anyone ever autocross/road race their truck?

[bad_burb]

Does anyone know the actual stock steering ratio?

[68 TT]

Originally Posted by Test Pilot

Aero, not much can be done here unless you are going all out race rig, get the truck low to reduce the amount of air it has to push, but likely it won't be a huge factor top speed on the 505 hp SRT-10 Ram was an aero limited 154.xxx. I think getting a C10 to 150 would be a feat, and a bit scary to drive at such speeds.

One thing I picked up from my friends who did the silver states and other top end speed run type races was that the frontal area is nicely reduced by lowering the vehicle as much as you can and by running only one side view mirror and making that one mirror as small as possible. Less frontal area means higher top end speed with the same HP.

Not a big deal in Auto-X but road courses where you might see some triple digit speeds it will help.

[68 TT]

I did a little cross reference work and found that the steering gear box changed in 1980 so the IROC box guts should fit into the 80-up square body gear box case.

Not as cool to have as the new 600 series box that came in some of the 99-up trucks but it at least it will give you the quicker steering ratio for a budget friendly price.

The IROC box I have cost me all of $22 at the pull it yourself wrecking yard so with a 80-up truck donor box and a seal kit I will have about $80 into the quick ratio steering box for the 67 C-10. Much more budget friendly than the $400+ a converted old box would cost.

[68Timber]

I just heard back:

John,

We can custom build a 2.75 turn box for $225 plus $75 core deposit. It would take a few days to build.

Feel free to contact us with further questions or to order.

Thanks,
Scott

1-800-399-7845
sales@CarSteering.com
www.CarSteering.com

Now that ain't to bad at all...

[tymbom]

Has anyone else thought about using a Porterbuilt drop member? Lower ride height, narrow track width, bolt on rack and pinion steering. I'm sure a set of 295-50-15's would fit alot better with the narrow track. Scrap all the air ride crap for some coil-overs. I think it would be pretty trick...

[68 TT]

Originally Posted by tymbom

Has anyone else thought about using a Porterbuilt drop member? Lower ride height, narrow track width, bolt on rack and pinion steering. I'm sure a set of 295-50-15's would fit alot better with the narrow track. Scrap all the air ride crap for some coil-overs. I think it would be pretty trick...

I thought about building a drop member that used 78-96 B-body A-arms and spindles. You could use either the 5 on 5 bolt pattern heavy duty B-body 12" rotors or the 5 on 4-3/4 F-body 1LE 12" rotors. The lower are the same as the 77-up 2nd gen F-body, X-body & A-body. The upper is different to compensate for the taller B-body spindle but should use the common F-body poly bushings.

I haven't done any measuring but I would bet it narrows the track width by a little just by where I know the frame stands for the motor mounts are located on the B-body frame vs. the trucks frame rails. Next time I am around a B-body I will take a front track width measurement to see.

It may be possible to graft in the B-body front frame section like the older trucks used to graft in the F-body subframes but turning it into a bolt-in drop member would be better.

[68 TT]

Originally Posted by tymbom

Has anyone else thought about using a Porterbuilt drop member? Lower ride height, narrow track width, bolt on rack and pinion steering. I'm sure a set of 295-50-15's would fit alot better with the narrow track. Scrap all the air ride crap for some coil-overs. I think it would be pretty trick...

I would love to see a 10" rim 295/50-15 on the front and a 12" rim 325/50-15 on the rear with it slammed to the ground. That would look down right evil. Who cares if it would handle better with lower profile tires.

[Test Pilot]

Originally Posted by 68 TT

One thing I picked up from my friends who did the silver states and other top end speed run type races was that the frontal area is nicely reduced by lowering the vehicle as much as you can and by running only one side view mirror and making that one mirror as small as possible. Less frontal area means higher top end speed with the same HP.

Not a big deal in Auto-X but road courses where you might see some triple digit speeds it will help.

This is correct, the frontal area is essentially the sillouette of the vehicle from the front view including the are between the tires, below the bumper.

Has anyone else thought about using a Porterbuilt drop member? Lower ride height, narrow track width, bolt on rack and pinion steering. I'm sure a set of 295-50-15's would fit alot better with the narrow track. Scrap all the air ride crap for some coil-overs. I think it would be pretty trick...

What concerns me with this is the geometry, I'm sure they make a fine product. It looks quite sturdy, but has the suspension been ran though the same design analysis of a car with a "performance" oriented suspension. I'm not saying the stock suspension is a "performance" design, but I'd like to know what data looks like, ie camber curve, roll center etc. I would hope they also give you a good bit of caster.


One issue with the oe setup is the tire sits back in the wheel well. If you dial in a bunch of caster it's really far back. A lot of caster is nice because you get the appropriate camber gain when turning. This is good because you can run less static negative camber, which results in better braking a more evenly loaded wheel/hub so on and so forth. If this is the case and the Porterbilt drop member addressed this that would certianly be a plus.

[ccreddell]

That is the case with the Dropmember-it is very well engineered. And it has been performance engineered. Not only that, but he also makes a Dropmember that accepts C-4 (corvette) front suspension components-including the spindle and 13" rotor. And its re-engineered to complement the truck. Oh, and it moves the tire forward slightly to center the wheel.

[ccreddell]

I went thru a dropmember post and found some answers for you.

http://67-72chevytrucks.com/vboard/s...d.php?t=201898

Look at posts #5 and #47 especially. And posts #101, 114, and 121 for the C-4 details.

[68 TT]

Originally Posted by ccreddell

I went thru a dropmember post and found some answers for you.

http://67-72chevytrucks.com/vboard/s...d.php?t=201898

Look at posts #5 and #47 especially. And posts #101, 114, and 121 for the C-4 details.

I like the idea of using C-4 parts but the sealed bearing hubs suck. I worked at a Corvette only shop while working my way through college. Those sealed wheel bearing assemblies are expensive and don't last that long.

I would go with a different spindle that could still use individual Timken wheel bearings that are inexpensive and a typical bearing hub. Something like CORE3 makes would be nice but a redrilled factory bearing hub from a drum brake truck or car could work too for a whole lot less money.

[ccreddell]

Originally Posted by 68 TT

I would go with a different spindle that could still use individual Timken wheel bearings that are inexpensive and a typical bearing hub. Something like CORE3 makes would be nice but a redrilled factory bearing hub from a drum brake truck or car could work too for a whole lot less money.

Then just go with the late C-10 truck spindle-its plenty strong enough and you can get some pretty large rotors on them.

[68 TT]

Originally Posted by ccreddell

Then just go with the late C-10 truck spindle-its plenty strong enough and you can get some pretty large rotors on them.

My 67 is drum brakes so I am going to look into a slip on rotor setup like the C3 Vette used where the rotor just sits on top of the bearing hub.

I like the idea of simple and inexpensive so the late truck 12" disc may be the way to go with just a slightly relocated upper A-arm mount point to give it 5 degrees of caster with a level shim stack and relocated crossmember mount bolt holes to center the wheel in the well.

[ccreddell]

Originally Posted by 68 TT

My 67 is drum brakes so I am going to look into a slip on rotor setup like the C3 Vette used where the rotor just sits on top of the bearing hub.

I like the idea of simple and inexpensive so the late truck 12" disc may be the way to go with just a slightly relocated upper A-arm mount point to give it 5 degrees of caster with a level shim stack and relocated crossmember mount bolt holes to center the wheel in the well.

Thats what the DM will give you-plus rack and pinion steering. Oh, and ground clearance.

[68 TT]

Originally Posted by ccreddell

Thats what the DM will give you-plus rack and pinion steering. Oh, and ground clearance.

Yes it will and PB's stuff is fantastic but my budget for this low priority toy can't handle the $2000+ hit for the front suspension alone.

My ideas I can implement for minimal investment using stock GM parts and will result in the best bang for the minimal bucks I have to work with. It will have its shortcomings but that is the price I will pay for working with next to nothing for a budget.

[tymbom]

The DM addresses the camber gain and centering the wheels in the wheel well. CPP and McGaughy's makes a 13" brake kit for the truck spindle. And CPP will be offering a 14" kit soon. I can't see any advantages of trying to put the B body suspension on a truck. McGaughy's even sells their set up with the 4.75x5 pattern if you really want them. I like the idea of sticking with the 5x5 pattern and upgrading to 5/8ths studs.

[68 TT]

Originally Posted by tymbom

The DM addresses the camber gain and centering the wheels in the wheel well. CPP and McGaughy's makes a 13" brake kit for the truck spindle. And CPP will be offering a 14" kit soon. I can't see any advantages of trying to put the B body suspension on a truck. McGaughy's even sells their set up with the 4.75x5 pattern if you really want them. I like the idea of sticking with the 5x5 pattern and upgrading to 5/8ths studs.

I never cared for the U-bolt secured lower A-arms so I would like to incorporate thru bolted style mounts and matching lower A-arms. The B-body weighs as much or more than most 2-wd trucks so the parts can handle the loads of a non-load hauling street toy no problem.

I am mostly converting to 5 on 4-3/4 to use up a bunch of spare parts I have sitting around taking up space. Camaro style rally wheels, larger pinion car 12-bolt posi with 4.11 gears, full set of four C3 Vette rotors and four matching 1.25" reach LS1 Camaro PBR calipers and a pair of C3 Vette front bearing hubs. I always upgrade to higher strength aftermarket 1/2" wheel studs so they should be plenty strong, the taller sidewall 15" tires will be my limiting factor.

[tymbom]

If you got a bunch of parts laying around that makes sense... I never liked the U-bolt on the lower control arms either. The DM does make a pretty good improvement there as well. I wish I could call Nate and order one up right now, but I'm in the same boat as everyone else.

[68Timber]

On the quicker ratio steering box quote, the price he gave me was only $30 more than a reman replacement. So the price is OK, but 2.75 turns LTL doesn't seem like a big improvement, at least to a novice like me. I've been reading an in-depth discussion here that let's me know we have some members who have been there and done that. I did reply and ask if 2.75 was the only option but haven't heard back yet.

Is that a quick enough ratio for a driver? 2.5 or 2.25 sounds much better, but without hands-on experience I don't really know what to ask for, or more accurately - I don't know what I really want and don't want to fall into the 'more is better' trap.

Thanks.

[71'tahoe]

TTT for good info!!

[68 TT]

Originally Posted by BRUISER

On the quicker ratio steering box quote, the price he gave me was only $30 more than a reman replacement. So the price is OK, but 2.75 turns LTL doesn't seem like a big improvement, at least to a novice like me. I've been reading an in-depth discussion here that let's me know we have some members who have been there and done that. I did reply and ask if 2.75 was the only option but haven't heard back yet.

Is that a quick enough ratio for a driver? 2.5 or 2.25 sounds much better, but without hands-on experience I don't really know what to ask for, or more accurately - I don't know what I really want and don't want to fall into the 'more is better' trap.

Thanks.

See if they can put the 2.25 IROC internals in the 80-91 housing. Maybe they are limited by the 79-earlier housing.

The difference between 2.75 and the IROC 2.25 is huge. I started with almost the same thing at 3 turns on my Malibu and installed the 2.25 IROC box. Wow what an improvement. The car really reacts when you turn the wheel even just 1/8 of a turn.

[68Timber]

I did hear back, 2.75 ltl is the best they can do with the stock unit. The calculator says that's a 21% improvement. That may be all I need. I'll have to check it against some other cars in the driveway and see what the rest of them are.

[Gemp]

For the price of that rebuild, That seem like a worth while improvement.

[RUSSOM]

Originally Posted by BRUISER

I did hear back, 2.75 ltl is the best they can do with the stock unit. The calculator says that's a 21% improvement. That may be all I need. I'll have to check it against some other cars in the driveway and see what the rest of them are.

Did you ever have them rebuild the box to the quicker ratio? If so, what is your report? Worth the money?

[68Timber]

Not yet. Still on the to do list.