Reatta Lowering

[Guest spyhunter2k]

*This is a continuation of the lowering discussion originally discussed in the "aftermarket hood scoop" thread.*

[Luftweg: "I think getting the car to handle correctly would be a big issue if it were lowered, no? I mean, you can't just lower it without throwing off other things, like important angles, etc..

Am I wrong about this?

You would certainly want at least as good handling as it is stock."]

I was told by a friend that lowering up to 2" does not significantly alter handling characteristics - that I would just need to make sure the car is realigned/wheel angles adjusted after lowering.

The worst that could happen is that handling would be negatively affected and I would have to pay to have the car restored to original ride height. Someone's going to have to take the plunge and find out. If this car will quit lighting up a new dash trouble light every time I drive it, I may get to try it!

[Guest spyhunter2k]

Can someone confirm that the rear transverse leaf spring is composite/fiberglas/plastic and not metal? This will affect which lowering options are available.

Thanks,

Seth

[ReattaBuckeye]

If you can find aftermarket coil springs for a Reatta you should be able to lower the front easily about 1-1/2" to 2" without any impact on geometry. You can also have custom coil springs made or cut to achieve the same lowered effect.

The rear transverse fiber glass leaf spring is similar to the late model Corvette design (since 1982) and you might contact some vette suspension experts about lowering the rear with different hangers but most vettes go with a different spring and axle spindles to get the rear end down a couple of inches.

[Guest spyhunter2k]

Ok. If it's plastic, the option of taking it to a suspension shop for "de-arching"(contolled flexing of a metal leaf spring in the opposite direction to reduce the arch height) is out of the question.

Although there are a couple of other alternatives, the most practical and obvious remaining option is to replace the spring itself with one that has a reduced arch height but identical width and spring rate. Several sources on the web mention a company called Birchmount Auto Spring Company out of Canada that will make a custom metal spring to replace your current metal or plastic one. I will call them tomorrow to discuss the specifics. Others on the web have quoted a price of around $250 for the custom spring, which I think is well within reason. When I call I will ask them how they need the current spring data. Ideally, I would send them an actual used Reatta spring so that they can take the measurements themselves.

All they have to do is make sure the new spring will fit and that it replicates the current spring's rate. They should be able to do flex measurements or something and be told how much weight normally rests on the spring (1300lbs. according to '90 curb weight X .35 rear) and calculate how they need to make the spring in order to achieve 1.5" of drop.

I will let all know how the conversation goes.

Seth

[ReattaBuckeye]

seth,

check out these links for lowering 1984-1996 Corvettes which have a similar transverse mounted fiberglass (plastic) mono leaf-spring.

http://www.madvet.com/shop?frame=1.237.3862

http://www.madvet.com/shop?frame=1088

These Corvette lowering kits are simply a swap to longer threaded bolts for about $70 plus shipping! I'm not say these will work for a Reatta but I'd take a look at them to see if they might be adapted or if the idea can be copied for a Reatta?!?!

[Guest Greg Ross]

You might just do a search of past treads, this has been discussed at great length before. Corvette lowering Kit will not adapt, without a differential back there the design is entirely different.

To do the Steel Spring swap I'd say its' going to be cheaper to plan on buying two. First one will be a guess and the second one ordered to compensate for how to correct the ride height after the first one has been tested. Still trial and error. The List of Testing and R & D you're asking for would cost a shop like $1,000.

[Guest spyhunter2k]

I was thinking the same thing about possibly having to buy two. Hopefully if I can provide them with enough data and an actual Reatta spring for reference they'll be able to get the requested drop amount very close on the first try.

[Guest spyhunter2k]

I just had a great conversation with Tony from Birchmount Auto Spring in Canada. He said they can make a custom spring for the Reatta. I gave him the vehicle weight/distribution. He wants a sample for testing and for fabricating matching end mounts. He thinks he may be able to find me a used spring nearby but didn't know if I had cheaper access to one.

Is there anyone here that has a used one available? I would pay for it and just have you ship it directly to Birchmount, providing Tony isn't able to find one at a cheaper price nearby.

I asked about how accurate they could hit the requested drop (I'm requesting a spring that would drop the rear 1.5"). He said they can normally hit it pretty close, probably within .25", especially if they have a sample.

So... anyone with rear spring they want to sell to further the cause?

[Guest spyhunter2k]

Tony at Birchmount was able to locate a '90 spring at a salvage yard in northen Canada for $180. It will be shipped in to him by Tuesday of next week for him to begin testing on it.

He said he can replicate the width of the factory spring no problem. He did say his metal spring is likely to be a bit thicker than the factory composite one, though, and asked if I knew how much room he would have to play with here. I advised that I would ask around to some that had actually been underneath the car.

Can someone give some insight here?

Thanks very much!

Seth

[Jim]

I offered you one for $ 20 plus shipping which would have been about $ 15 for a total of $ 35. I guess I will have to raise my prices if I want to make a sale.

[Guest spyhunter2k]

Hi Jim. I spoke with Tony at noon today, a couple of hours before I got your email. He said he'd located one and is actually footing the cost himself to get it since he hasn't made a custom spring for a Reatta yet and wants one for future reference. Plus I mentioned that it was very likely others would order a custom spring from him as well if I (as a guinea pig of sorts) tried it out and made sure it worked.

I'll call him Monday and see if he has ordered the spring yet. $35 is much better than $180, so I'd like to get yours if possible, even if it's to save him money and not me. I'll let you know, and thanks for the reply.

Seth

[Guest F14CRAZY]

Reattas drop down a couple inches at speeds in excess of 130 mph

[luftweg]

but it's governed at 125, no?

[Guest F14CRAZY]

Correct. I was just messing (someone made that up in a previous post). Hijack over

[Guest spyhunter2k]

I have received the custom rear spring back from Birchmount in Canada (actually got it back over a week ago). They were concerned at first that the fit may be affected from the stacked metal leaves being thicker than the factory composite spring. When they called to say it was finished they said that it shouldn't be a problem after all, as they used a stronger type of steel and made the spring using two leaves instead of the more common three. I have the spring sitting in my garage now, as the car still needs to be painted (which is supposed to happen near the end of the week). After that, I will take it in to be lowered using the new spring.

Birchmount mentioned that they were pretty confident in hitting the desired 1.5" of drop, but that if it was slightly off the spring can be modified a bit (de-arched or either arched a bit more) by a knowledgeable mechanic or springsmith. As soon as the car has been lowered to my satisfaction I will post before/after pics on the forum.

Seth

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[luftweg]

... and how come only 1.5 inches? wouldn't like 2.5 be more worth it, or would that throw off the suspension/steering way to far (the 'ricer syndrome')?

[Guest spyhunter2k]

There are approximately 3 inches of space between the top of the tire and the bottom of the wheel well on a Reatta. The ideal look for me personally is to have about 1" of space showing. I want the car to look lowered, but not "slammed." I requested a drop of at least 1.5", but to make sure that if it was off, to be off on the more-than-1.5" side. So I pretty much requested a 1.5"-1.75" drop, depending on how accurate they thought they could be.

To further fill the wheel arch, I intend to get 17 or 18" wheels. If the tires I use with the 17s/18s have a sidewall height that is the same as the 15" wheels, then the 17/18 wheel tire combo would pretty much completely fill the wheel well (for every one inch more in wheel diameter, the car sits .5" heigher and wheel goes up into wheel well .5" more). But the thing is, you're not going to run 65 series tires with 18" wheels-probably something closer to 40s. So the net result would be a tire/wheel combination that's about 1" greater diameter than the present 15s with the puffy 65 series tires, and therefore a (voila!) perfectly filled wheel arch (about 1" of space showing).

Plus 1.5" is the most common desired drop that I've seen most people having based on their comments here. I do plan on giving feedback to Birchmount as to the actual drop of the car. Based on that, I'm sure they would be able to accomodate requests for slightly different drop heights and be able to hit these marks pretty closely.

I will probably be cutting the front springs as Jeff suggested above. No one makes a set of custom lowering front coil springs for the Reatta, at least that I can find. Ideally, someone would know of another car model that uses a spring of similar height and spring rate and I would order those, but I don't think that's ever been established. It would definitely be a better option than cutting, but everything's a tradeoff. The time it would take to research this isn't worth it to me for the small potential advantage this option would have over cutting. Though I reserve the right to change my mind...

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[Guest spyhunter2k]

Was his car a Reatta? From what I've read, most people haven't experienced many problems from cutting their springs, as long as it's only one coil or so and it was done by a cutting tool and not a torch.

I really hope I'm not about to face the trial and error process of figuring out which lowered springs intended for use on another model will fit the Reatta and achieve the 2" drop I want for the front. If I have to I will, but I'd rather just cut the springs. Anyone else heard of good/bad experiences with this?

Thanks,

Seth

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[Guest spyhunter2k]

What parts store does he work at? They may have the same book at the one near me.

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[Guest spyhunter2k]

Thanks anyway. My next step is to call the tech support line for Eibach to see if they have data that will allow us to sort out which spring will fit the Reatta in front and achieve a 2" drop. If they're willing to do the research work for me, then I will let them. Have I already mentioned that I decided on slightly more drop in the front than rear (1.5-1.75" rear, 2" front)? If not, I have. The car looks a bit raised in the front to me for some reason.

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[Guest spyhunter2k]

Thanks. That sounds like a place to start. It would be a problem if the spring achieves no drop at all, as I need the front end to come down by 2" and you say the modified cradle bushings could only help out by an inch or so. But maybe just knowing that the El Dorado springs fit will allow them to find another spring with a similar fit that has a lower drop and similar spring rate to the Reatta.

[2seater]

Usually, if you go to a shorter coil, the spring rate needs to be increased somewhat to have the same weight potential at full compression. This assumes the same number of turns for the longer and shorter coils. If the shorter spring is the same in all respects except less turns to achieve the ride height, the spring rate will be higher. It is easiest to imagine the coil spring is simply a torsion bar wound in a cylinder. Reducing the number of turns, is analogous to making the torsion bar shorter causing a greater twist per inch of length at the same travel distance. In variable rate springs, with some close coils and some further apart, the coils that are close together is the soft part, the further apart is stiffer.

[Guest maybe2fast]

with the 17s the front needs to be dropped

[Guest spyhunter2k]

Well guys, after much research, I?m planning at this point to try cutting the springs. After reading a lot of other forums where many people gave uneducated opinions this post made up my mind. I actually have one of the books that is mentioned below and can vouch for what is said.

?So you say cutting down coil springs is not the right way to tune your suspension? You better write a letter to Fred Phun the author of "How to make your car handle". You guys like to cite this book as a good resource. He uses nearly a page introducing two different ways to shorten springs, and then goes into the process in detail in chapter 4.

You might also want to write a letter to Herb Adams the author of the book "Chassis Engineering" he is a professional engineer who designs specailized suspension parts and works as a consultant to companies like Goodyear, Oldsmobile, Pontiac, and Koni.

On page 33-35 he goes into a detailed discussion of cutting coil springs to adjust ride height, and change spring rate. He has the following to say on the bottom of page 33.

" ... If you put new springs on your car, they will settle as much as an inch within the the first few months. Obviously if your car was the correct height when you installed the new springs, it will be too low after a few months.

This is why I recommend you cut your existing springs and save the cost of new springs. The results will almost certainly be better. Your car's existing springs have already taken a permanent set. So you know what you will end up with. If you want to lower your car, you can cut your existing springs to achieve the ride height you want with one operation."

I won't type out the whole book but you get the point.

For those of you who think the after market does it right !!

I'll close with a comment by Carol Smith from his book "Engineer to Win" You might want to note he is talking about specialty manufactures of springs for high dollar race cars, not Joe consumer wannabe race driver.

"Most of the springs advertised in the classified section of our beloved lunatic fringe publications are absolute JUNK. They are made from cheap wire, badly designed, badly coiled (often hot coiled, an outmoded process for springs in our range), badly heat treated, badly finished and brilliantly plated and marketed."

Thanks but I'll take a known quantity (i.e. an OEM quality spring) and spend the time to learn how to "do it right" myself.??

After reading the above post and many others, it seems like the bottom line is that cutting only a coil or so off springs can give good results, but only when proper care is taken to prevent fitment problems and the amount of material used is not excessive. There are many comments from people on the web that cut their springs and had no problems whatsoever. It seems that the few people that experienced problems had either not measured carefully and had ended up with an uneven ride, had used an improper cutting method that involved heat (like using a torch), had cut way too much off (to ?slam? the car) or had failed to ensure the cut coils were properly re-seated. I have a hard time spending a lot of money on new coils that could be junk without at least trying to do it the simple way first. If this fails, then what this person proposes may be my next alternative:

?If you cut a coil out of a spring, the rate inevitably goes up, but the geometry of the last coil (the new dead coil on the end,) changes. At the factory, the last coils are wound at a specific angle to nest fully in the spring pocket (usually stamped into the control arm or built into the frame or subframe. For a manufactured spring, the last coil seats fully into the pocket, the interior coils of the spring are not wound to do this. Cutting the end coil out means one of these interior coils is now the end coil and it probably won't seat properly in the pocket, meaning the entire coil won't seat, and thus be dead. This makes the resulting coil rate pretty unpredictable until you install the spring and put weight on it. Only then can you figure out what percentage of the coil really is dead and calculate the spring rate. (If you even bother to calculate it -- most folks just cur the spring, install it, and pray.)

It's much better to adjust the rates and heights independently. You can do this by buying the spring rate you want first and then adjusting the car to get the ride height you want. Most racing spring manufacturers make springs of varying rates (both progressive and linear,) and one is going to be close to the rate you want (Hypercoils makes springs in increments of 25 lt-lbs, which should get you pretty close to your ideal spring rate.)

Adjusting the ride height is best done using an adjustable spring perch. These are available for many cars, or if you're good with a welder (very good,) you can buy one from a race car chassis shop like Lefthander chassis or Coleman Racing. This allows you to run any rate spring at any height (within reason).?

I?ll keep you all updated.

Seth

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[Rawja]

On the subject of errors, the Eldorado has been front wheel drive since 1967. The 86-91 Eldorado was in fact the platform-mate of the Riviera on which our Reattas are based. The weight differences are probably due to the Eldorado being more car rather than the powertrain as both the HT engine used 86-93 and the Northstar were primarily aluminum vs. the 3800 in cast iron.

[Rawja]

Here's somthing interesting. I was thinking about the front strut setup you've been describing and started noodling around with Monroe's eCatalog. As it turns out the 92 Eldorado uses the same front struts as our Reattas (71854). Somewhat strangely, the Eldorado of similar vintage and platform does not.

It would follow that if there's an aftermarket spring that fits the 92 Eldorado, it would fit the Reatta as well, no?

Reatta Strut Page

92 Eldorado Strut Page

[DTakas]

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Edited January 2, 2019 by DTakas (see edit history)

[Guest spyhunter2k]

Crapola. Your mention of weight just made me realize I might have made a mistake in my instructions to Birchmount. I advised that the car weighed 3700 lbs, as is stated in the Road/Track section of the reatta.net website. Looking at the service manual, it says that the weight is 3381.9lbs.

Is the discrepancy because Road/Track figures include gas and weight of driver? I'm wondering how much this will throw off the requested drop of the rear...

How many different types of weight figures are there for vehicles?

[Guest spyhunter2k]

Something I noticed from the Monroe Catalog. Only the 92-93 Eldorados with the speed sensitive suspension option have the same front strut. All other 92-99s or so with the base level suspension use a different strut.

There is only one spring listed in most aftermarket company's catalogs for those years though, so either one type of spring fits both struts (which seems to argue against the same strut necessarily equaling the same spring) or they fit the more common suspension option that doesn't have SSS (in which case it's possible they wouldn't fit the SSS eldorado, or its equivalent, the Reatta).

I'll call Eibach and see how much we can sort out over the phone. I'm just worried that without the spring specs that I don't have (total unloaded height/loaded height/spring rate they won't be able to identify an equivalent.

I'll keep you all posted. As soon as I figure out what weight I should have told Birchmount for the rear spring, I'll call them to see what difference my error may cause in the rear height.

Thanks for your help so far!

[Guest F14CRAZY]

I think the 3700 lbs is a convertible, and the 33xx is a coupe

[Guest spyhunter2k]

That could be.

This is interesting. I didn't realize there were so many weight figures:

"GVW is the maximum rated weight for the car, full of people, luggage, dogs, bags of cement, whatever.

There is no standard difference between the curb weight the GVW, the GVW is based on the safe operating capacity that a vehicle can hold & can be affected by available suspension travel, tire load ratings, balance under load, etc.

The quoted "curb weight" of a car is also often defined differently between manufacturers. there is an official standard for the car's weight as far as the EPA is concerned for figuring fuel economy (one of the suspect reasons for the focus on lower weight in the US STi) but the brochure-published/owner's manual/car magazine tested weigts can all be different as well.

In racing terms you often define vehicle weights as "wet" which means full filled with all fluids but (usually) without the driver.

Other times you have a minimum weight which includes the driver.

Weight dsitribution figures are also sometimes w/driver others w/o."

My mechanic mentioned relocating the strut tower braces to lower the front of the car. He wants me to bring it in so he can take a look at the front suspension. He said this would effectively lower the front supsension assembly on the frame. At least, that was what I got out of the conversation. It will probably be a week or so before I can take it to him. I'll send updates as I have them.

Seth

[Guest spyhunter2k]

I've been delayed on the lowering project by the body/bumper smoothing project. I'm trying to finish smoothing and painting the bumpers before I lower the car.

I did go by the shop to talk to my mechanic about my kit car and brought up the front lowering issue. He grabbed a front strut and showed me what he wants to do to lower the front. He says he's done it this way many times. I'm attaching a pic that shows what he wants to do.

[Guest Greg Ross]

Very practical approach, and there's no science involved, ie; an inch is an inch!

EDBSO posted a great article, maybe a year ago about mods for adjustible struts.