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Post by STROMI 121 on Oct 16, 2017 13:30:22 GMT -5
For coil sprung cars you may use a hump plate they may be 1⁄4" x 6" x 22" centered in the hump they will be measured from the top center of the hump and must start no lower than the center of the frame. Hump plate must be at least 2" from rear end housing. On 77 and newer gm s you may use a 1⁄4 x 6 x 30 hump plate.
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Post by cheezwhiz31 on Oct 16, 2017 15:04:10 GMT -5
doesn't say where it needs to be welded to the outside tire facing side of the frame rail... Hmm!?! i'd think about that one. since the inner/backside of the hump rail is the issue spot.
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Post by STROMI 121 on Oct 16, 2017 15:28:52 GMT -5
Ive never blown the humps with hump plates. They always bend at the base of the hump. Between the hump and the body mount.
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Post by Luke Wells on Oct 16, 2017 19:13:30 GMT -5
I've seen several Caddys, 74-76 GMs, and metrics short leafed that have been very hard and very successful.
If it's done right the bumper will flip up, stop at the leafs, and be a brick wall.
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Post by STROMI 121 on Oct 16, 2017 21:56:11 GMT -5
The thing with a 73 caddy you don't want them to fold or roll.
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Post by Luke Wells on Oct 16, 2017 22:15:12 GMT -5
I guess I'm not fully understanding. Unless youre building a full blown plated front to back promod they will eventually go somewhere right?
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noser23x
Feature Winner
R.W.C.
Posts: 1,969
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Post by noser23x on Oct 16, 2017 22:20:14 GMT -5
Ive never blown the humps with hump plates. They always bend at the base of the hump. Between the hump and the body mount. To me, whats the best of 2 evils? Imo and what ive seen and worked with, any leafed car is more prone to go inside the radius of the hump over hump plates, while it does have benefit behind the hump (also more prone to dumping infront of humps, but gas tank protector helps that). So, I look at it as, whats more manageable, taking the infront of hump variable out assuming both are even with gas tank protector. Extremes, 1 is more likely to bend in hump, 1 is more likely to bend behind it. I have a feeling I know what rule set this is for, and if I'm trying to get a car done for feature, its alot easier to get a car fixed behind hump then the hump itself for me.
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Post by bluecrew72 on Oct 17, 2017 8:09:02 GMT -5
Two other key questions here is if there is any rule on leaf clamps and what is thickness rule on leafs?? I had missed the GTP tight comment, so forget about bellying mount the front wherever works the best, side or bottom, to hit your spring perches on rearend, with everyone running small tires probably want to try and get it on the side so you don't have anything hanging down off bottom of frame. Have a leaf long enough to where you typically have issue, if it's where the hump comes down before the body mount, mount it there pull down tight till that shackle flips back and spring eye hits the frame.
With the 1" thread tying the frame to rearend and the spring setup there is no way the hump will move unless threaded rod breaks OR the main leaf bends which is usually when they break (enter thickness and clamping questions) and this should take care of your issue behind the hump. From there it's all what you do behind the spring which it sounds like you have pretty figured out.
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Post by STROMI 121 on Oct 17, 2017 9:19:37 GMT -5
Spring rules are on the first post.
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Post by bluecrew72 on Oct 17, 2017 10:34:52 GMT -5
What about clamping?
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Post by STROMI 121 on Oct 17, 2017 11:49:47 GMT -5
Leaf spring clamps may be 2'' wide 3/8 thick 4 per side allowed
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Post by bluecrew72 on Oct 17, 2017 13:18:54 GMT -5
well that works out nicely...
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Post by STROMI 121 on Oct 17, 2017 14:14:40 GMT -5
Would you flat stack or leave them normal to pull down on the hump?
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Post by bluecrew72 on Oct 17, 2017 15:54:20 GMT -5
I like the arc pulled down the hump flatten them out a bit and have the pressure upward for support, not really sure if it's right but jmo... clamp post pulling it down and use clamps size to your advantage.
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Post by smashincwa on Oct 17, 2017 21:24:47 GMT -5
I think the knee jerk is that a well leafed converted factory coiled car is always stronger than a hump plated one as long as you can keep the rearend on the perch and the main can't bow - which your rules allow.
With leafs, you can drop the rear down and let the body rip/ or smash down to the frame. This bulks the sheetmetal nice and puts the strength closer to the package tray. This is what I'd want it to do.
The real advantage however is that you can change the bend vector of the front frame because the rear is squatted. The limitation is if there is a height requirement for the rear frame/bumper and what you want the frame "angle' to be for the front. Can you tilt or prebend the front or rear? What are the track conditions, as in... you dont want a squatted rear on a sloppy track. These are some things I'd be thinking about.
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