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#1 |
Registered User
Join Date: May 2016
Location: Idaho
Posts: 87
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First Post - a lot of 4x4 and 3/4 ton questions
Hello everyone.
I have been looking for a while for a good project 3/4 ton 4x4 and finally closed the deal on one yesterday, a 1968 GMC. It was quite a drive to get it but I was able to get it for a good price. The body is a little rougher than I wanted but I'll get some good body work practice out of it! I am not a stranger to restorations as I completely redid my 1971 Chevelle back in high school with my father, but I am new to 4x4 components so I'll probably have a lot of questions for you all in that area. This looks like a nice forum, I'm glad to be here. -old_iron Last edited by Old_iron; 05-04-2016 at 02:20 PM. |
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#2 |
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Location: Ephrata, WA
Posts: 308
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Re: First Post - 1968 GMC 4x4 3/4 Ton
Good luck. I know what you mean about "the body being rougher than I wanted".
It is a lot of work, but many people have done it, and like us.. "are" doing it.
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68 C10 SSB 383 12 Charger 6.4L 12 Accord 3.5L (Wife's ride) 05 Ram 1500 5.7L My build thread - http://67-72chevytrucks.com/vboard/s...d.php?t=676545 |
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#3 |
Registered User
Join Date: May 2016
Location: Idaho
Posts: 87
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Re: First Post - 1968 GMC 4x4 3/4 Ton
The goal for this truck is to mainly:
1. Plow snow in winter via detachable plow (like a Meyer) 2. Handle really well /stable in the snow and ice 3. Haul heavy loads of firewood and such out of the woods, and on 55mph roads 4. Utilize either a fixed or trailer-hitch-mount winch up front Rarely: 4. Tow heavy trailered loads (maybe up to 12,000 lbs) short distances What it currently has: Mid-70s open Dana 60 rear, not sure of ratio yet Not sure of the front Mid-70s Np205 transfer case Chevy 4 speed truck trans 305 v6 Non-power brakes Non-power steering Steel wheels (ignore the split wheels on the rear, have replacements for them). I am going to swap in a moderate 350 with HEI. My questions for all of you: 1. What rear ratio should I go with for the rear? 2. Does the front need to be the same ratio? 3. What type of rear should I run, open, posi track/limited, locker? 4. Are their differences between 1/2 ton and 3/4 ton power brake boosters/master and power steering units? 5. Will the stock 305 bellhousing , flywheel and clutch work with a 350? 6. I will probably want to lift it 2-3 inches. Is there front spring lift kits that are 3/4 ton specifically? 7. When lifting what parts have to be changed/replaced other than the springs? 8. Should I upgrade the suspension to 1 ton to handle having a plow in the front? 9. I have a set of steel Ford wheels (the front ones in my photo). The hub hole is larger than the hubs. With the loads I want to handle, is it important that I use Chevy wheels that have the same size hole as the hub to hold the load? 10. Is the stock granny-gear trans the best option? Appreciate the advise, I am in over my head with some of this. |
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#4 | |
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Location: Anza, CA
Posts: 160
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Re: First Post - 1968 GMC 4x4 3/4 Ton
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#5 |
Registered User
Join Date: May 2016
Location: Idaho
Posts: 87
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Thank you Chknlyps2 for all of your answers. Someone on here must know about snow plowing...
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1968 GMC 3/4 Ton 4x4 K20 / 2500 1971 Chevrolet Chevelle Malibu |
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#6 |
20' Daredevil (Ret)
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Location: Jefferson State
Posts: 13,647
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Welcome to the board!
Can't help with snowplows but I'll try to add a bit to the above reply. 6. I will probably want to lift it 2-3 inches. Is there front spring lift kits that are 3/4 ton specifically? Several years ago when I bought my front 2.5" Softrides, they only listed one for both 1/2T or 3/4T truck. I imagine some spring companies can custom build them for use with a plow. 7. When lifting what parts have to be changed/replaced other than the springs? For a 2" or 2.5" lift, you need longer front shocks. Stock rear shocks will work just fine up front. Brake lines are long enough, nothing else needs changing.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#7 |
Registered User
Join Date: Oct 2013
Location: Palisade Colorado
Posts: 172
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Have you driven the truck? if so, whats it like to drive? I've only seen pictures of the 305 V6, I hope someday ill get to catch a glimpse of one, or maybe even drive one. They seem like really neat little engines! I have also heard they have a considerable amount of torque
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#8 |
Registered User
Join Date: Dec 2009
Location: El Dorado Ca
Posts: 3,374
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Hi, welcome to the forum! another K20!!!! yay! I can answer some of your questions.If you want to raise your truck a couple inches and not change shocks, use an add-a-leaf kit,comes with a couple new leaves you add in the front and one thicker one for the rear, this will add some more strength to your existing springs and some lift, for less than $200.00, I have these in several K20's you may need to get longer Ubolts, but not always.I know guys that have snow plows on dana 44 front ends with no trouble, you may want to upgrade to a dana 44 with disc brakes, from a 71-76 K20, and you will need to use a master cylinder/brackets and booster with braces,from a 71-72 K20 or C20....you have a sm465 trans if it is mated to a 205 tcase, that is the best you can get , I have a couple of those combo's in my trucks, (bulletproof)how to tell if you have a sm465 for sure is if you put it in reverse you have to push shift lever away from you and down, sm420 pull it towards you and down,not sure about your v6 bellhousing? only know small and bigblock chevy v8's...4:10 gear ratios for these trucks that haul heavy loads and tow heavy trailers is about the best ...that is what I have in all my trucks, hope this helps you, please ask all the questions you want, we love to help...love to see these old trucks get back to health!
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#9 |
Registered User
Join Date: Mar 2015
Location: st cloud mn
Posts: 163
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Re: First Post - a lot of 4x4 and 3/4 ton questions
For use in snow, never use a posi or locker in the front. It will cause the front end to wander, like stepping on the gas in a front wheel drive car. For plowing snow I would go with the add a leafs. Plows add a lot of weight to the front. Make sure you go through the front end on the truck, plowing snow will find the week parts. Especially your lock out hubs. A posi or locker would work well in the rear. I helped my cousin plow snow for several years, he had many customers. He had to put all new u joints in the truck every year. It was a 1 ton ford.
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#10 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: First Post - a lot of 4x4 and 3/4 ton questions
If you swap the v6 for a 350 you may not have to beef the front springs. That 6 weighs a few hundred pounds more than the 350. The bell will need to be changed for sure. Does that 6 run now? I had one in a 62 4 x4 and it pushed snow like it was its job. It's heavy right on top of the front axle which is always good and it has a ton of low end torque. That thing will push a house over. It's not speedy but all the ones I had (which numberd 3) were always turn key runners. If it runs good and drives try it out before you just change it. You can always put in a 350 after if you decide it's not the deal.
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#11 | |||||||
Registered User
Join Date: May 2016
Location: Idaho
Posts: 87
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Re: First Post - a lot of 4x4 and 3/4 ton questions
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a. What are the benefits of having discs up front instead of drums? b. Are there different booster/master cylinder units - one that I specifically will want/need compared to others? I want robust and dependable braking. Quote:
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It's missing one of the front hubs to I was going to get some used Warns. Are there ones that are stronger than others? With driving on ice wouldn't a locker possibly break traction when it locks and make turns more difficult? Again, I don't have a clue, I'm trying to sort through things I've read other people post and try to find the relevent info for my situation. Quote:
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1968 GMC 3/4 Ton 4x4 K20 / 2500 1971 Chevrolet Chevelle Malibu |
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#12 |
20' Daredevil (Ret)
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Location: Jefferson State
Posts: 13,647
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Re: First Post - a lot of 4x4 and 3/4 ton questions
[QUOTE=Old_iron;7583395]So, put stock rear shocks up front Yes
and keep stock rear shocks for the rear? I did, but have no rear lift, just AALs and overloads, so not sure what you'll need if you lift the rear. What are the benefits of having discs up front instead of drums? Better performance when wet, less prone to pulling (to one side), no adjustments to mess with. Do I have to pull off the inspection covers to find the ratios of both axles? Do I take the numbers on the ring gear and plug them in somewhere to find the ratio? You can jack it up & rotate a tire, and count the number of driveshaft revolutions. Getting the numbers off the gears will also work, or count the teeth, and divide the number of teeth on the ring gear by the number of teeth on the pinion. You're gonna have the inspection cover off anyway, to clean out the old oil so you can put in new oil.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#13 |
6>8 Plugless........
![]() Join Date: Sep 2007
Location: Prairie City, Ia
Posts: 17,140
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Welcome to the forum and that looks like a pretty nice truck to start out with! You've gotten a lot of good info so far. I'll reply to the locker on ice. Most lockers ratchet or unlock during a turn not under heavy acceleration. They are great IMO. The disc brake front end will be easier to get parts for over the years too.
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Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project Tired of spark plugs? Check this out. |
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#14 |
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Join Date: Dec 2007
Location: Santa Maria, Ca.
Posts: 1,423
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Re: First Post - a lot of 4x4 and 3/4 ton questions
You might look at the front axle to see if the tag is still on it. The tag will tell you the gear ratio and most likely the rear would be the same. It would be on one of the cover bolts.
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69 Chevy 4x4 383 Power ![]() |
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#15 | |
Registered User
Join Date: May 2016
Location: Idaho
Posts: 87
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Quote:
Thanks, I'll do that first.
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1968 GMC 3/4 Ton 4x4 K20 / 2500 1971 Chevrolet Chevelle Malibu |
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#16 |
6>8 Plugless........
![]() Join Date: Sep 2007
Location: Prairie City, Ia
Posts: 17,140
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Re: First Post - a lot of 4x4 and 3/4 ton questions
It depends on the scenario really. If the front end loses traction the rear will push the front of the truck straight or what ever direction the tires are turned. If the rear loses traction, then you'll slide/swing which ever direction the inertia base is greater. I'd still rather have a posi/locker for pushing snow than not have one. Without one then you really only have 1 tire in the front applying power and one in the rear. It doesn't work well in deep snow and I'm betting you'll see your fair share.
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Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project Tired of spark plugs? Check this out. |
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#17 |
Registered User
Join Date: Mar 2015
Location: st cloud mn
Posts: 163
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Re: First Post - a lot of 4x4 and 3/4 ton questions
For plowing snow you are going to to have a couple hundred pounds extra in the box anyway to help traction. I would start at about 500 extra and see how it handles. You may need more.
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#18 |
Registered User
Join Date: Mar 2013
Location: Campbellsville, KY
Posts: 888
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Re: First Post - a lot of 4x4 and 3/4 ton questions
If you're keeping stock diameter tires 4.10 sounds like the ratio you want, and yes, both axles need to be the same ratio for extended use. If you're increasing tire diameter to 35", 4.56's might be better, 33's may be a draw. Torque peak on your monster V6 is at just 1,600 RPM, FWIW. (Most truck-spec small blocks of the era peak from 2,000-2,800.)
The NP205 is about as tough as you can get. I had one in a '74 K10 (behind a TH350 - ha ha ha) and upon researching its merits and what lube it needed, the consensus was use whatever lube the transmission ahead needs (80w90 or ATF) and that it would hold over 800 lb.-ft of torque. :shock:
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Alex V. ------ 1967 C10 Suburban, 350/NP435, Green/Green, PS, PB, HD cooling, charging, shocks, and springs. 1985 GMC C3500 SRW, Sierra Classic, 454/TH400, white/blue. |
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#19 | |
Registered User
Join Date: May 2016
Location: Idaho
Posts: 87
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Re: First Post - 1968 GMC 4x4 3/4 Ton
Are their differences between 1/2 ton and 3/4 ton power brake boosters/master and power steering units?
Do they differ between 1967-1972 and 1973+? Can I bolt on 1973+ braking system and power steering system? With the loads I want to haul, is it important that I use Chevy wheels that have the same size hole as the hub to support the load instead of the studs? Quote:
I may able to buy pair of 4x4 3/4 ton axles (D44front D60rear) in 4.10 with Posi from a 1973+ Chevy. Are there any downsides to swapping these in? Any additional parts needed for this? Are those axles wider / make the wheels stick out further?
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1968 GMC 3/4 Ton 4x4 K20 / 2500 1971 Chevrolet Chevelle Malibu |
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#20 |
20' Daredevil (Ret)
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Location: Jefferson State
Posts: 13,647
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Re: First Post - 1968 GMC 4x4 3/4 Ton
No. You'll likely get differing opinions, and while hub support isn't a bad thing, studs will support more than the truck can carry. I don't recall when the stud size changed from 1/2" to 9/16" but I would stick with the larger ones, which is what my '72 K20 has. I have hauled many cords of green hardwood with no issues, and once weighed a load of topsoil on certified scales at 6,000 pounds. Drove kinda weird and I don't recommend it but nothing broke. Aftermarket wheels with no hub support.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#21 | |
Registered User
Join Date: May 2016
Location: Idaho
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Re: First Post - 1968 GMC 4x4 3/4 Ton
Quote:
Thanks Mike, good to know. Do you have any tips about my other questions?
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1968 GMC 3/4 Ton 4x4 K20 / 2500 1971 Chevrolet Chevelle Malibu |
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#22 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,647
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Not really, at least no good honest reliable information!
![]() Your SPID (glove box door sticker -- if it's still there) will show the original tire size, and I think also the gear ratio. If the tires were 7.50-16s, then yes, 31.6" would be about the right diameter.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#23 |
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Join Date: Mar 2013
Location: Campbellsville, KY
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Re: First Post - a lot of 4x4 and 3/4 ton questions
That tire diameter sounds right - I can't imagine it was any taller than 32" from the factory. Then if you plan on keeping your SM465, my opinion is 4.10's are the way to go. 4.56's will give even more grunt, but will limit your speed more than 4.10's. Regardless of where the power peaks are at on your V-6, I'm not sure what's considered safe sustained RPM for them and that may play into how limited you'd be if you were to go with 4.56's.
I can't answer any of your other axle questions - I'm not versed in what years interchange best. I have the hydraulic assist "hydro-boost" brakes on my '85 1-ton and they work well - all other factors aside I think about the toughest setup you could get on a budget would be the brakes (including hydro-boost) and axles from an 80's K30 or heavy K20, but the equipment your truck already has under it already certainly isn't too weak for the task.
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Alex V. ------ 1967 C10 Suburban, 350/NP435, Green/Green, PS, PB, HD cooling, charging, shocks, and springs. 1985 GMC C3500 SRW, Sierra Classic, 454/TH400, white/blue. |
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#24 |
Registered User
Join Date: May 2016
Location: Idaho
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Re: First Post - a lot of 4x4 and 3/4 ton questions
Thanks Alex and Mike.
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1968 GMC 3/4 Ton 4x4 K20 / 2500 1971 Chevrolet Chevelle Malibu |
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#25 |
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Re: First Post - a lot of 4x4 and 3/4 ton questions
With a 31.5" tall tire and the 1 to 1 4th gear ratio that your SM465 has, at 55 mph your rpm with different gear ratios will be as follows.
3.73 = 2188 rpm 4.10 = 2405 rpm 4.56 = 2675 rpm I also think 4.10's would be your best bet. |
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