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bass gt · Posted: Thu May 29, 2008 8:37 am Post subject: 951 A arms

Guy's,

I didn't want to hijack Dans other thread, so i thought i would open up a new one. Ok, this is concerning the fitment of 944/951 late Ali A arms and hubs onto a 931 chassis.
If i were to source the complete hub/arm assembly, will this match the 931 mounting points? The 924 A arms have a rear pin which sits in the caster block on the chassis rail. Looking at 951 A arms, they don't seem to have this. So whats their secret??? I am looking to fit a complete 951/968 hub/brake assembly as it gives me the ABS rings and would allow me to widen my track without resorting to wheel spacers. Don't worry about brake lines, or speedo drives or struts or body panels ect.. I am just querying whether the actual Ali A arm can be mounted onto a 931 chassis. obviously the steering control arm needs to be lengthened, but again, not an issue as i am fabricating new rose jointed items anyway.

Regards,

Steve
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Front Wheel Drive is the Devil's work.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Steve, I just happened to have a 951 in the garage. Hopefully this picture will help, there is a bolt threaded on both ends which connects the a-arm to the caster block:

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1987 951 - M193 Version for Japan

bass gt · Posted: Thu May 29, 2008 10:33 am Post subject:

Thanks!! Thats what i was looking for. So i wonder if the caster block on the 931 sits in the same positin as the 944.
Could you measure the distance between the two inner A arm bush faces? I could then compare that to the 931 distance/A arm

Many Thanks,

Steve
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Front Wheel Drive is the Devil's work.

ic932 · Joined: 11 Feb 2005 Posts: 1104 Location: UK

Steve, 951 castor blocks are simply bolted on to the arm.

The only fitment issue is described in Dan's thread.

The dimension between front bush and castor block is the same on all wishbones whether alloy or steel, that's why they are interchangable between the 931 and 951...

I did this work a number of years ago using 86' arms and 968 hubs/spindles/calipers ect. I needed the 86' arms to keep the rims under the 931 wings. The correct geometry was easily achieved afterwards.

My latest 931 based project uses a late 944 non-sunroof shell, advantage being - alloy x-member, bolt in intercooler capability, sensible fusebox/battery location...

bass gt · Posted: Thu May 29, 2008 10:58 am Post subject:

Thanks,

So if i fitted Post 86 A arms and hubs, i would achieve an increase in track. Hmm, interesting.
So the main fitment issue is the front bush into the steel crossmember. As the later bush is larger, i guess this fouls within the early crossmember.
Ok, what about fitting the later hubs onto the early A arms?? is this feasible???

Steve
_________________
Front Wheel Drive is the Devil's work.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Steve, some dimensions for you, I think ic932 may have answered your question anyway...

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1987 951 - M193 Version for Japan

bass gt · Posted: Thu May 29, 2008 11:10 am Post subject:

Wow!! thanks. very useful. I might go down the route of strengthening the stock A arms and fitting 968 hubs. The additional track would be nice, but i'm really after the ABS ring and sensor. However, i do have a spare crossmember, so i might look at modding that to take the later arms as well. Kills many birds with one stone.

Steve
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Front Wheel Drive is the Devil's work.

morghen · Joined: 21 Jan 2005 Posts: 8883 Location: Romania

wow can i have that in a bigger resolution please?
thanks.
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gegge · Joined: 27 Jul 2007 Posts: 1124 Location: Sweden

Added some info:

"944 85.5-86 NA/Turbo 951.341.027.00, 951.341.028.00

944/968 87-95 NA/S/S2/Turbo non-M758/M030 944.341.027.02, 944.341.028.02

951(S) 944/968 87-95 M758/M030 & 89 Turbo
Pin on the ball joint is 19mm vs 17mm, stiffer bushings 951.341.927.031, 951.341.928.031 These superseed 951.341.027.031, 951.341.028.031

Germany said use 951.341.927/8.031 until the parts supply runs out, then they would start shipping the new 944.etc unit.

By visually looking at the new control arm,

- the new arm has "webbing" I guess to make it stronger
- larger build-up of aluminum around the ball joint
- larger build-up of aluminum around the anti-roll bar mounting hole
- anti-roll bar mounting hole is enlarged on new unit
- the ball joint bottom is larger and hangs below the control arm hole (the 951 unit sits flush at the bottom)

Otherwise, the dimensions are the same. The new unit is stamped as a 1997 manufacture, the 951 part has a 1988 stamp.

The 968 arms have the additional tab for the air deflector but the ball joint is competely different. Whereas the 951S arms have a circlip that can be removed to allow access to the balljoint, the 968 arms have a machined cup that encloses the entire assembly

The following is a statement released by Porsche Motorsports North America concerning the 944 Aluminum Control Arms: (my notes are in italics)
To all Porsche 944 & 968 Competitors Re: 944 & 968 Control Arm Usage In Racing Applications

The following A arms should be installed in 944 and 968 Series vehicles according to the conditions noted:

944 341 027 02 L/S Production version arm (round groove 360 degrees on ball joint)
944 341 028 02 R/S Production version arm
(these are standard 968 arms)

These parts are good for moderate competition. (Time trials etc.)

951 341 027 32 L/S Competition version arm (slotted groove on side of ball joint)
951 341 028 32 R/S Competition version arm
(Note these are no longer available)

These parts are recommended for long distance races or heavy competition.

Neither set of arms noted above pose a problem, as long as

1) the ride height is not lowered beyond the point which causes binding of the ball joint when the suspension reaches full travel

2) the front sway bar is not greater than the M030 package sway bar in either 0.D. or wall thickness

3) the lower bore in the strut is not worn out

4) the parts are assembled following the steps outlined in the Porsche Service Manual. (Despite the fact that this may be slightly contrary to the Service Manual, it is imperative that the bolt and nut (original Porsche Parts) be replaced each time they are removed.

As always in racing, it is important to inspect the arms for nicks or cuts from road debris after each event to avoid development of any cracks. Please note that the leading cause of failure we have seen on both the Production and Competition version arms, in racing applications, is the failure to follow the instructions I have listed above.

Alwin SpringerDirector of Porsche Motorsport N. A."
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