Lower Control Arm Bolts aren't perfectly aligned
06-01-2017, 07:13 AM
#16
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Obviously, driving with the rear LCA bolts not torqued is something to be taken NOT lightly and definitely done thoughtfully.
Shouldn't be doing a Lightning Lap at VIR that way, but a drive up and down and around the block at 15-20 MPH is not going to result in catastrophe.
06-01-2017, 09:43 AM
#17
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Sorry, you will never convince me driving around knowing your suspension is not properly torqued is a good idea. I'll add this to my file which includes cutting a hole in the fender to replace the clutch master. Sorry, it "may work" but still not a good idea IMO - especially when a proper procedure is fully spelled out in the WSM.
I get that we are all DIY minded trying to figure out how to do as much as possible without going to a shop. But unless you own alignment equipment (or plan on doing the whole thing with other methods at home) it's going to a shop anyway. As I've stated before, part of a proper alignment is checking & adjusting ride height so the shop should be doing this anyway.
Many years ago I "snugged" the front control arm bolts but forgot to torque them (part of the pan gasket job). Less than a mile down the road on the way to work (first drive) something felt funny.
Guess what happened? One bolt fell out, the other was wobbling.
I get that we are all DIY minded trying to figure out how to do as much as possible without going to a shop. But unless you own alignment equipment (or plan on doing the whole thing with other methods at home) it's going to a shop anyway. As I've stated before, part of a proper alignment is checking & adjusting ride height so the shop should be doing this anyway.
Many years ago I "snugged" the front control arm bolts but forgot to torque them (part of the pan gasket job). Less than a mile down the road on the way to work (first drive) something felt funny.
Guess what happened? One bolt fell out, the other was wobbling.
06-01-2017, 11:15 PM
#18
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Eric when you install the front LCA the front lower bolts get tightened the rear clamp bolts are left loose so the bushing can find its home,
the front bushing will let the LCA move to its home ,
This is confirmed after driving the car and a few brake applications,
it will be clearly seen that the rear bushing has seated firmly into the clamp.
Once this is done then the rear clamp is torqued with the car on the ground.
If you dont do things this way then your doing it wrong.
NOTE The shop i work at also has a nice alignment machine.
I also do ride height setting and the 928 alignments after shocks and or motor mount jobs.
NOTE it will become evident that the rear bushing is fully seated when you can see the rubber having a slight bulge where it meets the curved face of the clamping area.
NOTE this procedure is made to be done like this as is evidenced by the extended collars on the upper portion of the rear seating surfaces these will hold the lower clamps in place and prevent the rear bushing from moving sideways even if the bolts are loose
Simply clamping the bushing or leaving loose then lowering the car will not apply the necessary force to move the LCA rearwards to its seated position.
This means that the bushing will move over time, this means your time spent doing an alignment will be wasted as the settings change depending on how much the pivot point moves to its new home.
the front bushing will let the LCA move to its home ,
This is confirmed after driving the car and a few brake applications,
it will be clearly seen that the rear bushing has seated firmly into the clamp.
Once this is done then the rear clamp is torqued with the car on the ground.
If you dont do things this way then your doing it wrong.
NOTE The shop i work at also has a nice alignment machine.
I also do ride height setting and the 928 alignments after shocks and or motor mount jobs.
NOTE it will become evident that the rear bushing is fully seated when you can see the rubber having a slight bulge where it meets the curved face of the clamping area.
NOTE this procedure is made to be done like this as is evidenced by the extended collars on the upper portion of the rear seating surfaces these will hold the lower clamps in place and prevent the rear bushing from moving sideways even if the bolts are loose
Simply clamping the bushing or leaving loose then lowering the car will not apply the necessary force to move the LCA rearwards to its seated position.
This means that the bushing will move over time, this means your time spent doing an alignment will be wasted as the settings change depending on how much the pivot point moves to its new home.
06-01-2017, 11:30 PM
#19
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This is confirmed after driving the car and a few brake applications,
it will be clearly seen that the rear bushing has seated firmly into the clamp.
Once this is done then the rear clamp is torqued with the car on the ground.
If you dont do things this way then your doing it wrong.
it will be clearly seen that the rear bushing has seated firmly into the clamp.
Once this is done then the rear clamp is torqued with the car on the ground.
If you dont do things this way then your doing it wrong.
The factory has a specific tool just for this which can be easily duplicated on most (if not all) alignment machines. Jim Page did this decades ago in Green Bay and does every 928 alignment this way (which includes his own).
The WSM says to leave the bolts loose until suspension is settled. It does NOT say the technician should go for a test drive to settle the suspension.
Do what you want, I'm following the factory procedure as I've been doing for 20+ years with my cars.
In case anyone is wondering, this is the portion of the WSM being discussed here:
Volume IV
Page 40-5
Bolt #19
From the manual:
"Screw in until only 2 threads are visible. Do not tighten to 120Nm (88 fltb) until assembly is completed and springs have settled"
Other pages show the proper procedure for pulling down the chassis to settle the suspension:
06-02-2017, 06:46 AM
#20
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Really? Driving around the block with the rear LCA bolts one turn loose is like cutting a hole in the sheet metal?
That is reductio ad absurdum.
Have you ever been hoisted on your own petard?
That is reductio ad absurdum.
Have you ever been hoisted on your own petard?
06-02-2017, 07:33 AM
#21
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I raised this very issue a while ago as I did not like the idea of driving around with the rear bolts loose. Previously I jacked the car up on the lower control arm, torqued the rear bolts, drove around until settled and then loosened and then retorqued. I realised this conflicted with the manual and that the WSM does not advise one to drive around until it settles- as Eric says it implies tightening after ti is settled but now how it should be allowed to settle so indirectly implies te pull down method shoudl be used. I cannot do this so had no choice and after my recent efforts with the suspension I jacked the arm up to take the deadweight, torqued it up to the factory setting and then backed it off one full turn and put an index mark on the rear bolts. Drove around to let the system settle then took it to the alignment shop. Before alignment I checked the rear bolts- they had not moved and then torqued them up- it took a full turn surprise surprise and we the did the alignment.
Realistically I suppose the best thing to do is to drive around more and then check the alignment again to see if there is any change but I rather suspect that would be somewhat excessive. Bottom line is I am happy with my car's handling, I do not see any signs of odd tyre wear or handlnig behaviour- quite the opposite. Given my bushings are on their last legs I suspect it is all a bit irrelevant. Put new bushes on all around and the procedure is probably much more critical.
For sure it is an interesting topic and I do not push the envelope until the rear bolts are fully torqued.
Regards
Fred
Realistically I suppose the best thing to do is to drive around more and then check the alignment again to see if there is any change but I rather suspect that would be somewhat excessive. Bottom line is I am happy with my car's handling, I do not see any signs of odd tyre wear or handlnig behaviour- quite the opposite. Given my bushings are on their last legs I suspect it is all a bit irrelevant. Put new bushes on all around and the procedure is probably much more critical.
For sure it is an interesting topic and I do not push the envelope until the rear bolts are fully torqued.
Regards
Fred
06-02-2017, 03:55 PM
#22
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Fred jacking the car up on the LCA means your also fighting the sway bar.
That said this isnt a planes gonna crash scenario leaving the rear clamp bolts loose and driving it and applying the brakes.
For sure your not pushing any envelope driving the car around the block and putting on the brakes a few times with the rear clamp bolts 1 turn loose.
Nothing is gonna fall off or be damaged by doing this, But it will seat the rear bushings better than any other method and it will reduce the chances of the front end changing due to shifting parts.
The main reason for doing this is to seat the LCA so it finds its home thus its not gonna move in a few thousand miles and change the alignment settings.
Essentially these instructions are for a shop mechanic that doesnt have the luxury of having a car come back in a month or so with a front end thats pulling.
So he can check on his previously aligned front end and then get to do it all over again.
My friend said you have to be smarter than the bushing LOL.
Good luck on what ever course you choose
That said this isnt a planes gonna crash scenario leaving the rear clamp bolts loose and driving it and applying the brakes.
For sure your not pushing any envelope driving the car around the block and putting on the brakes a few times with the rear clamp bolts 1 turn loose.
Nothing is gonna fall off or be damaged by doing this, But it will seat the rear bushings better than any other method and it will reduce the chances of the front end changing due to shifting parts.
The main reason for doing this is to seat the LCA so it finds its home thus its not gonna move in a few thousand miles and change the alignment settings.
Essentially these instructions are for a shop mechanic that doesnt have the luxury of having a car come back in a month or so with a front end thats pulling.
So he can check on his previously aligned front end and then get to do it all over again.
My friend said you have to be smarter than the bushing LOL.
Good luck on what ever course you choose