Autocross Ranger: V8 Swap, SLA, IRS

Thanks for all the input. I have some BFG rivals on the way and will be bedlining and finishing out the interior this weekend!

Questions on brake rotor sizes. (And my ignorance will show with my questions) Do you really need larger brakes on a high powered autocross vehicle? Is brake fade a problem on autocross runs? Do you get more benefit out of larger brakes than you get out of the lower rotating mass of the smaller rotors and the smaller diameter/lighter wheels you can then use?

In reply to jharry3:

I use the Wilwood drag race brakes front and rear on my EM car. They have 2 piston calipers with a 10" non-ventilated disc and I have no brake overheating issues at all. Autocrossing doesn't need much for brakes.

http://www.wilwood.com/BrakeKits/BrakeKitsProdFront.aspx?itemno=140-1012-D&year=1978&make=Ford&model=Mustang+II&option=All

jharry3 wrote: Questions on brake rotor sizes. (And my ignorance will show with my questions) Do you really need larger brakes on a high powered autocross vehicle? Is brake fade a problem on autocross runs? Do you get more benefit out of larger brakes than you get out of the lower rotating mass of the smaller rotors and the smaller diameter/lighter wheels you can then use?

On a heavy car, the additional rotor size/mass helps with heat rejection and prevents pad burn-in ("warping").

On a light Ford Ranger? Maybe not, but at the very least those 4-pot calipers are super easy to do pad changes on.

I agree. I doubt I'll ever see a need for this big of a brake package during a sub minute autocross run. There are a few local time attack and road course events local to me though. I have thought it would be fun to get into these and that's where I think I'll see the most benefit.

...and who doesn't like seeing the inside of an 18" wheel stuffed to the gills with brakes(for a relatively cheap/grassroots kind of way)

Well, my '11 Mustang had the standard GT brakes (2-piston sliding caliper), and after a season or two of autocross, I melted the stock pads/rotors together. Swapping to that Brembo setup (same as the '15+ 4-pots) fixed the problem.

My car is made of depleted uranium, however.

I discolored the front rotors a bit on my '12 Camaro SS with 14" rotors and Brembo 4-pots. That was the end of last season with two weekends back to back with 6+ each Sunday. Did get some lovely pad burn-in as well. Never did get brake fade, but they were a bit warm.

We'll see what the 11" PBR calipers will do first. By mid summer I should be ready to mount the 14" setup. It'll be a good comparison.

any idea as to how much your new weapon/toy is gonna weigh?

I hope this weekend I'll have time to stick it back on the scales.

The reason I ask is there is a 3000 lb weight minimum on CAM-T and 3200 on CAM-C and 2300 on CAM-S

Else you are in CAM-S, but then you don't have to worry about the floor covering.

Given a stock 89 SWB Ranger is 3100 lbs, you might not want to try to save too much weight.

In my somewhat limited experience with autocrossing a Ranger, I've found that it's not a finesse vehicle. It's got relatively poor weight distribution, and balance isn't anywhere near a sports car, so you have to excel in other areas. It's much easier to accentuate the advantages of a truck than it is to change and improve the deficiencies. The biggest advantage of a truck, in my opinion is that you can typically cram tons of tire under it. Grip seems to be the name of the game. It's not going to be about finesse. You have to accelerate out of turns, brake as late as possible, and balance over/understeer in the corners with the skinny pedal. Probably a more point and shoot approach, but you still have to be smooth with inputs. Because of that, I say go as big as you can regarding brakes/tires. As the build progresses, and your weight balance and suspension types change, you may be able to go away from the aggressive point and shoot tactic, and the massive grip/brake approach might no longer be the best. Just my opinion.

Yeah with last year's setup I was right at 3000 lbs. I imagine I'll be in the 2800-2900 range, but we'll know for sure in a few days. I hoping it'll be under 3K so I can add weight where I want it.

STM317, Great insight! I really appreciate it. I'll be putting 315 BFG Rivals on it. I would have gone with the 335s but I only have a 10.5 wide wheel. Like you said tire clearances is a non-issue per say with a truck.

In reply to JGRAHAM:

My goal is to have 315 Rivals at some point too, but you're going to beat me to it by a mile.

Be prepared for the IRS to add weight when the time comes. But it will probably be in a place where you don't mind adding it.

STM317,

Very true. I will weigh my IRS sub assembly soon to get a rough idea of the weight.

Started on the rear flares. The plasma really makes short work of the existing bodywork.

I'm not sure if you've mentioned what IRS you'll be using, or how your specific approach might affect weight, but for the Rolling Thunder project that swapped a Cobra IRS in, the stock rear axle/leafs/hangers weighed about 260lbs, and their cobra IRS weighed 360ish. So without considering any metal added or removed to join the Ranger frame with the IRS, they saw about 100lbs added.

I've got a Thunderbird IRS with the aluminum lower control arms and an aluminum differential housing. The tbird subframe is very beefy, being constructed of heavy wall mild steel. Originally I had planned to make an aluminum subframe for the IRS, but if losing the weight is of no real advantage then I'll save all the fab time for something else.

More trailer flares for the rear? The fronts came out really nice.

Yeah. Going to try and match the front set.

The final items being addressed…..

I pulled the extra leafs out of the rear packs that I had installed last season. Last year I was trying to make the whole truck, front & rear as stiff and as low as possible. I think that might have been the wrong approach. The truck tended to understeer considerably. I’ve been reading a lot on what others have done and it seems that most RWD/front bias setups use a very low spring rate in relation to the front, most of the time it’s over half the front rate. Pulling the leafs also got my ride height where I want it. Keep in mind the rear end setup is only going to be under the truck one more season so I don't have a whole lot of motivation to invest too much time in it. I’ll probably install some new spring bushings, but that will be it for this leaf sprung, solid axle setup.

Just one last thought on the rear setup (and I know it goes against me putting more time in it); Does a leaf spring setup need at pan hard or similar link to keep the rear end aligned? What did older racing leaf sprung setups have under them? I imagine a spring pack alone should do fine in keeping the axle from side shifting for most applications, but what about in extreme cases? Any insight would be great.

I also got the matching rear flares tacked on. Final weld and rust patina will come later in the week.

Will you be doing a hub swap on the TBird rear so that you can keep your current wheels and run Mustang brakes? I'll be curious to see how the new softer rear springs work out for you. Are you running any kind of rear sway bar? The flares match up nicely with the fronts. Nice work!

I've put a pan hard on both a leaf sprung camaro and a ranger. IMO both cars (truck) felt much more stable and consistent with the pan hard installed. Relying on the leafs to control basically two motions of the axle seemed to asking to much of them for race purposes, even more so with wide sticky tires. If you can throw something together without to much time or $$ invested in the solid axle set up I think you would probably like a pan hard/watts.

I'm really digging the flares. Looks good!

I would put a Panhard or Watts link in because leaf springs allow quite a bit of lateral movement and you will want to adjust rear roll center to adjust balance. Raising rear RC decreases understeer, lowering RC increases understeer

Thanks Guys. Yeah I've got Tbird hubs that have been remachined for the 5 X 4.5 pattern. This might just be a pipe dream, but I've been thinking about adapting my current 11" front PBR brakes to the rear. When I get the S550 front brakes installed the PBRs will be sitting on a shelf if I don't repurpose them.

I'm running an explorer rear sway bar. I carried it over when I swapped in the 8.8 rear end.

Well I think I'll probably go ahead and fab up a pan hard bar for it then. I just didn't get a warm fuzzy feeling thinking about all the lateral loading the rear end is going to be seeing. Thanks for swaying me into doing it!

This is the one I use http://www.speedwaymotors.com/Panhard-Behind-Rear-End-Bracket-Weld-On,3381.html

I had the bolt on version but this one is lighter