SirRobyn0
Full Access Member
- Joined
- Dec 6, 2019
- Posts
- 6,742
- Reaction score
- 11,319
- Location
- In the woods in Western Washington
- First Name
- Rob
- Truck Year
- 1984
- Truck Model
- C20
- Engine Size
- 305
Those of you who have been around for a while probably know I've been talking about this for the last few years. I really wanna make a move on this soon, so I'm starting a new thread on it. My intent is to first of all discuss how I'm going to go about this, and then once I actually do the work I'll post how I felt about doing the job and how it turned out.
Specs on the truck 1984 C20 305 - 700R4 (recent HD rebuild) 3.41 current rear gears 31" tall tires, when the 305 is done she'll likely get a stock or near stock 350. Reason for the change I have an 18' open trailer that I occasionally tow typical weigh of the trailer loaded is between 5K - 6K. Truck is also used to haul feed for the farm typical trips are 200 - 300 miles round trip bringing back a ton of feed in the bed, no trailer. If I need more than a ton of feed then I put 2 tons of feed on the trailer. I also frequently daily drive the truck to the shop I manage in the city.
I think leaning towards 4.10's though I will listen if you have something to say about it, a lot of C20's and C30's came factory with 4.10's as well. I know last time this was discussed there was a strong camp in favor of me going with 4.56's. Certainly I don't want to make the change to 4.10's and wish I had gone for more, but also know that I'm not really to into the idea of towing or hauling in overdrive. Maybe it's fine with low rear end gears and a HD 700R4 but I can't afford to rebuild it a second time, so I'm not interested in taking that risk. So that means with 4.56's I'd be just shy of 3K at 60MPH and at 3,200RPM at 65MPH, not including converter slip, (my converter does lockup in 3rd). With 4.10's I'd be just shy of 3K at 65MPH and hitting 3,200RPM at 70MPH. I tend not to tow at 70 unless traffic forces that. I can post a big long chart of speeds and RPM's if anyone wants to see it.
We do have a lot of hills around here and where there isn't a hill there are mountain passes. I think I need to pick a most likely to be happy with ratio and try it.
The main thing I want to discuss is not the ratio but it's:
#1. What do I need to gather up for tools?
#2. Where I'm going to do it at? Options, the farm or the shop. The problem with shop is other than coming in an hour early or staying an hour late it's hard to have time to work on my personal vehicle there. At the farm I have air compressor, but no lift or press. My truck has a dump kit on the factory bed so some of the work could be done from above with the bed raised. I guess the big question there is will I need a press?
#3. And how much time I need to budget to do the job? I'm a first timer. I've been a mechanic for a long time, but other than to replace axle shafts and bearing I've always let a diff man or shop tackle this sort of work, but I can't afford $1,500 - $2,000 to have a diff shop build it.
#4. I'm thinking of buying from East Coast Gear Supply. Seems like they have decent prices. My options there are motive brand gears for $220 or yukon for $296. Any preferences? I'm open to using another supplier to.
#5. East coast gear also has an install / rebuild kit available. Comes with Carrier bearings, Pinion Bearings, Pinion Nut, Pinion Seal, Crush Sleeve, Pinion Shims, Loctite, Marking Compound, Adjustable Differential Shims, Oil Slinger, Ring Gear Bolts for $280. Keeping in mind I'm a first timer seems like getting a kit might be the way to go.
#6. There is an anomaly with the left side. When run with the wheels off the ground there is some lateral movement of the brake drum. It's been like this since before I bought the truck. Could very well be in the drum, but possibly a very mildly bent axle, which I'll be checking for. I'd take recommendations on brands and sources for axles if I need one.
#7. I've watch a number of videos and read a few things on doing ring & pinion gears, but very much open to your suggestions / tips ect.
Thanks.
Specs on the truck 1984 C20 305 - 700R4 (recent HD rebuild) 3.41 current rear gears 31" tall tires, when the 305 is done she'll likely get a stock or near stock 350. Reason for the change I have an 18' open trailer that I occasionally tow typical weigh of the trailer loaded is between 5K - 6K. Truck is also used to haul feed for the farm typical trips are 200 - 300 miles round trip bringing back a ton of feed in the bed, no trailer. If I need more than a ton of feed then I put 2 tons of feed on the trailer. I also frequently daily drive the truck to the shop I manage in the city.
I think leaning towards 4.10's though I will listen if you have something to say about it, a lot of C20's and C30's came factory with 4.10's as well. I know last time this was discussed there was a strong camp in favor of me going with 4.56's. Certainly I don't want to make the change to 4.10's and wish I had gone for more, but also know that I'm not really to into the idea of towing or hauling in overdrive. Maybe it's fine with low rear end gears and a HD 700R4 but I can't afford to rebuild it a second time, so I'm not interested in taking that risk. So that means with 4.56's I'd be just shy of 3K at 60MPH and at 3,200RPM at 65MPH, not including converter slip, (my converter does lockup in 3rd). With 4.10's I'd be just shy of 3K at 65MPH and hitting 3,200RPM at 70MPH. I tend not to tow at 70 unless traffic forces that. I can post a big long chart of speeds and RPM's if anyone wants to see it.
We do have a lot of hills around here and where there isn't a hill there are mountain passes. I think I need to pick a most likely to be happy with ratio and try it.
The main thing I want to discuss is not the ratio but it's:
#1. What do I need to gather up for tools?
#2. Where I'm going to do it at? Options, the farm or the shop. The problem with shop is other than coming in an hour early or staying an hour late it's hard to have time to work on my personal vehicle there. At the farm I have air compressor, but no lift or press. My truck has a dump kit on the factory bed so some of the work could be done from above with the bed raised. I guess the big question there is will I need a press?
#3. And how much time I need to budget to do the job? I'm a first timer. I've been a mechanic for a long time, but other than to replace axle shafts and bearing I've always let a diff man or shop tackle this sort of work, but I can't afford $1,500 - $2,000 to have a diff shop build it.
#4. I'm thinking of buying from East Coast Gear Supply. Seems like they have decent prices. My options there are motive brand gears for $220 or yukon for $296. Any preferences? I'm open to using another supplier to.
#5. East coast gear also has an install / rebuild kit available. Comes with Carrier bearings, Pinion Bearings, Pinion Nut, Pinion Seal, Crush Sleeve, Pinion Shims, Loctite, Marking Compound, Adjustable Differential Shims, Oil Slinger, Ring Gear Bolts for $280. Keeping in mind I'm a first timer seems like getting a kit might be the way to go.
#6. There is an anomaly with the left side. When run with the wheels off the ground there is some lateral movement of the brake drum. It's been like this since before I bought the truck. Could very well be in the drum, but possibly a very mildly bent axle, which I'll be checking for. I'd take recommendations on brands and sources for axles if I need one.
#7. I've watch a number of videos and read a few things on doing ring & pinion gears, but very much open to your suggestions / tips ect.
Thanks.
