Dynotech 4" vs stock drive shaft

no164ford

Registered User
Any one know the weight savings going from a stock aod drive shaft to a 4" dynotech? Also are they stronger? I once twisted and broke a Mark VIII drive shaft don't want to try that anymore LOL!
 
Get the dyno tech.

Mainly its a high speed balance issue it fixes.

I also twisted a shortened Mark 8 shaft.

Zero problems from the dynotech.
 
I've never weighed auto driveshafts, but here are the weights for 5-speed driveshafts:

Stock: 21.2 pounds
3.5" aluminum from SCP: 14.9 pounds
4" aluminum from SCP: 16.5 pounds
 
I would not get the 4.0" shaft because I think it's too tight of a fit and not needed for the power level you are going to be at. The 3.5" diameter shaft will do the job and will fit much better.

David
 
I have had 1.59 60' w/3:73's going to install 4:10's this year and a few outher things to try to get the in the 1.4's or better 60' That is why I am thinking about upgrading
I would not get the 4.0" shaft because I think it's too tight of a fit and not needed for the power level you are going to be at. The 3.5" diameter shaft will do the job and will fit much better.

David
 
I have had 1.59 60' w/3:73's going to install 4:10's this year and a few outher things to try to get the in the 1.4's or better 60' That is why I am thinking about upgrading

With the gear change, it should make it easier to turn your tires. Provided all is the same with the car.
 
I would not get the 4.0" shaft because I think it's too tight of a fit and not needed for the power level you are going to be at. The 3.5" diameter shaft will do the job and will fit much better.

David

I run the 3.5" shaft for the same reason. The 4" shaft rubbed on everything and required more shimming of the trans crossmember and rearend than I wanted.

Granted, I don't run drag slicks, so I'm going to stay out of that part of the debate.
 
When I weighed my 5 speed stock shaft in comparison to my aluminum 3.5 it was 11 lbs lighter. I just went to a 4" with the t56
 
I have had 1.59 60' w/3:73's going to install 4:10's this year and a few outher things to try to get the in the 1.4's or better 60' That is why I am thinking about upgrading

Do you have a 3.50" aluminum shaft now ? Switching from 3.73s to 4.10s will be less stress on driveshaft and more on the halfshafts.

David
 
You are right, I was thinking the outher way 4:10 would be more stress. Right now I run a stock driveshaft not sure how much it will take. I also have 28" Hoosier slicks. Waht are you running in your cars Dave?

Do you have a 3.50" aluminum shaft now ? Switching from 3.73s to 4.10s will be less stress on driveshaft and more on the halfshafts.

David
 
I run the 3.5" shaft for the same reason. The 4" shaft rubbed on everything and required more shimming of the trans crossmember and rearend than I wanted.

Granted, I don't run drag slicks, so I'm going to stay out of that part of the debate.

Funny thing, It seems to fit just fine in my car. Guess I should check to see it its rubbing.
 
You are right, I was thinking the outher way 4:10 would be more stress. Right now I run a stock driveshaft not sure how much it will take. I also have 28" Hoosier slicks. Waht are you running in your cars Dave?

I'm using a 3.5" aluminum driveshaft in both of my SCs, that was made by a company down in FL that I assume compares to the Dynatech . Both have 3.73 gears and use the same Hoosier QTP 28" x 11.50 x 16" DOT slicks. The 91 SC still uses stock halfshafts, but the 93 SC uses Driveshaft shop level 2 halfshafts (direct replacments). Both cars would be a little quicker on the track with 4.10s, but I just don't like the higher cruising rpms. Driveshaft loop also fits around the 3.5" shaft easier.

David
 
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I'm using a 3.5" aluminum driveshaft in both of my SCs, that was made by a company down in FL that I assume compares to the Dynatech . Both have 3.73 gears and use the same Hoosier QTP 28" x 11.50 x 16" DOT slicks. The 91 SC still uses stock halfshafts, but the 93 SC uses Driveshaft shop level 2 halfshafts (direct replacments). Both cars would be a little quicker on the track with 4.10s, but I just don't like the higher cruising rpms. Driveshaft loop also fits around the 3.5" shaft easier.

David

Really wish I could get a part number as I called the owner as suggested in other posts, but he didn't have the information to build another one. Possible to get an order number and or date to have him reference?
 
Really wish I could get a part number as I called the owner as suggested in other posts, but he didn't have the information to build another one. Possible to get an order number and or date to have him reference?

Sorry, I don't have anything other than the contact info posted on TCCOA. The first one was bought as part of a group buy on TCCoA organized by a guy named Kodiac Kid or something like that back around 2003. I ordered another one from the same company in 2005 for my 93 SC and the owner still had all the info from the first group buy so all I had to supply was the length. Last one I bought 10 years ago was about $425 shipped.

David

PS: Precision Shaft Technologies driveshafts were made using the standard size 1330 u-joints with 1-1/16" bearing caps and stock replacement end yokes that were supposed to be cryo treated and balanced to 8500 rpm.
 
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I'm using a 3.5" aluminum driveshaft in both of my SCs, that was made by a company down in FL that I assume compares to the Dynatech . Both have 3.73 gears and use the same Hoosier QTP 28" x 11.50 x 16" DOT slicks. The 91 SC still uses stock halfshafts, but the 93 SC uses Driveshaft shop level 2 halfshafts (direct replacments). Both cars would be a little quicker on the track with 4.10s, but I just don't like the higher cruising rpms. Driveshaft loop also fits around the 3.5" shaft easier.

David

This is one of the reasons i went Wide Ratio. It's the equivalent of 4.30s coming out of the hole and still cruises the same as any other 3.73 setup
 
Really wish I could get a part number as I called the owner as suggested in other posts, but he didn't have the information to build another one. Possible to get an order number and or date to have him reference?

I think dirty dog is selling dynotechs.
 
Got the drive shaft to day and installed it.

1990 SC AOD stock shaft 21# 11oz

3.5" Dynotech 15# 5oz They say every 7-10 lbs rotating mass shaves a tenth off:rolleyes:

Biggest thing is it should be way better balanced.

Also swapped rears SC iron housing w/3:90's to a Lincoln aluminum w/4:10's that shaved 19lbs
 
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