The Story Of A Cummins Suburban (Lots Of Pics)

[justcuz]

Are you going to keep those front springs? I see they have wear buttons on the ends, but thickness of the material and the fact that with 3 leafs the weight of the engine did not sag it much, means those springs are pretty stiff. (whew, run on sentence) It seems to me that a lot of flex/force would be transferred to the chassis with those springs. Have you seen the conversion were they use Chevy 1/2 ton 52 inch back springs on the front? They move the front mount forward about 2 inches. This would give you a little more clearence for the Dana 60 and allow more spring flex than your lift springs would allow. It should save the chassis. The only reason I bring this up is I had a lift on my 1976 3/4 ton that only had 2 leafs. I swapped them out for another companies multi leaf spring with thinner leaf material and the ride was improved dramatically.
How much lighter is the 4 cylinder Cummins? I have heard they weigh about 800 lbs, which is not too much heavier than a complete big block, correct?
I enjoy reading this thread because you have been very creative in making things work. This is a credit to your skills and thought process as a mechanic and fabricator.

[mosesburb]

Originally Posted by justcuz

Are you going to keep those front springs?

For the foreseeable future, the front springs will remain. I have spent (and need to spend) so much money on this project that, at this point, I can not justify replacing new parts with new parts.

Originally Posted by justcuz

Have you seen the conversion were they use Chevy 1/2 ton 52 inch back springs on the front? They move the front mount forward about 2 inches. This would give you a little more clearence for the Dana 60 and allow more spring flex than your lift springs would allow. It should save the chassis.

I had done some investigation on this several years ago and in talking with some people who had done the conversion, decided it was not for me. The biggest issue with it is the flex. The rear springs have a lower rate than the front springs and are narrower in width. The guys I spoke with that are running them said body roll increased dramatically. This was not an issue for them, but I do not want a weaker spring that is too flexible under this much weight. If I decide to go with something different, I will probably have some custom springs made in the '73+ length, with a spring rate that will work well for this mess I am building. I wish I could have done it earlier in the project, but I had no way to calculate the weight on the front axle to be accurate enough to get the spring rate right the first time.

Originally Posted by justcuz

How much lighter is the 4 cylinder Cummins? I have heard they weigh about 800 lbs, which is not too much heavier than a complete big block, correct?

I'd say that 800# would be fully dressed with accessories and flywheel. Yes, that is about the same as a dressed big block.

Originally Posted by justcuz

I enjoy reading this thread because you have been very creative in making things work. This is a credit to your skills and thought process as a mechanic and fabricator.

Thank you. I try to think things through before I start on a particular aspect of a project so that I do not have to go back and re-do something I just did. While this sounds good, it does not always work out as planned, but by reducing the amount of "re-do's" it helps keep morale up and forward progress happening.