F41 Suspension

[Joe S.]

Hello to all and Happy Thanksgiving,

I need some expert help on sorting out F41 suspension on a 1967 Corvette Small Block 350HP.

I am in the process of doing a chassis off restoration on what I thought was a numbers matching car and attempting to restore as such. So far all areas have checked out until now.

In assembling the rear end suspension I discovered that the differential is from a 1977 and up Corvette. The first clue was the bolts to mount the spring are 7/16 instead of 9/16. Further investigation uncovered a seven leaf rear spring and a 7/8" front sway bar. Currently the half shafts are attached to the differential yokes with u bolts and their is no rear sway bar on the car, is this correct for F41 Suspension?

I am in the process of locating the correct differential housing. However, in reading the NCRS Technical Information & Judging manual I cannot determine the correct set up for this car if it came with f41 suspension option.

The manual states the stock front sway bar should be 3/4" for a small block 7/8" for big block and 15/16" for F41 suspension. It also states that heavy duty suspension, I assume this is F41, utilizes a 7 leaf rear spring instead of the stock 9 leaf. Also, their is no indication as to the size of the sway bar for the rear or the method for attaching the half shafts to the differential for F41 suspension, the manual says all small blocks use U bolts.

Can someone help me in configuring my suspension correctly?
1.Was F41 suspension available for small blocks and was this also referred to as heavy duty suspension?
2.Could it be that this car was supplied from the factory with a 7/8" front sway bar instead of the 3/4" or F41 15/16"?
3.What are the correct mounting devices for the half shafts to the differential yokes with F41 suspension in a small block, if applicable?
4.What is the correct diameter sway bar for the rear in an F41 application and/or was a rear sway bar a factory option in a small block car without F41 or heavy duty suspension and what diameter if so.
(Note; this car was a late build car, July build date, and was shipped with 1968 casting heads as referred to in NCRS manual)

I apologize for the lengthy correspondence; I wanted to make sure I covered all aspects of my dilemma. Please respond to my e mail joesimon1@optonline.net or on this site.

Thank You
Joe Simon

[Stephen L.]

Re: F41 Suspension

According to Nolan Adams, F41 was officially only available with the L71 & L88 engines.
F41 is Heavy Duty Suspension.
Small Block differentials used the U bolts.
Small Block Cars did not have rear sway bars.

[Wayne M.]

Re: F41 Suspension

......What is the correct diameter sway bar for the rear in an F41 application .....Joe Simon

Joe -- to add to what Steve has said, the rear sway bar ('67 BB only) would be 9/16" diameter, and straight between the rubber bushings [ie. no offset jag].

I'm surprised this is not mentioned in the '67 TIM&JG -- it is in the '65 one.

[Gerard F.]

Re: F41 Suspension

Joe,

Also a small block would have had a 9 leaf rear spring. The S/B trailing arms have no holes for the sway bar mount.

Looks like someone put a suspension kit on your car.

Here's a photo of original 67 small block front springs for comparison to yours:



I think you can tell the difference from heavier springs by the number of coils and thickness of the coil material.

[John H.]

Re: F41 Suspension

Joe -

You have mail.

[Charles A.]

Re: F41 Suspension

Looking for information on the F41 and have read Noland Adams comments but with so many cars that came with it are you sure it was not available on an L-68 car? I have the correct front sway bar but unsure on the rear. What is the dimension on the rear? Also in 67 was the F-41 rear spring mounted to the differential rear cover with 7/16 or 9/16 bolts?

[Joe L.]

Re: F41 Suspension

Looking for information on the F41 and have read Noland Adams comments but with so many cars that came with it are you sure it was not available on an L-68 car? I have the correct front sway bar but unsure on the rear. What is the dimension on the rear? Also in 67 was the F-41 rear spring mounted to the differential rear cover with 7/16 or 9/16 bolts?

Charles-----


ALL 1963-77 Corvettes originally used 9/16" bolts to secure the spring to the differential cover. Any 1963-77 Corvette found with 7/16" spring bolts has had the cover replaced with the 78-79 cover which was also the GM SERVICE cover for 1963-77 applications for many years.

[John H.]

Re: F41 Suspension

are you sure it was not available on an L-68 car? What is the dimension on the rear?

F41 in '67 was only available with L-71 or L-88. There was only one rear stabilizer bar - 7/16" diameter.

[Joe L.]

Re: F41 Suspension

F41 in '67 was only available with L-71 or L-88. There was only one rear stabilizer bar - 7/16" diameter.

John-----


9/16". 7/16" was the 75-81 FE-2 rear bar.

[Stephen L.]

Re: F41 Suspension

F41 in '67 was only available with L-71 or L-88. There was only one rear stabilizer bar - 7/16" diameter.

John Hinkley,
My 67 L36 BB with sway bar (not F41 suspension package) has a 9/16 diameter sway bar. It came on the car from St Louis.

[John H.]

Re: F41 Suspension

Yup, fat-finger typo - should have been 9/16"; too late to edit the original post now.

[Charles A.]

Re: F41 Suspension

Is the standard big block suspension a 7/16 rear sway bar?

[Joe L.]

Re: F41 Suspension

Is the standard big block suspension a 7/16 rear sway bar?

Charles-----


All 1965-74 Corvette big blocks, regardless of suspension package, were equipped with a 9/16" rear sway bar. There were 3 slightly different configurations, but all were 9/16".

[Gene M.]

Re: F41 Suspension

John and Jerry,
As I looking at Jerry's spring photos a thought popped into my head. Over the years I have removed some springs that did not exhibit a notch to illustrate direction to install. I have always had the closer coils on top in those cases. What did the factory do? Jerry's photo looks to have the closer coils on the left side. Not all springs are obvious for top and bottom without the notch because the spacing looks uniform.

[Bill M.]

Re: F41 Suspension

I have always had the closer coils on top in those cases. What did the factory do?

Closer coils up is correct. (Shop Manual)