question on hwy cruising

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travisschroer

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ok so my motor is almost ready to go in i checked over the trans and am debating on installing the tci 220000 shift kit.

here is the two things that concern me is i have the infamous 7 1/4 and i plan on towing roughly 2000 lbs (motorcycle and gear and 5x8 trailer) will the stock axle live??

also i have a 38 mile commute and the gear calculator say 2600rpm with 25 inch tires if i go to 17"s or 2800 with the stock 185/70r13. i know i am being a worry wart but is that to high or will it be ok i plan on this being my DD.
 
2,600 or 2,800 are both reasonable RPMs to be turning out on the highway. I don't see any issue here.

But I do see an issue with towing and a 7 1/4 rear end. I think you are asking a lot from something that is barely adequate for moving people down the road.
 
normal driving does not hurt the 7-1/4" rear
neither will occasional towing
what hurts the 7-1/4" rear is hard launches from a dead stop, as in drag racing or stop light to stop light racing, doing burnouts, or any other type of high torque application
the rule for keeping a 7-1/4 rear happy is to be easy on the throttle, even more so when towing a trailer, if you follow common sense the 7-1/4" rear will last a long time
 
the motor is a decent slant it is cammed and 9-1 desktop dyno says 190hp and 248ftlbs is that gonna be too much with the towing? or should i just bite the bullet and find a ford 8" from a maverick(i know i know its a ford part but it is good axle)
 
As stated, As long as your not hammering it, the 7.25 will work fine.

Leave the 8" for the Ford folks. If you really are worried about it go with a 8.25 or 8.75.
 
Ok thank all of you for the reassurance I'll double check the oil levels prolly put some synthetic 75-90 in her but I guess I'll keep the ol 7 1/4 for now
 
travisschroer said:
Ok thank all of you for the reassurance I'll double check the oil levels prolly put some synthetic 75-90 in her but I guess I'll keep the ol 7 1/4 for now
Click to expand...

Do a double check on the proper gear oil.

Sometimes synthetics aren't the best answer for our old rides.
 
big bolt disk brakes and an 8-1/4" rear is the cool hot set up for towing
drum brakes are more of a problem when towing than the 7-1/4" rear
just make sure the 8-1/4" rear doesn't have the 2:45 ratio in it
 
I would be a LOT MORE CONCERNED about the suspension and BRAKES towing ?how? much weight including the trailer? Does the trailer have brakes?
 
i am worried about the all wheel drums and am looking into discs for the front just looking for sbp discs and like i said its not crazy heavy(600lb enclosed trailer,430lbs bike, about 15-20 gallons of fuel and maybe 150lbs of tools) i figure id round up and assume 2000lbs for the trailer. the car already has air shocks on the rear. but i figure i have about 4 months till racing season restarts :blob: and then i will have to worry about towing
 
travisschroer said:
the motor is a decent slant it is cammed and 9-1 desktop dyno says 190hp and 248ftlbs is that gonna be too much with the towing? or should i just bite the bullet and find a ford 8" from a maverick(i know i know its a ford part but it is good axle)
Click to expand...

190/248 is alot for cam and compression... what else have you done to the motor?

and i would go with the Trans-go shifts kit over anything TCI...
 
travisschroer said:
its not crazy heavy(600lb enclosed trailer,430lbs bike, about 15-20 gallons of fuel and maybe 150lbs of tools) i figure id round up and assume 2000lbs for the trailer.
Click to expand...

That is some SERIOUS weight for an A body, and is a substantial part of the car's curb weight. You certainly need good brakes on the car, and BRAKES ON THE TRAILER. I believe, here, any trailer over 1500 lbs is required to have brakes and a "break away" device
 
caferacerx said:
normal driving does not hurt the 7-1/4" rear
neither will occasional towing
what hurts the 7-1/4" rear is hard launches from a dead stop, as in drag racing or stop light to stop light racing, doing burnouts, or any other type of high torque application
the rule for keeping a 7-1/4 rear happy is to be easy on the throttle, even more so when towing a trailer, if you follow common sense the 7-1/4" rear will last a long time
Click to expand...

Dude, 7 1/4s routinely tore up behind stone stock slants with little old blue haired ladies drivin um.
 
the exact specs on the motor are .040 8.7-1 pistons head is milled .020 to clean everything up using a holley 350cfm carb comp cams 264s cam (264 duration 220 at .50 1.6 rockers should put me at .477 at the valve) and a 2 1/4 exhaust havent decided on muffler yet. honestly im sure the desktop dyno is a best case scenario but im shooting for 150 and 220 N/A. im thinking next year it will have a mitsubishi 16g hanging off the side with 8psi of boost. then il be shooting for 210 and 300ftlbs :burnout:
 
No 6000 rpm launches with the trailer behind you !!

Install a large tranny cooler to make sure the fluid stays cool.

Change rear end lube for peace of mind.

No 130 mph towing and it should be ok.

Don't ask....


P5167718.jpg
 
yellowdartdave said:
No 6000 rpm launches with the trailer behind you !!

Install a large tranny cooler to make sure the fluid stays cool.

Change rear end lube for peace of mind.

No 130 mph towing and it should be ok.

Don't ask....
Click to expand...
Sorry but with an details like that, this is begging to be asked why.
 
travisschroer said:
ok so my motor is almost ready to go in i checked over the trans and am debating on installing the tci 220000 shift kit.

here is the two things that concern me is i have the infamous 7 1/4 and i plan on towing roughly 2000 lbs (motorcycle and gear and 5x8 trailer) will the stock axle live??

also i have a 38 mile commute and the gear calculator say 2600rpm with 25 inch tires if i go to 17"s or 2800 with the stock 185/70r13. i know i am being a worry wart but is that to high or will it be ok i plan on this being my DD.
Click to expand...

Drivers have towed all sorts of things with cars just like yours ever since the first ones were sold. 7.25 rear, drum brakes, etc.., are DOT approved.
If you know your vehicles abilities you can adjust your following distance
and other factors accordingly.
 
yellowdartdave said:
No 6000 rpm launches with the trailer behind you !!

Install a large tranny cooler to make sure the fluid stays cool.

Change rear end lube for peace of mind.

No 130 mph towing and it should be ok.

Don't ask....


P5167718.jpg
Click to expand...
ok need details mostly with the 130mph towing:prayer:

btw very nice 2 stroker i built a rd400 and a suzuki water buffalo before kinda unpredictable to drive but thats the fun:glasses7:
 
travisschroer said:
the exact specs on the motor are .040 8.7-1 pistons head is milled .020 to clean everything up using a holley 350cfm carb comp cams 264s cam (264 duration 220 at .50 1.6 rockers should put me at .477 at the valve) and a 2 1/4 exhaust havent decided on muffler yet. honestly im sure the desktop dyno is a best case scenario but im shooting for 150 and 220 N/A. im thinking next year it will have a mitsubishi 16g hanging off the side with 8psi of boost. then il be shooting for 210 and 300ftlbs :burnout:
Click to expand...

yea your looking at maybe 150hp... did you work the head a little bit?

also where do you plan on getting 1.6 rockers??
 
805moparkid said:
yea your looking at maybe 150hp... did you work the head a little bit?

also where do you plan on getting 1.6 rockers??
Click to expand...

no i just cleaned up the ports myself nothing pro just cleaned up. on the rocker i have not had a chance to actually measure them but they came off a buddys duster that his dad built in the 80s dad swears up and down they are high ratio said they were either a true 1.5 (the factorys are actually 1.35 or so) or a 1.6 he couldnt remember but they do seem to be a deeper stamping than any factory ones ive seen? honestly im not to worried about power id like to turbo just for the oooh factor but mpg and drivability are gonna be the main things right now and congrats on the early a body just saw your post 805 this motor is for a 64 dart :D
 
travisschroer said:
no i just cleaned up the ports myself nothing pro just cleaned up. on the rocker i have not had a chance to actually measure them but they came off a buddys duster that his dad built in the 80s dad swears up and down they are high ratio said they were either a true 1.5 (the factorys are actually 1.35 or so) or a 1.6 he couldnt remember but they do seem to be a deeper stamping than any factory ones ive seen? honestly im not to worried about power id like to turbo just for the oooh factor but mpg and drivability are gonna be the main things right now and congrats on the early a body just saw your post 805 this motor is for a 64 dart :D
Click to expand...

your right the stockers are around 1.35 to 1.4...
 
travisschroer said:
ok need details mostly with the 130mph towing:prayer:

btw very nice 2 stroker i built a rd400 and a suzuki water buffalo before kinda unpredictable to drive but thats the fun:glasses7:
Click to expand...


130mph .... Coming thru Atlanta Sat. evening I slowly passed a guy on a Sportster 1100. When he saw the 2 bikes on the trailer, he downshifted and hauled butt. I eased the Mustang into 3rd, banged 4th and smoked past him at 130+. He could only run about 110, so it was no problem.

I think his tie flapping in the breeze slowed him down!

To bad you live so far from Deals Gap and the Tail Of The Dragon.
We have a 2-Stroke meet there every May.

DealsGap07-1.jpg
 
i wish i still had a smoker i sold my water buffalo last year and the rd was sold before that one but one day i want to do a cross country in the dart i might have to drag my turbo triumph to hang with you guys
 
The weak part of the 7 1/4 is the spider gears, and to a lesser but related extent, the side gears. Pull your cover and check their condition. If there is any pitting on them or lots of backlash or play between the spiders and their shaft, replace them or the whole rear. If they look in good shape, button it back up, top it off with a good quality GL-5 gear oil and call it a day. Just drive it easy.....strain is what kills them. If I remember correctly, someone has high quality replacement spiders and side gears for these so you may want to upgrade if you choose to keep the 7 1/4.
 
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