Front racing suspension...

[zbronc]

OK tired of searching, time to start asking....I run a 69 bronco with a 351 Cleveland in mud drag competition. I run 3.5 duff coils with old school double shocks. My problem is that on rougher tracks my diff smacks my oil pan sometimes. It started as a dimple and evolved to an official 3" dent. Time to change...
THE GOAL
I want to keep my lift as low as possible for stability at speed. I am looking to eliminate the factory shock mount to make room for fenderwell exit headers. I need a front suspension that gives drag race performance like a 90/10 or an 80/20. I need the front to rise upon acceleration (rear weight transfer) but compress very firm (to protect the oilpan) and come down slower. Weight of setup is important, must be light and strong.
OPTIONS
I'm considering 2 options. 4.5 BC coils rated for a winch and a single adjustable remote reservoir shock in front of the coil OR swapping to front coilovers. My only concern with the coilover setup is not getting the spring rate or height correct and trashing the oil pan on the first test run (no experience with coilovers) Does a coilover setup save any weight over coils and buckets?
I know this is a different application than what most wheelers use and my current suspension works great on the trails (we have no rocks) but i guess thats why i'm having trouble finding info.

Ok guys...got any suggestions?

 

[broncow72]

Call this guy and tell him exactly what you want and he will help you. Personally, I like the coil over set up for adjustability.

www.raceshock.com

 

[bmc69]

On our two dirt/mud racers we use progressive urethane bump stops..the big honkers that look like a pyramid with slots cut through it. Energy makes the ones we use...we mount them on beefy brackets that give the desired distance between bump stop and where it hit s the axle.

The better solution..but pricey is one that has not been out long very but we are going to try on a racer we are building now..the racing progressive fluid dampers/stops that look like a beefy shock design. I'd have to go poke around for the link. Put they are pricey as heck too...

 

[zbronc]

Thanks for the link...the search continues.

 

[Apogee]

Your axle hitting the oil pan is a bumpstop problem, not spring rate or damping problem. I know in motorcross you want your suspension to bottom once or twice per lap so that you know you're using all of your suspension. I would think you could lower your truck and still not hit the oil pan with the proper urethane or air/oil bump stops. My vote goes to the coilovers with good bump stops for maximum adjustability.

 

[broncnaz]

X3 on the bumpstops no matter what spring you run they will keep you from hitting the oil pan springs wont do that. Coil over shocks are your best bet as they can be ordered to do exactly what you need them to do if you know all you spec's. Dount there's much of a weight savings if any as most coil overs end up needing taller mounting brackets that you currently have. You should be able to fit some fenderwell headers without removing the front shock mount I run fenderwells on my 73 with a 302 with just the inner wheel well cut so they can pass through.

 

[Apogee]

Poly-Performance will swap out coilover springs with you if you buy your shocks from them until you get your rates right, so long as the springs are still in good shape and not abused. I assume you're not looking for long-travel shocks as I can't see the need unless this thing is being run up cinder hills in Iceland or something. ;D

 

[PBR]

"air bumps" or "bump shocks" are made by fox and king and that is the best way to solve your bottoming out problem. also having a good shock that is tunable with compression and rebound would be huge for your racing application. proper shock valving can do anything you want or need if you spend the time doing it. good shocks are expensive but as everyone knows you get what you pay for.

 

[zbronc]

Thanks for the input....I'm already running the big progressive bumpstops, they were installed after the very first dimple showed in the pan. They have prevented disaster so far. This is a problem that anyone running a cleveland motor in a bronco is familiar with. We use an oil pan from a 351M motor which hangs down farther. My suspension isnt bottoming out but is limited by the lift height. Most of the time 3.5" of lift is OK to clear the pan for mild wheeling but as the suspension settles it becomes more of a problem. The springs have 2 seasons on them.
Broncnaz...The fenderwell exit headers will be easier if the shock mount is removed. Clevelands are a little bigger than a 302 and have a different angle on the heads. I need room for 2 1/8 inch primary tubes going to 3 1/2 inch collectors.

Any more suggestions...

 

[Apogee]

Is pushing your front axle forward and option? How much room does a custom oil pan get you? Dry sump? Just throwing out ideas. ;D

 

[zbronc]

Moving the axle forward is in the planning stages, just not sure if i want to do it to this truck or build another totally redesigned racer. Aftermarket pans seem to have a larger sump. I have considered cutting and rewelding my pan but was saving that as a last resort. Dont want to go the dry sump route.
I was hoping to get the best of both worlds- better reacting front suspension and improved clearance. Has anyone tried 4" coils for a 78-79 bronco, does anyone know the spring rate for them?

 

[Apogee]

...I was hoping to get the best of both worlds- better reacting front suspension and improved clearance. Has anyone tried 4" coils for a 78-79 bronco, does anyone know the spring rate for them?

Do a search on "buckboard" and "pissing blood" and lots of stuff about those springs will come up. Let's just say that body roll will not be an issue. Typically the better brands will just use a longer, flexy spring to offset the weight difference of the full size rigs. Rancho and Superstiff use a higher spring rate rather than a longer spring...end result is a very rough ride depending on the weight of your vehicle. Hopefully someone will chime in with the exact rates if they know them.

 

[zbronc]

Thanks for the info, my motor actually weighs about 90lbs heavier than a "regular" smallblock...also considering swapping to a big block eventually, so i kinda favor a heavier spring rate.

 

[wildbill]

My 68 is a sand drager and runs leaf springs on the front had a boss 302 in it never hit the pan. It is a little rufffffffffffffffffffff like a j**p but dose what is needed. If I were to do it now I would go with coil over good luck with your's. Bill %) ;D PS both my broncos run wheel well headers.

 

[357Bronco]

Lower your bumpstops.You want that front end to go up, who cares how far it goes down. Ive run with no shocks at all before, just properly installed bumpstops and limiting straps. Yes its bouncy, but depending on the track you can really transfer weight. If your tracks are rough, a single shock mounted in front of the spring is fine, and you get the room you need for your headers.Glad to see there are others who enjoy drag racing their Bronco,also bonus points for the Cleveland!!!!

 

[broncnaz]

Thanks for the input....I'm already running the big progressive bumpstops, they were installed after the very first dimple showed in the pan. They have prevented disaster so far. This is a problem that anyone running a cleveland motor in a bronco is familiar with. We use an oil pan from a 351M motor which hangs down farther. My suspension isnt bottoming out but is limited by the lift height. Most of the time 3.5" of lift is OK to clear the pan for mild wheeling but as the suspension settles it becomes more of a problem. The springs have 2 seasons on them.
Broncnaz...The fenderwell exit headers will be easier if the shock mount is removed. Clevelands are a little bigger than a 302 and have a different angle on the heads. I need room for 2 1/8 inch primary tubes going to 3 1/2 inch collectors.

Any more suggestions...

As others said put another spacer under the bumpstops. As for the headers its up to you Those are pretty big primaries your running that engine must be a monster. I still think theres enough room to run them without removing the shock mount if they are built right. they should fit in betwwen the mount and firewall you'll probably have to cut out some of the inner fenderwell but theres about a 2in gap between it and the firewall so that might help some although it may heat your feet up some. I'll try to post some pics of mine so you can get a idea of how they run mine are only 1 5/8" primaries.

Here's the pics There is about 1/2" to 3/4" clarance between the headers and wheel wells if you cut out the rear of the wheel well you'll gain about 2 more inches. Here's a couple more pics might be a good idea to step down to 2 in primaries either way I still think they can be made to work drivers side might be a PITA you might want to contact mcguyver he runs a 351C in at least one of his EB's and has a some exeperiance with the header issues on them.

 

[68ford]

hydraulic bumpstops.
http://classicbroncos.com/photos/showphoto.php/photo/3193/cat/500/perpage/12/sort/1/ppuser/12243

one of those should work.

 

[zbronc]

Thanks for input guys.... I already have spacers under my bumpstops and not running shocks on the front is not an option.
Broncnaz, that looks pretty good do you have a pic of the whole header including the collector area? It looks like the passenger side is "stacked" , not sure if that will clear my heads though.

I'm suprised no one has any input on my idea of winch rated 4.5" BC coils and an adjustable shock in front of the coil. Any experience with these coils out there? The folks at BC seem very helpful and i've had good luck with their products. I like to try to give all the vendors a little business so maybe no ONE vendor dominates the market. I actually had one well known vendor insist that there was no size difference between 28 and 31 spline axles!!!! They said they just had more splines cut in!!!!They lost alot of my business after that.

Does anyone know of a good tech article that deals with swapping a broncos front to coilovers?

 

[zbronc]

68Ford, I like your setup... do you have deteails or pics of the front swap. What kind of coilovers are you running and how much lift do they equal out to. Do you have any good pics of the upper and lower mounts?

Thanks

 

[Desert Thrasher]

You mentioned you use a 351m oilpan, but is it a front sump or rear? When I first put my cleveland in my bronco, I put a very big dent in the front sump pan after a hard landing, so I switched to a rear sump pan and it helped a great deal. I did still end up getting a small dent in the pan where the front hangs a bit lower to clear the oil pump, but its not too bad. And thats with stock bump stops, Im thinking of putting some bigger ones in soon.