BDS 6" lift

[76stepsidechevy]

Im in the process of putting in a 6" bds lift on my 76 k10 shortbed (350 465 205) and im looking for some advice. Ive lifted jeeps in the past but this it my first truck. I put in the rear springs this weekend with a newly built 12 bolt rear (got rear ended, broke the rear and one stock spring) The truck had an old 4" rancho kit with front springs and rear blocks before.

The new 6" bds rear springs have a degree shim on them and I have some vibration starting at around 50 mph. Im wondering if I need to drop the t case or should try running without the shims or different shims. I have a two month old tom woods driveshaft that was in the accident but seems undamaged.

The new front springs which I ran out of time to install this weekend also have shims. Im afraid using those shims will correct my pinion angle but take out some caster and make it wander on the road, Its got quite a rake to it now with those old sagged rancho springs up front and its hard to keep straight already. Im also wondering if i'll need to make any other changes up front as far as steering.

[Chevy1TonFun]

The rear shaft sounds like it needs to rebalanced or the drive angle is to much. As for the front, give the shims a shot and if needed swap them out for the right ones.

[76stepsidechevy]

Its only a single cardon shaft in the rear and the transfer case isn't dropped, I was taught with a single cardon you needed to have both angles the same or it would vibrate. The angle doesn't look all the great but I think more shim would just make it worse. I have a pile of shims left over from experimenting with my jeeps rear cv shaft I just hate to be taking my truck apart until I get it right in this weather.

[maskale]

Originally Posted by 76stepsidechevy

Its only a single cardon shaft in the rear and the transfer case isn't dropped, I was taught with a single cardon you needed to have both angles the same or it would vibrate. The angle doesn't look all the great but I think more shim would just make it worse. I have a pile of shims left over from experimenting with my jeeps rear cv shaft I just hate to be taking my truck apart until I get it right in this weather.

So u know the angles need to be the same, and u admit the angles dont look great. So why ask? Go fix it.

Dont stack ur shims.



If ur angles are good then ur problem is somewhere else.

For checking for vibration its best to run a known set of good smooth hwy tires. An old set of 44" boggers wont tell u much about ur drive line.

[76stepsidechevy]

Originally Posted by maskale

So u know the angles need to be the same, and u admit the angles dont look great. So why ask? Go fix it.

Dont stack ur shims.



If ur angles are good then ur problem is somewhere else.

For checking for vibration its best to run a known set of good smooth hwy tires. An old set of 44" boggers wont tell u much about ur drive line.

I just want to know why they include a set of shims they know is going to make your angles wrong. You cant address one end and not the other and expect the angles to be right. I realize something has to be done about the rear I was more currious about the front before I put them in.

Ive got a set 33 bfg a/ts that are now far too small but smooth.

[76stepsidechevy]

Just went out and checked the rear angles with an angle finder. Looks like without the shims the angles would match. There off by 9 degrees, probably 8 degree shims in there...

[maskale]

Originally Posted by 76stepsidechevy

You cant address one end and not the other and expect the angles to be right.

What do u mean by "end"? U talking about front and back?

Front and rear angles are independent of each other and will be set up accrding to ur driveshaft.

U said ur rear is single cardian so ur Tcase out put and pinion should be parallel minus 1.5-3* on the pinion.


U didnt say what ur front shaft is. What is it?

I would worry more about the rear shaft and getting it right. U dont always use 4x4 and when u do its usually low speed, so being off on ur degrees more up front wont make much difference, well u wont feel it anyways.

I have my rear dialled in. The front pinion should come up several degrees more, I already have 3* shims in it, but dont want to add more. For what I use my truck the incorrect angle has been just fine. Yes it may wear faster when I actually use 4x4, but not enough to worry about it.

I also have a 76 Step short 4x4 with 6" lift, just finished building it about 3 months ago.

[76stepsidechevy]

Im talking about the rear driveshaft now, haven't swapped the front springs yet. I mean you cant move the pinion angle and not address the t case. The bds lift kit has no transfer case drop or anything so why include the shims. It appears that if I remove the rear shims the angles will be paralell minus 1.5 for spring wrap.

As far as the front I'd rather have the caster be correct and be able to steer the truck at the expense of a little vibes in 4wd. I think the shims they included are 4* Does your truck wander with the shims?

Did you end up using shims in the rear? I know every truck is different but it would at least get me in the ballpark.

Do you have any pics of your truck ? I kinda started a little build here after being side swiped the friday before christmas. My truck had an ancient 4" rancho lift and my rear end and one rear leaf were broken in the accident. Nobody withing driving distance had another 12 bolt with 3.73s so I bought the cheapest one localy just for the housing and put new gears and an eaton posi in. I figured it was a good enough excuse to upgrade my rear end and my suspension, looks like ill need some bigger tires now too.

[maskale]

The rear pinion angle has nothing do with the Tcase, meaning, just cause u move one doesn't mean u have to move the other. U move which ever one or both to get the angle u need. In this case just move the rear. U want the Tcase in a happy medium, make the rear happy and the front might not be, and vice versa.

Just cause they send shims don't mean u need them. Do what U need to do to get the angle.

I do have rear shims, I have a 6" lift via 2" springs and a shackle flip. So that also played apart in my angle vs blocks. I don't remember exactly the angle of my shims, but none are greater then 3.5, I wanna say 3.5 rear and 2.5 front, but thats a really foggy memory. FYI: I had to shim my rear pinion down and the front up.

On the front I have a double cardian, so needed to shim my pinion up, it is still to low, but works for me in 4x4. The truck does track straight.

Say what? Pics? Ok. In no order.

[76stepsidechevy]

Nice truck! Were the gas caps that low in the fenders in 76 or are they from a different year. Mine are up high, then again I have a newer hood too so who knows. I need a fender now and they only offer a 73-78 or 79 and up. Maybe its a repop vs. gm thing.

I guess I assumed those angles would be paralell with the right springs already. Im used to dealing with jeeps which have such short driveshafts that you need shims and transfer case drops to get the u joints into angles that they can operate at.

It seems I can just pull those shims and have paralell angles but they might be a bit steep for the u joints liking. I think there good up to 15 degrees if I remember correctly and I'll be at 10 so I guess ill be ok.

[maskale]

My truck was optioned with dual tanks. My right gas cap is much higher, thus the reason for routing the rear tank fill hose to the right side. I dont know if they are originals or not. I have not replaced them.

An angled drive shaft is actually better then a straight one. Unless very extreme to the point of binding U-joints will do just fine. A U-joint is basically a bearing inside its cups. The more they move the more they distribute the grease and keep the wear even on the needle bearings. Vibration will kill them faster then angle.

Left, is even with bottom of bed.



Right






First time flexing her and testing everything out, so stuff is hanging and only running on half the lug nuts. But u can see the caps are very different. I wish they weren't like that, but the cost and hassle aint worth it. 99% wont notice anyways.

[76stepsidechevy]

Ha, my truck had one tank from the factory but had the holes in both fenders when I got it. Both of mine are high like your right fender. The left fender just had a hole so ive been saving up parts to add the second tank. 16 gallons doesn't get you very far so the extra tank will be nice. Im guess both of my fenders were already repops. The truck was redone sometime in the 90s and I can tell the doors werent gm.

[maskale]

I had two 16 gallon tanks, now have a 25 rear and 16 driverside. If i were to do it again I would just go with the rear blazer tank, they make a 25 and a 31.

The hassle aint worth both tanks, just get a rear 31 and be done. Yes putting a rear tank is also a hassle, but so will adding another tank, especially to a non dual tank truck. The plus of the rear tank is weight on the rear tires.


Rear tank all the way.

[76stepsidechevy]

Yea I actually considered that alot. The useless hole in the drivers side fender bugs me though. Maybe ill set it up a bit different then factory with a transfer pump or something. I also have a holley tbi setup waiting to go on so im probably going to end up buying the right tank for the in tank pump anyways.

[maskale]

Just put a fill neck in the hole and put a cap on it. Noone will know.
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[76stepsidechevy]

lol thats what I have now. Im sure it bugs me more than anyone.

[76stepsidechevy]

Finally got those front springs put in today. Ended up leaving the shims on and it was a mistake, this thing is all over the place. Looks like i'll be taling them out and probably trying to find a single cardon front shaft or having one made. Even with the shims in the pinion angle isn't right for a cv shaft.

[mud.man.rj]

Wouldn't shimming the front throw the caster off, I use shims in back with my 6" spring lift but not the front.

[76stepsidechevy]

see that was my thought too but the bds lift springs came with shims already bolted to the springs both front and back. Guess I should have trusted my instict. How big of a shim are you running in the back? Im getting vibes around 50 with what looks like 8* shims back there.

[mud.man.rj]

I think you are right with about 8 degree shims, same as mine, my front didn't lift enough for me for clearance if abused a bit so I pulled my front packs apart pulled the shims that also came with mine and added and extra leaf on the bottom just for more height. I would have the rear shaft checked.

[76stepsidechevy]

Rear shaft is a 2 month old tom woods but the reason for this build was an accident. I got rear ended and most of the impact hit the pass side rear tire, the pumpkin cracked and the spring on that side broke in 3 places. I think the shaft is ok but I guess it wouldn't hurt to have it checked, even just put the rear on jackstands and let it idle in gear and watch to see if its bent. One of the u joint cap bolts was mashed up but I couldn't find a corresponding mark on the driveshaft where it hit.

[mud.man.rj]

The thing is it wouldn't take much for a bit of a tweak to show at the rear of the shaft, you could run it up in the air but I would want to set up some kind of pointer at the shaft to check for runnout when turning, either way take a better look at it for piece of mind and eliminating the shaft from prob. I am leary though especially with the cap crushed.

[76stepsidechevy]

Thats a good point. I still have the stock shaft but Im not sure if it would reach with the 6" lift, the slip joint is trashed in it anyways. I'd think the vibes would be constant if the shaft were bent though, they start at about 50 then go away and come back around 65-70. I checked with an angle finder the other night too, lol angles look about 8 degrees off... Maybe I should put the front shims in the back.

[mud.man.rj]

Even if you could just do some kind of run out check up on stands, sure the other shaft won't fit for lenght, I had to have one made. I never touched my t.case at all, no drop.

[76stepsidechevy]

Yea, I'll throw it up on stands in the morning and check runout. Do you have a cv shaft up front? Looking at the angles if I were to go with a standard single cardon shaft the angles might work but they look like crap for my present cv even with the shims. Its almost undrivable as it is, the half hour drive home from my shop was work. I cant live with vibes on the highway in 4 wheel a lot easier then lousy steering.