I rebuilt the 12-bolt rear end under my '74 K10.  That was after I had observed/helped with rebuilding a couple of Dana 44's...

It definitely takes time to do it correctly.