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Discussion Starter #1
Is the tube width 3"?

If I previously measured right the center/center (front to back) leaf spring/shock mount bolts are 3.5" apart. The U bolts used to add lowering blocks show a 3.75" center/center width. I see I do need to drill out the upper axle housing leaf spring plate and the lower shock mount plate holes to 1/2" as they appear to be "slightly" smaller than 1/2" stock. Would the larger 1/2" hole then make the C/C spacing 3.75"?

...I know I could measure but recent abdominal surgery I can't lift anything over 10 lbs for awhile .....but I can shop for parts online :)
 

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Discussion Starter #5
Changing the hole size has nothing to do with changing the c/c distance.
You would have to slot the holes.
I am sure I am not the first to use lowering leaf spring blocks on a 67 8.2". For those who have, did you need to "oval" out the stock bolt holes to accommodate the 3" U bolt used to install them?

I am just going by what the published ID and C/C measurements of the U bolts from the supplier of blocks/hardware (Speedway) for their 3" axle housing U bolts. This is the note for the U bolts involved:

"Notes
Center to center of threaded end width is 3.685" with the inside to inside working width of 3.185"

My current measurement has C/C at 3.5"...although that is with a tape measure vs caliper so perhaps I am off by the .185" with my measurement....

I get I need to enlarge the stock hole size of the upper/lower rear spring plates to accommodate the slightly larger 1/2" U bolt size

So for those who use blocks, is this a plug and play or is some "elongation" of the stock hole positions required??
 

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Al - Waterloo, Iowa
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I just measured mine and the c/c of the bolts is indeed 3.5". I also drew this in cad using
Speedways dimensions. An 11/16" hole would be required. Other wise a 1/2" hole and then
remove (slot) about .10. It will be interesting to see what others have done in this situation.
I'm betting drilled 1/2" hole and hammered/squeezed the u-bolt into position.

 

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Discussion Starter #7
I just measured mine and the c/c of the bolts is indeed 3.5". I also drew this in cad using
Speedways dimensions. An 11/16" hole would be required. Other wise a 1/2" hole and then
remove (slot) about .10. It will be interesting to see what others have done in this situation.
I'm betting drilled 1/2" hole and hammered/squeezed the u-bolt into position.

Thanks so much for taking the time to do this. My tape measure was correct at 3.5" then

Yeah possibly "persuade" the U bolt by either compressing it together some (vice) and use some persuasion to put them through the top plate then bottom

I would think several have done lowering blocks before

Of course there is just going with a new "lowering" leaf spring....

Only lowering blocks I find are universal vs car specific but the block itself is the size of leaf and 5" wide to which is correct size

Ideally someone will reply as to how they did it but I suspect a 1/2" hole and a BFH is the method

Maybe there is also a U bolt the size of the stock holes... which I have yet to find

Again thanks for the CAD
 

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Al - Waterloo, Iowa
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You're welcome. Back in the day when I worked on these cars and others for a living
we had a local shop that custom made u-bolts for us as needed. The common use was
adding leafs to a pickup truck. If you have a local truck or spring shop. They should be
able to help. I just hate forcing parts to fit if avoidable.
 

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Discussion Starter #10
allanjs, I owe you a beer at least. Really appreciate the help. Only thing I can do now is lay here recovering from my surgery and hit the keyboard so again really appreciate the research

So I went through their site and they make several different U bolts. Even 7/16 which I believe is the size of the stock holes. I don't think they are 3/8" but even if they were they make that size also and all for the same $ as the 1/2" "universal" ones that come in block kits.

I think this 7/16" one is the ticket but I will need to confirm bolt size hole of my stock set up first

https://www.stengelbros.net/5U-056R...und-U-bolt-with-nuts-and-washers_p_13425.html

Thanks again

Roger
 

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Al - Waterloo, Iowa
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Roger, You are correct the t-bolts are 7/16-20. From the top of the axle tube to
the bottom end of the t-bolts measures ~4-3/4". That's without lowering blocks.
Add to that the lowering blocks plus I would add an additional 1/4" or so. With
3 leaf springs I only have about 2 threads showing. They use extra length lock
nuts (nylock) so a bunch of extra thread isn't needed and I think looks tacky.
 

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Discussion Starter #12
Al

Thanks for confirming base measurement & bolt size. I agree, also do not like long exposed threas after fastener. If that would occur I would just cut it down.

So starting with the 4 3/4" base:

4 3/4"
2" spacer
1/2" Pinion Angle spacer (1/4 on one end)
1/2" leaf (single)
1/8" Rubber spring isolator


That's 7 7/8"

...and they just happen to have that EXACT length :)
https://www.stengelbros.net/5U-058R...und-U-bolt-with-nuts-and-washers_p_13436.html

This size U bolt is 3 1/2" C/C so no drilling required....
 

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I would delete the rubber pads. They allow the axle to rock back & forth too much, especially when using a drop spacer. I’ve always had to squeeze in the 1/2” U bolt ends to make them fit through the holes.
 

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Discussion Starter #14
I would delete the rubber pads. They allow the axle to rock back & forth too much, especially when using a drop spacer. I’ve always had to squeeze in the 1/2” U bolt ends to make them fit through the holes.
I was planning on using the Energy Suspension pads vs rubber. They are considerably more dense than rubber

https://www.jegs.com/i/Energy-Suspension/355/3-6113G/10002/-1

Fortunately 7/16" U bolts are available so won't need to "adjust" for 1/2" ones. The stock holes in the axle housing/shock mount plates are 7/16" so drilling, at a minimum, would be required if going with 1/2" U bolts.
 

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I'd put the shim on top of the lowering block. To lower the pinion, put the thick end to the rear. The shim will cut into the poly pad in time. The poly pad will allow the rear axle to rock front to rear and you may have wheel hop problems. Very easy to see on a chassis dyno. Make sure your drop block has a centering bolt to retain the shim from slipping.
 

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Discussion Starter #17
The block does have centering pin. I will measure DL angles pre and post install to determine "if" I need the pinon shims. I may just need a spacer under tranny mount instead
 
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