GreenBes

Hey All,

Searched the Forums but can't find anything directly on point.

I am going to replace the front LCAs on my 97 SC3 with supra arms this weekend. I know that there are two bolts that attach the arm to the subframe and one bolt that attaches the balljoint to the steering knuckle.

Does anyone have the torque specs for these three mounting points?

It seems like you could remove the arms without having to remove the brake hardware - am I correct in assuming this?

Thanks,

Sam

stonewis

iTrader: (1)

I searched too, new dude! Try this... https://www.clublexus.com/forums/sus...l-arm-diy.html

GreenBes

That write up is not the proper way to change the arms and does not have the proper torque specs.

According to the Toyota Supra TIS printout - you must load the suspension before you torque the strut bolt to the arm and the camber bolts to the frame. Failure to do so will eat up your bushings in a heartbeat (as they will have an extra load on them even when the suspension is at rest).

Torque Specs

Castle Nut - 92 Ft/Lbs
Strut to LCA - 103 Ft/Lbs - TORQUE UNDER LOAD
Camber Bolts - 166 Ft/Lbs - TORQUE UNDER LOAD

The attaching arm I believe is 43 ft lbs for the nut and 33 ft/lbs for the bolts but I will double check - set the alignment before you attach these.

Don't forget! You will need an alignment after this job - even if you line up the bolts. Odds are with your old shredded bushings the camber and caster will be way off (and your tires will be chewed up from in the inside out or outside in depending on the degree of offset).

-Sam

RolxuSC400

I dont think that write up is wrong its just not complete with torque specs. I followed the same steps I saw in my owners manual and the same torque specs I have as you noted. The Lexus shop manual mentions nothing bout preloading and neither did the service tech I spoke with at the dealer.

If you feel comfortable doing it this way then go for it.

GreenBes

The TIS says to torque under load. So does the BMW TIS (when I worked on Bimmers back in the day).

The theory goes that if you lock the bushings when the suspension isn't loaded, when you lower the car back on the ground, the bushings will already be twisted just from resting under the weight of the car. When the suspension loads (on a bump for example) - you stretch the bushings even further and thus beyond their design capacity. This contributes to pre-mature failure of the bushings.

I am usually a BMW guy (have done countless BMW suspension rebuilds). Many people I know in the BMW circles who failed to load the suspension before torqueing the camber bolts would end up with failed bushings within a year or two of installation.

-Sam

RolxuSC400

I'll re-read the shop manual again and verify. If so, then I will redo them but since this isnt a daily driver it would take years for that to manifest itself to me but other may not be so lucky.

And yes u dont have to remove the brake hardware, well I didnt but guess u found that out by now from the shop manual.

GreenBes

The TIS will have it under "Installation Hint" in the steps.

-Sam

MitchB

Preloading the suspension to rotate the bushings into the "static" position is actually fairly common knowledge among mechanics.

One reason that it's not really brought up a lot is because you have to completely loosen the LCA bolts to do an alignment, at which point the bushings *should* rotate back to static position. And you simply can't replace the LCA without getting an alignment, so it usually all falls into place at alignment time anyway.

92blacktt

iTrader: (1)

^^sweet, so no point loading to torque it down if ur heading to the alignment shop right after!

jadu

iTrader: (42)

What are the benefits of using the supra LCA's? Are they stronger?

over40driv

I know they're cheaper than O.E. Lexus.

over40driv

Hadnt read the last 4 post. So in short you should install the LCA and then put the tire/wheel on, lower, the crawl under the lowered car and tighten the bolts and nuts?

MitchB

^ Yes, you should lower it down and tighten them. But, unless you lower it to ramps or high blocks, you'll never fit under there to tighten them up.

I had my SC300 on a lift. After setting the cams to the previous marks, I tightened the nuts enough to keep things from moving while the car was in the air. Then I lowered the lift to the very large blocks under the front wheels until the body just lifted off of the front lift arms.

At that point I crawled under with the wrenches. I loosed the cam nuts, letting the bushings rotate to unload them, then tightened and torqued the cam nuts to 166 ft/lbs.

Because the bushings in my car were not totally shot, my temporary alignment, back to a "perfect" alignment from two years ago, is very good. The steering wheel is perfectly centered, and I can tell that the toe-in is very good as well. This will hold me for a couple of weeks on a car that sometimes gets 20 miles a month put on it.

The really, really great news is that I no longer have any "bump steer". When one tire hit a road bump, the steering wheel would jerk a good 10 to 15 degrees out of my hand. The car didn't veer hardly at all, which meant that the other tire was still straight on the road.

As for price, the Supra parts are the same thing, but are around 100 bucks cheaper, EACH.