Upgrading to 17"+ wheels---Porsche bulletin---caster eccetrics & rear mount bolts

[veleno]

So I was wondering what your thoughts are on this "mod" based on the bulletin. Is it necessary or have to be done when upgrading to 17" or bigger wheels? Any pros/cons to doing it (or not)? Thanks

Forgot to mention, it's for an S2

[Techno Duck]

Its a good idea to replace the castor blocks regardless if they are original. The updated 968 ones are relatively inexpensive and have significantly less rubber than the original castor blocks.

For a street driven car only, you can get away without changing them with 17"s, but on a car that sees track or even spirited driving i would replace them.

[PHillary]

In your search for rims check out Victor Equipment they have some nice Porsche rims.

[flash968]

one of the issues with running 17s is that you generally go wider in tire. between that and the new grippier compounds, that means more load to the suspension. what this means on a street car is an increase in tendency to tramline (wander and chase grooves and such). fresh caster blocks go a LONG way toward reducing that tendency. it is amazing at just how much. you don't notice the degradation of the rubber in old caster blocks, because it happens so gradually.

[9FF]

one of the issues with running 17s is that you generally go wider in tire. between that and the new grippier compounds, that means more load to the suspension. what this means on a street car is an increase in tendency to tramline (wander and chase grooves and such). fresh caster blocks go a LONG way toward reducing that tendency. it is amazing at just how much. you don't notice the degradation of the rubber in old caster blocks, because it happens so gradually.

+1

You will also notice that the bulletin only refers to fitting 17's to 87+ cars. Probably porsche being cautious due to the weak design of the early hubs.

[veleno]

Got it, thanks.

So I should be looking at purchasing 968 caster blocks?
One for each side on the front, correct?
It'll be a R&R with my current arms?

How about the rear, anything else I should replace/upgrade?

[gtroth]

968 castor blocks are a great upgrade even if you are running 16s. I think you'll need an alignment if you upgrade though.

[Chunkerz]

Are the eccentric bolts needed as well, or can I reuse the ones from my original "D" shaped caster blocks?

[87m491]

did you stay with the 944 bolts or go to 968 units?
thx
Mike

[veleno]

I did upgrade to 18" wheels but did not do this mod. I rarely drive the car but when I get more road time I'll consider the change as I'd like to improve the handling and suspension.

[Porsche 924]

Damn! I just upgraded to 17's what exactly does this do??
I have 255/50/17 in the rear of my 87 924s does this affect me?

[9FF]

Originally Posted by Porsche 924

Damn! I just upgraded to 17's what exactly does this do??
I have 255/50/17 in the rear of my 87 924s does this affect me?

iirc you have early steel arms so you cannot fit the uprated 968 rear mount on your a-arms or the stronger eccentric. Your call, either convert to later arms or risk it.

One thing not mentioned here is when you go to 17in wheels Porsche issued a tech bulletin that stated tire pressure and castor alignment changes also:



Apologies for the bad iphone pic.

[Porsche 924]

Originally Posted by 9FF

iirc you have early steel arms so you cannot fit the uprated 968 rear mount on your a-arms or the stronger eccentric. Your call, either convert to later arms or risk it.

One thing not mentioned here is when you go to 17in wheels Porsche issued a tech bulletin that stated tire pressure and castor alignment changes also:



Apologies for the bad iphone pic.

Hmm I did rework my fenders, and I did check all my lines for clearance. So I need a rear sway bar. Also everything clears in the rear, why do I need a 17mm spacer?

[944CS]

You can also install Powerflex bushings on the original caster mount - this part will withstand the increased loads that a 17" wheel brings. Cheaper than buying new 968 mounts.