Help
Hi everybody,
I use my 05 Corolla for towing a small trailer, and it performs fine, except the rear suspension is getting pummeled. I want to upgrade my suspension so that the weight of the trailer doesn't push the rear end down so low...anybody know what I should do?
Since most people aren't towing with their corollas, there aren't a lot of suspension packages available aimed at towing. It seems like everybody wants to lower their corolla, but nobody's trying to raise it/reinforce it's suspension.
Any ideas?
Thanks a lot,
Jupiter
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How Do I Upgrade My 05 Corolla Suspension For Towing?
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#2
fishexpo101 
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Posted 13 October 2009 - 04:32 PM
Hello and welcome to the forums.
As you have already discovered, options are quite limited in the towing aspect for the Corolla. Gone are the old leaf spring days - where you could add helper springs or add-a-leaf sort of deals. Fortunately, there are few different options that might help with these coil spring/strut suspensions. One option is to install spacers that fit above/below the coil springs (generally aluminum/stainless steel blocks) or install inline polyurethane coil spacers - both will give you more ground clearance, greater suspension travel/displacement. Other option is to install a good performance spring - one that focuses on spring rates instead of how much of a drop you get get.
The first option can get hairy - since you are physically changing the height of the spring and with the poly spacers (changing effective spring rate) - the trailer may not react in the same way as before you lifted the rear end of the car. Nice thing about the spacers - can be a temporary modification - just pull the spacers out and you'll have the OEM spring in place. Cost is another - generally much cheaper than new springs all together. Unfortunately, most spacers are more for cosmetic issues than performance related abilities. Keep in mind that you are moving the struts past their normal stroke range - may cause some issues with damping function of the strut - not something you want to face when pulling a trailer.
The second option of performance springs - I personally have first hand experience with. I do tow on occasion with my Corolla - when on OEM springs, even moving a good bit of weight as far rearward as I dared, the suspension still displaced 3" or more in the rear. If I had anything in the trunk, I was basically riding on my bumpstops. When I swapped in TRD performance springs - a relatively mild suspension drop, about an 1"-1.25" drop all around - the increases spring rate more than compensated for the decrease in overall suspension stroke. I found that a loaded trailer and trunk full of stuff would only compress the suspension down about an 1" or so. I was well off the bumpstops - didn't bottom the suspension nearly as much as with OEM springs. Nice advantage of the springs, you get enhanced performance all around - not as much brake dive or acceleration squat like before. Corning behavior is also much more disciplined - makes the car feel more sure-footed. Downside - this is a more involved modification, OEM struts may not like the shorter stroke offered by the higher rate springs - will cause them to lose damping over time. But the same can be said with heavier loads on OEM springs and struts - so this aspect is not a deal breaker in my eyes.
Of course this also has to do with how much weight you are putting on the trailer. Easiest way is to toss the tongue of the trailer onto a scale and see how much weight there is on the tongue. Some loads will preclude this effort, as you cannot shift weight around too much if the payload fills the entire trailer. Ballast weight may not be an option either - depending on the total load you have. Sometimes, this is a function of the trailer itself - I've seen brand new, trailers that may weight in around 250 lbs total, but find out that the tongue weight was close to half that when empty - there the axle was located too far rearward and there was really too much bracing and extra stuff close (tongue jack and battery) close to the trailer tongue.
As you have already discovered, options are quite limited in the towing aspect for the Corolla. Gone are the old leaf spring days - where you could add helper springs or add-a-leaf sort of deals. Fortunately, there are few different options that might help with these coil spring/strut suspensions. One option is to install spacers that fit above/below the coil springs (generally aluminum/stainless steel blocks) or install inline polyurethane coil spacers - both will give you more ground clearance, greater suspension travel/displacement. Other option is to install a good performance spring - one that focuses on spring rates instead of how much of a drop you get get.
The first option can get hairy - since you are physically changing the height of the spring and with the poly spacers (changing effective spring rate) - the trailer may not react in the same way as before you lifted the rear end of the car. Nice thing about the spacers - can be a temporary modification - just pull the spacers out and you'll have the OEM spring in place. Cost is another - generally much cheaper than new springs all together. Unfortunately, most spacers are more for cosmetic issues than performance related abilities. Keep in mind that you are moving the struts past their normal stroke range - may cause some issues with damping function of the strut - not something you want to face when pulling a trailer.
The second option of performance springs - I personally have first hand experience with. I do tow on occasion with my Corolla - when on OEM springs, even moving a good bit of weight as far rearward as I dared, the suspension still displaced 3" or more in the rear. If I had anything in the trunk, I was basically riding on my bumpstops. When I swapped in TRD performance springs - a relatively mild suspension drop, about an 1"-1.25" drop all around - the increases spring rate more than compensated for the decrease in overall suspension stroke. I found that a loaded trailer and trunk full of stuff would only compress the suspension down about an 1" or so. I was well off the bumpstops - didn't bottom the suspension nearly as much as with OEM springs. Nice advantage of the springs, you get enhanced performance all around - not as much brake dive or acceleration squat like before. Corning behavior is also much more disciplined - makes the car feel more sure-footed. Downside - this is a more involved modification, OEM struts may not like the shorter stroke offered by the higher rate springs - will cause them to lose damping over time. But the same can be said with heavier loads on OEM springs and struts - so this aspect is not a deal breaker in my eyes.
Of course this also has to do with how much weight you are putting on the trailer. Easiest way is to toss the tongue of the trailer onto a scale and see how much weight there is on the tongue. Some loads will preclude this effort, as you cannot shift weight around too much if the payload fills the entire trailer. Ballast weight may not be an option either - depending on the total load you have. Sometimes, this is a function of the trailer itself - I've seen brand new, trailers that may weight in around 250 lbs total, but find out that the tongue weight was close to half that when empty - there the axle was located too far rearward and there was really too much bracing and extra stuff close (tongue jack and battery) close to the trailer tongue.
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#3
jupiterhenry
Posted 16 October 2009 - 07:52 PM
Thanks for the input! Do you have any recommendations for really stiff lowering springs, so that the inch or so of lowering will be offset by the stronger springs when the trailer is attached?
Also, I think I might upgrade the struts to better handle the abuse. Any recommendations there? Should I also do the shocks, or any other parts of the suspension?
Thanks
Also, I think I might upgrade the struts to better handle the abuse. Any recommendations there? Should I also do the shocks, or any other parts of the suspension?
Thanks
#4
fishexpo101
- I know Karate, Kung Fu, and 47 other dangerous words...
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Posted 19 October 2009 - 10:39 AM
For the 9th generation Corolla - TRD/Eibach, Megan Racing, H&R, and Progress are ones that many seem to like. Good mix of compliant ride (won't beat up your kidneys) and not such an extreme drop that you'll eat up all your suspension travel. Replacing the OEM struts with an upgraded strut is highly recommended on these lowering springs. The OEM struts will work, but probably see them start to lose their damping capabilities very quickly. For something like a TRD/Eibach paired up with a KYB GR-2 is considered a step up or logical upgrade from OEM. I would say that it rides just slightly stiffer than OEM - can hardly notice them during normal commuting. H&R and Progress springs tend to like stiffer struts like Tokico and Koni Yellow struts. They key here is to pair the spring and strut together - so the spring rate matches the damping (compression/rebound) and stroke of the strut. Retailers like Tirerack and others are pretty good resource for that information.
Other parts of the suspension that you might consider upgrading to polyurethane materials to help increase their durability - engine mount inserts, sway bar bushings, strut bushings, etc. Though, this is more for tightening the suspension than for towing consideration. Downside of the poly mounts and bushings is a considerable amount of vibration transmitted into the cabin. If there are any squeaks or rattles in the cabin, you'll find them pretty easily if you upgraded the rubber bushings to polyurethane material.
If you have an automatic transaxle - highly recommended to install an auxillary transmission fluid cooler. Adds a bit more capacity and keeps temps in check. Same can be done with an engine oil cooler - or even install an oil temp gauge to keep an eye on the temperatures. If you have the 5-speed - then no worries. Maybe a beefier clutch when the original one wears out on you. Brakes might need some looking at. I recommend swapping the OEM pads out for something that can take more heat and abuse, but still rotor friendly. There are a bunch of higher performance street pads - Hawk HPS, Porterfield R4-S, Carbotech, Axxis, etc. They do tend to dust more than OEM pads, but the increase in bite, higher coefficient of friction, and the ability to handle much more heat than OEM (resist brake fade) - are the things that make this almost a must have.
Assuming tires are up to the task, load wise. Might want to increase tire pressures to increase their load capacity (don't exceed max cold inflation PSI stamped on the sidewall). Or upgrade to better tires. Same with the brake fluid - if it hasn't been recently flushed out - good idea to have it done. I do mine every other year or around 30K miles. Brake fluid absorbs water like a sponge, replacing it on a normal basis keeps fluid performance in check (higher boiling point, reduces chance of brake fade) as well as keep corrosion from taking a hold in the brake system.
Other parts of the suspension that you might consider upgrading to polyurethane materials to help increase their durability - engine mount inserts, sway bar bushings, strut bushings, etc. Though, this is more for tightening the suspension than for towing consideration. Downside of the poly mounts and bushings is a considerable amount of vibration transmitted into the cabin. If there are any squeaks or rattles in the cabin, you'll find them pretty easily if you upgraded the rubber bushings to polyurethane material.
If you have an automatic transaxle - highly recommended to install an auxillary transmission fluid cooler. Adds a bit more capacity and keeps temps in check. Same can be done with an engine oil cooler - or even install an oil temp gauge to keep an eye on the temperatures. If you have the 5-speed - then no worries. Maybe a beefier clutch when the original one wears out on you. Brakes might need some looking at. I recommend swapping the OEM pads out for something that can take more heat and abuse, but still rotor friendly. There are a bunch of higher performance street pads - Hawk HPS, Porterfield R4-S, Carbotech, Axxis, etc. They do tend to dust more than OEM pads, but the increase in bite, higher coefficient of friction, and the ability to handle much more heat than OEM (resist brake fade) - are the things that make this almost a must have.
Assuming tires are up to the task, load wise. Might want to increase tire pressures to increase their load capacity (don't exceed max cold inflation PSI stamped on the sidewall). Or upgrade to better tires. Same with the brake fluid - if it hasn't been recently flushed out - good idea to have it done. I do mine every other year or around 30K miles. Brake fluid absorbs water like a sponge, replacing it on a normal basis keeps fluid performance in check (higher boiling point, reduces chance of brake fade) as well as keep corrosion from taking a hold in the brake system.
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