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Offset trailling arm modifications

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Old Apr 9, 2006 | 12:34 PM
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Default Offset trailling arm modifications

What type of modifications are needed with this installation (half shafts - length and dia., brake lines & sway bar), also what upgrades are needed that will alow the rear end to support 500+ rwhp -It's a 69 vert, M21, 3.36/1 ratio
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Old Apr 9, 2006 | 04:30 PM
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Originally Posted by 7of69
What type of modifications are needed with this installation (half shafts - length and dia., brake lines & sway bar), also what upgrades are needed that will alow the rear end to support 500+ rwhp -It's a 69 vert, M21, 3.36/1 ratio
Offset trailing arms are a direct bolt in. Stock everything works. You are actually just getting extra clearance at the front of the tire. Everything else remains as before.
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Old Apr 10, 2006 | 08:49 AM
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Will you be putting slicks on the car?
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Old Apr 10, 2006 | 09:12 AM
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If you want offset TA's go with the double offset TA's from VanSteel. They're the same as the regular offset but the rear leafspring mount is an inch towards the diff. on each side, this allows you to run a shorter spring which gives you more clearance b/w the spring and your rim/tire. (the wider the tire the more this should concern you) Do a search and you'll hear about members having their leaf spring hit their tire resulting in blown tires and suspension damage. You will have to have your leaf spring holes modified but IMO its well worth it. Check it out.
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Old Apr 10, 2006 | 02:48 PM
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how and where do you modify the spring?
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Old Apr 10, 2006 | 03:39 PM
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If you use the extra space you gain from the offset, you will not be able to use a sway bar in the stock location/mounting.
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Old Apr 10, 2006 | 07:27 PM
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Originally Posted by redc3
how and where do you modify the spring?
You can cut steel springs or you can order shortened fiberglass springs from us. No price increase for that either.
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Old Apr 11, 2006 | 09:14 AM
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Originally Posted by Van Steel
You can cut steel springs or you can order shortened fiberglass springs from us. No price increase for that either.
What's your view on running shorter springs and not relocating the spring bolt holes on the trailing arm inboard?

Last edited by shafrs3; Apr 11, 2006 at 09:17 AM.
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Old Apr 11, 2006 | 11:19 AM
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Originally Posted by Van Steel
You can cut steel springs or you can order shortened fiberglass springs from us. No price increase for that either.
whats the ballpark, if i wanted the modified spring and the offsets with bearings installed?
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Old Apr 11, 2006 | 01:19 PM
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Originally Posted by shafrs3
What's your view on running shorter springs and not relocating the spring bolt holes on the trailing arm inboard?
I shortened a steel spring by cutting on end of right next to the existing hole and then redrilling a new hole. I then measure the distance between the holes and added a new 3/8th center hole. This shortened the spring by about 2 inches. I then used the stock mounting bolts and stock swingarm location.
When you first install the spring with the wheels hanging down it looks weird, the bolts really tip in but once the weight in on the car and the spring flatens out is very hardly noticable. The new shorter spring is 1 inch shorter per side so this leaves a slight twist in the mounting bolts.
The next time the trailing arms were out I offset the mount to comprensate for this but I did run the crooked mounting bolts for years.
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Old Apr 11, 2006 | 02:22 PM
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Originally Posted by shafrs3
What's your view on running shorter springs and not relocating the spring bolt holes on the trailing arm inboard?
I think if you cut a 1/2" or 3/4" off each end your fine with standard arms or standard offsets. If you go 1" or more, we recommend double offsets. Some have gone 1" shorter on the spring an have had no problems. I would run doubles in this case just for piece of mind.
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Old Apr 11, 2006 | 02:23 PM
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Originally Posted by redc3
whats the ballpark, if i wanted the modified spring and the offsets with bearings installed?
Rebuilding your bearing assemblies and installing them on offset plus a shortened fiberglass spring will run you about $1245. plus freight. Thats witht the forum 10% discount taken out.
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Old Apr 14, 2006 | 11:38 AM
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I plan to add ZL1 flares with a min. tire width of 335 in the rear. The car has a street and saloum suspension package from Vette Brakes that I installed 12 years ago. The fiberglass spring has ruined two tires (255/60/15), will this still be a problem with an 18X10 rim? I want to build this vette from one that I have seen on this forum called Killer or Killer Vette, I think the owners name is Chris McDonald.
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Old Apr 14, 2006 | 04:42 PM
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Originally Posted by 7of69
I plan to add ZL1 flares with a min. tire width of 335 in the rear. The car has a street and saloum suspension package from Vette Brakes that I installed 12 years ago. The fiberglass spring has ruined two tires (255/60/15), will this still be a problem with an 18X10 rim? I want to build this vette from one that I have seen on this forum called Killer or Killer Vette, I think the owners name is Chris McDonald.
With 18's your spring will not hit. If anything the spring will sit just inside the rim. With flares you can go lager than 18x10.
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Old Apr 14, 2006 | 05:44 PM
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This is what happens when you have to wide of tires lol. I fixed it though when some mods. My car came with your offset trailing arms already.
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Old Apr 14, 2006 | 07:38 PM
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Originally Posted by Van Steel
I think if you cut a 1/2" or 3/4" off each end your fine with standard arms or standard offsets. If you go 1" or more, we recommend double offsets. Some have gone 1" shorter on the spring an have had no problems. I would run doubles in this case just for piece of mind.
How do you cut 1/2 or 3/4 inch off the spring at each end? YOu run into the existing hole? If you cut just past the one hole and then redrill that is about the longest you can leave the spring and yet remove the hole.
Drilling a leaf spring is not that hard, lots of oil, slow speed and a sharp drill bit.
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Old Apr 14, 2006 | 07:42 PM
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Originally Posted by norvalwilhelm
How do you cut 1/2 or 3/4 inch off the spring at each end? YOu run into the existing hole? If you cut just past the one hole and then redrill that is about the longest you can leave the spring and yet remove the hole.
Drilling a leaf spring is not that hard, lots of oil, slow speed and a sharp drill bit.
The spring rate goes up as you move the hole though.
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Old Apr 15, 2006 | 02:37 PM
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Originally Posted by norvalwilhelm
How do you cut 1/2 or 3/4 inch off the spring at each end? YOu run into the existing hole? If you cut just past the one hole and then redrill that is about the longest you can leave the spring and yet remove the hole.
Drilling a leaf spring is not that hard, lots of oil, slow speed and a sharp drill bit.

Sorry I meant, getting a fiberlass spring cut shorter.
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