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Patrick
Joined: 05 Dec 2007
Posts: 278
Location: Manila, PHILIPPINES
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 Posted: Sat Apr 19, 2014 11:07 am Post subject: Rear Alignment review |
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Hello All!
Its been maybe several years since i had the last alignment done, so i couldnt quite remember all the intricacies involved in setting rear wheel alignment. (I am having it done at an alignment shop). Also i remember the technician at the alignment place having a very difficult time setting the rear camber and toe (even with my homemade P221 tool), as well as adjusting the ride height.
So i started reading the old posts and wanted to verify the following:
1) Ride Height setting- I loosen up the bolt/nut (#22 on page 223 Haynes manual) between the 36mm eccentric adjuster and the torsion bar. I loosen up the 36mm adjuster nut. I raise the rear wheels off the ground (the lift in this case), and start turning the eccentric adjuster. No need to loosen any other bolts?
2) Camber and/or Toe- I loosen the 2 vertically oriented bolts (beside the slot where the P221 tool goes in) and the camber eccentric nut as well. I understand that this is where the "gymnastics" happens: i adjust camber first, and when i get it right i keep my hand on the wrench (with the nut on the camber eccentric still untightened), and use the other hand to move the P221`tool to adjust toe. So there ends up being an interplay of moving both hands to adjust one or both (P221 tool and/or Camber eccentric). I tighten up the 2 vertically oriented bolts and eccentric nut when i hopefully get the correct camber/toe. Done?
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1979 924 U.S. version
Single sidedraft Weber 40 |
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Grenadiers
Joined: 20 Feb 2007
Posts: 3222
Location: Nelson, WI & Prescott, AZ
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| Posted: Sat Apr 19, 2014 12:44 pm Post subject: |
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That sounds correct to me, as I did all this myself this past fall. I didn't coordinate the camber/toe as well; you'll have to tutor the tech doing this. As they'll probably be pretty baffled just looking at it~!
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
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924RACR
Joined: 29 Jul 2001
Posts: 9134
Location: Royal Oak, MI, USA
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| Posted: Sat Apr 19, 2014 10:06 pm Post subject: |
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Correct on part 2, but on part 1 there is also a second locking (non-eccentric) bolt right next the 36mm eccentric height adjustment bolt. The second bolt is 24mm on both sides.
On part 2, I like to monitor/recheck the alignment measurements as I tighten those bolts, because they can wander slightly as everything gets locked back down. Note that this gets worse the more you loosen these bolts...
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Vaughan Scott
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'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
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larchie
Joined: 19 Jun 2003
Posts: 297
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| Posted: Sun Apr 20, 2014 5:30 am Post subject: |
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Not having done alignment before, I want to correct the US federal bumper requirement of mandating a raised rear bumper, so this thread of of interest. On a previous post entitled 924 Attitude Adjustment, Jim Pasha was quoted as writing ...
| Jim Pasha wrote: | | On the 1978 and later cars with the 36mm adjustment nut, it is a one hour job to lower the rear and set the ride height. I would do this either with or just prior to an alignment session. To adjust the early 924, 1976-77, requires the torsion bars be removed and the trailing blades reset. The Porsche technical specification has the blade angle in the list of information. This applies to all 924/944 models so affected, irrespective of brakes and rear suspension. (Jim Pasha, "924 Brakes, Struts and More," Excellence (November, 1995) 107.) |
and with respect to the ride-height setting ...
| 924RACR wrote: | | ... there is also a second locking (non-eccentric) bolt right next the 36mm eccentric height adjustment bolt. The second bolt is 24mm on both sides. |
So as I understand it, the rear car height is adjusted on the spring plate and there's no necessity to remove the torsion bars from models 1978 on. So in the image below, mounting bolt A is loosened and then height is adjusted with the eccentric bolt B.
Porsche-Audi provides this note in the Workshop Manual:
| Porsche 924 Workshop Manual wrote: | | To make sure that axle loads are distributed evenly to both rear wheels, lift car at front cross member when making height adjustment. Both front wheels must just clear ground. Measure distance from center of torsion bar to floor. Max. difference between left and right is 10 mm. |
For the Camber and Toe Adjustment, the notes provided are brief:
| Porsche 924 Workshop Manual wrote: | Camber Adjustment: Loosen bolts between spring plate and diagonal arm flange, and adjust to specifications by turning camber eccentric.
Toe Adjustment: Adjust toe by repositioning diagonal arm flange in slots of spring plate, using Special Tool 9171. |
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Patrick
Joined: 05 Dec 2007
Posts: 278
Location: Manila, PHILIPPINES
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| Posted: Sun Apr 20, 2014 9:57 am Post subject: |
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Grenadiers- Baffled IS exactly what the technician had written all over his
face a few yrs back. Thanks.
924RACR- Yes i mentioned that second locking nut beside the 36mm bolt as
#22 on p.223 haynes manual (A in the pic larchie provided), thanks for mentioning anyway.
Larchie- Thanks for including those tidbits from the 924 workshop manual.
ALL- I dont remember reading anything on the forum that says to lift the front wheels as well when doing Rear ride height adjustments. Is it maybe not critical to not lift the front wheels??
Porsche 924 Workshop Manual wrote:
To make sure that axle loads are distributed evenly to both rear wheels, lift car at front cross member when making height adjustment. Both front wheels must just clear ground.
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1979 924 U.S. version
Single sidedraft Weber 40 |
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larchie
Joined: 19 Jun 2003
Posts: 297
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| Posted: Sun Apr 20, 2014 10:50 am Post subject: |
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| Patrick wrote: | | ALL- I dont remember reading anything on the forum that says to lift the front wheels as well when doing Rear ride height adjustments. Is it maybe not critical to not lift the front wheels?? |
This instruction was not in a Porsche 944 Workshop Manual which adjusted height by the same bolts as on the 924. That fact might not mean much since the suspension differs in other respects between the two models.
My guess is that raising the front of the car would not critical if you are reasonably sure that the load is balanced evenly. My intuition is if the car is lifted at the front cross member, the probability of attaining equal balance at the rear would not be significantly increased because a lift at the front cross member could transfer weight to the rear unevenly for a number of reasons including symmetrical differences in chassis components and precision of point of lift.
However, again I should caution, I don't have any experience of doing ride-height adjustment, so Grenadiers's and 924RACR's advice should be followed in this regard as alignment and chassis attitude is critical in competition. |
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Patrick
Joined: 05 Dec 2007
Posts: 278
Location: Manila, PHILIPPINES
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| Posted: Sun Apr 20, 2014 2:58 pm Post subject: |
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| Quote: | | However, again I should caution, I don't have any experience of doing ride-height adjustment, so Grenadiers's and 924RACR's advice should be followed in this regard as alignment and chassis attitude is critical in competition. |
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I agree as well. Thanks again!
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1979 924 U.S. version
Single sidedraft Weber 40 |
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924RACR
Joined: 29 Jul 2001
Posts: 9134
Location: Royal Oak, MI, USA
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| Posted: Sun Apr 20, 2014 9:50 pm Post subject: |
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Sorry, yeah, looks like I read your OP and missed that detail - OK!
I regularly just raise the back of the car alone when adjusting rear ride height/corner weights.
Amusingly enough, very typically if you have the car level in the air (well, ends of torsion bar carrier at same height from floor in case of non-level floor) and also have similar height measurements of the end of the adjuster plate, then the corner weights end up being pretty close, thanks to the 924 being pretty evenly balanced by design. 
But measure only at the spring plate; camber adjustment etc can lead to different measurements if you measure at the wheel or further down the suspension arm...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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Patrick
Joined: 05 Dec 2007
Posts: 278
Location: Manila, PHILIPPINES
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| Posted: Mon Apr 21, 2014 4:53 pm Post subject: |
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| Quote: | | Amusingly enough, very typically if you have the car level in the air (well, ends of torsion bar carrier at same height from floor in case of non-level floor) and also have similar height measurements of the end of the adjuster plate, then the corner weights end up being pretty close, thanks to the 924 being pretty evenly balanced by design |
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Nice to know its that good Definitely a keeper![/quote]
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1979 924 U.S. version
Single sidedraft Weber 40 |
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