Torsion bar re-index/springplate jacking
 

I am resetting my rear springplates & the 'Ferch' spec requires a 31 - 32 deg angle. However, at this angle the force required to jack the springplate into position actually lifts the car off the jack stands & bends the springplate! Not so good. I have the car angled with 2 wheels on the ground btw. I did it once before 2 years ago but this time isn’t looking too positive. The previous angle was around 34 deg for 23.5”, but I wanted to raise it a bit. 15” wheels & 50 series tires btw which is why it sounds so low. The a-arms in the front are level at 24 ¼” front ride height.

So I backed off thinking that I am too deep, but I tried 26 deg & ended up with a 22" rear height - just a wee bit low. But even here, because of the springplate wander, I had to use longer bolts & bring it in closer to the trailing arm for the stock bolts to fit.

So, is my springplate toast? Is there a method anybody has found? Maybe the car on 4 jackstands so it won’t take off? And I tried a floor jack & it wanders & the springplate just ends up slipping off my bottle jack with tremendous force.

Ideas?

Ian

IFRC you need to have the car 4 wheels off the ground and the chassis level. You should not have to jack the springplate at all. If you need to re-index, the tbars and springplate have to come out, reset the teeth whatever way you need to get the desired angle and retest the springplate angle. The springplate angle for whatever spec should be taken when it is in a free-fall dead position.

When I did mine I had the chassis level and measured the angle (to check) at the door sills. Shocks and sway bar disconnected and springplate only attached to the tbar. I don't think I even used the bushing cover (4 bolts) until I was pretty much dialed in on angle settings.
Hope this helps.

edit: if the springplate isn't creased (bent) it should be OK.

Ian, I've only done this once, but my car was on 4 jackstands at the time. As I recall, I used my floor jack to raise the springplates and I didn't have any issues that you describe, so maybe you're correct about the 4 vs 2. Good luck!

Mine (25mm rear bars) needed around 36 degrees (32 for the plate + 4 degrees for the car the way mine sat on just rear jack stands) to end up near stock ride height (stock "euro" ride height turns out to be around 26.5" at the rear fender on my car). The Bentley says 32 degrees should do it - I think they made a mistake.

I had to jack my spring plate up somewhat to get it to meet up with the banana arm, but no problems with lifting the car. The shock was still attached to the banana arm.

I did have both rear wheels off the ground - if you're doing one side only, the sway bar will hold up the banana arm making it more difficult to get the spring plate to match up. So the sway bar needs to be disconnected if it's a one-side only job. The angles will end up a bit weird also.

Yeah. That must be it. I didn't disconnect the sway so I'm just lifting too much. The springplate has survived, I believe.

Thanks guys. Now all I need is the time to do it.

Ian

It is my understanding that the proper way to do the spring plate is to remove the shock at the arm. You have to support the rear arm first when you do this. It is best to start w a bottle jack mostly extended to support the arm when you remove the shock.

Then you let the jack down until you can bolt up the spring plate to the arm.

Having said this, I have been lucky to not have to remove the shock but I did put a bottle jack under the spring plate to lift the spring plate up to the arm that is hanging from the shock and by working it.

I to had the car start to lift but was close enough that I could get it into place.

Yes, you should have the sway bar disconnected to do this.




For stock torsion bars

One more thought - when you lift the spring plate with the jack, you should have the jack contact as far rearward on the spring plate as is feasible. The further forward your contact point, the less rotation you will get before the car lifts ... I used a square block of ipe (a very very hard wood) between the jack and the plate to lift mine because I could not get the clumsy jack pad far enough rearward.

Just to clarify, if you have both rear wheels off the ground and you leave the shocks attached, it should be OK to leave the sway bar attached. If you just jacked up one side on the car, you will need to remove it.

Ian,

Just did mine recently, lowered front and rear. Did the rear with the front wheels still on the ground. For the angle just measure the angle at the door sill and then at the spring plate (unloaded - detached from the trailing arm) and calculate the difference. No need to jack up the front. After you get the spring plates at the desired angle, you should be able to fairly easily move the trailing arm by hand into location to attach it to the spring plate. I was able to do it no problem with both the shocks and the sway bar connected, but both rear wheels need to be off the ground or else the sway bar will make it next to impossible to line up the trailing arm and the spring plates. I found this out the hard way! I did have to use the jack to lift the spring plate, but only slightly, maybe 1" or less, then I pulled the trailing arm down and forward to line up the holes, starting with the trailing arm bolts and then the alignment bolts. I too have 15" wheels with stock tire sizes, and ended up with ground to fender heights of just under 25" front and 24.5" rear. I've attached a photo of what that looks like on mine for reference. I think it looks great, the front wheels fill the wells just perfectly. It took me 4 attempts on the rear, started out going way too low, then working my way back up.

Good luck.
http://forums.pelicanparts.com/uploa...1214227858.jpg

Once again, thanks for all of the hints guys. I know the whole procedure - it was just my flawed idea to do one side only by side jacking.

Of course, this was one of those jobs - it started with the front suspension - new EBs on the a-arm & then the back needed some adjustment etc & I was working too quickly & not thinking. At least I got to inspect & lube my Neatrix bushings after 3 years & they still look new.

I'll get at it next week after my flaming lower back calms down & I return from a 5 day business jaunt to Europe. My car has been static for 6 weeks now & I am itching to drive.

Ian