RSK w/ SD springs vs +'05 coil springs

[gnxtc2]

So this a$$hole decides to make a U-turn in front of me at the last minute. Well, it didn't pan out for him too well. He had to extricate out and sustained a possible broken leg. Anyway, the front passenger frame horn was bent along with the front RSK crossbar. Plus, the frame was parallelogram'd slightly.

My friend told me to do the '05 coil spring swap since I have to do some work. I have no complaints how my truck rides. I think it rides pretty good.

Anyway, has anyone gone from a RSK with SD springs to a +'05 coil sprung front? The rear uses the same springs.

Billy T.
[email protected]

 

[Zeb]

I’m pretty sure strokersace has had an 05 setup and RSK on the same OBS.

 

[gnxtc2]

Oh yea, here are some pics.

Billy T.
[email protected]

 

[Strokersace]

Dang Billy, that sucks.

As Zeb stated, I’ve had both setups on the same obs. Only I did the 05 coil spring 1st, then switched to an Rsk with 04 axles before I sold it. I only did the swap at the end of my ownership because the 05 suspension (front and rear) went into an 04 I bought to replace it, so the 04 donated its axles back to the obs.

No comparison that the 05 coil front was a better ride of the 2. Ran SD b-code rear springs on both setups, with a 2” block on the 05 setup and 4” clock with the rsk. Ran 5200lb coils with the 05 setup and V-code leafs with the rsk. Truck sat considerably lower with the coil spring setup which I liked much better for pulling my trailers.

I was actually in a similar accident with my truck when it had the 05 axles in it and outside of the body damage and having to get the frame horn straightened, the suspension was not affected at all.

The downside to doing an 05 setup as compared to getting your rsk setup fixed is having to run new rims all the way around and at the minimum spacers on the rear to cover from 8x6.5 to 8x170. Or swap rear axles too. Also because the frame is narrower on the front of an obs compared to the SD, the coil springs “lean” inward some. Also the radius arms angle out slightly from the frame to the axle. However, I never had an issue at all with binding or articulation. I think there is a company out there now that builds radius arm and coil spring brackets to compensate for this when installing on an obs. Can’t remember the name but they look like great quality. Although not cheap, I’d consider using them if I did the swap again.

 

[gnxtc2]

Dang Billy, that sucks.

I think there is a company out there now that builds radius arm and coil spring brackets to compensate for this when installing on an obs. Can’t remember the name but they look like great quality. Although not cheap, I’d consider using them if I did the swap again.

Thanks

Here is the company that I was thinking of using if I do the coil spring swap. https://www.rydmotorsports.com/coll...cts/ford-obs-05-superduty-axle-conversion-kit

Someone already wants my current axles.

And yes, if I do the swap, it'll have the same axles as I will get rear discs. I already know someone that has rims for a +05 swap.

Which axles are better, the 05-07 or the 08-10? I heard the 08-10 have bigger brakes?

Billy T.
[email protected]

 

[Zeb]

Billy, that sucks.

As Zeb stated, I’ve had both setups on the same obs. Only I did the 05 coil spring 1st, then switched to an Rsk with 04 axles before I sold it. I only did the swap at the end of my ownership because the 05 suspension (front and rear) went into an 04 I bought to replace it, so the 04 donated its axles back to the obs.

No comparison that the 05 coil front was a better ride of the 2. Ran SD b-code rear springs on both setups, with a 2” block on the 05 setup and 4” clock with the rsk. Ran 5200lb coils with the 05 setup and V-code leafs with the rsk. Truck sat considerably lower with the coil spring setup which I liked much better for pulling my trailers.

I was actually in a similar accident with my truck when it had the 05 axles in it and outside of the body damage and having to get the frame horn straightened, the suspension was not affected at all.

The downside to doing an 05 setup as compared to getting your rsk setup fixed is having to run new rims all the way around and at the minimum spacers on the rear to cover from 8x6.5 to 8x170. Or swap rear axles too. Also because the frame is narrower on the front of an obs compared to the SD, the coil springs “lean” inward some. Also the radius arms angle out slightly from the frame to the axle. However, I never had an issue at all with binding or articulation. I think there is a company out there now that builds radius arm and coil spring brackets to compensate for this when installing on an obs. Can’t remember the name but they look like great quality. Although not cheap, I’d consider using them if I did the swap again.

Man, you’ve done the swapping!!
I often wondered why you had both setups under the same truck, now I know.
Billy, glad you’re ok!
I don’t think there is much/any difference in 05-07 axles, versus 08-10.
There is a really in-depth thread on another forum (I believe it’s ford trucks, I’ll look and see) that discusses the differences on some of the brackets, etc between 05-07 and 08-10.

 

[Zeb]

The thread is on Ford truck Enthusiasts Forums, in the Excursion section, under Swapping 07 axles into an 01 Excursion.

 

[sootie]

Rear axles are the same 05-10. Front axle in 08 has the sway bar end links rotated 90 degrees.

11+ have bigger brakes and lack the tone ring to read speed in the rear.


Sucks to see such a clean obs get tore up

 

[Strokersace]

Thanks

Here is the company that I was thinking of using if I do the coil spring swap. https://www.rydmotorsports.com/coll...cts/ford-obs-05-superduty-axle-conversion-kit

Someone already wants my current axles.

And yes, if I do the swap, it'll have the same axles as I will get rear discs. I already know someone that has rims for a +05 swap.

Which axles are better, the 05-07 or the 08-10? I heard the 08-10 have bigger brakes?

Billy T.
[email protected]

Yes that’s the company. Don’t like the brodozer looking obs trucks in the pictures but parts look decent.

When I 1st did it, I was able to sell the axles and wheels for more than I had into the 05+ parts. I used all stock brackets. It was more hassle to get them off the 07 frame than it was to install on the obs!

Sootie is spot on below about the axle differences.

One thing I would love to try is to put the longer 08+ rear leaf springs on. I can only assume it’d improve the ride even further.

Man, you’ve done the swapping!!
I often wondered why you had both setups under the same truck, now I know.
Billy, glad you’re ok!
I don’t think there is much/any difference in 05-07 axles, versus 08-10.
There is a really in-depth thread on another forum (I believe it’s ford trucks, I’ll look and see) that discusses the differences on some of the brackets, etc between 05-07 and 08-10.

Yeah I got pretty good at swapping stuff on that truck. Had it for 14 years and it went through a lot of transformation. It started life as a 460 and converted it to a psd using everything from an exact optioned, same year truck that is wrecked. Multiple injector, oil, fuel, turbo combos; 3 swapped engines; and 4 different suspension setups during that timeframe. Sold it 2 years ago and just last week called the kid to try and buy it back, but found out he’d totaled it last year. However he’s swapping everything into another truck so it’ll live on!

 

[JCart]

Dang Billy, sorry to see one of my fav OBSs pranged, food that you’re ok though. Fawk.... the guys a dick and shoulda been throat punched to go with his broken leg, is what comes to mind. Yeesh.

RYD is close to me (relatively) I’m 300 miles inland from Vancouver. Not noticed any of their stuff up my way, but the web pix look pretty robust and not dorky. If you like I can ask a couple buddies of mine to see what the skinny is...
j

 

[bluedge8]

How close to "stock" height is an '05 conversion? I was wondering if an '05 conversion would be close to stock height of a '96 f350? Billy, I hope you document your project if you do it.

 

[lincolnlocker]

Rear axles are the same 05-10. Front axle in 08 has the sway bar end links rotated 90 degrees.

11+ have bigger brakes and lack the tone ring to read speed in the rear.


Sucks to see such a clean obs get tore up

Didnt they change the brakes from 13 on?

live life full throttle

 

[Strokersace]

How close to "stock" height is an '05 conversion? I was wondering if an '05 conversion would be close to stock height of a '96 f350? Billy, I hope you document your project if you do it.

With the right coil spring and block setup it can be lower than a factory 4x4 obs f350.

Here’s mine (bad picture but all I could find quick). 2” factory f250 rear blocks, 5200 lb coils, and 33” tires. Sat with the perfect amount of rake: front was 1 1/2” lower than the rear.

Sat 2” lower than a factory F350 4x4. It was perfect for me. I’d even considered dropping to a 4400lb coil and pulling the rear blocks. Would have been 2wd height then, but would have had to run a 31 to 31.5” tire.

 

[bluedge8]

With the right coil spring and block setup it can be lower than a factory 4x4 obs f350.

Here’s mine (bad picture but all I could find quick). 2” factory f250 rear blocks, 5200 lb coils, and 33” tires. Sat with the perfect amount of rake: front was 1 1/2” lower than the rear.

Sat 2” lower than a factory F350 4x4. It was perfect for me. I’d even considered dropping to a 4400lb coil and pulling the rear blocks. Would have been 2wd height then, but would have had to run a 31 to 31.5” tire.

Holy chit! I love it. My knees went to sh!t in the last 6 months, I just got my 2.25" PMF rsk with new v codes done last fall and the truck sits 4-6" higher than it used to. I was starting to think about selling just because it sucks to get into so bad. How does a guy find a donor frame with axles?

Sent from my SM-N950U using Tapatalk

 

[Strokersace]

Holy chit! I love it. My knees went to sh!t in the last 6 months, I just got my 2.25" PMF rsk with new v codes done last fall and the truck sits 4-6" higher than it used to. I was starting to think about selling just because it sucks to get into so bad. How does a guy find a donor frame with axles?

Sent from my SM-N950U using Tapatalk

I was looking for the pictures of the same truck with the 2.25” rsk w/ v codes and 4” blocks in the back but I don’t have any on my phone. With that setup I was easily able to clear 35’s and that’s what it had when I sold it.

The 33s in that picture above were very tight with the wheel offset and width of rim/tire. Had to be careful when turning and going through a dip or it would rub the fender. I switched to factory 2010 18” wheels with the same height tire and there were zero issues. Again sorry no pictures of it on my phone with those wheels.

Setup like the picture above and lower than a stock obs f350 it was very easy to get in and out of without steps. When I did the rsk, you almost had to jump in!

To find a wrecked truck is best but they’re available. I actually have the front frame section of a 2010 with the 4.10 geared axle out of my dually. I swapped the Dually to 3.73s. Just haven’t posted it for sale yet. If we lived closer together, I’d trade you your front end for it as I’m eyeballing getting an obs Dually and concerting it to a 4wd with rsk.

 

[sootie]

Didnt they change the brakes from 13 on?

live life full throttle

yep, they eliminated hydroboost on 13+ SRW trucks. Duallys still had hydroboost though. No dimensional changes that i'm aware of though.

 

[lincolnlocker]

yep, they eliminated hydroboost on 13+ SRW trucks. Duallys still had hydroboost though. No dimensional changes that i'm aware of though.

I thought the 13 front axle changed with a bigger knuckle that required a different caliper?

live life full throttle

 

[sootie]

I thought the 13 front axle changed with a bigger knuckle that required a different caliper?

live life full throttle

could be so. I'm not aware of any dimensional changes though...(as in, 17s still clear it so)

 

[Garbage_Mechanic]

Dang is what I say as well. Your truck is one of my favorites and it is painful to see it bent! I can't help you with the decision to go coil or not. I do have a comment that this is the second or 3rd time I have seen similar frame issues on a truck with RSK. Either the front of the frame was designed dumb, or designed to be a crumple point but either way, the fron of the OBS frame rails was not designed for the torque load of the anchor of the front axle (front spring eye) The coil conversion fixes this, but I recently found a write up on doing the Super Duty front leafs while NOT doing an RSK and very little ride height increase. Kind of sorry I just finished my upgraded RSK when I discovered it....

 

[Garbage_Mechanic]

Also, they frame may not be parallelogramed, the cab and front clip may have moved on the rubber mounts. Glad you are OK, and it is refreshing to concentrate on the fix and possible upgrade rather then spend 50 posts bitching about insurance companies etc...