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Improving ride quality '89 F350...rsk?

 
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Old 02-17-2019, 09:30 AM
nova801428
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Improving ride quality '89 F350...rsk?

So about 3 years ago I completed a Cummins swap and have been extremely happy so far. I've made some changes in my life and now my truck is currently my daily driver. Things that didnt bug me now irritate me on a daily basis. The main issue is how bumpy and terrible the ride is. I went from a 351w to a Cummins and never touched the suspension. I used to think the ride wasn't terrible but it's been so long I don't even remember anymore.

I'd like to improve the ride and I'm uncertain if a rsk will actually do that. For the price of an RSK I can almost buy Superduty axles and convert to coils (I know coils will ride better). I'm not sure if I need to buy new leafs because of the weight difference or were they all the same? The rear sits about 2.5" higher than the front.

Any advice or suggestions?

Thanks
 
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Old 02-18-2019, 10:19 AM
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No love? Lol
 
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Old 02-18-2019, 10:25 AM
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An RSK does improve ride quality from what I've read both from the longer spring but also the improvement of the shackle location/angle. There are different ratings for the springs. I am planning an RSK from PMF in the next few months, seems to be around $800 give or take depending on some options.

The issue with the SD coil axle is that it has a different lug pattern if I remember reading, so you'd need to swap the rear as well.

 
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Old 02-18-2019, 12:19 PM
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Originally Posted by nova801428 View Post
So about 3 years ago I completed a Cummins swap and have been extremely happy so far. I've made some changes in my life and now my truck is currently my daily driver. Things that didnt bug me now irritate me on a daily basis. The main issue is how bumpy and terrible the ride is. I went from a 351w to a Cummins and never touched the suspension. I used to think the ride wasn't terrible but it's been so long I don't even remember anymore.

I'd like to improve the ride and I'm uncertain if a rsk will actually do that. For the price of an RSK I can almost buy Superduty axles and convert to coils (I know coils will ride better). I'm not sure if I need to buy new leafs because of the weight difference or were they all the same? The rear sits about 2.5" higher than the front.

Any advice or suggestions?

Thanks
Convert to coils would be the best.
 
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Old 02-18-2019, 12:22 PM
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Originally Posted by Edgethis View Post
An RSK does improve ride quality from what I've read both from the longer spring but also the improvement of the shackle location/angle. There are different ratings for the springs. I am planning an RSK from PMF in the next few months, seems to be around $800 give or take depending on some options.

The issue with the SD coil axle is that it has a different lug pattern if I remember reading, so you'd need to swap the rear as well.
Thanks for the reply. I don't believe there is a superduty leaf spring RSK for 87-91 trucks. I'm limited to using the stock length springs.

I've never ridden in a truck with an RSK so it's hard for me to know if it will be worth it.

I'm in the process of swapping 05+ superduty axles in a project of mine. I wont know how it rides until late this year.

 
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Old 02-18-2019, 12:26 PM
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I believe you can run the RSK, jsut need to box the front of the frame where it mounts.

Here's a kit:

87-91 F350 RSK Kit
 
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Old 02-18-2019, 10:08 PM
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Originally Posted by nova801428 View Post
Thanks for the reply. I don't believe there is a superduty leaf spring RSK for 87-91 trucks. I'm limited to using the stock length springs.

I've never ridden in a truck with an RSK so it's hard for me to know if it will be worth it.

I'm in the process of swapping 05+ superduty axles in a project of mine. I wont know how it rides until late this year.
Funny thing is that back in the day i bought a brand new f350 1990 with a 460. 26000 canadian at the time! It was a dream truck back then, no one thought it was rough riding!
 
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Old 02-18-2019, 10:22 PM
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i got a stock 89 cc ongbed 4x4 with 351w and the ride is harsh i agree. i do have overload springs too from the factory, it bad on rough roads.
 
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Old 02-19-2019, 10:13 AM
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RSKs only really help if you’ve got a lift, therefore positive arch springs. If you’re stock, you have a negative arch, so as the axle moves up, it also moves back due to the front shackle. With a positive arch and stock shackles, the axle would have to move forward to go up, causing the pogo stick effect. I’m told the SD spring swap makes for a close to stock height with a softer ride gained from the length, and they can be had fairly cheap depending on where you live.
 
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Old 02-19-2019, 05:17 PM
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The RSKs all use a SD spring and move the shackle to the rear. You will get a bit of lift from the swap just by the way its made.
 
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Old 02-19-2019, 06:30 PM
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Originally Posted by Edgethis View Post
The RSKs all use a SD spring and move the shackle to the rear. You will get a bit of lift from the swap just by the way its made.
The RSK from sky specifically says it uses Ford 52" 80-97 leaf springs.
 
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Old 02-19-2019, 06:31 PM
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i think most the bad quality ride is from the rear springs.
 
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Old 02-19-2019, 06:43 PM
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Originally Posted by nova801428 View Post
The RSK from sky specifically says it uses Ford 52" 80-97 leaf springs.
You're right, that kit does say that. My bad for not double checking.

The better version (in my opinion) of RSks for our trucks come from PMF, they utilize the SD spring. Also their kit is bolt on and cheaper. I hadn't linked it before because it doesn't specifically say it'll fit 87-91. However, if you box the front frame rail I believe it'll fit.

PMF SD spring RSK for 92-97 F350
 
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Old 02-19-2019, 06:48 PM
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I like the factory setup, it keeps the pinion angle more accurate and keeps the driveshaft from bottoming out
 
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Old 02-19-2019, 07:29 PM
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Originally Posted by Edgethis View Post
You're right, that kit does say that. My bad for not double checking.

The better version (in my opinion) of RSks for our trucks come from PMF, they utilize the SD spring. Also their kit is bolt on and cheaper. I hadn't linked it before because it doesn't specifically say it'll fit 87-91. However, if you box the front frame rail I believe it'll fit.

PMF SD spring RSK for 92-97 F350
The only issue I see is the frame rails on the 87-91 look shorter in the front than the 92-96. I'm not sure how long superduty leafs are and how far forward the axle would have to go?
 

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