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Discussion Starter · #1 ·
Time to replace the sagging fiberglass springs on our '89 Tiger conversion... trying to make sense of the options. It looks like there are two main options:

Use steel leaf springs from a later Astro or S-10 truck, which requires new hangers, u-bolts, and other miscellaneous components, all sourced separately, or,

Buy a fiberglass-to-steel conversion kit that uses the original hangers and appears to include all necessary hardware. Two sources are:


and


The conversion kits sound a lot simpler, but I've seen some comments critical of them, but it wasn't clear quite why? They seem to be rated at 1410# each, anybody know what the original springs were rated at? I'm not looking to add any lift, just to get the rear end back up where it should be, with the extra weight of the camper conversion.
 

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1989 Astro RS on a 1998 AWD frame with a 1994 350 TBI
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I have an 89 that had the fiberglass springs, I went to a pick n pull and bought the complete steel springs with all parts on a 50% sale for like 100 bucks.. Since I do not know where in the world you are I figured I'd offer another option.
 

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Common Sense + Critical Thinking
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Buy a fiberglass-to-steel conversion kit that uses the original hangers and appears to include all necessary hardware.
Don't do it, go with the OEM mounts and put in regular leaf springs, not the conversion springs. I have done a few of these, and would never use the conversion springs, just my $0.02
 

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Common Sense + Critical Thinking
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1. I don't like the way they mount inside the old hanger.
2. If you decide to go with a lift later that uses the new front hangers, your springs won't be compatible and you will need new springs.
3. You can get rid of the cheapo clamshell that holds the leaf spring to the axle and use something much, much stronger(make sure to check yours for rust, last ones I removed I could bend them out of place with a pair of vice grips they were so rusted away)
4. You can use the regular or HD springs from an Astro, or from an S-10, etc.
5. If you ever need repairs, any spring/suspension shop can get you what you need quickly or you can grab a set from the junkyard, can't do that with the conversion set.
 

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I wouldn't do the conversion kit. Just take a trip to the local salvage yard and usually for about $100 you could get everything you need to switch to steel springs. Just make certain the springs and shackles are not rusted severely or the insulating pads/shims are broken or missing. Very easily swapped out, once you can get the bolts out.

Try to get a minimum 4 leaf spring pack from a donor vehicle that had little weight on the rear, no trailer hitch, no conversion and no heavily abused cargo van. The less weight the van or pickup had on the rear, the better for the springs. You can always add an extra heavy duty leaf for more support as long as the shackle bolts allow.

If your budget allows, you can purchase brand new steel spring packs in ranges from 1400 to 2100 lbs capacity and the price is less than the conversion packs, generally around $100-$250 each.
 

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Discussion Starter · #7 ·
I have two problems with junkyard components; first, here in New England everything is rusty even if I can find a vehicle that old in the yard (my van came from Arizona and is super clean for a 1989), and while I would normally do all the work myself I can't due to an injury, so sourcing new parts and taking them to a shop is a lot simpler.
If I buy all new parts, the conversion kit actually is a bit cheaper than replacement stock springs with all the required parts. Having stock parts is certainly an advantage in case of trouble while traveling. I don't plan on adding a lift, unless I convert to 4WD some day, but in that case I'd be more likely to look for another van already converted.
 

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Yes, if you think you will do a lift later, it will affect this. But, if running stock, the conversion kit is economical, and easy to install. Many thousands have been used,I don't know of any issues, but I did not search the threads. My 94 has been fine, beating up and down these mountain roads. But,one thing, it is a pain cleaning the rust from the clam, now that they are available again, pay extra for them, or even the kit that includes the bolts. Will save a bunch of time.
 

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Discussion Starter · #10 ·
Now the dilemma is what rating springs. I have a few more numbers now, but no conclusion as of yet:

The stock 97 Astro (ours is an 89) had a rear axle curb weight of 1631#, and a rear axle gross of 3150. I couldn't find numbers for other years.

One 88 Tiger had a rear axle weight of 2980, putting a Tiger close to the original Astro's design gross weight in the back, not surprising. I don't know if that included fuel.

Provan has no records going back that far, but did point out that I need to deduct the axle/tire/spring weight of 340# when considering spring ratings, giving me 2640 unsprung weight for the Tiger, 1270 unsprung for the stock Astro, and 2810 gross rating.

Add to that 176# of water, a full gas tank, maybe 200# for all the other stuff we carry, and [maybe] a 200# scooter on a hitch mount... that's 3216# unsprung weight (remember this the rear axle only).

The original fiberglass springs were apparently rated 900# each or 1800# for the pair, more than adequate for an empty Astro but way under the gross weight and definitely inadequate for a Tiger even if they weren't worn out.

New steel springs are available at 1410 (2820 for the pair) or 1750 (3500/pair), supporting that 3216# unsprung weight.

The 1750 springs would be more than adequate fully loaded, but might be too stiff with a light load?
 

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1986 Astro Allegro & 1989 Astro ProVan
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Now the dilemma is what rating springs. I have a few more numbers now, but no conclusion as of yet:

The stock 97 Astro (ours is an 89) had a rear axle curb weight of 1631#, and a rear axle gross of 3150. I couldn't find numbers for other years.

One 88 Tiger had a rear axle weight of 2980, putting a Tiger close to the original Astro's design gross weight in the back, not surprising. I don't know if that included fuel.

Provan has no records going back that far, but did point out that I need to deduct the axle/tire/spring weight of 340# when considering spring ratings, giving me 2640 unsprung weight for the Tiger, 1270 unsprung for the stock Astro, and 2810 gross rating.

Add to that 176# of water, a full gas tank, maybe 200# for all the other stuff we carry, and [maybe] a 200# scooter on a hitch mount... that's 3216# unsprung weight (remember this the rear axle only).

The original fiberglass springs were apparently rated 900# each or 1800# for the pair, more than adequate for an empty Astro but way under the gross weight and definitely inadequate for a Tiger even if they weren't worn out.

New steel springs are available at 1410 (2820 for the pair) or 1750 (3500/pair), supporting that 3216# unsprung weight.

The 1750 springs would be more than adequate fully loaded, but might be too stiff with a light load?

I would go with the HD springs...Autozone has a smoking deal right now with free shipping. I just paid $285. shipped for 22-1195hd springs, yes 2 of them. You will need to buy separate U-bolts and top plates. I did the replacement Fiberglass to steel kit on another 1st gen Astro, wish I didn't....Listen to Astrowill...I have read hundreds of his threads and can tell you...LISTEN TO ASTROWILL!!! Also he has links to the U-bolts and top plates in his avatar, among a million other helpful threads, including a Provan! Click it you won't regret it! Congrats on the Provan, I just pick one up also and that is where the new springs are going. I'm lifting mine, a 1989. Good luck!
 
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