New guy with a few questions. Stock class race Bronco.

[Crawlfab]

My name is Jay and I have a rock crawler fab shop here in Oklahoma. I have been racing a jeep zj in stock class offroad endurance racing and im getting out classed by the jeep wranglers so im looking for some info on building a bronco for the class.

Here is a video of the type courses we run. This is a higher class but can get the feel. most of our courses are 5-7 miles long and we race 2 hours. winner is the guy that runs the most laps.

https://www.youtube.com/watch?v=k35PG8hrDaM


Stock class rules are.

stock body and full stock frame.
stock drivetrain
axles can have internal upgrades bust must be factory axle.
suspension must stay factory style. so leafs stay leafs and coils stay coils.
one shock per wheel.
no shock through the body.
max of 35" tire.

Can gut it and cage it plus ditch all un needed bits under hood and inside. Can trim outer wheel wells for clearance but inners must remain untouched.

So I think I can build a simple cut and turn bronco with deavers all the way around with some 2.5" smooth body shocks. Need to be fuel injected so looking for a 90s with the 351.

What im unsure about is can a cut turn ttb be ran 70 through rough ground in 4wd with no issues? Also what issues am I looking at using a long travel ttb in moderate rocks and climbs? If shafts are the weak link I have no issues running rcv axles but at first figure on runnig dana 50 inner joint.

How much shock can I use in the front without cutting on the inner fenders? I will fab the coil buckets and plan on setting the 5.5 deavers at as close to 4" lift as I can.

What other issues am I looking at?

Thanks for any help.

[Crawlfab]

Well just got a message from the rule tech and it looks like may have a issue.

Sais it reads as any shock that can be adjusted is not allowed. So can a stripped down bronco on 35s with deaver springs be built to go fast with one say 5160 bilstein? Or is there another shock out there?

Here is the rule on suspension and shocks.


1.2.1.5: Suspension: Lifting of a vehicle is allowed as long as no other rule for the class is broken. Only non adjustable shocks without coil carriers or air charges are allowed. Non adjustable, non factory bump stops are allowed.

[Silverslk]

What is their definition of adjusted? Taken apart and revalved or bypass adjusted while on the truck? Smooth body Bilstein,Fox, King, etc aren't adjustable (and would work great) without disassembly so not sure what they mean.

[Crawlfab]

Im looking to get a better answer on that. I have a friend that races that reads it as any adjustable shock. Id like to read is as a 2.5" or 3" smooth body is ok and no external adjustable.

[Crawlfab]

Well got confirmation. Looks to be only sealed shocks. I get pretty much one bilstein 5100. They say no remote resi but have not got a ruling on piggybacks.

So with that how well is a single 5100 bilstein on a bronco work? Anybody know of a better shock? I have a message into bilstein as I have seen a few videos on youtube that they have a 60mm 5100 style shock for a semi. If they still make them they may do the trick for a cheater shock.

I get to ditch the full interior, glass, seats, doors, top, tailgate, dash, a/c, heat, and anything else I dont need. Will add back cage and some beard ultras. Can that get a bronco to weigh 4k?

[Silverslk]

Buy a 2.5 or 3.0, get the valving dialed and weld it shut. Ha ha

[Crawlfab]

have had that thought in my head.

[PaulW]

A Bilstein guy told me that they can take apart a 5100 and change the valves.
They have the tools specifically for that purpose.
PW

[Crawlfab]

A Bilstein guy told me that they can take apart a 5100 and change the valves.
They have the tools specifically for that purpose.
PW

The zj I have now is a full body with the v8 and id say close to 4k weight. It does real well for a hour on the 5100s now but they get so hot the boots will melt off and loose all valving. I think it could use more spring to combat the problem but most springs for it are more rock crawler oriented.

[Crawlfab]

Well picked up a white 95 model the other night. Its not bad has some rust over the rear fenders but was $1500. Will brobably move it over to the build side and get some parts on the way.

[Wrightracing.net]

What Motor are you going to run? Does the rules say you have to run the same engine that was available for that year of vehicle or any year but that model? If you can run a 400m because they were stock in the late 70's and early 80's bronco's.

Same with running a Ford 9" rather than the 8.8. Are there any rules about trussing the axle housings, front and rear? Another thing to think of and see if the rules says you can't run a full floater rear end. You can do a full floater ford 9" that is a stock looking axle yet much stronger.

[ChaseTruck754]

I'm all for the 9" over the 8.8 but why on earth a 400m over the 351w??????

[Wrightracing.net]

The thought is he has to stay stock and a 400m with a good set of heads will give him more torque which from what I saw in the video is needed over a hi-rev motor.

[ChaseTruck754]

I thought "stock" meant stock heads. Just keep the boat anchor cool and well oiled if you do go that route. Being into the 70's stuff there's guys that love the silly things. A lot of um don't though. They are torquey but have some serious oiling issues

[Crawlfab]

The 95 I picked up is a 351, e4od, electric case that will be changed to manual.

Here is the complete stock class rules for 2014. I think they need some work as they seem way vague.



1.2.1:  Stock Trail Vehicles.   This class is intended for vehicles in stock form with very little suspension modifications, limited in tire size, and performance modifications.1.2.1.1:  All stock trail class vehicles will be required to meet the Dirt Riot minimum safety standard requirements, which include; 4-point harnesses, solid metal hardtop over a 6-point cage that is tied into the frame of the vehicle, solid metal doors or door bars that extend from the b-pillar at shoulder height to the a-pillar at the ankle/knee height, 2 – 2.5pd rated fire extinguishers.

1.2.1.2: Frame: Stock Class vehicles must retain the entire stock chassis. Chassis modifications can be made only to strengthen the frame (adding material).

1.2.1.3: Body: Stock body must be maintained, trimming of fender wells is allowed for tire clearance only. No “comp cutting” of rear corners is allowed. No ‘boat siding” is allowed. No cutting of floor board material is allowed.

1.2.1.4: Drive train: Drive train modifications are limited to internal up-grades of axles and gears, all stock class vehicles must retain drive train components that were available to that vehicle from the manufacturer.

1.2.1.5: Suspension: Lifting of a vehicle is allowed as long as no other rule for the class is broken. Only non adjustable shocks without coil carriers or air charges are allowed. Non adjustable, non factory bump stops are allowed.

1.2.1.6: Tires: Tires are limited in max size to 35 inch diameter by sidewall designation, if a tire appears to be greater than 35 inches, a measurement will be taken to determine if that tire is acceptable.

1.2.1.7: Steering: Aftermarket steering components are allowed as long as no other rule is broken. Ram assist steering is acceptable, full hydro ram steering is not acceptable.

1.2.1.8: Fuel Cells: Stock fuel tanks can be retained as long as the vent is routed to eliminate spillage, and a non vented gas cap is used to prevent spillage.

1.2.1.9: F-Toy class legal vehicles may enter Stock Trail as long as they meet the 35” tire rule.

1.2.1.10: Window nets are highly recommended. 

[Wrightracing.net]

There are updates to route oil to the rear cylinders better to address those issues. If I were to race in the class, I would stroke a stock 351w out to a 408 with a carb. It would look like a stock motor and give easy relatively cheap Horse power and torque. As for heads, Factory Lighting heads, still stock:roll:.

If they did not specify no coil-over's but said it had to be stock you could have ran a coil-over. just like Score, OEM coils with a shock in the middle= coilover.

Now in the rear, run a Quarter Eliptical leaf spring, still a leaf spring suspension but more travel. for stocks, 3" tested and tuned then tig welded and sealed.

Basically build it like a old class 8. There are always ways to ride the line in those classes. If you want to be competitive you need to do it because the other guys are going to take every advantage they can.

I wonder if oem supercharged motors are legal?:twisted::shock:;):P

The Chevy Blazer guys in Class 3 complain that they have to run leafs in front with a solid axle when Ford Bronco's can run coilovers with the TTB. So there are always lines to walk.

[Wrightracing.net]

Vague is good,

[Crawlfab]

They have changed the rules again since I started the post. It did say stock inner fenders to be un touched but thats gone now and they said they are updating it to no schader valved shocks.

So plans are simple at the moment and if the shocks will hold up it should be easy to beat the others. My main issue is the axle upgrade rule as I plan to cut and turn the beams. I hope I can get it passed the tech.

I ordered deaver 5.5 coils and j40s. Plan on raising the buckets to lower the front lift and add new mounts to get rid o the pin shock mounts.. On shocks since they removed the one shock per corner im thinking dual 5165 bilsteins up front and then a single 12" 5165 out back.

Will gear the axles with 4.88s then spool and truss the 8.8 rear. For now I just plan on adding the dana 50 inner axle and then drive slugs if they fail I will add the rcv shafts.

Stock alcoas with 35 km2s.

The grand cherokee was fast but the suspension was too soft and the 5100s had a hour of racing before they failed. Even then I was running 21 min laps to the leaders 18-19s.

[Tchajagos]

What the heck is boat siding? Do they mean fiberglass? Shocks do seem to be a limiting factor in this class. Maybe try to lighten the bronco up in every way you can. It would put less stress on the limited shocks and you would be faster haha. Wonder how long before they change the rules for the shocks. If you are going 70 offroad with stock shocks for 2 hours you are going to have a bad time.

[Crawlfab]

Well boatsides are what they sound. We take and cut the rockers out and raise it a foot or so and tie it all back with boxed tube. Basically just gets the rockers out of the rocks.

If I can get c&t beams with extended arms past tech I feel all I have left is making shocks work. I have never been Iin bronco on deavers so dont know what to expect on the spring rate but feel if can get the 2 5160 up front it may work. The jeep grand I ran weighed 3900 race ready and had a single 5100 on the front and it was good for a hour even with the spring rate being to soft. I weighed the bronco on factory steels with 31s and aluminum spare at 4780. If I can strip it to 4500 race ready I think it will work.

On another note the next class up from stock is called stock mod and its pretty much open. Im debating moving to it as the rules are so open and will really let me make the bronco work.