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anybody have the rear transverse fiberglass leaf spring?


djardeli

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I've got a 1990 Chevy Lumina Euro, 214,000 km, with a fiberglass leaf spring in place of springs in the rear. The problem is the driver's side sits about 1/2 inch lower than the passenger's side, and only as measured from the rear. Measured from the front of the car, there is no such lean. My question is, what could cause this? I'm on my second pair of rear struts, 40,000 km on those. I'm on my second pair of rear trailing arms (which shouldn't affect this) The effect of this problem is there's a weight shift, and the car always wants to steer to the left slightly. If the wheel is held centered it tracks dead straight. I'm sick of mechanics telling me I need another alignment. Tires and outer tie rod ends are both quite new so it's hard to believe it's a front end problem. Only problem I see in the rear is a cracked rubber leaf spring bushing on the passenger's side, driver's side bushing looks ok. Seems like if that fiberglass part is warped, I have no choice but to replace it, and $800 dealer part. Is there a cheaper way out of this?

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Guest TurboSedan

hell for much much less than $800, ditch the leaf spring and get some adjustable coilovers. otherwise tho, check to see if the monoleaf has slipped out of one of the rear knuckles, or at least see if it is sitting in each knuckle evenly. that's about all i can think of....

joshua

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Coil overs are an option however beware. The area that the coilovers attach was never meant to hold the weight of the car. The added stress could cause some major problems. I am not sure if you could someone beef the area up, just most w-bodies were designed for the monoleaf.

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Guest TurboSedan

i have heard that too, but i honestly think that is more of a 'myth' than anything else. i have put 30,000+ miles on mine, most of which were hard fast city miles delivering pizza, along with frequent 500 mile interstate trips to and from home. there is no sign of damage or wear whatsover. they have only been on the car for about a year now but i think 30,000 miles in one year considering my job and driving style is a pretty extreme test of coilovers in a w-body. it seems coilovers are becoming more popular now tho, so maybe we'll get more user feedback too. just my 2c.

joshua

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It might be a myth, but I distinctly remember someone on the old Boardhost forum posting about it... said his friend with a '93 Grand Prix found stress cracks on the wheel well and had to get them welded. I asked for pics, and he said he'd get them, but never did.

 

It would seem to make sense though, as the wheel wells were never designed to be the loading point on the rear.

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91CuttyConv

 

That makes sense that there would be problems with the coil overs and weight distribution. That is a pretty small point to have 40% of the cars weight sitting. Has anyone ever replaced the rubber bushings where the Mono-leaf sits in the lower strut cradle? Any poly replacements? 8)

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I've replaced the leaf bushings before. Pretty easy, I just jacked up on the leaf (using a piece of wood as a cushion to prevent damaging the leaf), used some sandpaper and cleaner to clean off the edge of the leaf, and glued the new pad on there using the proper GM adhesive. Then removed the jack and let the car sit for a day or so. The car isn't mine, so I don't know how well that held up!

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Does the Lumina have the auxilary damper springs? I don't know if these would affect ride height. Found an online .pdf catalog from a manufacturer TecsPak (Thermoplastic Elastomer Compression Spring Package) claiming to make these for GM for the W-body. Will have to remove to these to replace struts, will a C-clamp compress them without slipping off, or is the special tool a must?

 

Bought the leaf spring bushings and adhesive from the dealer yesterday. Also available from gmpartsdirect.com, see Rear Struts thread for GM part numbers. GM's instruction sheet says "remove spring from vehicle", I hope thats not really necessary. Am replacing rear struts too, assume the bushings are easier to replace with struts removed, or doesnt matter?

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Guest TurboSedan

yeah i remember someone on the old board saying that too. fwiw, i haven't used a rear STB or sway bar with my coilovers at all in those 30,000+ hard miles i've put on them.

joshua

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Does the Lumina have the auxilary damper springs? I don't know if these would affect ride height. Found an online .pdf catalog from a manufacturer TecsPak (Thermoplastic Elastomer Compression Spring Package) claiming to make these for GM for the W-body. Will have to remove to these to replace struts, will a C-clamp compress them without slipping off, or is the special tool a must?

 

Bought the leaf spring bushings and adhesive from the dealer yesterday. Also available from gmpartsdirect.com, see Rear Struts thread for GM part numbers. GM's instruction sheet says "remove spring from vehicle", I hope thats not really necessary. Am replacing rear struts too, assume the bushings are easier to replace with struts removed, or doesnt matter?

 

You can use a bolt to compress the aux springs. A bolt of the right thread and size should do the trick. I have somewhere the specs for the bolt, but I'll have to dig around at home. I wouldn't use a C-clamp on them, the bolt works perfectly.

 

You don't need to remove the spring, I just jacked up on the edge of the spring using a piece of wood as a cushion so as not to scratch/damage the spring. I jacked it up enough that I could get sandpaper and a cleaning rag in there. Be careful not to stick your fingers in there though, if for some strange reason the jack pops out, your fingers will get crushed in there. Anyway, jacking up on the spring gave me enough room to slip the bushing under the spring.

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Hey Pabz,

are you ever gonna post some text about the paint job you did on your car? I've got a cutty with the same OEM paint scheme and it needs some serious paint work. I've bene practising on a spot on my front quarter panel, getting used to how the chemicals are mixed (albeit in small batches), the primer, sealer, basecoat.. safety.. etc.. etc.. all this before I shell out $$ for the whole thing. So, what's the chances of reading something about the paint job? Any pics of how it turned out?

 

BTW, i'm surprised you took out the whole leaf to put in the the bushings. Those things are fairly easy to install without damaging anything else like Splat described.. But then again I notice the bushings you put wrap around and are bonded to the ends of the spring? The OEM ones were just a thick, open-ended block that was held down by the force of the spring. Anyway, what does it matter. They are in, right?

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yeah I did the spring bushings on my sister's POS and I just jacked up the side of the spring I was working on and shoved them in there. holding fine, however I like seeing those pics, since I want to get a stiffer rear spring soon!

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Am replacing the spring bushings with the spring installed. WTF was used to glue them on? Any solvents that will dissolve it but not the spring? Still a bit of rubber stuck on there. Using a gasket scraper, but very slow going. Hopefully wont gouge the spring.

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Thanks for all the replies. I found out that the pull to the left wasn't just caused by the rear suspension, the guys who put the new tires on had them at 44 psi fronts, 35 psi rears, I've since put them all back to 33 psi and the pull is so minor now that it's not worth doing much about. I noticed underneath that, although the rubber is cracked on one side, the spring is still sitting where it's supposed to be. I asked my neighbourhood mechanic about this (2 hours labour to change out the insulators) and he said that if you drive with bad rear struts it'll make the leaf spring warp, which could be exactly what happened three years ago. In extremely cold weather I had a rear strut failure while driving. If only I could get the thing to stop going through outer tie rod ends..

 

hell for much much less than $800, ditch the leaf spring and get some adjustable coilovers. otherwise tho, check to see if the monoleaf has slipped out of one of the rear knuckles, or at least see if it is sitting in each knuckle evenly. that's about all i can think of....

joshua

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I re-did the whole rear suspension thats why i took it out, it was fun!!!

 

i have more pics at my site on the whole rear suspension

 

http://www.ualberta.ca/~ployola/W-Body/RS/

 

About the paint job, it took a while, i did all the prep work on the car, sanding priming body work then priming again untill it looked brand new, then took it to a shop of a friend, and had it painted there in a booth, when i did the priming though i did it outside on a clear hot day, i used the adhesive mixture for hardener and reducer, this was because i wanted it to adhere stongly to any old crappy primer on the car. I will get pics soon once its a nice day and not raining. The pearls are marvelous!!

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Thanks for all the replies. I found out that the pull to the left wasn't just caused by the rear suspension, the guys who put the new tires on had them at 44 psi fronts, 35 psi rears, I've since put them all back to 33 psi and the pull is so minor now that it's not worth doing much about. I noticed underneath that, although the rubber is cracked on one side, the spring is still sitting where it's supposed to be. I asked my neighbourhood mechanic about this (2 hours labour to change out the insulators) and he said that if you drive with bad rear struts it'll make the leaf spring warp, which could be exactly what happened three years ago. In extremely cold weather I had a rear strut failure while driving. If only I could get the thing to stop going through outer tie rod ends..

 

hell for much much less than $800, ditch the leaf spring and get some adjustable coilovers. otherwise tho, check to see if the monoleaf has slipped out of one of the rear knuckles, or at least see if it is sitting in each knuckle evenly. that's about all i can think of....

joshua

 

Got my Cutlass with a bad left rear strut. There was some kind of oil all over the left knuckle area. I assume that the strut oil deteriorated the left rubber bushing, because the left bushing was in a lot worse shape than the right. Just finished replacing rear struts today, next am doing the spring bushings.

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Get a rear spring from and '89 Grand Prix SE. the Best spring you can buy. Its not too High, not too low and it sure as shit don't bottom out. I saw what those coil overs look like....No different than the BS apc stuff at pepboys. Its amazing people have crap like that hold up there cars. I have no clue why people mock the mono leaf when its the best thing around. More cars should use it. Really light, progressive variable, lasts as long if not longer that a coil spring, action that is poses doesn't require a thick roll bar. GM put low load springs in a few cars. OH WELL CHANGE IT OUT!. Chevy springs are low, Olds springs are high to the point of them being HD, Pontiac and Buicks are just right. With the right spring you can drop your ar about an inch and still have it ride strong, you'll need acess to a spring chart. The only bad thing is that it's a tad pricey new, but hell tall those tradeoffs are worth it. If the aftermarket were smart enough theyd make a spring they'd make a bow that was lowered and stiff for you guys but instead they make this stack'em on stuff. Like I said before if the Corvette has is fore and aft, then its good for the W body's ass!

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Guest TurboSedan

i find it hard to believe that any monoleaf would bottom out. if i wanted a monoleaf, i would get one from an early 90's GTP. with over 200,000 miles :) throw a few dozen sandbags in the trunk and call it good. the monoleaf is the worst part of the GEN-1 w-body IMO.

joshua

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