Anyone have a layman's explanation between the F-41 vs F-40 suspension packages? and is HD service the same thing? Clearly front larger and rear sway bar, 12 Bolt, springs based on equipment via. T-400 and C-60 A/C seems to be the biggy's, (the spring charts can be confusing) and I assume as Donny says the shocks would be made out of unubtainium (or out of my price range anyways, what would be a reasonable newer shock replacement? HD, is that a taxi thing, something completely different, or added to F-40 F-41 as in HD radiator ? Any reasonable input is better than none. Assembly guide shows the 427 has a return fuel line, is that on all 427's or another mistake in the assembly guides, as there appears to be a few different assembly guides out there.
Thanks Bill Hickle
67 F-41 vs. F-40
Posted by 59Fins on 6/6/2019, 9:36 am, in reply to "67 F-41 vs. F-40"
First, Thanks for all the response on this, I finally bit the bullet and bought the HD moog springs as the GM literature I found says it has to have HD springs for F-41 basically said has to have all F-40 components and HD shocks and rear sway bar. So all I am short is front HD shocks, and since I’m will be driving it, they will be close, not spirals. If located would be way out of my price range, someone found me pleasureizer HD rear shocks from early 70’s by date code, they were a aqua color, so pulled the stickers off and painted them grey, with the 12 bolt, rear sway bar w /HD shocks and springs on rear I was really surprised how different it drives, but that’s also after driving on 10 bolt rear with air shocks and lighter duty springs since 2007! The 12 bolt is a 3.08 open, going to see how that works before putting a posi unit in, so far I like it, but once BB is in who knows, the 10 bolt was 3:36 rear, as car was originally a 283 PG car, now a crate 350 290hp GM offered and probably still do, that bolts up to most of the options of our year cars, have the original 283 matching numbers motor that I had rebuilt in 08’ it’s only 10 over as car had 78000 miles at that time, someone (PO) had stuck a t-400 in it, so needless to say, I’ve learned allot since then, and decided to go to 4 speed, and BB and 12 bolt, it’s been a long journey since I am by trade and work, a body guy, and it’s about the only thing I have not touched, my last car I over restored and didn’t want to drive it, couldn’t and wouldn’t pull it around on a trailer, so I sold it. Determined not to go overboard this go around to drive it, but want all my ducks in a row before I pull it apart, car has right at 89000 miles on the body, everything but body bushings have been replaced bushing and suspension wise, less putting front springs in and rebuilding power steering gear as it has a small leak, bought another rebuilt M20 from Donny, so should be good on parts outside a clutch, not sure what to use and brand but should have plenty of time to figure that out. Sorry about the ramble, board has been slow thought I give some coffee drinking reading this morning. Sure there will be other things that pop up, but I do have a 5500 tach, could use a restorable lens and nice black gauge housing if anyone has one squirreled away. About to put car away for summer’s heat to work on garage space, never ever enough room! 2 of the pics show my lack of space .... 2 are from Spearfish SD the summer before last, drove it from Phoenix, one is my engine saying “Let’s Go” I have Dino video but not sure how to post it : )
Bill Hickle 59 Fins Surprise AZ
Re: 67 F-41 vs. F-40
Posted by Bill H on 3/20/2019, 1:57 pm, in reply to "67 F-41 vs. F-40"
Bill,
You've received good info on the F40/F41 suspension options. The F40 was included in the SS427/Z24 package. The F41 was optional...I have both on my '68 Z24 Sport Coupe (same styling as your '67). I installed Bilstein shocks all around about seven years ago...they're the best for my normal driving habits. Don't remember all the details when purchasing them. I think I had to determine a 'stroke' range before buying them.
I've included (3) pics of my rear axle area.
Bill
Re: 67 F-41 vs. F-40
Posted by 59Fins on 3/19/2019, 8:20 am, in reply to "67 F-41 vs. F-40"
To All: Thanks for the input, someone had told me about the Eaton Detriot Spring, not that they expensive or not, just want it to look right, but that is part of the deal, some springs settle and some are so stiff, you wonder if your in a lumber wagon. I think I will call them and see what they say. Of course most say what you want to hear so you will buy from them, and just got to see if you feel confident in what they are telling you. Thanks again, Bill Hickle
Re: 67 F-41 vs. F-40
Posted by donnyb on 3/16/2019, 7:50 pm, in reply to "67 F-41 vs. F-40" VIP Member and Board Expert
F41 also includes a rear sway bar Bill. Make a huge difference in how the car handles and corners. My 68 has F41
Re: 67 F-41 vs. F-40
Posted by Paul Winvoices on 3/16/2019, 12:44 pm, in reply to "67 F-41 vs. F-40"
First Paul, not I had not, it appears to be a good resource but almost takes a mathematician to figure some of it out
I remembered using that when I did my 59 Impala years ago, and always thought the info must of been done with a poor copy machine' some old literature has been copied so many times it's hard to read, even the original books can ne like the chassis assembly guide!
So I downloaded it and printed it, easier to read when not sideways :>)
I have been trying to decide which springs to get for the front, but calculating what options and accessories to do it throws me into a spin, I know I am over thinking it, but would like the car to be ascetically correct, not numbers correct by date code as it will never be that. Not being able to find a front factory sway bar, I put a 1 inch in years ago ( brand? I don't remember), but what bothers me and maybe there is a simple solution are the sway bar brackets, cause anyone could tell they are after market
So with that being said, I put a 12 bolt in this last week, all new bushings, with a factory rear sway bar, I have also had it for years, used a set of brackets that were sold on eBay years ago, and off and on as well. I have had my car for 12 years or so, slowly collecting SS427 parts for a Clone, (so I can drive it) it won't be perfect and it will be driven, the gears in the 12 bolt are 3.08 open, wanted to try them once I get the BB in, the 10 bolt was 3.36, only drove it to Good Guys Friday and it was quite different with the larger rear springs, but since I have owned the car it has had air shocks which I realize have to go, so that is why I ask, what would be a good replacement, gas, hydraulic? brand or size, what are you guys using that drive your BB cars.
I have collected most of the stuff I need I believe, but figuring out front shocks and where to get them is also a question, some like Moog, some don't, parts book is like trying to read a calculator, I did talk with a guy from this place http://coilsprings.com/request_quote.aspx?type=classic
And was not real comfortable with the guy I spoke with, I can come up with an oe part # then, the options get thrown in, and I get lost.
Most of my life has been in the body industry, have never owned a BB car, so mechanics is not my strong suit. So I am fishing, I spend alot of time looking at GM parts books and assembly guides and now the heritage manual and get confused, and looking for ideas. It's going to be and has been "my car" not a build sheet car, I have even looked at some other SS427 build sheets from Doraville cause on springs the codes convert to part numbers, but also as Donny says, through the years they get superseded, and again you get lost.
Deciding a rear gear and posi unit will come in time, but want to get springs in it before long and decide what shocks, go to Napa and ask for 67 Impala HD shocks and paint them grey and leave it at that? It's why I am asking for input, I have the 5500 tach and hood and most moldings, all SS427 moldings, switched the car to 4 speed years ago, and added a bunch of options and accessories for my liking, it takes me a while to do things because of limited budget, we build the motor and dyno it next week, all machine work has been done.
My intent is to not try and fool anyone that it is a true Z24, however if there is a day to do something like a window sticker I would like a funny RPO code that says "clone" in some official compacity but not the actual RPO #, now that would be funny and correct at least I do. like RPO ENOLC or something like that or ZCL24, any input would be something to talk about...
Bill, I know these guys have been around a long time. I have never personally dealt with them, but throughout the magazines, car site posts and general word of mouth I would certainly try them if I ever have a need. I believe they will be able to custom build a spring that is correct for your specific car with your specific options. https://www.eatondetroitspring.com/
As far as shocks, Monroe and Gabriel are decades in the business. I have used both and have been happy with both. KYB is also a prominent shock manufacturer that makes both OE style and performance shocks. I expect that in the aftermarket your shock choices will be limited to small block or big block, they will never be broken down like GM did. Don't over think it, you'll drive yourself mad!
F40 Special Suspension consisted of h.d springs & h.d. shocks.
F41 Special Purpose Suspension consisted of standard springs (for ride & compliance), h.d. shocks plus front & rear stabilizers matched up as a team.
BTW taxis & police cars usually came with Z04 h.d. Chassis Equipment which included F40 suspension, front stabilizer added to 6-cylinder Biscayne & Bel Air sedans (when normally they were omitted from those applications) and a h.d. rear axle (12-bolt). Other stuff included were h.d. clutch on 6's, V01 h.d. radiator & a K79 alternator.
I have had F40 and F41 cars My 427 Caprice is an F41 and I replaced all suspension parts with OEM F41 parts and this is what I got. Stiffer shorter springs Stiffer shocks stiffer sway bar bushings (larger sway bar front) sway bar rear, panhard bar rear Car rides completely different than F40 car tighter, much stiffer, much less roll in corners 1-1.5 inches lower (front specifically) Hope that helps I would never go back to an F40 car so I would convert to F41. just my .02..
My 69 SS427 came with F40 suspension. The L72 big block did not have A/C, so the springs are shorter but firmer with heavy duty front sway bar and no rear sway bar. This combination held the front of the car up. The rear springs are heavier too, more coils and size. You could not beat the way My car handled with heavy duty shocks, factory blue ones, that they said were computer generated. The F41 suspension was generated for tow duty. I just put a rear sway bar on My car. The sway bar kept the tires on the ground when cornering while towing. The tires would come off the ground without the sway bar because the panhard bar would let them lift, but plant the inside tire on the ground. It was harder to slide the rear. Also wide tires would hit the fenders. Did You notice how the wheel drops when they the car is jacked up. A sway bar prevents this. F41 suspension rides a little softer. I am installing KYB heavy duty shocks. I used to use heavy duty Cadillac air shocks to raise the rear and give tire clearance. Factory cars came with 6 inch rims with G70 tires. They wore out the centers. I used 7 inch or wider with H 60 tires. I disagree with Jim, F40 with heavier rear springs or air shocks will handle better. I had My car since 1968, with many miles driven. NICK L72 427impalasportcoupe
on 3/16/2019, 10:49 am
