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front engine dragster style street rod

  
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front engine dragster style street rod

 
fedfan fedfan
New User | Posts: 3 | Joined: 12/12
Posted: 12/28/12
02:55 PM

Looking for info on or what it would take to build a front engine dragster style street rod where 2 passengers sit behind rear axle. I am thinking of a tube chassis with a 4-link rear suspension within the side frame work, and a 23t or 27 lakester body arround the tubes. How much wheel travel is needed and how short can a drive shaft be for that wheel travel? Is this possible and would it be driveable? I have seen some pictures of these but no details, are there any pictures or info out there?  

waynep71222 waynep71222
New User | Posts: 44 | Joined: 04/12
Posted: 12/29/12
05:12 AM

thats creative...

the rear axle is going to need to be wide to have tires on either side of the passenger compartment.   so you might want to think and study carefully which rims and tires you want to run..

i take it that you are going to build this your self...   you might want to start with a 9 inch rear end out of a lincoln full size..  so you get enough length between the wheels..60s through 76  models should do.. that gives you something you can shorten if you need to narrow it.. and a decent probably 5 on 5 bolt pattern except for a few years of lincoln to make it easier to find wheels.

because you will have your seat behind the housing.. and your legs over it.. you are not going to have a lot of room for a bunch of suspension..   you might want to look at the various air springs available..  check some of the pick up truck magazines for various sizes..  if you are not going to raise and lower it.. at command.. you should be able to do this without needing an air tank.. just the compressor and solenoid valves..   you might want to even look at big rig rear cab air springs..

there are some creative 3 link rear suspensions that use a forked upper center link to center the rear end..   that could be creative in its design  ..  perhaps even H shaped.. with 4 bushings or X shaped.. for additional lateral strength..  but hidden inside the drive shaft hump in the middle.
this would allow you to hide the suspension under the car.. leaving more hip room for the driver and passenger..  there are around 40 car and truck magazines on this site.  i can search out some pictures of what i am thinking about.

you might have to go indy car style for the shocks.. with rocking arms to translate the motion from vertical to horizontal    you might even be able to use some of this linkage for a rear sway bar..  there used to be some Neat shocks from 4 way shock company.. that had adjustable spring tension springs over them..  the coils were NOT pigtailed. onto.. but threaded into the clamps.. so the coil became not just a compression spring but an extension spring when the shock extended.. running something like that with some pull on it stops the inside of the turn side from lifting..  i can explain this more if you like the idea..


because of the limited suspension travel in the rear.. you might also want to study or think about some air suspension for your seats... so those BIG DEEP unexpected pot holes don't break your back...   mounting the seats on frame work.. that either has some vertical slides to allow the seats to move up and down.. without changing angle..  or some other creative device.. since most of the weight is going to be supported by the seat bottom..  if there is enough framework. it should work..   again.. air bags for suspension on the seat..  perhaps using some torn apart struts from small cars for nicely chromed strong shafts..


one thing.. if you have the rear area behind the seat compartment..   please think about creating some crush zones into the structure  design back there..  to prevent any tubing back there from entering the cockpit..   i had an idea a while back about crushable tubing sections where a round tubing section is slid into a hydroforming die...  pressure is used to create ribs/ridges in the tubing..  an internal tube is welded in but attached only at one end as a guide .. this was a thought for nascar racing.. where impacts are common.. this allows the tube to crush and absorb some of the impact.

do you own a proper NON CRUSH tubing bender ... they are not cheep.

you can MOCK up the seating area and some of the cage members in various materials..

flexible exhaust pipe.. the wound stuff..  bend it to shape.. and tack weld the individual windings to hold it stable..   grind them if you need to bend it a  little more...  once properly shaped.. you can tach weld them .. to make it rigid.. so you can have it duplicated...

you could also use thin wall electrical conduit and a cheep hydraulic pipe bender from HF or others.. to MOCK up the cage area...  as you want it comfortable.. for the long distance runs..   you will also want the cage taller than the top of your head...  significantly.. so if the back of the car hops up in the air on a bump.. you don't break your or your passengers neck if you hit the top of the cage...   with that said.. 5 point belts.. not 4..  think submarine belt..    but with bouncy seats it will have to attach to the seat frame.. with additional straps to the chassis.. that are fixed length ...  

things that you are going to make out of STRONG steel.. like 4130 chrome moly tubing...

please... spend the money and have a professional heat treating company stress relief the whole chrome moly part...  there are heat treating ovens available that can fit a full size funny car chassis in.. even a few around the country that have long enough ovens to slip a top fuel frame into... this requires a bare finish welded part. that all you holes are drilled and tapped.. all your brackets installed...  as you DO NOT WANT TO WELD or DRILL on chrome moly after its heat treated or stress relieved..  heat treating chrome moly requires exposure to direct flame in the expensive temp controlled oven..   not running along with a torch.. thats not going to fly.. you don't want chrome moly with soft and hard parts.. you want an even tensile strength all the way through..    reverse polarity does not pull the heat out of the welds..  

if you need to add something for a brake line.. machine a clamp to go around the TUBE..  drill and then split it like the big end of a engine connecting rod... wow.. that could be a whole new product line..  create it with a big blank flange so the rodder could drill his own holes  cut the big flange to shape and repolish it..

lastly...  chromed parts.. hydrogen embrittlement..  parts to be chromed that are structural or suspension .. need to be baked at like 900F for many hours just before the chrome plating happens.. before any can get back into the material..

i know that you probably know this.. but its early in the morning... so i thought i would get this out..


since you will be RIGHT on top of the drive shaft... even though its under the floor.. you might want to look at the new NHRA approved drive shaft enclosure tubes..  they make it a pain to get the shaft in and out.. but harder to work on makes it a LOT safer...  the days of a spinning drive shaft between ones legs are LONG gone..  except perhaps in funny car..  

build some brackets or use hot rod bushing at the end motor mount brackets and a steel plate across the transmission mounting area... so you can use 4 pieces of 3/4" ALL thread to support the motor and you can fine tune the height above your floor to ease the mock up.. it you use a square piece.. for the transmission mount you could  offset the bolt holes for the all thread.. so you can have the cross member installed and still have the all thread supporting the back of the transmission/engine assembly..  

fedfan fedfan
New User | Posts: 3 | Joined: 12/12
Posted: 12/29/12
10:10 AM

Thanks for the additional ideas and the cautions. If this is built, it will be a two seat with each persons legs going over the axle tubes not the center section. This should give more room for suspension travel, I am guessing about 4-5 inches total (3 up and 2 down). That looks like more than a lot of street rods that I have seen have. Does this sound like enough, and if only 4 inches, how short could the drive shaft be? I agree with you about the drive shaft protection. I was planning on a rear tube bumper shaped in an oval mounted outside of the passenger compartment in the event of a rear impact. Manufactor of engine has not been set yet, V8 of course, shorty glide for a trans. I would like a gear vender OD unit behind that, with a drive shaft length of 12 to 18 inches, the rear of the engine would have a gap between it and the firewall. I found a 23 T cowl extension to bridge this gap and cover things on the firewall and keep a clean look. I am interested to hear thoughts on my ideas or others ideas. Thank you  

waynep71222 waynep71222
New User | Posts: 44 | Joined: 04/12
Posted: 12/29/12
06:49 PM

i totally understood you about side by side seating with each pair of legs over the axle tube . the pumpkin in the middle...

if you want an overdrive...  instead of just a straight powerglide...  as the gear vendors unit is very long...

i have a few ideas... RODS like you are building are VERY LIGHT... if you are NOT drag racing it..  depending on the tire height...  you can install fairly short gears... as power to weight ratio is there... so you can drive it with possibly 323 gears or 308 gears and still PLANT you in the seat when you mash the go pedal..   but still creep along at 2 grand at 55...

you might want to look at possibly something that i just came up with.. but probably is around...

why not run a 700R4 or 4L60 version with the 4L60 has the removable bell housing so you can use a superbell  housing for safety of the toes and feet..   but let me get to the total idea..

TH350, th400, 700R4, 4l60   4l60... are all available in a 4x4 case where an adaptor is installed and the 4x4 transfer case is bolted on...

this is the back end of a 4L60E 4x4 case.. looks like it still has the transfer case adaptor on it..

IMG 0023

so why not use the short output shaft and the 4x4 700R4 or 4L60    or 4l60E if you wanted computerized shift with a custom short tail housing to give you 4 speeds and with overdrive in 4th with a shorter than normal transmission..

since you are building the car from scratch.. move the engine forward a few more inches..

give you enough room for some kind of drive shaft..

you can get  a fairly short drive shaft...   there are also offset u joints.. where the crosses are staggered to allow more off angle without  binding the the 2 pieces...  you can also use CV joints... thats the coming thing.. not old school...  but it will work on a light car...  so many ways to go..


i know a transmission guy on another forum.. i will ask about whats needed to create a Stubby 4l60 transmission..  

waynep71222 waynep71222
New User | Posts: 44 | Joined: 04/12
Posted: 12/29/12
10:10 PM

these are close to what you will need to make it work.. but there are a LOT of options..

gasser_rear_subframes


better start with pushing two kitchen chairs together and measuring how much seat width you are going to need to be comfortable.. without rubbing shoulder to shoulder..  

fedfan fedfan
New User | Posts: 3 | Joined: 12/12
Posted: 12/30/12
12:32 PM

Thanks again. I should have stated I am going to use a shorty glide for trans. My  thinking now is you are right about the weight and gearing and an OD unit will not be needed. I can not set the engine too far forward or will not have the look I am going after. Your idea will keep the engine back where it needs to be.  I think I am set on the round tube chassis built like FED dragster, with the 4-link bars in the frame sides. Roll bars/cage over the head either one or two bars simulating the old style 3 point or now required 5 point double bar style will be used. Seat room should be ok as these are commonly built street rods from these bodies.  

waynep71222 waynep71222
New User | Posts: 44 | Joined: 04/12
Posted: 12/30/12
01:02 PM

good luck with it..  keep us informed... take lots of pictures.. put them up on something like imageshack   then you can post them as you build...