I am attempting to replace the shocks on a 58 and have found that the shock manufactures have changed the design of the shocks that I had on the car. It seems like all the shocks being sold for my car are the same size.

My original ones that go on perfectly are Monroe 4008

Overall length is 16 1/8
From bottom of shock body to top nub is 11 ½

The new Monroe 4008 is now 5751

Overall length is 18 3/4
From bottom of shock body to top nub is 13 1/4

It seems Monroe, AC Delco, Gabriel all use the same dimensions.

I can not get these new shocks to fit can anyone please tell me if there is some kind of trick to installing these.

I am getting desperate.

Thanks

 

It might help if you'd say what your difficulty is, when you are trying to install them... the dimensions you quote aren't the whole story, and we don't know your level of expertise. Shocks have a wide range of travel. Once in position on the car, the spring keeps the shock near it's center position when the car is at rest; bumpy roads try to lengthen or shorten the shock against it's damping resistance, thus the "shock" of hitting bumps is "absorbed". Off the car, the shock can be, if a normal hydraulic shock, compressed or extended to any position and it will stay there until some external force moves it to a different position; if it's an air shock, it will try to extend completely open unless restrained by a wire tie installed by the factory to center the shock and to fit it in the shipping box.

Are your new shocks air shocks or normal hydraulic shocks?

If they are simple hydraulic fluid shocks, you can simply compress them to the dimension you require (takes a lot of weight/force, and they'll move verrrry slowly to a more compressed position). If they are air shocks and it's air pressure that won't allow the shock to be compressed enough (and stay compressed), then raising the frame with a floor jack, allowing the A-frame to droop down, should provide the needed space to install them.

If the new shocks are too tall even in the fully-closed position (which seems doubtful), perhaps they won't work, possibly because your springs are sagging or incorrect height aftermarket springs.

 

Don't know if this will help at all, but here goes:

If you are talking about the rear shocks.

I have an old 1985 Monroe catalog. It does not list either of the 2 shock numbers that you list (4008 and 5751). It does list 4 different series of shocks for the C1 Vettes (Gas-Matic - #5818, Monro-Matic #2126, Radial-Matic - #5718, & Load-Leveler - #54568).

It also lists the collasped and extended lengths for these shocks. Note that these lengths are from the center of the eye (if mounted through a horizontal stud), or from the bottom of the stem (not the end of the stem) if mounted via 2 bushings on the stem. Typically, 5/8" is then added to the length dimensions for stem mounts (for them to be centered between the 2 stem bushings at the actual body/frame mount).

The collasped dimensions range (between the 4 series of shocks) from 11-5/8" to 11-7/8".

The extended dimensions range from 19-1/2" to 20".

If your shocks fit within these ranges, then they should fit. If not, then "something is wrong"!

The only front shocks listed for C1's were (in 1985) Monro-Matic #1007. Their lengths are 8-7/8" to 14-1/4". Again, if your existing shocks fit within this range, they should fit.

New news!

I went to the Monroe website and see that the 5751 shock is for the front. It lists it's dimensions as 8.5 to 13.75. In other words, it should work. Do you have a ST-12 manual? It should show the correct way for the shock to mount.

Hope this helps,
Plasticman

 

Thanks so much for the replies. I would be dead without knowing the forum is there to help me when I panic.

I am beginning to think the 5751 shocks that came in the box are not really 5751. There are no # stamped on them but there is no way I can get them to fit. The auto parts store ordered in another pair to compare them to. The guys at the counter said they have never seen any not stamped with the part number and they seem to be different then the spec sheet says.