Poly Performance tower cuts for front 11" remote reservoir Fox shocks

jboswell11

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Hey Guys,

I got my rear 12" Fox RR shocks installed without issue last weekend but am a bit stumped with with one of the steps for the front.

I have removed the factory shock mounts and have the lower mount tacked in place (with a best guess starting point). I have a dummy shock setup at the length of 1/2 travel and am using that to attempt to place the poly tower in its approximate location so I can mark the cuts needed to blend it into the frame (like I did for the rears). This is where I am a struggling a bit... Does anyone have some tips for getting the poly towers marked close so I can cut them and then grind the cuts to tweak the location? the frame is a bit complicated right where the poly tower needs to live and I am hoping some of the more experienced fabricators have some pointers.

I am currently attempting to cardboard CAD pieces to show me my cuts on the towers... and it is a struggle
 
Best I can do is borrow a pic from one of Blaines builds as a reference.
cn0h2a-jpg.27540
 
You can either cut out the stock upright and use the tower as that upright brace, or leave it and cut the tower to it. I've done both ways. Blaine has done WAY more and like the one above would be the cleanest and quickest.
 
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Hey Guys,

I got my rear 12" Fox RR shocks installed without issue last weekend but am a bit stumped with with one of the steps for the front.

I have removed the factory shock mounts and have the lower mount tacked in place (with a best guess starting point). I have a dummy shock setup at the length of 1/2 travel and am using that to attempt to place the poly tower in its approximate location so I can mark the cuts needed to blend it into the frame (like I did for the rears). This is where I am a struggling a bit... Does anyone have some tips for getting the poly towers marked close so I can cut them and then grind the cuts to tweak the location? the frame is a bit complicated right where the poly tower needs to live and I am hoping some of the more experienced fabricators have some pointers.

I am currently attempting to cardboard CAD pieces to show me my cuts on the towers... and it is a struggle

I will be following, I am doing my rears this weekend then will move to the fronts. I’m a bit stumped there also. My plan is to put the lower mount in. Attach the bar lay the mount against the frame and trace the back then cut below that line a bit and start fitting from there.
 
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This is how I welded up the front lower on the hp30, I have the 12” fronts from @pcoplin abd probably should have done the 11” ones just because the extra inch is a lot more than an inch on the shock body…

3ABD96FA-B5B3-4187-8E5C-57DAEDDEE164.jpeg


D6F86E43-0F48-47F7-957F-7C5C93FCC403.jpeg
 
I will be following, I am doing my rears this weekend then will move to the fronts. I’m a bit stumped there also. My plan is to put the lower mount in. Attach the bar lay the mount against the frame and trace the back then cut below that line a bit and start fitting from there.

This is how I started the process (and possibly how I will get it complete) but I was getting nervous of screwing up the tower so I switched over to cardboard... have to take the family to the city so no progress today, however I have time... the snow is still flying in Iowa. I am so done with winter this year.
 
You can either cut out the stock upright and use the tower as that upright brace, or leave it and cut the tower to it. I've done both ways. Blaine has done WAY more and like the one above would be the cleanest and quickest.

Thanks Paul, this gives me an idea, tomorrow (due to commitments today) I'm thinking using the pieces of the old shock tower that I have removed may be a slick way to transfer the required geometry to the poly tower. It will require me to reconstruct the puzzle a bit as the shock tower is currently in a few chunks on the shop floor :)
 
Hey Guys,

I got my rear 12" Fox RR shocks installed without issue last weekend but am a bit stumped with with one of the steps for the front.

I have removed the factory shock mounts and have the lower mount tacked in place (with a best guess starting point). I have a dummy shock setup at the length of 1/2 travel and am using that to attempt to place the poly tower in its approximate location so I can mark the cuts needed to blend it into the frame (like I did for the rears). This is where I am a struggling a bit... Does anyone have some tips for getting the poly towers marked close so I can cut them and then grind the cuts to tweak the location? the frame is a bit complicated right where the poly tower needs to live and I am hoping some of the more experienced fabricators have some pointers.

I am currently attempting to cardboard CAD pieces to show me my cuts on the towers... and it is a struggle

A few things that may help. Your reference point is the hole in the factory fender that lined up over the top of the shock pin. That is what I use to keep the shock tower relatively located to where it should be. That will also let you keep the shock tower roughly centered fore and aft on the shock body.

Your mock up stick will screw you hard if it holds the top and bottom bolts square to each other. The frame curves inward which rotates the mount out of square with the lower mount. My mock up stick is two round tubes that slide inside one another to let that happen and set the distance apart for the two bolts.

I cope the lower mount into the C after capping off the back of the spring perch to support the cut edge. That cut is parallel and generally even with the back of the axle tube looking straight down on it. Tacked only to hold the mock up stick and set or help set the height, rotation, and tip out angle up the upper mount. If I need a 1/4" up or down, I can cut the tacks to get that.

DSC_4328.JPG

The edge highlighted in red is generally around 3/8" above the top of the lower control arm mount. Emphasis on generally and it is also parallel to the top to keep the two bolts relatively square to each other.
1679148817390.png


That edge is the edge as it comes from Poly. If you try to notch it into the gap, the shock will be too close to the axle and not as vertical as you would want.
1679148931731.png

The underside will need some trimming around the LCA bolt. And, the forward inboard side will need to be cut up some to clear the axle tube. We weld down the inside along the lower control arm mount, down the inner C and where it touches any place else.

DSC_4337.JPG


For the upper, I use the vertical brace as my forward limit, I remove it completely and then replace it with the forward leg of the tower. I don't worry about trimming it much until final, then I cut it down to about the same size as what I removed and hold the lower end up from the bottom of the frame a small amount.

DSC_4327.JPG

If you try to get the two faces roughly parallel, it seems to work out fairly well.

1679149487174.png


Once you start trying to fit up the mount and cope it in to close up the gaps, looking at where the mount side touches the spring perch, you will note a big gap as the front edge touches first. I smack that edge forward to help with that and kinda beat that whole side into submission to get it close enough to weld. I also gusset the edge of the perch back up to the mount to put back the support I removed when I cut off the rolled edge.
1679149723356.png

As in both mounts at the horizontal frame cut, those are trigger welds, some days I can do a good bead there, others I have to trigger weld them. It is the option of last resort though. But with so much surface area welded up on both sides of the closely fit down legs, they are just basically filler to make it look sorta like it was done well.
1679149969563.png
 
Last edited:
A few things that may help. Your reference point is the hole in the factory fender that lined up over the top of the shock pin. That is what I use to keep the shock tower relatively located to where it should be. That will also let you keep the shock tower roughly centered fore and aft on the shock body.

Your mock up stick will screw you hard if it holds the top and bottom bolts square to each other. The frame curves inward which rotates the mount out of square with the lower mount. My mock up stick is two round tubes that slide inside one another to let that happen and set the distance apart for the two bolts.

I cope the lower mount into the C after capping off the back of the spring perch to support the cut edge. That cut is parallel and generally even with the back of the axle tube looking straight down on it. Tacked only to hold the mock up stick and set or help set the height, rotation, and tip out angle up the upper mount. If I need a 1/4" up or down, I can cut the tacks to get that.

View attachment 408235
The edge highlighted in red is generally around 3/8" above the top of the lower control arm mount. Emphasis on generally and it is also parallel to the top to keep the two bolts relatively square to each other.
View attachment 408238

That edge is the edge as it comes from Poly. If you try to notch it into the gap, the shock will be too close to the axle and not as vertical as you would want.
View attachment 408239
The underside will need some trimming around the LCA bolt. And, the forward inboard side will need to be cut up some to clear the axle tube. We weld down the inside along the lower control arm mount, down the inner C and where it touches any place else.

View attachment 408242

For the upper, I use the vertical brace as my forward limit, I remove it completely and then replace it with the forward leg of the tower. I don't worry about trimming it much until final, then I cut it down to about the same size as what I removed and hold the lower end up from the bottom of the frame a small amount.

View attachment 408244
If you try to get the two faces roughly parallel, it seems to work out fairly well.

View attachment 408245

Once you start trying to fit up the mount and cope it in to close up the gaps, looking at where the mount side touches the spring perch, you will note a bit gap as the front edge touches first. I smack that edge forward to help with that and kinda beat that whole side into submission to get it close enough to weld. I also gusset the edge of the perch back up to the mount to put back the support I removed when I cut off the rolled edge.
View attachment 408246
As in both mounts at the horizontal frame cut, those are trigger welds, some days I can do a good bead there, others I have to trigger weld them. It is the option of last resort though. But with so much surface area welded up on both sides of the closely fit down legs, they are just basically filler to make it look sorta like it was done well.
View attachment 408247

Thank you for posting this! I think I'll get a second pair of poly towers on their way instead of trying to butcher the factory towers at the front. Beautiful and detailed work as always.

Why do you store rusty bolts in your floor jack? :LOL:
 
I see that I neglected a few key things. The vertical brace that extends down from the spring perch, that is also the cut line for the spring and shock perch back wall. Everything behind that line gets removed. I go right down the brace with a cut off disc watching my depth and remove it. The Top of the spring perch just cuts back at a line equal to the top edge of the rolled part.

FYI- this is not the only way to get this done, this is just the way I do it and have done it for many years.
 
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A few things that may help. Your reference point is the hole in the factory fender that lined up over the top of the shock pin. That is what I use to keep the shock tower relatively located to where it should be. That will also let you keep the shock tower roughly centered fore and aft on the shock body.

Your mock up stick will screw you hard if it holds the top and bottom bolts square to each other. The frame curves inward which rotates the mount out of square with the lower mount. My mock up stick is two round tubes that slide inside one another to let that happen and set the distance apart for the two bolts.

I cope the lower mount into the C after capping off the back of the spring perch to support the cut edge. That cut is parallel and generally even with the back of the axle tube looking straight down on it. Tacked only to hold the mock up stick and set or help set the height, rotation, and tip out angle up the upper mount. If I need a 1/4" up or down, I can cut the tacks to get that.

View attachment 408235
The edge highlighted in red is generally around 3/8" above the top of the lower control arm mount. Emphasis on generally and it is also parallel to the top to keep the two bolts relatively square to each other.
View attachment 408238

That edge is the edge as it comes from Poly. If you try to notch it into the gap, the shock will be too close to the axle and not as vertical as you would want.
View attachment 408239
The underside will need some trimming around the LCA bolt. And, the forward inboard side will need to be cut up some to clear the axle tube. We weld down the inside along the lower control arm mount, down the inner C and where it touches any place else.

View attachment 408242

For the upper, I use the vertical brace as my forward limit, I remove it completely and then replace it with the forward leg of the tower. I don't worry about trimming it much until final, then I cut it down to about the same size as what I removed and hold the lower end up from the bottom of the frame a small amount.

View attachment 408244
If you try to get the two faces roughly parallel, it seems to work out fairly well.

View attachment 408245

Once you start trying to fit up the mount and cope it in to close up the gaps, looking at where the mount side touches the spring perch, you will note a big gap as the front edge touches first. I smack that edge forward to help with that and kinda beat that whole side into submission to get it close enough to weld. I also gusset the edge of the perch back up to the mount to put back the support I removed when I cut off the rolled edge.
View attachment 408246
As in both mounts at the horizontal frame cut, those are trigger welds, some days I can do a good bead there, others I have to trigger weld them. It is the option of last resort though. But with so much surface area welded up on both sides of the closely fit down legs, they are just basically filler to make it look sorta like it was done well.
View attachment 408247

Geez... wish I'd had this writeup at my fingertips when I did mine. Would have saved me alot of trial and error and pondering.

Incredible work as always, Blaine.
 
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I see that I neglected a few key things. The vertical brace that extends down from the spring perch, that is also the cut line for the spring and shock perch back wall. Everything behind that line gets removed. I go right down the brace with a cut off disc watching my depth and remove it. The Top of the spring perch just cuts back at a line equal to the top edge of the rolled part.

FYI- this is not the only way to get this done, this is just the way I do it and have done it for many years.

@mrblaine do you have a source for longer spacers for the shocks. My shocks came with .375” and I need .500” to fit the mounts. I looked at McMaster but didn’t see any.