48 fire truck roadster

Drive ratios??

Earthman, your post just raised a question in my mind that hadn't occurred before.

Need some help with the math: anyone, feel free to jump in here.

BBC 454 effective operating range RPM 1,000 to 5,000.

700r4 tranny, anyone know options for gear ratios?

Rockwell differential 5.13 ratio, tire diameter 33", rolling diameter 32.5".

Is the overdrive lockup on the 700r4 going to give me enough RPM to cruise on the highway, or will it be putzing along at 55mph wide open? Shouldn't have an issue with low end in the least.

Thanks Earthman, exactly what I was looking for

Earthman's link is excellent for calculating RPM/MPH ratios. All you need is the drive ratios for the tranny you are using, which is easily found.

The 700r4 ratios are 1-3.06, 2-1.62, 3-1.00, OD-0.70. Gives me speeds for each gear from 1,000 to 4,000 RPM. - 1st: 6 to 25 mph, 2nd: 12 to 47, 3rd: 19 to 76, OD: 27 to 109.

Tells me the combination will work well, and confirms that I need an OD tranny, that a 350 or 400 won't work. Should be able to spin the tires with out much effort as well.

I think that sectioning it would make it too short for the tires. Also given that you're not 5'7' your head will be sticking out over the windshield or you'll be sitting so low you'll have your knees smacking your cheeks.

I like the profile the way it is. It really helps to get it outside where you can det a look at it doesn't it?

I would love to see you section it lol... so far you are at about 80% of what i want to do to mine. beside the roadster dually and BBC.

Not much to report, Been a slow couple of weeks for progress on the roadster. Rounding up parts and welding supplies, moving stuff around so the frame is next to the fabrication tools instead of the other end of the shop (I'm lazy).

Cut the original front springs, that were on the 6400 fire truck front axle, making quarter elliptical springs out of them. Also removed one third of the leaves. Made a couple of templates for the bracket that will connect the springs to the front axle. Thinking modified four link, using the springs as the upper links. Going to try clamping the springs to the frame with long "U" bolts and supporting the frame on the ends of the springs to see how much it settles on the springs. Hope to then have a better idea about how to put it together.

DJ came by Wednesday and looked at it, but didn't see any problems with it. I know they are there; was hoping he would find them, so I don't have to do this twice. Will get some pics up soon.

Oh, and other interruptions the last few weeks have been four wheeling around the east end of the Superstition Mountains. Weather has been perfect for it. Got my GMC pickup hung up a couple of times, so went and bought another Jeep today (sold the one in the avatar a year ago). So little time, so many distractions.

Bought a Jeep? Sounds like you're going over to the dark side. What do you think - about 3-4 weeks of wheeling, (before it gets too hot) then you'll be back on the firetruckster?

Hey, you think that 454 would fit in the Jeep?

Hey Truckster,
I really like your build, just wanted to say 'Hi' from the other side of the valley.
I'm near 75th Ave & 101 in N Peoria.
I just sold my Jeep (too expensive & time consuming, haven't used it for probably 8 years) which has given me the cash to get my garage in order & start on a couple go-carts (rat rod influenced)!
If you ever need an additional pair of willing (though minimally skilled) hands, leeme know & I'll see if I can get the wife busy & ride out there.
:-D
-Chaz

Understand the cost and time in Jeeps. I think this is the 6th or 7th one I've owned. Insanity is doing the same thing over and over and expecting different results. (Einstein or Freud, can't remember which)

Not a lot of progress to report. Did get the front quarter ellipticals "U" bolted to the frame so I could get a better idea of what I'm trying to do.

Also tacked in a new permanent front crossmember and lopped off the front of the frame to where the radiator will mount.

Put a piece of channel across under the eyes of the springs and lifted the front of the frame with a jack so the frame was off the jack stands, and then stood on the frame and bounced it best I could. My highly calibrated eye and highly calibrated legs and feet indicated it is the right spring rate and capacity when the rest of the metal and accouterments are attached. We will see if that proves out.

The "U" bolt plates are proof of concept installations only. If this works, will replace those with something better looking. Will need to install lower links and further trim the front of the frame after I get the radiator brackets figured out. Still working out a bolt on bat wing for the axle as well.

DJ3100 said:

Bought a Jeep? Sounds like you're going over to the dark side. What do you think - about 3-4 weeks of wheeling, (before it gets too hot) then you'll be back on the firetruckster?

Hey, you think that 454 would fit in the Jeep?

Click to expand...

Remember, I've been to the dark side before. At that time, this WAS the dark side. I don't know I'm going to get 3-4 weeks. Had to get wheels to put the tires on off the GMC, found a leaking axle seal (on a 13,000 mile Jeep, one month out of warranty) that I missed when I bought it, had to repair that. Waiting on the lift components now so that the new wheels/not quite new tires will fit in the fender wells. $$$ getting thin.

Don''t even want a 454 in it, the last Jeep had a LT-1 in it, it was pretty snug. But then I've seen V-10 Viper engines in them. Enough about Jeeps, back to the rusty stuff.

The front suspension is looking good to me. I can't see anything that would be a problem. You'd be better off hearing that from someone who knows something, though. Maybe there will be something to see at Goodguys tomorrow.

As far as the Jeep goes -you gotta keep it at least until next winter. No getting PO'd and selling it in July when its 110 and 80%. And by the way, the trick is do something different this time. You might get the same result, but at least you won't be adding to the insanity.

rusty

truckster said:

Remember, I've been to the dark side before. At that time, this WAS the dark side. I don't know I'm going to get 3-4 weeks. Had to get wheels to put the tires on off the GMC, found a leaking axle seal (on a 13,000 mile Jeep, one month out of warranty) that I missed when I bought it, had to repair that. Waiting on the lift components now so that the new wheels/not quite new tires will fit in the fender wells. $$$ getting thin.

Don''t even want a 454 in it, the last Jeep had a LT-1 in it, it was pretty snug. But then I've seen V-10 Viper engines in them. Enough about Jeeps, back to the rusty stuff.

Click to expand...

real jeeps are rusty

Managed to find some time to design and build four bat wings, although they look more like boomerangs, ordered some rod ends from Midwest Control to give me some options on making lower control arms to go with the 1/4 elliptical springs which will also constitute the upper control arms.

These are somewhat large, but look right with the axle. The holes in the platten table are 1 3/4" square to give you an idea of size.

Very cool. Glad to see you're still at it. It will be handy to get that thing rolling around.

It's a roller!

Finally back to work on it. Lost almost 3 months due to broken and separated ribs (big undo on a mountain bike).

Finished the rough fit on the front quarter elliptical suspension. It uses lower control arms with spherical ball joints on the trailing edge to allow adjustment in caster.

Settled right in at 5" of ground to frame clearance and there is a lot of adjustment up or down for ride height by changing stand-off spacer in the front "U" bolt position.

Front of frame is run long for now until I get the radiator, grill, and shock brackets on.

Bolts are long to allow the shoulder to make full span across the brackets. Will trim the bolts when I disassemble it all to finish weld.

Now to figure out how to steer the beast.

Sorry to hear about your misfortune Truckster but happy to see a progress post.Really interesting suspension. I like to see axles, front and back,out like this so it looks almost like they are independent from the frame.

That really came out nice. Glad to see some progress. I'll be interested to see how the steering works out.

truckster said:

It's a roller!

Finally back to work on it. Lost almost 3 months due to broken and separated ribs (big undo on a mountain bike).

Finished the rough fit on the front quarter elliptical suspension. It uses lower control arms with spherical ball joints on the trailing edge to allow adjustment in caster.

Settled right in at 5" of ground to frame clearance and there is a lot of adjustment up or down for ride height by changing stand-off spacer in the front "U" bolt position.

Front of frame is run long for now until I get the radiator, grill, and shock brackets on.

Bolts are long to allow the shoulder to make full span across the brackets. Will trim the bolts when I disassemble it all to finish weld.

Now to figure out how to steer the beast.

Click to expand...

Those are really nice batwings!

Thanks for sharing your progress![

Regards,
Shea

im ready to see more truckster