18x10 rears and lowering question
#1
Instructor
Thread Starter
18x10 rears and lowering question
I've read that this size rim will fit with stock trailing arms and that the stock rear spring will sit in the rim at normal ride height (29.5"). My question is if I go with 10" bolts and drop it 2.5" to 27", will this then move the spring back down to the rim? I have a stock composite spring and was wondering if it can/should be cut back if I go this route.
#2
Instructor
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Location: Jacksonville FL
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I've read that this size rim will fit with stock trailing arms and that the stock rear spring will sit in the rim at normal ride height (29.5"). My question is if I go with 10" bolts and drop it 2.5" to 27", will this then move the spring back down to the rim? I have a stock composite spring and was wondering if it can/should be cut back if I go this route.
I think there are too many variables, and would rather spend the $90 on the wheelrite and be sure. http://store.summitracing.com/partde...5&autoview=sku
I ended up ordering 18x10 4.5 BS Torq Thrust IIs for the rear and 17x8 4.5"bs in the front. Here are some pics.
http://web.mac.com/clsjohnson/iWeb/7...els_Tires.html
In these pics, the car is riding high and the spring isn't extended like it will be under acceleration. When I measured with the tool, I had the jack under the one shock mount so the entire rear's weight was on one side of the spring.
EDIT: This pic will show that 10" wheels and 4.5" bs is going to stick out an inch or two, and will look better with flares...
In this pic, I don't have the rear trim on, I haven't installed the flares yet, the height isn't set yet, the motor isn't in the car, so it doesn't look like it will
Last edited by Chris Johnson; 09-23-2008 at 12:32 AM.
#3
Melting Slicks
I have 18x10s with 5.5" backspacing. I also have offset trailing arms, 10" bolts and my rear spring is 1.5" shorter than stock. See the pic below for where my spring sets in relationship to the wheel/tires. I also had to remove the swaybar as the wheel/tire rubbed on hard turns. Rod
#4
Burning Brakes
Member Since: Aug 2007
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I have 18x10s with 5.5" backspacing. I also have offset trailing arms, 10" bolts and my rear spring is 1.5" shorter than stock. See the pic below for where my spring sets in relationship to the wheel/tires. I also had to remove the swaybar as the wheel/tire rubbed on hard turns. Rod
EDIT>>> It looks like the spring would tuck inside the wheel if the bolt was shorter.
#5
Race Director
I am running a 18X10 with a 5.5 backspace and stock trailing arms. Here is a shot of my dual mount spring. I can't remember if this is the 1 inch shorter both sides or the 1/2 shorter both sides. It is with 8 inch bolts. I am now running the 1/2 shorter spring. The 1 inch shorter was the wrong spring rate so I exchanged it for a harder spring and I only wanted it 1/2 inch shorter.
#6
Racer
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The shorter spring is the key. I have 15 X 10" Convo Pros with 5" backspace on my '74. I have a composite spring that is 1.5" shorter than stock. I have about 3/8" of an inch clearance between the rim and the spring. I have read that you can get 5.5" backspace if you go with 18" rims.
If you don't want to buy a new spring, there was a post on the forum a year or so ago with instructions for redrilling the hole in an existing spring and then cutting it yourself - I don't recall who posted it, but you should be able to do a search on it.
If you don't want to buy a new spring, there was a post on the forum a year or so ago with instructions for redrilling the hole in an existing spring and then cutting it yourself - I don't recall who posted it, but you should be able to do a search on it.
#7
Burning Brakes
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The shorter spring is the key. I have 15 X 10" Convo Pros with 5" backspace on my '74. I have a composite spring that is 1.5" shorter than stock. I have about 3/8" of an inch clearance between the rim and the spring. I have read that you can get 5.5" backspace if you go with 18" rims.
If you don't want to buy a new spring, there was a post on the forum a year or so ago with instructions for redrilling the hole in an existing spring and then cutting it yourself - I don't recall who posted it, but you should be able to do a search on it.
If you don't want to buy a new spring, there was a post on the forum a year or so ago with instructions for redrilling the hole in an existing spring and then cutting it yourself - I don't recall who posted it, but you should be able to do a search on it.
#8
Melting Slicks
Could you post the link if you find it? Thanks
#9
Instructor
Thread Starter
Thanks for the pics. Very . It looks like shorter spring is needed for the 10" bolts. I've been told that offset trailing arms are not needed and issue is really the frame before the t/a's. I also e-mailed VanSteel and Dan cautioned me that I could bind the half shafts if they are not kept on a slight downward angle when lowering (that's something I didn't think of) and to keep the bolt higher than the rim in case of a flat.
Not sure if this the one but it gives the process of cutting a rear spring.
http://forums.corvetteforum.com/show....php?t=1416946
Not sure if this the one but it gives the process of cutting a rear spring.
http://forums.corvetteforum.com/show....php?t=1416946
#10
I just read all the stuff in here and i have a fitment question.Ihave a 70 bb and would like to use 17x8.5 w/4.5backspace and 255/70r17 on rear----17x8 w4.5backspace and 255/45r17 on front WHAT SURPRISES AM I IN FOR ????????????
#11
Melting Slicks
I don't see why that wouldn't work, some C3's came stock with 255's. A 255 on a 15" rim(stock) would actually be wider on the sidewall than the sidewall of a 255 on a 17" rim.
#12
Safety Car
The 4.5" backspace on the rear shouldnt be a problem.
On the front, just check how close the tie rod is to your current 4" backspace wheels, some guys have issues with it bieng close.
Nick
#14
I have 18x10s with 5.5" backspacing. I also have offset trailing arms, 10" bolts and my rear spring is 1.5" shorter than stock. See the pic below for where my spring sets in relationship to the wheel/tires. I also had to remove the swaybar as the wheel/tire rubbed on hard turns. Rod
#15
I am running a 18X10 with a 5.5 backspace and stock trailing arms. Here is a shot of my dual mount spring. I can't remember if this is the 1 inch shorter both sides or the 1/2 shorter both sides. It is with 8 inch bolts. I am now running the 1/2 shorter spring. The 1 inch shorter was the wrong spring rate so I exchanged it for a harder spring and I only wanted it 1/2 inch shorter.
I dont know this older suspension tech, so please bare with me and the stupid questions I'm trying to understand.
I want to do 10" bolts, and I was planning on on doing the VBP dual mount composite monospring... which as far as I know only come in one size for an 81... should I be asking for a shorter spring?
#16
Race Director
we're talkinga bout the width of the spring from one side of the car to the other right?
I dont know this older suspension tech, so please bare with me and the stupid questions I'm trying to understand.
I want to do 10" bolts, and I was planning on on doing the VBP dual mount composite monospring... which as far as I know only come in one size for an 81... should I be asking for a shorter spring?
I dont know this older suspension tech, so please bare with me and the stupid questions I'm trying to understand.
I want to do 10" bolts, and I was planning on on doing the VBP dual mount composite monospring... which as far as I know only come in one size for an 81... should I be asking for a shorter spring?
You can custom order any width spring from VB you want. They will make it for you. The spring rate is also variable, I asked for a little stiffer spring rate as the first one even set on the stiffest setting was to soft.