Driveshaft Question re-when/under what conditions is an upgrade needed

[KC BadCat]

ok.....have a question about when/if I need to change out driveshafts; I still have the oem two part system.

current condition: around 575 rwhp, original tires and gearing

anticipated end point: around 660 rwhp, maybe 3.73s, and tires such as NITTO 555s, maybe something a little more rain friendly

useage: no racing of any kind from a dead start, either on the street or strip, and no road track type stuff........I am more of a highway cruiser, and am more than willing to do a quick and short 40 to 120 type of race if provoked or motivated.....

I am wrong type of engineer to ponder this one successfully...chemical engineers only have a single statics course and no dynamics type of course....so I can't even begin to get a handle on the theoretical stresses of hooking a tire from a dead start versus hitting it hard at about 40 mph

..any thoughts or comments on this one? I don't really want to replace the ds unless there is a good reason. It just somewhat seems reasonable to me that I am much less likely to bend/break drivetrain components at 40 mph than from a hard start.

thanks in advance....John

[Joe G]

From my research, it's not really about how much power you have, it's how you use it.

Running hard - especially from a dead stop (drag strip) is the worst for the DS.

So - person #1 has a totally stock car, but ran at the drag strip all the time, while person #2 has a new SC, 600+rwhp, but never hits it hard - #1 would always benefit from the improved DS more than #2.

That said, the one piece DS is good insurance "just in case".

[Vette Killer]

I replaced mine as soon as I passed the 525 to the ground threshold and I do not abuse my car....I saw the pics of what happens when one fails and it just was not worth the risk to me. I went with the 1 piece DSS; easy install and about $700 if memory serves....need to have the adjustable UCA as well though so you can set the pinion angle at -1.5 degrees. The upside is you can some RWHP as you are not losing it in driveline deflection through the hanger.

[Birdman]

ok.....have a question about when/if I need to change out driveshafts; I still have the oem two part system.

current condition: around 575 rwhp, original tires and gearing

anticipated end point: around 660 rwhp, maybe 3.73s, and tires such as NITTO 555s, maybe something a little more rain friendly

useage: no racing of any kind from a dead start, either on the street or strip, and no road track type stuff........I am more of a highway cruiser, and am more than willing to do a quick and short 40 to 120 type of race if provoked or motivated.....

I am wrong type of engineer to ponder this one successfully...chemical engineers only have a single statics course and no dynamics type of course....so I can't even begin to get a handle on the theoretical stresses of hooking a tire from a dead start versus hitting it hard at about 40 mph

..any thoughts or comments on this one? I don't really want to replace the ds unless there is a good reason. It just somewhat seems reasonable to me that I am much less likely to bend/break drivetrain components at 40 mph than from a hard start.

thanks in advance....John

John the stock one is good until 155mph. If you are not drag racing the car like you say IMO there is no real need to change out the DS to a one piece. That said with 660 RWHP you will have to take extra care not to put too much load on the driveline when driving in an agressive manor. :tiphat2:

[Gr8snkbite]

he shouldnt need the adj UCA if hes not messing with the suspension...

but if you did get BC..get the J&M...it comes "preset" for stock height...

[KC BadCat]

:moneyman:


There's your answer.

:grin:

..ah hmmmm.....this is a tech thread monkey breath.........:doh2:

all kidding aside......I am very interested in a discussion of the different stresses, loads etc from different styles of driving

[HSURB]

From my research, it's not really about how much power you have, it's how you use it.

Running hard - especially from a dead stop (drag strip) is the worst for the DS.

So - person #1 has a totally stock car, but ran at the drag strip all the time, while person #2 has a new SC, 600+rwhp, but never hits it hard - #1 would always benefit from the improved DS more than #2.

That said, the one piece DS is good insurance "just in case".

What about person #3 that doesn't ever drive it?

All joking aside, I would be curious to learn more about this as well. Is the single piece drive shaft the best way to go?

HSURB®

[Joe G]

What about person #3 that doesn't ever drive it?

All joking aside, I would be curious to learn more about this as well. Is the single piece drive shaft the best way to go?

HSURB®

Yes.

You need a roll cage too.

Never can be too careful there in the man shed.

[KC BadCat]

...I really appreciate the thoughtful responses....and yes, the other ones too.....LOL

an upgraded ds is of course added insurance against a possible disaster....but as with any change, you run the risk of unintended consequences

in the case of the one piece replacements....there have been numerous cases involving poor fitment, balance etc.....as well as high speed harmonics, vibration etc....the oem two piece really does well at higher speeds

the two piece replacement would seem to be a good match for my rwhp....but the only one I know about is extremely pricey...about twice the cost of a single piece.....ah, decisions, decisions.........I really have only heard of a couple of folks screwing up driveshafts, so either it is an issue that only comes up with extreme conditions....or everyone that beats on their car is bright enough to change it out....:doh2:

[Joe G]

in the case of the one piece replacements....there have been numerous cases involving poor fitment, balance etc.....as well as high speed harmonics, vibration etc....the oem two piece really does well at higher speeds


Yep - that's what I've heard too.

Those would drive me nuts.

[Vette Killer]

Yep - that's what I've heard too.

Those would drive me nuts.

If you set the pinion angle properly it is not there....I initially had a vibration that came in about 100 MPH and stayed until about 130 until I found the angle that worked but that assumes the rest of the drivetrain is true (and you buy a well known quality druveshaft that was balanced properly by removing weight instead of adding stick-ons/weld-ons that can come off)....to each their own though....after getting the angle right for my setup there is no drivetrain vibration and have had the car to an estimated 185-190...hard to judge for sure as you run out of speedo well before then...

[Gr8snkbite]

theres a sticky in the tech section on pinion angles george posted...read up on it...its also on the home page as part of the techy articles. just for reference, before removing the stocker, check the angle of both the DS and pinion. two piece DS is checked on both pieces..but you cant go wrong with a single...i dont baby my car, and have had zero issues with the dynotech DS. i did adj pinion, only b/c of installing the FRPP system. 0 to -2 angle is optimum..

[HARLEYDEALER]

I not sure, maybe something like these may be an indication! Bill:doh2:
Note when the CF driveshaft let loose it did almost no damage, the steel one took out the trans, lower trans bolt mounts on block, tunnel and fuel tank with C16. Only front DS loop was being used then! I'll post picture of twisted steel shaft when I fine it. Bill:boxing::wow2:

[Birdman]

Bill was that steel one the stock two piece or a one piece? How were you driving at the time, drag racing, hard launch etc?
Why did the carbon fiber DS break? I heard the heat from the exhaust weakens the resins used in the CF....

[HARLEYDEALER]

The steel one was a after market and don't tell no one, it broke on the dyno while making a pull, the point I was making use f&R loops. The CF was my fault, While up on the lift, right after the build I ran her in gear not knowing or checking, that the DS was rubbing on the exhaust. Didn't look hurt but the shinny finish was dull were it rubbed, found out THAT"S BAD! First hard launch I thought I blew the transmission. Blew apart right at the rub. I have about 6000 miles on the car using CF DS with no other problems and broke everything in the drive line except for the CF DS. Thats 9" rear end gears, 35 spline axles and twisted two output shafts in the transmission, so I believe in them! Bill

Lookly here, another paragraph! on the picture below that small scuff on the shaft did not hurt the shaft, maybe due to it being close to the end were she is molded on the flange, not sure!

[Birdman]

Bill....any pics of the rear DS loop? What make are you using? I currently only have a front one.

[HARLEYDEALER]

With the CF and fuel cell, there is nothing to hit, so no rear loop, sorry. Bill

[Iceman]

George - I have a front and a rear loop. I'll get pics next time I'm on a lift. I think the front is BMR and the rear CHE? Can't really recall much other than the need to turn the bolts over on the rear to make it fit with out banging anything.

[onecrazydog]

I have been thinking about adding a DS to the upgrade list... I had a half shaft snap when launching the vette at 4000 rpm... Major damage!!


I like that pst carbon fiber ds... Seems to be a good design with no vibration issues... I don't think that ds loops have to be used with them, correct? They are light and strong... Downside, if it gets gouged it's toast...

Would one have to buy a whole new ds or could you get it retubed?

[Gr8snkbite]

I have been thinking about adding a DS to the upgrade list... I had a half shaft snap when launching the vette at 4000 rpm... Major damage!!


I like that pst carbon fiber ds... Seems to be a good design with no vibration issues... I don't think that ds loops have to be used with them, correct? They are light and strong... Downside, if it gets gouged it's toast...

Would one have to buy a whole new ds or could you get it retubed?

It'll basically dissenegrate...you'll need a replacement. Though a nice design, and light weight with no worries of tunnel damage, I'd rather have the alum dynotech ds. Not much heavier, yet no worries getting the car home. The only real need for the cf one is straight drag time. You planning to drag? If so, maybe one of each for specific uses. Regular driving I'd rather not. Jmo. My dynotech on the 07 never gave me a problem, not one, not even vibs..

[Tommy Gun]

It'll basically dissenegrate...you'll need a replacement. Though a nice design, and light weight with no worries of tunnel damage, I'd rather have the alum dynotech ds. Not much heavier, yet no worries getting the car home. The only real need for the cf one is straight drag time. You planning to drag? If so, maybe one of each for specific uses. Regular driving I'd rather not. Jmo. My dynotech on the 07 never gave me a problem, not one, not even vibs..


+1


.

[onecrazydog]

It'll basically dissenegrate...you'll need a replacement. Though a nice design, and light weight with no worries of tunnel damage, I'd rather have the alum dynotech ds. Not much heavier, yet no worries getting the car home. The only real need for the cf one is straight drag time. You planning to drag? If so, maybe one of each for specific uses. Regular driving I'd rather not. Jmo. My dynotech on the 07 never gave me a problem, not one, not even vibs..

I don't have the willpower to drive my car regular... Lol!! I am sure an alumin shaft would be fine with front and back loops, I just figured at that point one is close to the price of a cf one ... I will check out the dynotech ones... Still have many months of winter so I am just checking out all the options on the final round of mods for the Shelby!!

What kind of loops are peeps running?

I am going to go to the local track on street car fridays next summer

[onecrazydog]

What are the differences between the dynotech and dss driveshafts?

[Tommy Gun]

I have a Dynotech 3.5 and BMR loops.

.

[onecrazydog]

I have a Dynotech 3.5 and BMR loops.

.

Are these the same ones you have? Do you have pics of them installed?

http://www.bmrsuspension.com/index.cfm?page=products&vehicleid=20&maincatid=97&catid=280

[onecrazydog]

:waiting2:

[onecrazydog]

I have a Dynotech 3.5 and BMR loops.

.

This is the way I will go... Still would like to see pics of them on the car...

[onecrazydog]

Parts ordered!!





:waiting2:

[CH53Driver]

Parts ordered!!





:waiting2:


Sweet. Pics upon delivery!:waiting2:

[onecrazydog]

So is the driveshaft an easy swap out?

[Gr8snkbite]

yea...done in an hour or so...especially with your lift. make sure to mark both ends before removing the old one first, in event you put it back. probably have to loosen the exh joint in the center to move it for more clearance...but dont have to remove

[onecrazydog]

yea...done in an hour or so...especially with your lift. make sure to mark both ends before removing the old one first, in event you put it back. probably have to loosen the exh joint in the center to move it for more clearance...but dont have to remove

Thanks SA, is the Dynotech one piece or is there a flange to install too? Do you know the driveshaft torque specs? I am going to install it on my friends lift while the exhaust is out of the car still!!


Will i have to reset the pinion angle if my car is factory ride height?

[onecrazydog]

Bump...

[onecrazydog]

WOOT!! Driveshaft and loops shipped today!! I have a great vendor!!


:waiting2: for SA's answers to post 32...

[Gr8snkbite]

Thanks SA, is the Dynotech one piece or is there a flange to install too? Do you know the driveshaft torque specs? I am going to install it on my friends lift while the exhaust is out of the car still!!


Will i have to reset the pinion angle if my car is factory ride height?

There will be a flange to bolt to the pinion first. Use a small amount of blue locktite. The front bolts right tot he tranny hub. Don't remember the spec rout off hand but will post them Sunday when I get home. Still use stock specs. If car is still stock height, no need to change pinion angle.

[onecrazydog]

There will be a flange to bolt to the pinion first. Use a small amount of blue locktite. The front bolts right tot he tranny hub. Don't remember the spec rout off hand but will post them Sunday when I get home. Still use stock specs. If car is still stock height, no need to change pinion angle.


You da man!! Thank you!!

[Gr8snkbite]

You da man!! Thank you!!

pinion shaft bolts are 41 ft/lb (55Nm)

tranny shaft bolts are 76 ft/lb (103Nm)

[onecrazydog]

Awesome!! Thanks Bud!! Front loop came today, rest will be delivered tomorrow!!

[onecrazydog]

http://www.onecrazydog.com/pictures/albums/Shelby_Mods/P1020038.JPG

http://www.onecrazydog.com/pictures/albums/Shelby_Mods/P1020043.JPG

Stickers!!

http://www.onecrazydog.com/pictures/albums/Shelby_Mods/P1020044.JPG

[Gr8snkbite]

Sweet

[Joker]

Nice!

[Alloy Dave]

http://www.onecrazydog.com/pictures/albums/Shelby_Mods/P1020038.JPG

http://www.onecrazydog.com/pictures/albums/Shelby_Mods/P1020043.JPG

Stickers!!

http://www.onecrazydog.com/pictures/albums/Shelby_Mods/P1020044.JPG

OCD, be careful with those loops....they look a lot like my setup.

I had to use spacers under the rear one to keep the shaft from hitting the loop.

Also, from this point on, you cannot allow the wheels to hang when raising/jacking up the car...as the shaft will sit on the rear loop. (I suppose if you're really careful and slow this would not hurt anything...but at least be aware of it and if you have any shop work on your car, make DARN sure they are aware of it).

[68fastback]

...and the front is really the important one since if the front joint goes it beats the crap out the car as long as the rear wheels are turning. If the rear joint fails you'll probably clutch/neutral PDQ.

[Gr8snkbite]

OCD, be careful with those loops....they look a lot like my setup.

I had to use spacers under the rear one to keep the shaft from hitting the loop.

Also, from this point on, you cannot allow the wheels to hang when raising/jacking up the car...as the shaft will sit on the rear loop. (I suppose if you're really careful and slow this would not hurt anything...but at least be aware of it and if you have any shop work on your car, make DARN sure they are aware of it).

funny you mention that Dave. I would suspect that to be the case with a stock suspension...maybe. In my case, with my FRPP lowered 07, i had it on a fork lift (while doing the header job), rear struts extended all the way, and the shaft missed the loop by an inch. maybe the FRPP struts allowed for that..dunno..but it didnt hit. but stacey, it is something to monitor.

[Alloy Dave]

funny you mention that Dave. I would suspect that to be the case with a stock suspension...maybe. In my case, with my FRPP lowered 07, i had it on a fork lift (while doing the header job), rear struts extended all the way, and the shaft missed the loop by an inch. maybe the FRPP struts allowed for that..dunno..but it didnt hit. but stacey, it is something to monitor.

I agree, it seems likely that if you are lowered, the geometry could be quite different.