Mike,

I haven't received any response from you before this one... are you sure that you aren't confusing me with someone else? There is a thread going over at the H.A.M.B. with a couple of guys with similar issues... perhaps you've been communicating with one of them.

In any case, thanks for getting back with me here!

I have a few questions. In order to select the right coil springs, don't you need to know the compressed and uncompressed height of the spring, and the weight of the vehicle? Some of this information is hard for me to specify, because the truck had already been modified from stock before I got it. My sense was the the Monte Carlo sub-frame resulted in about a 2" drop, and leaves were removed from the rear springs in order to get the rear to match the front.

Since, as you said, raising the front by 2" creates problems with getting the front-end aligned, this time around I'm thinking of splitting the difference and raising the Monte Carlo front-end 1" from stock, and lowering the rear-end 1" from stock.

Since I've also installed bigger tires, I think the 1" would be a good compromise.

I can probably take my truck over to the the scrap yard where they have some scales and get you the exact weight. Given the weight, and my desire to raise it 1" fully loaded, you could select the right spring for the application, right?

The rear springs are going to be more difficult to manage long distance, if for no other reason than the shipping costs. I'm thinking that I should get the front-end the way I want it then at least attempt to work with the local spring shop who did the work last to see if they can get it right (they may tell me to take a flying-leap, I don't know) .

How would you like to proceed?

-DV

 

Hi,
Mike will be right with you on an answer (there's more than one of us that uses this). What we were referring to was a question posted on our forum. From the username and pics we were fairly sure it's you. Hope we didn't make a mistake. We didn't link to the thread on our forum, figuring that's not allowed, we're not here to steal any traffic.

 

No problem. Yes, I did post a message on your forum. I haven't been back to check it (I assumed probably incorrectly that I would get an email notice of any response). In any case, thanks again for getting back with me.

-DV

 

EatonDetroitSpring,

Thanks for your input, its nice to see vendor support on technical issues

Hopefully this all works out
Bobby

 

Just a quick update...
It's raining cats-and-dogs here, and will continue for several more days so I haven't had a chance to go and have the truck weighed. Just from scouring the web, it appears that a '52 F1 with a V8 tipped the scales at 3550 lbs. I assume the my 302 weighs close to the same as the flatty, but we should add about 100 lbs for A/C, PS/PB and other modern conveniences that have been added. Let's not forget the Americans are heavier now than they were in '52 (especially THIS American). Kidding...

I think that the '79 Monte Carlo with the 305 and A/C weighed around 3100 lbs. So it appears that those stock Monte Carlo springs were carrying 550 lbs more than they were designed to carry (not counting me), which would explain why they were sagging so much.

-DV

 

When you have it weighed, it would be good to get the front end weight and the rear end weight for future reference. First weigh it totally on the scale for the total weight, then just park the truck with the front wheels on the scale pad and the rears off of it on the ground and reweigh it. Subtract the front end weight you just got from the total weight to get the rear axle weight, or turn the truck around on the scale and weigh it once more.
You can't really compare gross weights to determine how much weight was supported with the MC springs, since the CG is much further back on a sedan than on your truck.

 

By the way, I stumbled across this primer on coil spring selection. I wish that I had found this BEFORE I started ordering parts.

-DV

 

Excellent info

yea, that info would have saved you alot of headaches....live and learn I guess

Bobby

 

It's been several weeks since I updated this thread. We've been busy on other things and just got back around to revisiting the suspension this last week. We're very close to having it all sorted-out, and I wanted to document what was done for future travelers.

Coil springs - I couldn't get comfortable with the "here, try this" approach. I did that once and was not happy with the results. I decided that I needed to buckle down and learn how to go about selecting coil springs. The break-though came when I found a complete Moog spring spec chart. (By the way, if you're reading this way in the future and the link no longer works, PM me and I'll send it to you in a spreadsheet).

The first thing that I needed to do was figure out what springs were on the Monte Carlo clip from the factory. I went to Rock Auto and found that it most likely had Moog #5602 springs on it. Looking at the spec chart, those springs have a spring rate of 347 lbs per inch, and are 15.88 in. uncompressed.

The next thing that I needed to know was the weight of my truck. I took it to the local scrap yard and had them weigh it. It tipped the scales at 1940 lbs at the front wheels. With this weight on the stock Monte Carlo springs, the compressed length should be [15.88 - (1940 lbs/347 lbs per inch)] = about 10.3 inches. I also knew from sight that this height was about an inch lower than I wanted to be.

Now all I had to do was find a set of springs that would give me a comparable spring rate and a compressed height of around 11.3-11.5 inches. There were a number of choices that would have probably worked but I went with the Moog #5006 springs which have a spring rate of 355 lbs/in, and an uncompressed height if 16.88 inches. With the weight of my truck on them the compressed height should be 11.42 inches, a little over an inch taller than where I started. Just out of curiosity I checked to see what kind of cars these springs came on, which included a number of GM cars including the 75-81 Camaro. This is a little ironic because when I started this thread almost a year ago I incorrectly identified my front clip as a Camaro (I later discovered it was off of a G Body, not an F Body).

Anyway, I ordered the Moog #5006 springs from Rock Auto for $83 and installed them. I don't know why, but I was very pleasantly surprised that it all worked exactly as the calculations predicted. I love it when this happens.

Front springs problem solved, now the rear springs. We removed the rear springs and took them apart, only to discover that all the spring shop had done was add a helper leaf second from the top (and charged me $430!). This helper spring was heavier gauge than the other leafs, and it had more of an arch to it. At this point, I concluded that I didn't have much to lose since the springs were unusable as they were. After much careful deliberation, I licked my finger, stuck it in the air, and decided to trim the helper leaf and move it from second from the top down to fourth from the top. I figured moving it from #2 to #3 wasn't going to change much, so #2 to #4 was the next step. This worked perfectly. I got lucky on it this time, because I didn't have many options other than going back to a spring shop and paying (again) for a new set of springs and hoping that they work. If I ever do go to a spring shop again, I'm going to do more homework so I'll be able to at least ask the right questions to make sure that I don't get springs that I won't be happy with.

These two changes got the truck riding quite nicely, but I was still left with the issue of the "wandering" steering. I needed to get the truck realigned anyway since I replaced the front coil springs, so I went back to my alignment guy and had him drive the truck BEFORE he put it on the rack. He correctly surmised that the front end probably didn't have enough positive caster. It appears that the Previous Owners didn't provide enough caster when they spliced in the Monte Carlo subframe. My alignment guy adjusted the caster as much as he could, and it drives MUCH better now. I can live with it as it is, but I'd like to find a way to get another 5 deg of positive caster (I'm at -3, spec is +2). It appears that Moog makes some upper control arm bushings that have eccentric holes that can add caster, however I haven't found one for my Monte Carlo clip. There are also some tubular adjustable upper control arms which can add caster, but these are rather expensive.

The truck is driving pretty good right now, so I don't have to be in a hurry to do anything. If any of you know of another way to get more positive caster I'd love to hear it.

 

After doing more research, I'm not sure that the lack of caster is the fault of the previous owner who installed the Monte Carlo clip. In order to adjust caster, you need a lot of camber adjustment (adding caster takes away camber). I need more camber so I can adjust for more caster.

The fact that I don't have enough camber is most likely due to settling of the crossmember, which I understand is a common problem. I'm going to take it to a frame shop where they can bend the frame to get more camber, then use shims to get more caster.

 

I suspect the lack of camber is due to raising the front end. IFS is typically designed to gain camber as the front squats, since the reason for squating is chassis roll in a turn. Conversely when you raise the chassis, you lose camber. The designed at rest position is usually with the lower control arm parallel to the ground. MonteCarlo's are not noted as high performance handling chassis and are likely to be "camber challenged" from the factory.
Has someone who knows what they are doing at a frame shop told you they could "bend the frame" to give you more camber? That doesn't sound like the best solution, and someone who just starts bending, could permanently screw up your frame.
Late model GM chassis are used a lot in circle track racing. You might want to first go to your local bull ring track and talk to the guys running up front to see if they have suggestions for you, they may be aware of parts that can help, different length A arms etc.
Personally I'm concerned you are trying to beautify a pig by buying it a fur coat as my father would say. I would be very wary of a modified chassis when considering purchasing an abandoned project, especially one using an uncommon donor or done by a backyard hack (you can usually get a strong clue by the quality of the work). There is often a hidden reason they want to part with it or that the particular swap is not commonly done. I suspect the latter case here, since MC front clips are very plentiful, I'd expect it would be a common swap if it didn't have some serious issues. I could be (and hopefully for your sake am) wrong, but sometimes it's best to start over.

 

Doraville,At the nhra in louisville, ky 2 years ago UPS has a set of scales there to weigh eyeryone rides so I weighed HOMADE, my 51 F1, not finished at this time but their scales weigh each corner which I thought was pretty cool. I have a LT1 with 700 R4 and 10 bolt camaro rear, 4 wheel disc and fiberglass fenders, no bumpers, in frame aluminum tank with 1/2 fuel, no floor in bed at that time, the weight was as follows
left front 954 lb
right front 964lb
left rear 495 lb
right rear 558 lb
2971 lb total but the interesting part for me was how close the weight were from corner to corner front and rear, I can realy tell the difference in handling after finishing the truck and want to weigh again this year on the UPS scales at the NHRA show in Louisville this August, Garry

 

Monte Carlo clips are a very common swap for '52 and earlier Ford's as well as a wide variety of other old cars and trucks. I've seen dozens of them just at the local cruise nights that I attend around the Atlanta area... and I wasn't even looking for them. Truthfully, people will say that they have a "Camaro clip" if it has either an F Body (Camaro/Firebird) or a G Body (Monte Carlo/Regal/Cutlass/Grand Prix) clip. Several times I've had guys tell me that they have a Camaro clip on a truck that I know has a track width too narrow for a Camaro, and then after being pressed on the issue they'll admit that it's a G Body clip.

I know that which IFS to use, as well as whether to install an IFS at all, is an endless debate on this list. I was hoping to avoid that debate. The truck had a Monte Carlo clip in it when I bought it, and is specifically one of the reasons why I bought the truck. Now that I have the ride (stiffness and ride height) where I want it, and the camber within spec, it drives pretty good like it is. I wouldn't mind getting a little more caster if I can.

In the process of researching ways to get more camber and caster, I discovered that sagging crossmembers is a fairly common occurrence among various types of front-ends (Camaros, Novas, Monte Carlos, Crown Vics). I found a lot of people out there looking for ways to get more camber. You can spend a lot of money on (and a lot of labor installing) custom parts designed to get more camber, or you can take it to a frame shop and let them do the alignment. The frame shop has a tool in their toolbox that a normal alignment shop doesn't have, and that is to tweak the crossmember to gain more camber.

Let's not forget that the only way to align an old twin I beam suspension was to bend it. It's not that big a deal for someone that knows what they're doing (which any frame shop should know).

But, I learned my lesson with the spring shop. I'm going to check around until I find someone who has done this exact type of thing before I take the leap.

 

A "modern" MC frame is a multicomponent tubular perimeter structure engineered with controlled crush zones. The factory builds in alignment points so that a frame shop with a frame table can measure to those points and the manuals tell them how to chain down the chassis and where to apply pressure to bring a collision damaged chassis back into spec alignment. A composite chassis (C channel ladder frame with a grafted IFS clip) has no such references or manual and has not been field tested to see how it will react to applied bending force. It could bend in completely unexpected places. IMHO opinion it is going to take someone very familiar with doing this type work to sucessfully adjust your alignment. Again I might talk to a local circle track chassis builder for recommendations since they spend a lot of time straightening and reclipping hybrid chassis. I'm not at all saying you can't/shouldn't bend your chassis to improve the alignment, just that someone who thinks they know more than they do can make a mess in a hurry once they start applying pressure and/or heat. If MC clips are so popular, then I'd expect someone has figured out how to fix this problem without resorting to something as drastic and nearly irreversable. A beam axle is far far easier to align by bending than a frame, but I know of a lot of them being FUBARed in the process.

 

Maybe. As you said, these cars may have been a bit "camber-challenged" from the beginning. Raising them would tend to take the camber in the negative direction. In the end, I only raised it an inch. It's hard to believe that it would've had that much impact.

Hey, I'm from the south. We love metaphors, especially pig metaphors. Here's another one:

"Never get in a mud-wrestling match with a pig. You'll both get covered in mud from head-to-toe, and the pig will enjoy it!"