Calvert U-bolts size vs. '66 9" small bearing axle

[fairlaniac]

I asked Calvert which of their U-bolts to use. They mentioned the 2.75 I.D. for my '66 Fairlane 9" axle housing. So I have them and just checking. This is the housing where the tubes neck down to the small axle bearing. The housing at that end measures 2.810". The U-bolts are 2.770 I.D. Are they to fit nicely over the axle tube or are you to spread the u-bolt slightly or tap it over? The next size is 3" and would seem sloppy?

Thanks,

[thatdarncat]

I asked Calvert which of their U-bolts to use. They mentioned the 2.75 I.D. for my '66 Fairlane 9" axle housing. So I have them and just checking. This is the housing where the tubes neck down to the small axle bearing. The housing at that end measures 2.810". The U-bolts are 2.770 I.D. Are they to fit nicely over the axle tube or are you to spread the u-bolt slightly or tap it over? The next size is 3" and would seem sloppy?

Thanks,

I just checked the ones I have for my project. Mine is a ‘67 Mustang/Cougar 9” housing, but has the same necked down ends, and should be the same except for spring pad location. I measured my housing in the u-bolt area and it generally measures around 2.79” - 2.80”, so a tad under yours. I also have the Calvert 2.75” - 1/2” U-Bolts and they measure about 2.77” - 2.78” on the unthreaded portion. So they’re close, but definitely an interference fit. For mine I’d just tap them into place, but yours are a bit tighter. You definitely don’t want to use the 3” ones. 

[fairlaniac]

I asked Calvert which of their U-bolts to use. They mentioned the 2.75 I.D. for my '66 Fairlane 9" axle housing. So I have them and just checking. This is the housing where the tubes neck down to the small axle bearing. The housing at that end measures 2.810". The U-bolts are 2.770 I.D. Are they to fit nicely over the axle tube or are you to spread the u-bolt slightly or tap it over? The next size is 3" and would seem sloppy?

Thanks,

I just checked the ones I have for my project. Mine is a ‘67 Mustang/Cougar 9” housing, but has the same necked down ends, and should be the same except for spring pad location. I measured my housing in the u-bolt area and it generally measures around 2.79” - 2.80”, so a tad under yours. I also have the Calvert 2.75” - 1/2” U-Bolts and they measure about 2.77” - 2.78” on the unthreaded portion. So they’re close, but definitely an interference fit. For mine I’d just tap them into place, but yours are a bit tighter. You definitely don’t want to use the 3” ones.

Thanks Kevin!

[Gaugster]

I can confirm 2.75" as well. Calvert recommended the 2.75" u bolts for my 9". It's the light duty rear end found in Mustang's and Cougars like my '68. The part number they suggested is UR275x70. Keep in mind the length also if you have any pinion shims and/or lowering blocks.

[TomP]

You should not be using lowering blocks with CalTracs. Get flatter springs or take a leaf out