[HWYSTR455]

Originally Posted by 78w72

a cromo 3" 'shaft with 1350 forged yokes is not anywhere near $350 or even $400-500 from what i have seen, cheapest i found is strange at $600+ shipped, other places like dennys & even local were as much or more. this is for a 3" cromo shaft with th400 forged 1350 ends for a 2nd gen firebird, maybe much shorter ones are a little cheaper but not seeing anything close to $350... got a link to a company that makes a fully forged 1350 shaft & yoke for $350 or even $450 HWYSTR?

pretty sure factory shafts & yokes vary in strength based on the engine & vehicle, i doubt a late 70's or early 80s firebird with a 301 or 305 making all of 150 hp uses the same rated shaft as a early to mid 70's 400/455 or other makes with 454s & 460s etc etc. saying ALL stock driveshafts are rated for no more 350 ft lbs cant be true, when a stock early 70's 455 had 450+ or close to 500lb/ft. GM or any company would never put a 350lb/ft rated shaft behind a 455 or other big torque engines.

i fully agree a beefier shaft & yoke is best for cars making bigger power or that are raced, im not suggesting anyone at that power level or purpose use a stock shaft, although countless people have for decades with very low failure rates. heck it took ta man getting into the 10's & probably decades of serious abuse to break his stock one at the yoke & mine is doing ok after just as much abuse behind numerous torquey engines & now knockin on 10's door... but i realize thats pushing it even with the new 3" .083 shaft & solid u-joints but stock yoke i have, i will be buying a strange forged 1350 asap at my current power level & i should have done that right off the bat but that doesnt always happen when youre doing a full resto & engine build, you tend to cut corners on some things.

i still feel a cromo forged 1350 is not needed for the average guy on the street with a mild (at or below 400lb/ft or 350-400hp), they do make other options like nodular iron yokes that are much stronger than stock cast iron, pair that with a .083 3" non cromo shaft & solid u-joints & it will live behind a mild 400 or 455 on the street at half the price of fully forged. just mentioning some options when youre not a racer making 500+hp & 600lb/ft of torque.

https://www.strangeengineering.net/p...range-hd.html/

Sure, here's a 3.5" strange chrome moly with ends and U-joints for $465:

https://www.strangeengineering.net/p...iveshaft.html/

Your link goes to a slip yoke, and it's $85 for a nodular iron, which is plenty strong for the 'street' section.

You get the mack-daddy forged items of course it's more. You go to a big-name supplier, of course it's more. You go to a local driveline shop and it's a solid 25% or more off.

Why try to bloat it? To prove a point? Again, all I'm doing is providing my opinion, take it or leave it. No need to attack me.

My last driveshaft, 3.5" CM shaft, ends, balanced, was $285 at a local shop. I sourced my own joints and slip. Done.

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[HWYSTR455]

Here's a 3" CM strange with u-joints & ends for $279:

https://www.strangeengineering.net/p...eld-ends.html/

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[Formulajones]

Wow $285 for a chrome molly shaft complete? Damn! I have to say you guys have it good in Virginia when it comes to prices.

I've used a local driveline shop out here for 15 years now. I can't even touch a chrome molly shaft for $285. In fact I can't even have a mild steel shaft with 1330 joints good for 600hp done for $285.

He does use DOM tube though which is stronger than a typical steel tube, and that shaft I recently had done with 1330 joints for 600 hp was $450.

Did a bigger one for dad's car in steel with 1350 joints and that one was $600.

I just recently did an aluminum 4" with 1350's for my car and I actually mail ordered that one from PEM and it was $600 delivered.

[Formulajones]

Originally Posted by HWYSTR455

Here's a 3" CM strange with u-joints & ends for $279:

https://www.strangeengineering.net/p...eld-ends.html/

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That's interesting, I like it.

Does it have a guestimated HP rating? I don't see one.

[ta man]

One of the nice features of a 1350 diff yoke is the positive end retention of the u joint. There is zero chance of the u joint or shaft walking either way, plus it does not need to be over tight crushing the u joint bearings.
I was one of these guys with a $12000 plus engine, $3000 tranny, $1000 dollar convertor beating on a stock driveshaft..It eventually bit me in the ass.
After snapping the front yoke..possibly caused by the rear u joint letting go it cracked the tranny case. R/R of the tranny, swapped guts into another transmission, finding issues with the swap R/R fixed the issues. Or maybe at that time caused tranny issues we didnt see..leading to a full rebuild again.
One thing I've learned here is spend money on good parts or good service it will pay for itself and save money in the future.

[78w72]

Originally Posted by HWYSTR455

Sure, here's a 3.5" strange chrome moly with ends and U-joints for $465:

https://www.strangeengineering.net/p...iveshaft.html/

Your link goes to a slip yoke, and it's $85 for a nodular iron, which is plenty strong for the 'street' section.

You get the mack-daddy forged items of course it's more. You go to a big-name supplier, of course it's more. You go to a local driveline shop and it's a solid 25% or more off.

Why try to bloat it? To prove a point? Again, all I'm doing is providing my opinion, take it or leave it. No need to attack me.

My last driveshaft, 3.5" CM shaft, ends, balanced, was $285 at a local shop. I sourced my own joints and slip. Done.

.

attack you??? OK. im not "bloating it" or trying to prove a point & definitely not "attacking" you.. sorry if you interpreted my post & question that way. it was posted as a question & stating cost of a complete forged driveshaft, nothing more... your post i was replying to said "If you choose to have a shaft made, the majority of the cost is labor and ends, it makes sense to just have a whole new shaft made. With u-joints, ends, and a slip yoke, expect to pay in the $350-$500 range."

yes the link i posted was to a nodular slip yoke, i was providing that as an alternative to the fully forged stuff some are suggesting that isnt needed for the average street car.

the links you posted dont include the forged 1350 yoke & that has to be factored in the pricing of a complete shaft that is being discussed here. its over $600 shipped from strange or summit. thats all i was saying, no need to take that any other way.

done.

[ta man]

Originally Posted by 78w72

attack you??? OK. im not "bloating it" or trying to prove a point & definitely not "attacking" you.. sorry if you interpreted my post & question that way. it was posted as a question & stating cost of a complete forged driveshaft, nothing more... your post i was replying to said "If you choose to have a shaft made, the majority of the cost is labor and ends, it makes sense to just have a whole new shaft made. With u-joints, ends, and a slip yoke, expect to pay in the $350-$500 range."

yes the link i posted was to a nodular slip yoke, i was providing that as an alternative to the fully forged stuff some are suggesting that isnt needed for the average street car.

the links you posted dont include the forged 1350 yoke & that has to be factored in the pricing of a complete shaft that is being discussed here. its over $600 shipped from strange or summit. thats all i was saying, no need to take that any other way.

done.

The OP doesn't have an average street car. Take a good look at his combo used...to me it doesn't make sense to not ante up and put a full CM driveshaft complete with CM trans input and diff yoke. Just be done with it..what is an extra 500 to 600 dollars for a bulletproof setup instead of a what if ??

[78w72]

Originally Posted by ta man

The OP doesn't have an average street car. Take a good look at his combo used...to me it doesn't make sense to not ante up and put a full CM driveshaft complete with CM trans input and diff yoke. Just be done with it..what is an extra 500 to 600 dollars for a bulletproof setup instead of a what if ??

i fully agree with that & did look at his combo, i said many times above that for that power level a stock shaft probably isnt a good idea & the ~$600 for a forged 1350 one is well worth it. or that there is a middle ground for guys with a little less extreme of street cars than yours or mine with 600lb/ft stroker motors by using a nodular iron yoke on a new DOM 3" shaft & solid joints smaller than 1350 for about half the price.

what i mentioned is that in reality many people with less power than the OP but well above stock OE power levels have & do get away with a stock shafts & yokes. i think yours & mine prove that until you have big power & regularly drag race a car at our times a stock shaft failure is pretty rare for a street car. & like you & myself did, many people dont want/need to or cant afford a $600 shaft for their street car.

same logic applies to lots of things with these cars, some ask for ideas on a mild streetable build & get people telling them they need forged rods & crank & aluminum heads with huge cams for max power to avoid the what if... just keeping it in perspective.

[grivera]

Originally Posted by Schurkey

Using that conversion joint as a "fuse"?

This is temporary until I upgrade the rear

[Formulajones]

Originally Posted by grivera

This is temporary until I upgrade the rear

I've done the "adapter" joints in the past to get by until the yoke change on the rearend was done.

In fact when talking to the local driveline shop about it, it's not really the combination u-joint that is the weak link, it's the stock cast yoke on the rearend that will break first.

You're running an automatic and no trans brake, you'll be fine to drive and enjoy the car until the yoke upgrade, I wouldn't worry about it.

[HWYSTR455]

Originally Posted by Formulajones

That's interesting, I like it.

Does it have a guestimated HP rating? I don't see one.

I'm certain it's way more than an OE, and bet more than a DOM steel 3.5". Call and ask.

There's an area along I-95 outside of DC that has a bunch of commercial truck repair shops, there's a couple driveshaft shops over there. They do them all day long. The one I checked and made sure they had a quality balance machine, and asked what RPM they balance to.

Granted, it's been like 4 years since they did a shaft for me, but suspect they are still roughly in the same price range.

There's a couple different types of iron shaft ends, the OE ones are general cast ones. There are some nodular iron ones that are pretty dang strong, and those are usually the ones I use for under 650ftlbs.


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[HWYSTR455]

Ok, I looked, and in the description it says this:

"The Cast Iron Weld ends are recommended for cars making around 600 WHP or less. For cars making more we typically recommend our U1702 3 inch Chrome Moly Driveshaft with Forged Ends."

That's rear wheel HP.

By the way, smaller diameter shafts reach critical speed earlier.

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[Formulajones]

Okay, the shafts I'm having made have forged ends so that could be some of the price difference. I'm guessing if I requested the forged ends on the chrome molly shaft the price would go up a bit.

[grivera]

The 3" CM with forged ends is $365

https://www.strangeengineering.net/p...seemless.html/

[tooski]

Perhaps my experience will be discounted.
The oem driveshaft in my 68 was dinged enough to cause vibration. I had a 3" ds made with 1310 solid joints to retain the yokes I had.
I have street tires that go up in smoke from a standing start. I reverted to punching it from a 20 mph rolling start. No spin as far as I can tell, I believe I am stressing the driveline fairly well.
Slight wag on the 1-2 shift. I'd like to think that my car would be into the 12's, but I have no dragstrips near me. The 3.07 gear would be a limiting factor.
Did this a couple of times or more a month this past summer.

[HWYSTR455]

Driveshaft critical speed calculator:

http://www.wallaceracing.com/driveshaftspeed.php

"Critical Speed is the RPM at which the driveshaft is computer projected to bend or whip. Exceeding Critical Speed can produce vibrations that can result in driveshaft failure. The vibrations can also cause damage to the differential gears and bearings."

"at 100 mph with a 1:1 high gear, a 3.55:1 rear gear, and 26-inch-tall tires, the engine would spin 6,422 rpm."

Most opt to have a level of cushion, and add 15-20% to calculations. Again, the numbers are for a 'perfect' environment (material runout, welds, balance, angles, tail shaft bearing runout, slip yoke clearance in bearing, u-joint slop, pinion yoke u-joint centering, pinion yoke bearing runout, etc).

As an example, a OE type 3" shaft .083 mild steel and 1310 ends at 50" long reaches critical speed at @ 4450 RPM.

The Driveshaft Shop is one of the leading performance driveshaft shops on the planet. They can solve just about any problems, and offer some of the finest products:

https://driveshaftshop.com/driveshafts-101/

I suggest knowing what you're talking about when you call them.

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[grivera]

That Wallace calculator didn't work for me. Looking at this chart from PST CM and mild steel of same thickness are the same on critical speed chart.

https://pstds.com/critical-speed-chart

[Formulajones]

The critical speed is why the lighter weight driveshafts have an advantage.

It's one reason OEM went aluminum. You see this on trucks a lot. With there longer shafts, the older trucks used carrier bearings so they could run 2 shorter steel shafts. When they got away from the carrier bearing and started using one piece driveshafts they went aluminum. The lighter weight works in your favor, has a higher critical speed before it starts the whipping action. Plus you gain the benefit of less rotational mass that doesn't zap HP.

If you look at the PST chart posted by Will, you'll see the aluminum has a higher critical speed than even the chrome molly.

[HWYSTR455]

Try to remember that critical speed calculations are calculated on perfect factors, and are only a guide. And there are other factors that contribute to critical speed (and tube strength) that are not taken into account.

For example, runout on the length of the tube. Doesn't matter what the tube is made of if that runout is boogered. You could have an area that is thicker or thinner in the wall of the material, say maybe even a area in the middle of the tube. You could have it balanced along the entire length, and that spot could still cause a problem.

Some materials when made have less runout of those types, for example, aluminum. Not only that, but it the runout on one spot, like maybe in the example above, it's going to be less weight, and have less of an impact.

When a shaft 'noodles' more and more, the material can and does weaken. Hence, when you don't know the history of a shaft, replace it. You could install a used shaft that 'looks' perfectly fine and it could fail the very next time it gets put into use.

For OE shafts, there's a reason they are only balanced to about 3500 RPM, because they generally have a critical speed rating of about 4500. Sure, they can survive a number of 6000 RPM passes, but it's a time bomb.

If you're restoring a car, upgrading a car, or building a performance car, just put a new driveshaft in it, simple. Just plant it in your head that it's an item that needs attention. It just make no sense to me to put 10, 20, 30k or more into a car just to destroy it because of not spending $500 or so by a driveshaft failure.

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[FrankieT/A]

Originally Posted by Formulajones

The critical speed is why the lighter weight driveshafts have an advantage.

It's one reason OEM went aluminum. You see this on trucks a lot. With there longer shafts, the older trucks used carrier bearings so they could run 2 shorter steel shafts. When they got away from the carrier bearing and started using one piece driveshafts they went aluminum. The lighter weight works in your favor, has a higher critical speed before it starts the whipping action. Plus you gain the benefit of less rotational mass that doesn't zap HP.

If you look at the PST chart posted by Will, you'll see the aluminum has a higher critical speed than even the chrome molly.

3.5 vs. 3.0 makes a big difference in critical speed...

The thing that worries me about aluminum is the strength of the ears where the U joints mount. They look like they would break right off doing a hole shot.