F41 suspension rear shock

[James S.]

My car is a 1969 L36 427 cuid.Does anyone know the diameters of F41 rear shocks PN 3171489 and PN 4940607 and the length of the lower mount stud for rear standard shock and rear F41 shock? I have the 7 leaf rear spring and sway bar.

[Mike T.]

Re: F41 suspension rear shock

James - When I bought my 65 396 Roadster, a previous owner had installed a set of what I believed to be F-41 Shocks, rears are #3171489, dated 7 B 68, fronts are dated 11 B 68 but the stamped part # on the fronts is: #3171488.
I removed them in favor of a set of KYB's donated by a good friend from the NCRS so they are off the car and easy to measure. Do you want the diameter of both front and rear shocks?

[James S.]

Re: F41 suspension rear shock

James - When I bought my 65 396 Roadster, a previous owner had installed a set of what I believed to be F-41 Shocks, rears are #3171489, dated 7 B 68, fronts are dated 11 B 68 but the stamped part # on the fronts is: #3171488.
I removed them in favor of a set of KYB's donated by a good friend from the NCRS so they are off the car and easy to measure. Do you want the diameter of both front and rear shocks?

Hi, your PN 3171488 is for '68 F 41 rear shock. yes I would like to know the diameter of the body. There was a reduced size in Jan 1,'69 rear PN 4940607.IMG_2341.jpg Here is a pic of fThanks.om NCRS Judging manual for clarification.

[Mike T.]

Re: F41 suspension rear shock

IMG_4091.jpgLooking at that second paragraph, the JM mentions those numbers (Frt 3171488 - Rear 3171489) were used for 68's and part of 1969 which makes sense since the stamped dates are July and November of 1968. The main body width of the fronts comes out to 1.644 inches and the rears are 2.226.

[Joe L.]

Re: F41 suspension rear shock

My car is a 1969 L36 427 cuid.Does anyone know the diameters of F41 rear shocks PN 3171489 and PN 4940607 and the length of the lower mount stud for rear standard shock and rear F41 shock? I have the 7 leaf rear spring and sway bar.

James-------

The late 1969 F-41 shocks were GM #4940607 and available in SERVICE under GM #4940459 (on box part number which box included grommets and installation instructions). These were actually available in SERVICE from 1970 until about 2005. There were some differences in the configuration over the years such as the deletion of stamped part numbers and a reduction in the OD of the "washer" at the top of the shock. However, I believe the OD of the tube section as well as virtually all other dimensions remained the same over all the years of their availability. The tube section is 2.00" OD.

Attached are photos of the shock as manufactured in the mid 80's to mid 90's:


DSCN4164.jpgDSCN4166.jpg

[James S.]

Re: F41 suspension rear shock

Hi there thanks for the picture. Can you provide a picture of the front F41 shock PN 3171488 in the way you presented the rear shock? Much better than in JM. Does anyone have a F41 rear shock for 1969 PN 4904607 for an outside dimension of body. Would anyone know if the rear F41 shock PN 3171489 was used into the Model Year 1969 until stock was depleted? Would it be possible to measure the length of the lower rear mounting stud for the rear F41 and also look for casting marks for ID of part. Mine do not have markings like I was told to look for. I have read on a forum somewhere that the standard suspension lower shock mount stud was 1/4 inch shorter then F41. Also if possible to measures the diameter of the rod on the front coil spring for research information , please include engine package. After years of driving these vehicles on the road it would be more likely that the paper tags would be missing. The measurements would be a better ID of the parts.
Thanks, Jim Santoro

[Mike T.]

Re: F41 suspension rear shock

Jim - Just took a couple pics of the front F-41 shocks.
IMG_3590.jpgIMG_3588.jpg

[Joe L.]

Re: F41 suspension rear shock

Hi there thanks for the picture. Can you provide a picture of the front F41 shock PN 3171488 in the way you presented the rear shock? Much better than in JM. Does anyone have a F41 rear shock for 1969 PN 4904607 for an outside dimension of body. Would anyone know if the rear F41 shock PN 3171489 was used into the Model Year 1969 until stock was depleted? Would it be possible to measure the length of the lower rear mounting stud for the rear F41 and also look for casting marks for ID of part. Mine do not have markings like I was told to look for. I have read on a forum somewhere that the standard suspension lower shock mount stud was 1/4 inch shorter then F41. Also if possible to measures the diameter of the rod on the front coil spring for research information , please include engine package. After years of driving these vehicles on the road it would be more likely that the paper tags would be missing. The measurements would be a better ID of the parts.
Thanks, Jim Santoro

Jim------


There was no shock of GM #4904607. The part number was 4940607. The ones that I have measure 2.0" OD as I previously described.

ORIGINAL F-41 shock mounts have the part number 3829265 or 3829265-66 "debossed" on the un-machined section of the shaft. Later replacements have no part number, at all.

Wire diameter of F-41 front springs is 0.686".

[Joe L.]

Re: F41 suspension rear shock

James------


Here are some photos of the original shock mount shafts. Note the part number embossed on the center section of the shafts as 3829265-66. The reason why both part numbers are embossed is because for the F-41 shafts both the left and right side shafts were manufactured from the same forging; only the machining was different (location of flat on spindle support end). Later GM shafts as well as aftermarket/reproduction have no part number embossments.

DSCN4170.jpgDSCN4171.jpgDSCN4172.jpg

The standard suspension shock mount shafts, GM #3820929 and 3820930 also have the part numbers embossed on the unmachined section. However, these shafts used a different forging for each. So, the specific part number for each is embossed. Below are photos of a GM #3820929:

DSCN4174.jpgDSCN4175.jpgDSCN4173.jpg

The shaft lengths for both the standard suspension and F-41 suspension shafts are identical: 2-1/4" for the shock end and 3-1/4" for the spindle support end.

The standard suspension shafts were discontinued from SERVICE in 1978 and replaced by the F-41 shafts for all 1963+ Corvette applications. It's POSSIBLE that the F-41 shafts were used in PRODUCTION for all C3 Corvette applications after about 1978 but not according to the AIM's; they specify the 3820929 and 3820930 for standard suspension applications right through 1982. If so, then the 3820929 and 3820930 were available to PRODUCTION right to the end of 1982 but not available in SERVICE after 1978.