Rear shock mounts?

[hvy chevy]

What's the best way to mount longer travel rear shocks on a 70 Blazer? I'd rather not cut holes in the floor. 14 bolt axle in and I cut off the stock lower mounts.

Should I make a new upper crossmember curved up to gain an inch or two? Inboarding them a little.

Do I install tabs on the top of the axle? Or tabs on the front pointed down?
Thanks!

(old pic)

 

[Greg72]

12" travel shocks..... w/ 2" body lift

 

[hvy chevy]

Aahhh... thank you kind sir!!

 

[GRINCH]

Here are mine mounted outside the frame rail. I have a 1" body lift. I will update my thread soon. I boxed in the mount after these pics were shot.

http://coloradok5.com/forums/showthread.php?p=2778000&highlight=shocks#post2778000

 

[hvy chevy]

Here's what I'm going with (see pics) I had to bring them out away from the frame so the shock body wouldn't hit my spring pack.

To strengthen these, I'm going to mount a piece of tubing from the back of the shock mount across the top of the frame to the back of the other shock mount, therefore adding a new crossmember, so to speak

(maybe add a little gusset inside the shock mount as well??)

What do you guys think?

 

[GRINCH]

I would not mount to the frame as pictured. Even with gussets. I would weld your tower to a plate and bolt it to the frame, even incorporate a lip on the plate to catch under the frame. Probably overkill but I have seen them rip holes in the frame when welded like that. I am a little concerned with my mount. I still need to take some pics of my mounts and update my thread.

 

[Greg72]

Agreed.

Triangulate both sides down to the lower part of the frame, and weld a backing plate to sit against the vertical part of the frame too. Then bolt them to the frame with some good Gr-8 bolts.

The forces are massive, so beef them up as much as you can. Those two current sides will act like "can openers" against the frame so you need to work out a way to speed those forces out across a larger flat surface.

 

[hvy chevy]

Thanks for the advise, sounds overkill, but you guys have the experience...

Now, here's what I'm going with (lol)
(gussets still to come)

 

[GRINCH]

I like it!!

 

[Greg72]

What sort of angle is that shock at now? (front to back)

It looks like it's getting pretty steep; it might be worth dropping the lower mount another 1" to allow the shock to sit more upright. That lower shock mount is tucked in pretty tight the the back of the wheel, so I wouldn't worry about it hanging up on rocks, etc.

Or

Based on the look of those rear springs and the amount of actual bump travel you'll get there is NO way you need that much shaft showing at static ride height. I'd guess you need maybe 5" showing, but those pics show what looks more like 8"

 

[hvy chevy]

You're right, I guess I got too focused on the mount and didn't measure the shock.

8" of shaft showing (I hate it when too much shaft is showing...lol )

and 32 degrees on the shock.

So, I'll move the upper mount down and back some (good thing I made the backing plate big.

What would be a good shock angle?

 

[GRINCH]

What would be a good shock angle?

I'm sure Greg will chime in with his recommendation as well

The best is straight up and down with the direction of the wheel. You need to figure in shackle movement as well as spring deflection. If you graphed it all out it would be an oval.
But bottom line is as straight as possible. I would go 2 degress for each inch of lift.

 

[hvy chevy]

Thanks. I was just going close to the stock location, but after all this work, I want to get it right.

Ok, so back to work...

 

[hvy chevy]

Ok, 15 degrees and 5" of shaft exposed.

I guess I'll be remaking these upper mounts... oh the joy, of doing it right the first time.. Doh, I mean second time

 

[GRINCH]

and 3rd and 4th ........

 

[hvy chevy]

and 3rd and 4th ........

lol...

Ok, how's this? 17 degrees, and 5" of exposed shaft (14" shocks)

I'm ready to burn these in, unless you guys see anymore flaws

 

[Greg72]

Check the garage forum for "shock effectiveness" thread. I remember posting up a table of values based on installed angle. 17 is way better than 35 degrees. Nice job!

EDIT: (now that I'm not at home surfing on an iPad it's easier to do the research)

Found it. Here are the details....

angle = damping

90 = 100.0%
80 = 98.5%
70 = 94.0%
60 = 86.6%
50 = 76.6%
40 = 64.3%
30 = 50.0%
20 = 34.2%
10 = 17.4%
0 = 0.0%

It's worth the effort to do it right, and certainly getting that shock collapsed down to 5" stickout will be a big help too. No point wasting shock length on bump that you can't use anyway...especially since it would be a lot more useful for droop anyway.

 

[hvy chevy]

Thanks for all the research and info, I'm sure thankful you guys helped me get it right, beers on me

Ok, last pics, I added two little gussets, now I need to drill some holes and I'm done

 

[GRINCH]

Nice Work!

For a little extra. Make a backing plate for the back side. Although not really needed since you have a plate under/over the frame. But it wouldn't hurt.

One more thing!! Did you measure what your up travel is going to be? Pull a string between your spring eye bolts and then measure from the string to the top of your spring pack. Add a little to this measurement for shackle swing. This will get you close to what your up travel will be.

 

[hvy chevy]

Thanks Grinch, no I didn't measure yet...I guess I should have. Worst case, I can lower the the lower shock mount if I need more up travel. I will measure tmrw.

I was just soo anxious to finally drive this out of the garage, I just couldn't wait any longer