Lifting my 90 model k5

[jbristo67]

I recently bought a 1990 k5 blazer. 86k original miles efi 350. I want to lift it enough so that I can run 35's what is the most cost effective way to get there? Also how much lift do I need? I also want to keep my gear ratios as close to stock as possible for gas mileage purposes so what do I need to re gear to? Thanks in Advance for the help
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[68Timber]

4" spring front, block rear. 4.11 gears will put cruise rpm at 70 mph at 1,933 rpm. Might be a touch low for a brick up in the breeze at speed. 4.56 gears will raise engine rpm at 70 mph to 2,145. That should be enough to keep it from downshifting constantly if the engine is healthy, but I haven't done it myself to know for sure.

[jbristo67]

I think in that case ill run 456. Yeah motor is beyond healthy. What should I expect to spend on gears
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[68Timber]

$400 to $500 in parts for a front and rear gear swap full kit, another $400 to $500 in labor to change the ring and pinion front and rear.

[jbristo67]

I don't believe in paying for labor
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[LONGHAIR]

Originally Posted by jbristo67

I don't believe in paying for labor
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Unless you know someone willing to trade you labor for something else, make an exception on this one. This is not a job to tackle yourself, it is best left to a pro.

[jbristo67]

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[68Timber]

I don't either. My latest gear/posi is being done on favor for favor trade - best way.

[Ski-me]

2.5" BDS front leaf springs, 2.5" blocks in back.

35" tires on 15" wheels.

At 70 MPH with 3.73 gears, I am at about 1,800 RPM's and it does downshift if I go up any grade....

I do rub on my front fender if I turn sharp while hitting a bump. 4" lift would probably solve that but I prefer it lower.

[riz]

I have 4" of suspension and 2" of body lift to fit my 35s..... I curerently have 3:42 gears but plan on swapping to 4:56s for the proper driving rpms... My engine is a very healthy balanced and blueprinted 350.

RIZ

[jbristo67]

Originally Posted by Ski-me

2.5" BDS front leaf springs, 2.5" blocks in back.

35" tires on 15" wheels.

At 70 MPH with 3.73 gears, I am at about 1,800 RPM's and it does downshift if I go up any grade....

I do rub on my front fender if I turn sharp while hitting a bump. 4" lift would probably solve that but I prefer it lower.

dude your blazer is exactly what I'm going for. I will prob run black 20's instead of 15's but your blazer is sweet.
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[Ski-me]

Originally Posted by jbristo67

dude your blazer is exactly what I'm going for. I will prob run black 20's instead of 15's but your blazer is sweet.
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While we are on the subject...how many leafs do you currently have in the rear (including the Overload on the bottom)? 5 or 6? Just curious.

I assume just two leafs up front....correct?

[bohmankid]

Mine has a 4 inch lift by Procomp. Springs in the front, blocks in the rear. 35x12.5 R16 tires don't rub.
Also, an alternative do the blocks would be a shackle flip. I wish I would have done that instead of the blocks.

[Ski-me]

Originally Posted by bohmankid

Mine has a 4 inch lift by Procomp. Springs in the front, blocks in the rear. 35x12.5 R16 tires don't rub.
Also, an alternative do the blocks would be a shackle flip. I wish I would have done that instead of the blocks.

Attachment 1047282

I've heard that a lot on the blocks but never really understood the real reason. Why would you prefer the spring lift or shackle flip vs. a lift block? What are the measurable differences you've experience?

U-joint life? Axle wrap (and how can you tell)? Etc.

A lot of people "say" the leaf lift is preferable but why?

Thanks!

[Prerunner1982]

Originally Posted by Ski-me

I've heard that a lot on the blocks but never really understood the real reason. Why would you prefer the spring lift or shackle flip vs. a lift block? What are the measurable differences you've experience?

U-joint life? Axle wrap (and how can you tell)? Etc.

A lot of people "say" the leaf lift is preferable but why?

Thanks!

Axle Wrap- the rear end will bounce and/or thunk when accelerating or getting on the gas hard. The block put more leverage on the leaf twisting it into a lazy S (S on it's side) shape. Then the spring tries to pop back into it's original position, back and forth they fight until the torque is released.

A lift leaf pack will be arched more than the stock spring with a block and have less leverage, therefore will better counter act the torque load.

This may also help the rear u-joint life since the pinion of the axle will not be snapping up and down violently.

A shackle flip provides the lift, keeps the stock spring for a better ride and flex (less arch = better flex) and since the leverage between the axle and the leaf pack has not change (other than due to tire size) it is not as likely to cause axle wrap as a block would.

They make traction bars and add on leaves that are meant to counter act axle wrap as well.

[dman1982]

if you have the cash i would go with something other than rough country, the price is right on them but takes them forever to smooth out, they live up to their name when it comes to rough....my k10 has a 6 inch lift (i ordered a 4) and its a rough ride...but my 35's fit under there nice and sweet...thing is tho i got those 35's with some 3.08 gears with the th350 tranny, not cool going down the highway and its super slow outta the hole

[cdm10700]

i had 35s on a 4 in lift no problems with turning or anything
what transmissions you guys running to get the lower rpms at 70mph
i have sm465, 205, 3:73 and i think it runs about 2100 2200 at 55

[dman1982]

Originally Posted by cdm10700

i had 35s on a 4 in lift no problems with turning or anything
what transmissions you guys running to get the lower rpms at 70mph
i have sm465, 205, 3:73 and i think it runs about 2100 2200 at 55

i believe they have the 700's...overdrive

[Ski-me]

Originally Posted by dman1982

i believe they have the 700's...overdrive

Yea, 700r4.

Be careful with 3.73 gears. Just because they are higher doesn't necessarily mean better gas mileage with larger tires. Mine has to work pretty hard to get the thing rolling down the road. My MPG is about 11.

I met another guy who has 33 inch tires and went from 3.73 to 4.56. His mileage went from 11 to 14. So keep that in mind as you analyze gearing.

[79Betty]

Also depends on the motor, th350 4.11's 35's i get about 13 highway. Hopen my 465 swap and 3.08's will counter it and help...
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[cdm10700]

you will get better mileage with 465 and 3:08s?

[79Betty]

With my 350 n 4.10's im crusin at 3,000 rpm. Both final drive's are 1:1 so i'll be crusin at about 1900 with 3.08's. more in my power range. At 3k my motor is about topped out. With the 4 speed i'll have my town gas milage, as the gears one lower in the tranny, but one higher in the axles make up for it... Hard to explain on here lol. Woth my 350 n 3.08's it's too high in town so it'll make up for it. This's my cruiser not my toy.
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[dman1982]

^^^^^i so agree!!!!^^

[DetroitDan]

I had a 91 Blazer last year with a 4 inch all-spring lift and BFG 35s. Could get them to rub hitting a bump while turning (into my driveway, every day) so I clearanced it with a sawzall just a little. Had 3.08s and a 700r4 behind a tbi 350, too much tire height for those gears, but I would definitely not recommend 4.56s. Way too much imo. 3.73s would be enough to satisfy most, 4.10s are pretty much ideal. Keep in mind, your carriers won't support a drastic swap. May want to consider swapping in 3/4 axles, easy swap. Radial tires rarely measure anywhere near their stated size, so you're probably only getting a 33 anyway.
Hey Ski-me, are you sure that's only 2.5 inches of lift?! Mine had the same exact tires and yours is as tall, probably taller. I would have bet that was a six inch lift. Doesnt look like theres any bodylift there either.

[Ski-me]

Originally Posted by DetroitDan

I had a 91 Blazer last year with a 4 inch all-spring lift and BFG 35s. Could get them to rub hitting a bump while turning (into my driveway, every day) so I clearanced it with a sawzall just a little. Had 3.08s and a 700r4 behind a tbi 350, too much tire height for those gears, but I would definitely not recommend 4.56s. Way too much imo. 3.73s would be enough to satisfy most, 4.10s are pretty much ideal. Keep in mind, your carriers won't support a drastic swap. May want to consider swapping in 3/4 axles, easy swap. Radial tires rarely measure anywhere near their stated size, so you're probably only getting a 33 anyway.
Hey Ski-me, are you sure that's only 2.5 inches of lift?! Mine had the same exact tires and yours is as tall, probably taller. I would have bet that was a six inch lift. Doesnt look like theres any bodylift there either.

Sorry man, missed your question from way back....But yes, it is only a 2.5" lift from BDS. In fact, I felt that it was just a "little springy" so I took one leaf out up front. It now rides more smoothly too. Block in rear measures a little over 2" and the rear springs are new, stock height replacements.

15x10 wheels.