School the Newbe

[Yacster]

Hey folks. I purchased the C25 in my avatar last September. For more pics click here http://67-72chevytrucks.com/vboard/s...289510&page=47 scroll down
Since then, I did a FULL brake job including new lines on all corners, Tune-up, cleaned up the carb and engine, and replaced the 2 core rad with a 4 core that I scored off Amazon.com for $201 shipped to the house (I'm still waiting for the cops to arrest me for stealing it), replaced all of the hoses thermostat and water outlet. Anyway my biggest delimma is the rear. It has 4.56 gears in the original Dana 60 non posi. I am not thrilled about drums in the front. I ultimately want to put disc brakes in the front and I would like to keep the stock stance of the truck. As you can surmise the wheels are 8 lug. I hope I painted a a clear picture for you.
Now here is my question to all of you guys who have done what I'm looking to do: Do I change everything over to 6 lug (get a disc brake conversion kit for the front, find a rear for the back and if so what would I take it out of? OR Is there an 8 lug disc brake conversion(that I haven't seen in a cataloge yet) and change the carrier and gear set in the rear end housing currently on the truck? OR I am a moron with those 2 suggestions and you've got a much easier solution.
Help me out ohh wise ones!! Thanks

[biggestjohn]

Going 6 lug gets you much better wheel options, but can be real expensive.

8-lug rear conversions can be done. I would suggest taking rear hubs to a machinist and have them square up the back side of the stud bosses (the rear disc face goes on the rear side of the hub) Mine were .021" out, the disk run out was crazy.Black Bird has the rear kit. I did not use them, wish that I did though!!!(would have been cheaper in the ling run)

http://www.blackbirdscustomtrucks.com/index7.html

I used a bracket kit off of ebay, thinner bracket, no instructions, the so-called instructions on ebay ad were WRONG, even after notifying the seller of the mistakes.(never answered any e-mails)



Nothing is going to be cheap about this.......have fun.

Others will chime in on the fronts.


BTW: Nice truck!!

[BlazinC5]

There are alot of variables you posed to us. Ultimatly, it depends on what you intend to use your truck for. Streeting it around or towing/hauling. dunno what your looking for there... obviously the gear ratio is an issue so I'll add my 2 cents there too. I am also assuming your going to have a 1:1 gear ratio for your tranny in top gear... (Stock tranny). Lets see, Dana 60,, Great axle, Lots of parts to look at for changing them around... 3.50 - 3.73 would be good in general with some 28"-30" dia. tires. Play with this gear calculator, it may help in deciding on your own.. http://www.coastdriveline.com/htmlfo...lculator2.html 1700-2700RPM at 60mph for these trucks is pretty good with no overdrive. if you wanna tow, 4.11's work well,,, but bu-bye fuel mileage still. I know you can get 5 lug axle shafts for a dana 60 too. and getting ahold of 5 lug disk + spindles and a-arm assemblies for a front is pretty easy too. If I were you and had a 1:1 tranny.... I would consider these options...
For street: I would go with 5 lug axle shafts in the Dana 60 for bullet proof horsepower capabilities or a 12bolt, 5 lug swap for economy pricing. junk yard it and find a 5 lug disk front end (1970-72) to keep with the era of your truck or update a lil with the 73 to i think around 1987 I believe, A-arm assemblies can work. I herd they will bolt up to crossmembers, and are a lil wider. There again your axle ratio and tire size for RPM play factors for fuel economy and performance..
For towing/hauling: keep the Dana 60 and look into a 3/4 ton, 8 lug 1973 and newer A-arm assembly with disk brakes.. I would change the gear ratio too, probably to a 4:11. The rear end ratio of 4:11 ain't the best for fuel,, but is better than 4:56 and tows good. Large dia. rear tires, (30"-32") could help with fuel usage unloaded and give a little to the raked stance of the truck with smaller dia. tires in the front.
5 lug wheels vs. 8 lug wheels,, there is little to dispute. 5 lug completely dwarfs 8 lug for choices. You will find alot more choices in 5 lug pattern. But strength is why 8 lug was used for trucks haulin more than a$$... the 6 lug wheels on the market are also limited for choices too. Not near as many as the 5 lug. 6 lug was more a 4x4 and pre 1970's 2wd thing with chevy.
So there are my thoughts. hope I didn't discourage you any and good luck with whatever direction you choose.
BTW... Welcome to the board... your wallet will never forgive your obsession.

[Yacster]

BigJohn- Thanks for the compliment on the truck I'd take the credit but I bought it that way. As for converting the rear over to disc brakes, I dont think I'm going to go that deep. I'll just keep them drum.

Blazin- I guess the best way for me to go right now would be to just swap out the gears. I had 3.54 or 73's in mind. 4 series with out OD is a killer on fuel economy. 3.73's would still have enough umph to get me going. The truck will be my sunny day driver and tow vehicle for my F.A.S.T. 66 Skylark. I do not intend to hot rod the truck, I still want it's primary use as a truck. Right now it has a 307 2 bbl in it. Not too much to hot rod there. I have a SB Buick 340 4 bbl. factory Hi-Compression engine that I plan to place in there (in 66 it was advertised as 10.50:1 from the factory 260 HP - thing runs great). That will be more than ample to haul my race car or anything else in that weight range. I'd hate to change it all over to 5 lug . . . If that's my option I am sure there is a guy on the board who has 100 sets sitting in his yard right? And if I go that route it ain't just a spindle swap. It's a lot deeper than that, ain't it!?

[Sicklajoie]

You've got yourself a sweet truck. Congrats!
I almost bought a blue and white C/20 in Yaphank a year ago. It had 4.56's also... man did that thing scream.

[BlazinC5]

Yacster: Yeah, I do believe that it is more than just spindles. And, you are prolly correct on lots of people having the 5 lug assemblies layin around. Shoot, I even have a complete extra setup from a 71 GMC. I'll probably sell them off someday. But, it sounds like you got a pretty good plan going for your truck now.

[Rooster's 67]

I did an eight lug conversion on a 3/4 ton 65 model for a buddy...if i recall I bought a front clip off of a mid 80's R20 2wd suburban, installed the later model ball joints on original 65 arms, then swapped in the newer spindles, rotors, power steering box, center link and all tierods oh and the sway bar also.
Kinda the same swap as the half tons, just using 3/4 ton stuff instead.
As a side note GM didn't change much over the years.
I will see if I can dig up pics.

[Yacster]

Rooster. Thanks so much for that reply. I am a visual person without pics I have trouble "seeing" things (as opposed to auditory folks). My truck already has PS. Will I still have to swap the existing PS box, or will the center link assembly out of the 80's 3/4 ton bolt up to that? I am sure I can find a 2wd 3/4 ton chevy somewhere near by at a wrecking yard. I am so glad they didn't change much over time. Would it be safe to assume that any 8 lug disk assembly (GM 3/4 ton) prior to say 87 would work?


Sicklajoie- Believe me I know. I'm showing 35-3700 RMP at 65 mph. On the hwy I try to keep it under 60 but on Long Island they just about run you over at that speed...lol

[Rooster's 67]

Yacster, The best way to do the conversion is find a proper 8 lug donor truck and have them cut the frame behind the shocks. That way you can reference the proper location for the power steering box and idler arm on the frame. I had to drill a new location for the idler, and I made my own spacer plate/reinforcement plate for the box. If you use the factory locations it will change the geometry of the steering linkage. I am unsure as to the interchangeability of the center link, depending on what the box is off of originally, it may not have to change.

Once again if you get the whole front frame section you will have any and all parts you may need.

Also keep in mind the brake line routing is different on the later model trucks.

Also I believe donors could be 73-87 C20's or 73-91 R20's I also think the four door C20's went to 91. Pretty much any square body truck of 3/4 ton 2WD should be a viable donor.
Also Vans used the same suspension as the trucks but the steering linkages are different but the basic suspension is the same, spindles, arms, disks, calipers, etc

Also holler at me if ya need more pics of the conversion i did on that c20

the First pic also shows the correct brake hose routing and you can see the original mounting locations for idler, and the new location that I referenced from the Suspension pick up points.
The second pic show the location I used for the proportioning valve.

[Yacster]

Rooster again- Thanks for the detailed reply. A good shot of the PS box/pitman arm would complete the set.