Grandpa’s Blazer gettin fixed up…

[Jon52]

So question. From the factory this K5 had 31.95” tires. So how will 33”s be so terrible? I am confused? Ignorance to the geometry and impact of the gearing but was hoping 1” body lift could get me into 33”s with 17” rims. Going for this look as concept. Yeah this was AI generated based on year Make model 1” body lift on 33”s.

 

[HankScorpio]

You should play with this gear calculator a little bit.
https://grimmjeeper.com/gears.html
Just plug in which trans, t-case, ratio, tire and its all there to compare.
A 3.08 gear with a 33" at 3000 rpm is 91 mph. With 35" tire its 96. Or at 70mph with a 33 its 2400 rpm vs 2100 rpm with a 35.

A 3.08 will feel really underpowered pulling a boat with either tire but it will work. Since you don't need to be running 70,80,90mph you can swap some of that top end speed for low end power by lowering the gears. A gear ratio calculator like above really helps see what the changes will do for your truck.

 

[82355]

I was hoping you were going to paint the PA6 Styled Wheels back to white and use them!

They sucked from the factory with 3.07’s.

Martin

 

[Blue85]

From the factory this K5 had 31.95” tires.

Where do you get that number? Metric conversion without rounding? There's no such precision.

 

[AJMBLAZER]

Found it… last box of parts I opened. Does this tell a story about rear end gearing?

View attachment 523948

It had 10-15 tires when new. That’s an old measurement roughly equivalent to 31x10.5R15’s. Maybe 30” tall on the truck.

Assuming you keep similar wheel dimensions to stock (8 inches wide with about 4 inches of backspacing) and your springs aren’t too saggy then you should be able to fit 33’s. If you go with a narrower tire instead of a wider tire they will fit easier.

 

[sweetk30]

Where do you get that number? Metric conversion without rounding? There's no such precision.

Better go look at tires specs then . There is no perfect tire thats exactly to size on sidewall .

 

[mudmobeeler]

I'm running a 33x12.50r17 on a 17x8.5 (or possibly 9 inch wide) rim on my blazer with zero lift at the moment. Mine being an M1009 though I do believe they had an extra leaf up front compared to civilian K5s but I'm not 100% positive on that. I do have a one inch body lift and new body bushings from Offroad Design that I need to install. It will rub some if you flex it out, especially if you're turned any.

If I was going to stick with 33s, I would do the one inch body lift and possibly some 2 inch springs front and rear. Or some 56 inch springs in the rear from a 3/4 ton and a 2 1/2 inch shackle flip to account for towing my little trailer/a boat trailer some.

 

[AJMBLAZER]

M1009's just had the standard higher GVWR diesel K5 springs.

 

[mudmobeeler]

M1009's just had the standard higher GVWR diesel K5 springs.

I didnt know if it was anything "special" for the military or not. Wasn't thinking about the diesel aspect of it but does make sense.

 

[AJMBLAZER]

Virtually everything about the CUCV's was off the shelf parts. Even the charging system was parts GM could source, not special CUCV only stuff.

 

[imiceman44]

Where do you get that number? Metric conversion without rounding? There's no such precision.

31x9.5

 

[Blue85]

Better go look at tires specs then . There is no perfect tire thats exactly to size on sidewall .

There has never been a sidewall with x.95 on it. Never a decimal point except .5. You are correct that the size printed on the tire is only a "class" and not the actual dimensions - I'm not arguing that, just that the number posted was bogus.

31x9.5

31's were not common until later in the 80's. According to the brochure https://ck5.com/forums/threads/1978.324340/, they came with H78-15B standard, which is a skinny 29" tire. If you ordered anything else, would that be on the RPO sticker?

 

[imiceman44]

There has never been a sidewall with x.95 on it. Never a decimal point except .5. You are correct that the size printed on the tire is only a "class" and not the actual dimensions - I'm not arguing that, just that the number posted was bogus.

31's were not common until later in the 80's. According to the brochure https://ck5.com/forums/threads/1978.324340/, they came with H78-15B standard, which is a skinny 29" tire. If you ordered anything else, would that be on the RPO sticker?

Who's to say it's original

 

[82355]

31's were not common until later in the 80's. According to the brochure https://ck5.com/forums/threads/1978.324340/, they came with H78-15B standard, which is a skinny 29" tire. If you ordered anything else, would that be on the RPO sticker?

His SPID shows that it was ordered with 10-15/B tires on 15"x8" PA6 Styled Wheels.

Martin

 

[Blue85]

His SPID shows that it was ordered with 10-15/B tires on 15"x8" PA6 Styled Wheels.

Martin

That's 29.25" tall, right?

Who's to say it's original

Nobody is suggesting the vehicle has it's original sized tire today. The argument was that going to a 33" tire isn't much of a change from original - as in the original gearing should be OK. Of course, that gearing was never great to begin with.

I think what you're suggesting is that maybe the gears have been changed at some point, so it should be verified rather than relying on the sticker.

 

[imiceman44]

That's 29.25" tall, right?

Nobody is suggesting the vehicle has it's original sized tire today. The argument was that going to a 33" tire isn't much of a change from original - as in the original gearing should be OK. Of course, that gearing was never great to begin with.

I think what you're suggesting is that maybe the gears have been changed at some point, so it should be verified rather than relying on the sticker.

I was just explaining the 31.95, I agree that for his purposes he needs to get the math from the original tire size, and whether the gears were changed or not I don't know. I wasn't implying it.

 

[Jon52]

Help. Front drive axle issues.

So pulled them off pressed out u-joints with penetrating oil and deployed the torch… good news got them apart. Bad news bent the ears in the process. I can get pass side together but only 2 clips will go in. Other side tried to put u-joint in the “good” inner shaft only to find it is bent too just enough you can’t get ujoint into the pocket with the caps off.

Anyone have a good set of stock drive axles or know wheee I can get a set?

It is the Dana44 10-bolt

 

[Jon52]

That's 29.25" tall, right?

Nobody is suggesting the vehicle has it's original sized tire today. The argument was that going to a 33" tire isn't much of a change from original - as in the original gearing should be OK. Of course, that gearing was never great to begin with.

I think what you're suggesting is that maybe the gears have been changed at some point, so it should be verified rather than relying on the sticker.

Grandpa never changed the gears. I got info from stamped numbers on tag and inside pumpkin. But I could be wrong. Just a noob.

 

[fourwheelerjeff]

Help. Front drive axle issues.

So pulled them off pressed out u-joints with penetrating oil and deployed the torch… good news got them apart. Bad news bent the ears in the process. I can get pass side together but only 2 clips will go in. Other side tried to put u-joint in the “good” inner shaft only to find it is bent too just enough you can’t get ujoint into the pocket with the caps off.

Anyone have a good set of stock drive axles or know wheee I can get a set?

It is the Dana44 10-bolt

View attachment 524575

View attachment 524576

is the inner shaft or outer shaft bent? or do you want to replace both for peace of mind?

 

[Jon52]

There has never been a sidewall with x.95 on it. Never a decimal point except .5. You are correct that the size printed on the tire is only a "class" and not the actual dimensions - I'm not arguing that, just that the number posted was bogus.

31's were not common until later in the 80's. According to the brochure https://ck5.com/forums/threads/1978.324340/, they came with H78-15B standard, which is a skinny 29" tire. If you ordered anything else, would that be on the RPO sticker?

Yeah I got the 31.95 off a Chevy build info site online. It’s on the internet so it has to be accurate. I mean, right??? LoL