rear drop question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

76bonanza · 05-23-2006, 03:42 PM

My rear drop is supposed to be 4 inches. I am redoing my rear drop because the PO used 4 inch blocks and I am going to drop springs. My question is I like the hieght in the rear but not sure how old the coils are now so dont know if it is 4 inch or not. I am running 275 60 15 tires and it sits about 30.5 inches to the high part of the wheel wells to the ground. Does this sound right? I just want to make sure 4 inch drop springs will leave me in the same general area.

Thanks for any help

see ten · 05-23-2006, 03:48 PM

Try measuring from the frame to the axle tube. ECE claims a 6" drop will leave 3" between the frame and the axle. So we can assume that a new factory spring will leave 9" between the frame and axle. Do the math from there to figure your amount of drop or sag.

Gennoy · 05-23-2006, 06:59 PM

Here was a picture of mine with a 4" drop spring in the back and an old L60-15 on. That tire should be 27.9" tall which is close to the same size as a 275/60R15 (28"). Maybe the tires were a little flat cause it doesn't look like it is 27.9" tall in the picture. You can tell the top of the wheel well is about 29.5 inches or so.

76bonanza · 05-23-2006, 08:37 PM

if this is were I am supposed to messure. it is like 4 and 1/8 inchs so by your calculations see ten it is closer to a five inch drop. The blocks are 4 inches exactly and about 3/4 inch of sag. Does this sound right? So if I get ECE's 5 inch rear drop kit. With springs shocks and all the fixins it should leave me close to the same? I dont want to get it lower than the front it is about 3/4 inch rake now would like to get as close to level as possible with out going over. I think that ECE kits has all I need yes? I dont need to notch it or anything do I.

see ten · 05-23-2006, 09:57 PM

To me it looks like 5" would put you right were you want to be. Give the guys at ECE a call and bend their ear a bit. I am sure they can point you in the right direction. A notch shouldn't be necessary for 5". ECE claims you don't need a notch with 6" but I think it wouldn't hurt.

70c10 · 05-23-2006, 10:26 PM

I have 4" drop springs on the rear with 275/60/15 and I think mine is also 30.5".

05-23-2006, 03:42 PM	#1
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	rear drop question My rear drop is supposed to be 4 inches. I am redoing my rear drop because the PO used 4 inch blocks and I am going to drop springs. My question is I like the hieght in the rear but not sure how old the coils are now so dont know if it is 4 inch or not. I am running 275 60 15 tires and it sits about 30.5 inches to the high part of the wheel wells to the ground. Does this sound right? I just want to make sure 4 inch drop springs will leave me in the same general area. Thanks for any help __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

05-23-2006, 03:48 PM	#2
see ten WTB this ad Join Date: Sep 2004 Location: Lafayette Georgia Posts: 5,074	Re: rear drop question Try measuring from the frame to the axle tube. ECE claims a 6" drop will leave 3" between the frame and the axle. So we can assume that a new factory spring will leave 9" between the frame and axle. Do the math from there to figure your amount of drop or sag.

05-23-2006, 06:59 PM	#3
Gennoy Registered User Join Date: Nov 2005 Location: Antelope, CA Posts: 21	Re: rear drop question Here was a picture of mine with a 4" drop spring in the back and an old L60-15 on. That tire should be 27.9" tall which is close to the same size as a 275/60R15 (28"). Maybe the tires were a little flat cause it doesn't look like it is 27.9" tall in the picture. You can tell the top of the wheel well is about 29.5 inches or so. __________________ 1969 Chevrolet C-10 SWB

05-23-2006, 08:37 PM	#4
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	Re: rear drop question if this is were I am supposed to messure. it is like 4 and 1/8 inchs so by your calculations see ten it is closer to a five inch drop. The blocks are 4 inches exactly and about 3/4 inch of sag. Does this sound right? So if I get ECE's 5 inch rear drop kit. With springs shocks and all the fixins it should leave me close to the same? I dont want to get it lower than the front it is about 3/4 inch rake now would like to get as close to level as possible with out going over. I think that ECE kits has all I need yes? I dont need to notch it or anything do I. Attached Images __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

05-23-2006, 09:57 PM	#5
see ten WTB this ad Join Date: Sep 2004 Location: Lafayette Georgia Posts: 5,074	Re: rear drop question To me it looks like 5" would put you right were you want to be. Give the guys at ECE a call and bend their ear a bit. I am sure they can point you in the right direction. A notch shouldn't be necessary for 5". ECE claims you don't need a notch with 6" but I think it wouldn't hurt.

05-23-2006, 10:26 PM	#6
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	Re: rear drop question I have 4" drop springs on the rear with 275/60/15 and I think mine is also 30.5". __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads



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