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MT ET Street SS on the street, whats at risk to break?

A

andrewwoz

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69 Super Bee with a 590hp/625tq 505, passon hemi OD 4 speed, Mcleod RST clutch, stock drive shaft, 741 8 3/4 with eaton trutrac/3.55 gear and stock axles.

Currently running 255/70R15 cooper cobras but thinking about going to 275/60R15 Mickey Thomspon ET Street S/S and running them somewhere between 30 and 35 PSI.

What is the weakest link and what am I going to break if I'm driving it hard on the street?
 
Motor mounts (then fan shroud/radiator) & u-joints?
Depending what you have...
 
My opinion only.
The driveshaft/ujoints would be my first bet, followed closely by the stock axles. My first step would be a stouter shaft and 1350 joints/billet yokes on both ends. (That's what I used on a lighter car with less power than yours... with a powerglide. Transbrake and 14x32 slicks, however)
With that much power, a stick, and traction, you WILL FIND the weak link in your drivetrain..... maybe a couple times.
 
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I don't think you'll break a damn thing as long as the car is solid and everything else is in good condition. The tires are more likely to break loose and spin before anything has a chance to break.

My setup is a 526 stroker, hemi 4-speed 3.54 Dana and CalTracs with 28.5x12.5x15 M/T's. Stock driveshaft with bigger rear yoke to mate to the Dana.
 
BDF6 said:
Motor mounts (then fan shroud/radiator) & u-joints?
Depending what you have...
Click to expand...

Forgot to add the mounts are brand new mity mounts and I have a schumacher torque strap on it.

Thanks for all the replies, the plan is to eventually go to a dana and upgrading the driveshaft would happen at the same time, I had the current stock driveshaft balanced and fitted with new u joints, I do not recall what u joints they used but I believe they said it was a step up from what was on it when I brought it in.
 
Solid cross shaft ujoints would be an upgrade from greasable ones.
I think (note, think!) the stock 741 uses the smaller of the two typical Mopar joints (7260 or 7290?).
It might be worth your while to crawl under and find out exactly what you have. (Greasable 7260 would be the least desirable. Look for zerk fittings.) Dimensions are available on line.
A 1350 joint is about 100% stronger than a 7260.
 
Even a 7290 yoke is a huge upgrade over the 7260 yoke and
they are a dime a dozen.

With production or SS springs a pinion snubber will help prevent the
yoke from enough motion to bind on itself. This is particularly an issue
with the little yoke!
 
I raced my wifes 73 4 speed Challenger using slicks leaving 5000 rpm for a season. It did twist the splines on the stock axles about 1/2 spline rotation. Stock parts: close ratio 833 23 spline, motor mounts, (no torque strap), u joints, 742 8 3/4, leaf springs, gas street shocks. It did run a tall pinion snubber. Doors still fit nice 20 years later. Did put the stock 3.55 and aftermarket axles back in it.
Doug
 
When I installed my Dana I had to have the driveshaft shortened. They used the original yoke BUT a u-joint that adapts the original yoke to the Dana yoke. This is a common practice and virtually every combo you can think of is readily available. The weak point is the u-joint, not so much the yoke(s).

Universal Joint size and dimensions specifications and part numbers 1000 series to 1880 series

Denny's Driveshafts stock a wide variety of universal joints in various sizes for all car, light truck and heavy truck applications. Choose from 1000 series to 1880 series from the industries best brands Dana Spicer, Neapco and AAM
www.dennysdriveshaft.com
 
If you can find the dana numbers for the u joints and yokes you want, I scored all the parts to convert a trunion 833 to slip yoke from autoplicity all genuine dana/spicer stuff. If you decide to beef it up there. I live real close to Denny’s driveshaft. But I was able to find a local heavy truck shop that welded and balanced for like 100$. I supplied the tubing and ends
 
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