Lowering 6" in rear....shim? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Spot1984 · 10-17-2011, 07:16 PM

I'm lowering the rear 6 inches in my 70 swb. I was wondering what degree of shim I would need. Thanks guys

**CC69Rat** · 10-17-2011, 08:49 PM

I would say ~4 deg. Coil springs or leaf rear?

I have two C10s and one S10 I have used these blocks and shims, and I wouldn't buy them from anyone else. http://www.jagsthatrun.com/Pages/Par...lignShims.html

Not my site just a highly recommended vendor. they sell shims, blocks, Ubolts, etc. Anything you need. Hope this helps.

72BlckButy · 10-18-2011, 12:22 AM

Curious why you're needing a shim. Lowered mine with a 6" drop spring with new u-bolts and didn't have any issues. Also, don't forget the shock relocator's...

gearys 5600 · 10-18-2011, 12:50 AM

Quote:

Originally Posted by 72BlckButy

Curious why you're needing a shim. Lowered mine with a 6" drop spring with new u-bolts and didn't have any issues. Also, don't forget the shock relocator's...

x-2 ...

Mine is lowered 7" in the rear with no shims and no issues.

**CC69Rat** · 10-18-2011, 06:05 AM

With C10s and / or the trailing arm suspension setup it may not be something 'required' to run however on my S10 ext cab (2.85" rear drop) I had to run a 3 deg shim to pull the pinion back around to factory spec. (It's actrually better than factory). It's just a safety thing to make sure when the geometry changes my bet would be the pinion angle would change a bit too. It may not be something noticable on the C10s (?) This is my first time building one.. Personally I plan to spec mine to 1 deg neg at the pinion. If it takes a shim, so be it. If not.. Even better. Out of curiosity, Nate (or X2). With a 6 or 7" drop and no shim, where does it put the pinion in relation to the drive shaft / U joint? I don't know, just wondering.. It may not be something even needed on the C10's. In no way doubting you guys.. Just trying to learn the C10s.

With my experience (Lifted Jeeps, dropped S10) Pinion angle has been something to consider and it may not be necessary on the trailing arms (?). Cool stuff man.

Later
Posted via Mobile Device

Sammy · 10-18-2011, 08:30 AM

I could be wrong but was at the understanding that 6 is the exact max limit recommended before needing pinon angle adjustment due to possible early failure rates. Can anyone clear this issue up? Two piece shaft might also play a huge factor also. Shock relocating mounts would be almost a must do.
If so that would explain why some see as a non-issue others do..???

**1970 CST Short Wide** · 10-18-2011, 10:04 AM

I have a short bed with a 6" drop and a 1 pieace drive shaft and Ford 9". With out the 4deg shim I got a vibration. Just my 2c

OJ1988 · 10-18-2011, 10:08 AM

Get an angle finer, and measure you pinion angle, and tailshaft angle. Thats the only way to know if and how much shim you need.

firedog · 10-18-2011, 10:44 AM

No shim on my bagged truck but there is a certain height that if I am driving at 45 there is obvious out of balance noise but just a flick of a switch and it's gone...
Posted via Mobile Device

**leddzepp** · 10-18-2011, 10:45 AM

Quote:

Originally Posted by OJ1988

Get an angle finer, and measure you pinion angle, and tailshaft angle. Thats the only way to know if and how much shim you need.

bingo.

OJ1988 · 10-18-2011, 10:56 AM

Should be finder not finer.

10-17-2011, 07:16 PM	#1
Spot1984 Registered User Join Date: Mar 2010 Location: Grand Island, Nebraska Posts: 106	Lowering 6" in rear....shim? I'm lowering the rear 6 inches in my 70 swb. I was wondering what degree of shim I would need. Thanks guys __________________ 1970 Chevy C10 shortbox- 454 1970 Chevy Nova- 383 1987 Grand National

10-17-2011, 08:49 PM	#2
CC69Rat Senior Member Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,206	Re: Lowering 6" in rear....shim? I would say ~4 deg. Coil springs or leaf rear? I have two C10s and one S10 I have used these blocks and shims, and I wouldn't buy them from anyone else. http://www.jagsthatrun.com/Pages/Par...lignShims.html Not my site just a highly recommended vendor. they sell shims, blocks, Ubolts, etc. Anything you need. Hope this helps. __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

10-18-2011, 12:22 AM	#3
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: Lowering 6" in rear....shim? Curious why you're needing a shim. Lowered mine with a 6" drop spring with new u-bolts and didn't have any issues. Also, don't forget the shock relocator's... __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package)

10-18-2011, 06:05 AM	#5
CC69Rat Senior Member Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,206	Re: Lowering 6" in rear....shim? With C10s and / or the trailing arm suspension setup it may not be something 'required' to run however on my S10 ext cab (2.85" rear drop) I had to run a 3 deg shim to pull the pinion back around to factory spec. (It's actrually better than factory). It's just a safety thing to make sure when the geometry changes my bet would be the pinion angle would change a bit too. It may not be something noticable on the C10s (?) This is my first time building one.. Personally I plan to spec mine to 1 deg neg at the pinion. If it takes a shim, so be it. If not.. Even better. Out of curiosity, Nate (or X2). With a 6 or 7" drop and no shim, where does it put the pinion in relation to the drive shaft / U joint? I don't know, just wondering.. It may not be something even needed on the C10's. In no way doubting you guys.. Just trying to learn the C10s. With my experience (Lifted Jeeps, dropped S10) Pinion angle has been something to consider and it may not be necessary on the trailing arms (?). Cool stuff man. Later Posted via Mobile Device __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

10-18-2011, 08:30 AM	#6
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: Lowering 6" in rear....shim? I could be wrong but was at the understanding that 6 is the exact max limit recommended before needing pinon angle adjustment due to possible early failure rates. Can anyone clear this issue up? Two piece shaft might also play a huge factor also. Shock relocating mounts would be almost a must do. If so that would explain why some see as a non-issue others do..??? __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

10-18-2011, 10:04 AM	#7
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,099	Re: Lowering 6" in rear....shim? I have a short bed with a 6" drop and a 1 pieace drive shaft and Ford 9". With out the 4deg shim I got a vibration. Just my 2c __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

10-18-2011, 10:08 AM	#8
OJ1988 Just a car guy Join Date: Feb 2006 Location: New Washington, IN Posts: 991	Re: Lowering 6" in rear....shim? Get an angle finer, and measure you pinion angle, and tailshaft angle. Thats the only way to know if and how much shim you need. __________________ 1955 belair Blown Pro Street cruiser 1971 Camaro Pro Touring 1973 Vega Drag Car 1970 C20 tow rig

10-18-2011, 10:44 AM	#9
firedog Registered User Join Date: Jun 2000 Location: Festus, Missouri Posts: 1,005	Re: Lowering 6" in rear....shim? No shim on my bagged truck but there is a certain height that if I am driving at 45 there is obvious out of balance noise but just a flick of a switch and it's gone... Posted via Mobile Device __________________ SOLD 1968 Chevy SWB Fleet 350/350 combo Tach/tilt/buddy buckets Bagged/18" Wheels Black on Black Project "Pandemic" the Farm Rat 1927 Chevy Capitol Truck Rat rod '30 Model A Frame Dual Carb 5.3 LS http://www.67-72chevytrucks.com/vboa...d.php?t=804162 2007 GMC 4 DOOR 2WD BUILT 5.3 STAGE 3 CAM 93 TUNE LIFTED 22X12 WHEELS 33" TIRES 2023 Jeep RENEGADE Wifes ride

10-18-2011, 10:56 AM	#11
OJ1988 Just a car guy Join Date: Feb 2006 Location: New Washington, IN Posts: 991	Re: Lowering 6" in rear....shim? Should be finder not finer. __________________ 1955 belair Blown Pro Street cruiser 1971 Camaro Pro Touring 1973 Vega Drag Car 1970 C20 tow rig



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