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Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.

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  #1  
Old 01-21-2009, 05:44 PM
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Backhalfing question

I am about to undergo a project backhalfing a truck. I am using a prewelded kit. I was just wondering what determines the height that the crossmember is welded to the original frame meaning up and down. Is it a huge deal? Should the engine and trans be in the truck to do this? Thanks in advance for the help
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Old 01-21-2009, 07:36 PM
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If your referring to a Pro Stree/Drag type rear half, it all depends on where you want your ride height. Youll need to mock everything up, with shocks and what not if you want to know exactly where the truck will sit when its all complete.
If your talking a bagged/air suspension rear clip, TwistedMinis is the man to talk to.

Kyle
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Old 01-21-2009, 07:40 PM
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Ummmm...
Not enough info to say anything other then yes the locations, all of them have to be right...

Application, Kit maker, what is it supposed to do when you are done(stock bed or?) That kind of info would be really helpful.
may be a picture or link...
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Old 01-21-2009, 11:39 PM
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I guess I did leave a bunch out sorry haha
Anyway the truck is a prostreet truck that I want to sit as low as I can get it without to many major issues. It is a 4-link setup with coilovers. The bed will not be stock I will only be using bedsides. What I am more worried about is driveshaft angle. Is this something I need to take into consideration? Sorry for the questions I just never backhalfed anything before
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Old 01-22-2009, 12:43 AM
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Ok so yes it all matters.
Pull the front end down to the height you want square and level the chassis.
Have a dummy engine & Trans then set up the rear axle.
I would not worry about the pinion angle (you can set that when you do the rear suspension) and you want at least 5 of angle on the shaft.
From there you just set the frame where you want it and rock & Roll.
Things to pay attention to are clearing the shaft to Cross members, shock mounts, link mounts and keeping it square to the front frame.
Mostly measure 6-times and have fun!
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Old 01-22-2009, 01:19 PM
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You do want to have the pinion angle as close as you can, because if off enough it will effect the shock angle and ride hight
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Old 01-22-2009, 02:53 PM
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You will need to know a few more things also. What tire you are using, since the hub is determining the axle height. How high the axle is determines where the lower suspension (ladder or 4 link) bars will need to mount

You will need to keep the lower suspension arms (ladder or 4 link) parallel to the ground or slight uphill from the rear end. The chassis will dictate what length of shock you will once the frame is set into place.

Read the "How To" article from Chris Alston. It is for a car so you will need to substitute Truck for Car.

http://www.cachassisworks.com/Storie...AC-004_WEB.pdf
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