Okay this is a question that has been asked multiple times, but there is also conflicting information in regards to the proper tightness of the upper front shock nut.

I changed out my front shocks today on my 81 Vette and the instructions that come with the AC Delco Gas shocks refer to using the torque specs in the shop manual and AIM book to tighten the top shock nut. Checking the torque specs in the books it lists 90 inch pounds or 7.5 foot pounds. Searching on the forum others referred to tighten just enough until you see the rubber bushing bulging just past the washer edge.

So I followed my own findings and used a tightness in between both recommendations. I tightened the top nut until I saw it pass the rim of the top washer, then took my torque wrench and checked. The torque was not close so I cranked down the nut a little more, but got no where near 90 inch pounds. If you crank the nut down to 90 inch pounds the rubber bushing would be as flat as a pancake. I backed off the nut and then just tightened with a 3/8 inch rachet and 9/16 socket until I felt a decent amount of firmness, but not over tightened. The rubber bushing is just past the top washer about 1/16 of an inch.

I took a few pictures to show where the bushings ended up as far as the compression. Not positive this was the optimum way to tighten but looks to be close without over compressing the bushing.

Thoughts?

 

It should be snugged down so that the rubber bushing "squishes" out to the diameter of the flat washer. In my opinion, you're a tad over-tight with the rubber expanded out beyond the washer.

Lars

 

Thanks for helping clarify Lars. I will make the adjustment as you suggested. Just don't understand the 90 inch pounds in the book, that would be way to tight :-).


Much appreciated!

Randy

 

Inch pounds and foot pounds are not the same when it comes to torque.

 

The AIM spec of 90 inch pounds is based on the bushing spec of the original material utilized by GM at the time. You need to lower your expectations for aftermarket parts regarding FFF form/fit/function. Highly unlikely that the current material would compress to the retainer diameter at 90 inch pounds some 35 years of cheaper aftermarket production later.

 

That makes sense Hammerhead, the factory bushings must have been much harder/dense. I converted inch pounds to foot pounds when installing and there is no way 90 inch pounds/7.5 foot pounds could be reached with these aftermarket rubber bushings without completely crushing. Maybe if they were poly and hard it would be reached.

I took Lars advice and retightened the top nut properly with the top rubber bushing being even with the top washer circumference.

Great discussion, good information to remember when working on cars, hopefully this information discussed helps others reading too.

Randy

 

Extra insurance to keep the top mount from working aloose once the rubber loses some of it's compression..........