M758

In general rear end low = more rear end grip. More rear toe in means better stability underbraking as the rear suspension tends torward toe out during heavy braking. I am not sure how toe inpacts corner exit, but has large roll in corner entry.

Rake seems to impact corner entry and exit. It also seems have more impact on softer cars. One way to tune a stock spring 944 for autocross is by using the spare tire. Add in the spare tire to lower the rear and add rear grip. Remove it and run low fuel to help get the car to rotate. Running my stock 83 in autocross I used this feature to run some pretty strong times. The car I believe had some static toe out and would rotate very well. However one day with low fuel and no spare it got to be too much and started limiting my ability to put power down. So I put the spare back in and that helped alot. Truthfully I never aligned the rear of my 83 autocrosser as I did it for full on street tires so I can't tell you all the settings, but after driving it for a full season I found it to be quite quick despite rolling ship in the ocean and having to man handle the manual steering.

If you run a bit front sway bar you many need to keep the rear end up so that it does not push.

knfeparty

yeah I run a 26.8 w/ delrin- not too big

but I'm putting in m030 struts soon- so the front springs are a bit stronger

the 18mm rear bar is in there- for late na m030, is the rear bar supposed to be 18mm or 20mm? The 19mm adjustable is only for the 968, correct?

I've always run it with no spare and less than half a tank. It definitely rotates easily, usually too easily, and I've seen lots of pics with the butt end in the air. I'd rather have it loose than heavy, though. I'm thinking taking the spare out and about 1/2 fuel (but rear carpet in is mandatory, apparently, since snaps make it "non-removable" for stock) and getting it aligned with enough rake so that with those items in it is even or just slightly raked. I'll use toe in to keep the back end from going everywhere on corner entry.

I was thinking, as far as ride height, would the most sensible thing to do (effort wise) be drop the rear all the way with the eccentrics and use the strut perches in the front to adjust rake?

944CS

if you align it with toe in the car won't rotate as well-align it with zero toe front and rear, it won't be anything a good driver can't keep under control

M758

That applies to autocross. On race track you would not be able to trail brake with out toe in. Hard braking will cause the rear to toe out and makes anything other that straight line braking very very difficult.

Last race I had zero rear toe and hitting the brakes in very gentle bend at 100 mph meant make an imeadiate correction to keep from spinning. Hard to be fast that way.

944CS

i know people who run zero rear toe, including myself, and have no trouble...maybe there is something up with your setup

Oddjob

I dont think Joe is offbase here. Zero toe in the rear of a 944 (or 911 for that matter) is not stable on a road course. Even if you run full solid suspension bushings, zero static toe will go to toe out under braking. This will cause tail wagging and instability in high speed braking zones, and oversteer characteristics during turn-in.

You can compensate the alignment induced oversteer by reducing spring rates in the back, but thats a band aid to cover up an alignment problem. And straight line braking stability will still be compromised.

The quirks wont be very dramatic on short, low speed road courses, and maybe even preferred at an autocross - but at a high speed, fast sweeping turn, heavy braking track, pushing a 944 hard with zero toe in back is going to be a handful.

alex

This one of the most informative threads I have seen come along in a while. Its one thing to ask, "Should I get Konis/Bilsteins/Coil Overs," but this the stuff that digs to the next level.

Oddjob

Maybe I missed it in this or one of your other threads: when you are upgrading to factory M030 front struts (yes, the M030 front springs are about 35 lb/in stiffer than the stock springs), are you also going with the M030 25.5mm rear torsion bars and M030 rear konis? And if you are using 968 M030 fronts, can you get away with using the 968 M030 rear shocks, or only the 944/951 rear M030 konis? The 968 M030 rears have the barrel helper spring on them (so I doubt this would be allowed per stock class rules), which would stiffen up the rear of the car, in addition to the larger M030 t-bars.

M758

I have been racing my car for over 5 years. The rear toe information was given to be Chris Cervelli. Chris raced 944 Turbos for many years with all the best parts and knows his stuff. (if you don't know who Chris is do a seach and you will be informed quite qucikly) Just like oddjob stated you need some static toe in in the rear of the car to make it stable under braking. On a road course you need that stablilty to brake deep into a corner and you use some trail braking to help rotate the car if needed. As for being a band aid I guess you could say that it is a band aid for the Porsche's design of the rear suspension in 944 and early 911s.

knfeparty

to answer oddjob's question-
I've done a lot of rulebook reading.

Front struts are free so long as the mounting dimensions are the same. To my knowledge this is true between the 968 m030 struts (which I need to post pictures of- the ones I just got from ebay are BUSTED) and the 944 m030 struts. Need to look at the part numbers again but what was sold to me as 968 struts might actually be 944 struts (which is what I really want anyway). Also, the 968 m030 springs are the same spring rate as the 944 ones- 28N/mm (not that I couldn't just change out the springs if I could find them).

Rear shocks are free, but adding coilivers or the 968 helpers in the back is not. I'm using new koni sports- I guess the valving is a little softer than the m030, but I'm not going to get new shocks.

I am not changing the rear tbars- I'm doing a 944 m030 conversion so I would have to use whatever size came with the 1989 8v NA m030, which is I believe what was already on the car (it came with the koni package, m474 I think? Whichever package came with 25.5 and 18mm swaybars).

Front swaybars are free, so I'm running the 26.8mm with delrin. I could add bracket braces provided I don't have to drill anything, and I could even run a weltmeister in the front for that matter.

The rear sway is not free- I have to run exactly what would have come with the car ordered from the factory with the m030 option package, which is I believe the 20mm non-adjustable.

Oddjob

Your car will have 23.5mm rear t-bars, the M030 t-bars are 25.5mm.

knfeparty

Are you sure that's the 944 m030 and not just for the 968? I mean that's great news that I can get some stiffer tbars.

But that sucks that I have to work on them.

knfeparty

Here's another Q- m030 had different hubs/spindles. Will the m030 struts go onto the regular spindles? I need to get the spindles/hubs if I want to be totally legal, but I have ABS hubs so they may already be the same. I haven't seen any m030 spindles/hubs for sale.

Oddjob

The Turbo S and S2s M030s for sure had 25.5 bars. Since very, very few 944 N/As were ordered or imported with M030 suspension, you probably wont find too many examples to compare to. But you will be able to find porsche literature that will document that +87 944 series cars with the M030 suspension option had 25.5mm t-bars.

M030 hubs and spindles are in reference to the 944S2 M030 and Turbo S front hubs and spindles that use the 928S4 Calipers. These parts and brakes were NOT used or included with the 944 N/A M030 package.

knfeparty

YES!!! Less parts to buy!

Well it sounds like the 25.5 tbars are a big upgrade...and technically I HAVE to run them to be legal. Sounds like a nice Christmas break project...
A lift makes tbars a lot less painful, right?

I am running a bit of toe in right now and the car is still really tail happy (mostly on exit, but on entry too) and doesn't trail brake really well (although it does to a good extent). I am definitely going with zero toe in the front as I am going to be running max camber and still doing a bit of street driving.

So to recap, here's what I'm planning on doing:
koni sports-->968 m030 koni struts/springs 28N/mm, drop to add slight rake
rear tbars 23.5-->25.5
run slight rear toe in and low fuel/ no spare. Add fuel/spare if rear is too loose.

When I add my new tbars, I should index them for the new lowered height, right? And restore the eccentrics to about middle setting?