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What are you guys using for U-bolts? My current U-joint dimensions are 2 7/8" ID and 6" long.

My engine's output is close to 500hp. I am upgrading the differential to True Track, 3.5:1, and Strange 31 splines shaft w/sealed bearings. I had already upgraded the driveshaft and to 1350 u-joints.

I think most u-bolts are Grade 5. I found a set of Grade 8 from Dayton, p/n 361-400. These have a 5/8 bolt diameter and the OEM ones are 7/16" (edited). I wouldn't expect to much of an issue to enlarge the holes to 5/8".

Are there other Grade 8 alternatives? Is Grade 8 really needed? Thoughts?

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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Not 100% sure but the grade 5 maybe in there for a reason. I know grade 8 are much harder and stronger in some applications, but that hardness also makes them more brittle. grade 5 are designed to stretch since they are softer. I know when we build steel structures and cranes, we use grade 5 or A325 structural hardware because they are designed to stretch. We do not use grade 8 because they are too hard and brittle. Not sure if the same applies for u bolts and this application.

Kevin
1971 Mach 1

408C Stroker - C4 w/3,000 stall - 8.8" Rear w/3.73's - Disc brakes all way around.

 

 

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I'm 90% sure the original u-bolts are 7/16" diameter

 

I think the 7/16" ones get torqued to 45 foot pounds, the 1/2" ones get torqued to 65 foot pounds.

 

If you start going with giant high grade u-bolts and actually torque them to what the specification is for the size / grade / thread you are going to get clamping forces so high that there will be collateral damage. Spring plates will get bent in horseshoes, you might actually make your axle tube an oval.

 

I'd stay with regular old u-bolts. If you find a local truck / trailer supply place with a u-bolt machine you can get decent ones bent to your specification. A buddy of mine has a u-bolt machine and I have all mine made out of blanks, the hardware that is supplied is normally very thick hard washers and the nuts are almost as long as coupler nuts.

 

I've got 7/16" ones on my drivers side, and 1/2" ones on my passenger side. The only reason I went with larger u-bolts on one side was because the spring plate is the mount for the panhard setup I have and I wanted a little more beef.

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them from bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

 

What do you mean with "boxing in" the perches?

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

 

What do you mean with "boxing in" the perches?

 

I think I get what you mean. So basically to box it in I will need to weld a piece through the width at the end of the perch. Will something welded like shown in this picture in yellow work?

Edit: the "yellow" will probably need to be wide enough to be welded to the forward edge of the perch.

 

20190213-132610-boxed.jpg

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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Yes, that is the way to box the perches. I would fill the entire area in, though.

 

You can also box the spring plates, just use large enough holes in the box plate to get the nuts on with a socket. The nuts still tighten against the original plate.

 

I agree with the others, about Grade 8 versus Grade 5 u-bolts. Interestingly enough, Currie sells only Grade 8 u-bolts. If I did use Grade 8 u-bolts I would torque them only to the Ford torque spec of 30-50 LB-FT.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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ok. So here is a modified sketch :). Basically cut and weld a square piece that fits that space. Should the top of the piece be welded to the differential housing?

 

 

20190213-132610-boxed-2.jpg

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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Tony, I researched this ad nauseam back when I rebuilt my car in 2015. These were the u-bolts I ended up with. This supplier knows their sh*t when it comes to axles and hardware.

 

https://www.stengelbros.net/361-425-Round-Bend-12-x-30625-x-675-Grade-5--U-bolt-Kit_p_360.html

Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic! ::thumb::

 

 

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Tony, I researched this ad nauseam back when I rebuilt my car in 2015. These were the u-bolts I ended up with. This supplier knows their sh*t when it comes to axles and hardware.

 

https://www.stengelbros.net/361-425-Round-Bend-12-x-30625-x-675-Grade-5--U-bolt-Kit_p_360.html

 

Thanks. The u-bolts in your link are 3.0625" ID. Mine are 2 7/8", which is the diameter of the axle.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them from bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

 

Chuck ... like these

 

http://www.ohiomustang.com/store/order_page.asp?itemid=3318

Ohio Mustang Supply

440-949-2556

 

http://www.7173mustangs.com/images/oms_sig_banner.jpg

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them from bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

 

Chuck ... like these

 

http://www.ohiomustang.com/store/order_page.asp?itemid=3318

 

Don, I said "I have yet to find", now, thanks to you, "I have found". :P Good to know that they are now available from our favorite wise guy. Chuck

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them from bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

 

Chuck ... like these

 

http://www.ohiomustang.com/store/order_page.asp?itemid=3318

 

Don, what are the 3 dimensions on those U-bolts? (Diameter (A) x Distance Between Legs (B) x Leg Length ©)

Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic! ::thumb::

 

 

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I would use the Regular U bolts if possible. I have yet to find a replacement U bolt that has a flattened inner radius (OEM) to better grip the axle tube. I would suggest "boxing in" the spring perches to keep them from bending on hard launches. If they bend and pop off the locating pin in the spring VERY bad things can happen, been there done that, a LONG time ago. Chuck

 

https://www.currieenterprises.com/CE-7000BX

 

Chuck ... like these

 

http://www.ohiomustang.com/store/order_page.asp?itemid=3318

 

Don, what are the 3 dimensions on those U-bolts?  (Diameter (A) x Distance Between Legs (B) x Leg Length ©)

AMK lists  B @ 3.20 and C @ 5.75

There are 71 - 3 Mustang specific ... 67 - 70 are shorter

Ohio Mustang Supply

440-949-2556

 

http://www.7173mustangs.com/images/oms_sig_banner.jpg

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Don, what are the 3 dimensions on those U-bolts?  (Diameter (A) x Distance Between Legs (B) x Leg Length ©)

AMK lists  B @ 3.20 and C @ 5.75

There are 71 - 3 Mustang specific ... 67 - 70 are shorter

Thank you Don for the information. I need to measure my new springs. They are Maier's 4.5 leaf which are thicker than stock, plus I am using a 2 degree shim (edit: it is 4 degrees). With that said, I think these U-bolts may be too short.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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Don, what are the 3 dimensions on those U-bolts?  (Diameter (A) x Distance Between Legs (B) x Leg Length ©)

AMK lists  B @ 3.20 and C @ 5.75

There are 71 - 3 Mustang specific ... 67 - 70 are shorter

 

Thanks for the answers...is the bolt diameter 7/16"-20 or 1/2"-20?...asking for a friend

Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic! ::thumb::

 

 

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Thank you everyone. I like the fact that Don's U-bols have the flattened top, but after measuring they will be a bit short since I am replacing the OEM springs with 4.5 leaf springs plus the angle shim. I ended up purchasing Dayton's 361-450 U-bolt kit. They are Grade 5 with 1/2 bolts. I will have to drill the plates to fit these but that shouldn't be a big deal.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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Don, what are the 3 dimensions on those U-bolts?  (Diameter (A) x Distance Between Legs (B) x Leg Length ©)

AMK lists  B @ 3.20 and C @ 5.75

There are 71 - 3 Mustang specific ... 67 - 70 are shorter

 

Thanks for the answers...is the bolt diameter 7/16"-20 or 1/2"-20?...asking for a friend

 

So I'll guess they're 7/16"-20 since Don doesn't know...

Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic! ::thumb::

 

 

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AMK lists  B @ 3.20 and C @ 5.75

There are 71 - 3 Mustang specific ... 67 - 70 are shorter

 

Thanks for the answers...is the bolt diameter 7/16"-20 or 1/2"-20?...asking for a friend

 

So I'll guess they're 7/16"-20 since Don doesn't know...

 

Yes, my OEM ones are 7/16".

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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  • 2 weeks later...

I just did this. If your housing necks down at the bearing it is not a 3” housing. If you have 5 leaf springs the Scott drake ones did not work. I went with 1/2” ones fro summit. Rough country I think. I have to open up the holes in the under mount plate. But like you I figured the 1/2” would be stronger than the 7/16” stockers.

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AMK lists  B @ 3.20 and C @ 5.75

There are 71 - 3 Mustang specific ... 67 - 70 are shorter

 

Thanks for the answers...is the bolt diameter 7/16"-20 or 1/2"-20?...asking for a friend

 

So I'll guess they're 7/16"-20 since Don doesn't know...

 

Sorry don't read every post on this site / everyday

7/16

Ohio Mustang Supply

440-949-2556

 

http://www.7173mustangs.com/images/oms_sig_banner.jpg

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Thanks for the answers...is the bolt diameter 7/16"-20 or 1/2"-20?...asking for a friend

 

So I'll guess they're 7/16"-20 since Don doesn't know...

 

Sorry don't read every post on this site / everyday

7/16

 

...just teasin' ya Don since you didn't give that dimension's answer in your "AMK lists  B @ 3.20 and C @ 5.75" answer above. I know you know everything... ;)

Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic! ::thumb::

 

 

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I bought the Dayton 351-450 from here: https://www.stengelbros.net/361-450-Round-Bend-12-x-2875-x-6875-Grade-5--U-bolt-Kit_p_376.html

These are 6 7/8 long, 1/2 diameter and with a 2 7/8" bend. They come with nuts and washers. The nuts are longer than standard to help with thread engagement.

The bend I measured on mine was 0.1" more than 2 7/8", but according to the vendor it was within spec. I ended up closing them in the vise slightly until the bolts were spaced to fit in the plate holes. I also drilled the plate to 1/2". Based on my experience, I think the 2 3/4" would have fit well.

I installed mine yesterday and after tightening they hug the differential tightly. You can tighten the 1/2" to 65 ft-lbs per the vendor's spec. The length of the bolt worked well with my 4.5 leaf spring and 4 degree shim plate. I have an about extra 1/2" of threads left at the bottom.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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