Mancini XHD springs :(

I like all the pictures and the ride height shown but these springs move the rear forward . OK with little tires but not with larger Diameter.

I have a set here I removed. there was 3/8 of an inch difference on location. They also stretch the rear shackles forward due to arch.

Offset shackles should be used with these springs . they look like a Z from the side. Or shim the rear hangers forward. B-bodys don't have the removable hangers you must use the offsets. Also shim the front spring hangers back. 3/8 flat stock with the holes drilled for placement on the studs before installing the front hangers.

Measure this distance below from side to side. The difference is usually the size of the shim needed to straighten the rear in the car. Most are usually off around 3/8. 340 4 spd cars with boxes and sure grips are usually located correctly but not all. The reason why most /6 and 318 cars ride sway back. The picture below is a 340 auto. It was off 3/8 that area shown is usually much wider when correct.

The incorrect position can be seen easy when we put it on a body fixture as seen below. Incorrect position is what will tear up a sure grip and cause a handling problem . Just some info and a thought you all should consider.

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Thank You for the comprehensive reply, I would say these springs have moved my axle forward at least 1/2 - 3/4 of inch over where they were located with my OE springs, and repositioned (pulled) my rear hangers to 7 o'clock position where as before they where at approx. 4:30/5:00 o'clock. It's my belief that my passenger tire setting even closer to the front quarter is coming from the increased ride height created by the additional arch of the pass spring that's adding 1" - 1.25 extra ride height. I have already ordered the Calvert Racing split mono's std ride height with their Caltrac traction bars. After a 15 minute call with Calvert it was apparent they know their sh-t!