52" up front with a Cummins

[gerlbaum]

Hi all,

I am about ready to drop my Cummins into my 1973 k10. While I had the bay cleared, I wanted to do some suspension work. I am considering putting my 52" springs up front, with an add-a-leaf in the pack (extra weight of cummins is ~500 over my 350 - Cummins wet is 1100, 350 wet is around 500-600).

I was curious if you thought this might flex too much with the extra weight. I was thinking the add-a-leaf would be enough for the extra weight capacity. This would be 70% on road vehicle, the other time some mild 4x4.

I appreciate your opinions.

[boz42]

I run a 91 V3500 with stock 48" springs & a '75 K5 with 56" leafs under the front. In my experience the longer leafs in the front flex well & make a rig ride better, but it does allow the front end to walk around a little more than stock. I would think this would be even more noticable with the wieght of the 5.9. If you are not planning on a lot of wheeling I would stick with stock length.

[woodwright]

You might want to run a panhard bar to limit side to side movement. Are you running crossover?

[gerlbaum]

Thanks for the replies fellas. I will definitely be going to a cross over set up no matter what. I already have my 2wd box. However it wont be going on until my motor is in since I am not sure about the clearances. Most likely I will be welding/fabbing my own. I was thinking the flex might be too much with the 52s but wanted to add an add-a-leaf and since those are stiff, it might "even" out the flex plus help with the extra weight. But I have no experience with the the ride quality of 52s so I have nothing to compare.

[lowrollin70gmc]

I've been back and forth with 52s under my Cummins K20 and at the moment I'm staying away from them. I think the amount of sway from that heavy motor would make it a handful on the street. If it's a mostly off road truck I think it'd work great but I'm not willing to give up my street manners in my hunting / winter driver.

From what I've talked to people about they ride smooth due to the increased length but side to side stability is compromised. Maybe 52s with a sway bar disconnect for the best of both worlds?

[gerlbaum]

That might be an option. I have an f350 and it was horrible on turns until I put super stiff shocks on it. I was thinking the add a leaf might help stiffen the leafs - I am just not sure how much. I know for rear springs they make short and long ones, the short ones really stiffen it up. Maybe add both, essentially creating a custom leaf pack (maybe temporary until I save up enough for a rear set of custom leafs).

[gerlbaum]

Well, to be on the safe side I ordered the Superlift 6" kit. I am just too unsure about the 52"s up front with that much weight.

[andrewmp6]

I'd love to see some pictures of it once you get the cummins in it.

[gerlbaum]

Thanks, I will. I have taken a few since I have started. Quite frankly, I am not sure why everyone worries about the frame. A wet cummins is 300 to 400 lbs heavier than a 454 and I know a lot of the guys with 454s top them off with plows and have had no issues. The biggest issue with the cummins is the height of the block itself. I had a 6" lift already so there were no fitment issues at all. You don't need to pound the firewall in and you can take the head off with it in the truck. Also, I had a dual electric fan set up so there is plenty of room for my rad, condensor, and intercooler. I added some billet freeze plugs and tappet cover. Apparently under higher boost these things on the cummins can blow out. I've still got to do the killer dowel pin fix before I button the motor up.

I do appreciate your interest. This has been my obsession for the past year.

[andrewmp6]

If you really want to run the 52s maybe call up denverspringandsuspension.com i know they do custom work you might be able to get 52s that are stiffer.For years i use to be anti diesel because i knew nothing about them,But after helping a friend put a 4bt in a f250 he has opened my eyes.Its a 95 4x4 he use to get like 12mpg with a 351 now its getting about 26mpg on the highway and has more power to me driving it.I would like to do a swap one day but im cheap its gonna be a while for me.

[mknittle]

Putting longer more flexable springs on then stiffening them up with a add a leaf kind of seems like it would be counter productive.