P221 Toe-in Adjuster - How do you use it??
 

Hi All,

I'm about to get my 1971 911 aligned at a local shop with a top-o-line Hunter rack. The tech would like to learn the intricacies of aligning a 911 and realizes there are some special tools needed. Everywhere I've searched and read on this forum states that the rear toe-in can't be accomplished correctly without the use of this P221 adjuster tool:

http://www.pelicanparts.com/catalog/...oe_in_P221.JPG

I have searched the Web and this forum for hours to find out how it's used. I've looked at my spring plates, I've read my official Porsche shop manuals (Section W, I think it was), my Clymer, Chilton's, Mitchell's, 911 Performance Handbook, 101 Projects, etc. -- no mention of the P221.

Do you remove the toe-in bolt and replace it with this while adjusting camber then place the toe-in bolt back in? I've got the tool in my Pelican cart, but don't want to purchase it if I won't need it.

I'm clueless. Can anyone provide me some insight?

Thanks,

Ron

Not sure about you but i wouldn't let some tech with no knowledge about Porsche alignments learn on my car ... unless he does it for free and you can verify the final specs !

Just sayin ...

Cheers !
Phil

What Wildcat said!

Aligning the rear of a 911 isn't rocket science, but it's not intuitive for someone who's never done it before.

Thanks. He's done many foreign cars but not an early 911. In Iowa, you don't have many choices.

I'll be standing there right with him all the way. It's a $200 job he's doing for $40, so not too much can go wrong. With the tire-clamping laser adjusters, rack and computer readouts, it should get pretty close to specs, if not spot on. If not, I'll find somewhere else.

I've been tearing apart and rebuilding Porsche's since the mid 80s; never touched the alignment though.

Forgot to add... and I'm not trying to be a smartass or ungrateful... I do understand the intricacies of an alignment and all the labor involved. However, I'm not hoping for a discussion about the merits of a certified Porsche tech doing the job vs. a tech that's done thousands of alignments, but not on an early 911.

I would just like to know the use of the P221 so we both can learn.

Thanks,

Ron

here are some guesses - the big ("nut") end is for leverage; middle end is to fit in the hole (which locates it); small end (not the offset cam like nubbin) is to move things

pull what you need to get the tool in and make it effective

The P221 is used to set the rear toe on 924/944/968 cars. On your car the eccentric is already on the spring plate you use a 12mm allen to turn it.
There are 2 eccentrics on the spring plate the forward one is toe the rear one is camber.
If your tech has a Hunter machine it will show him how to adjust them. If not I'm sure you can find the instructions on the web. If you can't PM me I'll send them to you

Dan J is spot on: the toe eccentric is "built in" on the 911.

It's true that the 911 rear alignment is not rocket science, but it can be very frustrating unless you understand the fundamentals of how toe and camber adjustments are made. Street alignments are generally a bit simpler than more aggressive track/race setup. Here's a few things to know as you go through the alignment:
1. Take base measurements of your alignment on the rack before you pull the rear wheels. Determine your target camber and toe at this time.
2. Remove a rear wheel and take some measurements so that you can assess changes in the alignment before you button it back up and check your work on the rack. I like to measure the distance from a point on the brake caliper to a point on the spring plate for toe, and the top of the rotor and the tub for camber.
3. remove the toe eccentric, loosen the nut on the camber eccentric, and then loosen the bolts/nuts at the end of the spring plate (keep these 2 relatively snug).
4. play with the camber eccentric and note that it changes the up-and-down relationship between the spring plate and the trailing arm (the higher the trailing arm is in relationship to the spring plate, the more camber you achieve). Adjust for more or less camber, depending on your target (check the measurement mentioned in point #2 above). Snug the two bolts at the end of the spring plate a little tighter and snug the camber eccentric before you move on.
5. now put the toe eccentric back and use it to change the front-to-back relationship between the spring plate and the trailing arm. Shortening the distance between the hub and the spring plate give more toe in, and increasing the distance more toe out). Note that your camber will change slightly as you adjust toe.
6. get to where you think you need to be, then tighten everything up, put the wheel back on and check your work. Expect to have to pull everything back apart and try again (at least 2-3 times on the first wheel).

Great! Thanks guys! I couldn't understand why Pelican, ZDMak, et al, list that the P221 toe-in adjustment tool is needed for the 911 as I could see the toe-in bolt/adjuster was already there -- made no sense unless I was supposed to remove the bolt and use the tool; or, I was missing some other hole in the suspension where the P221 would go.

Since I'm installing Turbo Tie Rods, bump steer kit, and lowering it to Euro specs, I figured I'd get the alignment. Perhaps I'll check the computer readout on the rear and if it's not out of whack, I'll just get the front taken care of.

Another question, but may need a new thread...

In Vol I of my Porsche Workshop manual's alignment section, it has an added sheet with typewritten notes that state new rear specs were introduced for improvement of road stability and tire wear with the 1973 model 911 but they are applicable to 70-72 models also. It states the rear Toe is +10' (+0 degrees/-10') and the rear camber is 0 degrees (+/- 10'). A handwritten note says that -10' rear camber is best for good loadability and handling (perhaps 'roadability' as the 'l' could be an 'r'). These specs don't jive with my other Porsche aftermarket manuals.

I only plan on street driving my 911. Do these specs sound good to provide to the alignment shop?

He always is...... :D

I'd do +10' toe total, -.5 degree camber frt, +10' per side toe, -1 degree camber rear
for a street car but that's just me

you're only saying that 'cause I'm pimping out your spare rooms

if your doing all those changes make sure you do a corner weight balance.