964 Front Chassis and Suspension Differences

scootermcrad · 01:38 PM

These seem like simple questions, but after pouring over Bill's incredible sticky post, I didn't see what I was after. Maybe because the answers are obvious and assumed. However I know a lot more about pre '89 911's than I do the 964's, so I would like to ask.

First question: Are all the standard 964 C2 and C4 front chassis the same? And by "standard" I mean, not including RS or other more specialized configurations. Did the C2 maintain the same front suspension pan features as the C4 that made clearance for the AWD components (t-tube assembly, front differential, driveshafts, etc.), or was that changed for the C2?

If anyone can post some pictures of a bare/stripped chassis showing differences, if any, that would be really appreciated.

Second question: Are there any major differences between the C2 and C4 front suspension components, or are they all pretty much the same with the exception of the hub assemblies? I saw in Bill's post about the RS type uprights having a different brake caliper mounting arrangement. But I'm considering that sort of "non standard", for the sake of this discussion. Targeted components being the LCA's, struts, uprights, LCA longitudinal mounting brackets, cross member, and sway bar components.

Any help would be really appreciated! Thanks everyone!

Marine Blue · 02-02-2023, 04:40 PM

Unfortunately I haven’t been around both to know but one way to confirm is a parts search for front suspension components here on Pelican’s website to determine if there are any part number differences.

Hopefully someone that has worked on both will chime in.

scootermcrad · 02-03-2023, 04:54 AM

Thanks! Yeah, I know it's sort of a strange request for information. I wasn't sure if I should ask on the main 911 board, or here.

I have a project in the works that may require me to scavenge a 964 front clip and some suspension parts, and I'm trying to get educated. Not having much luck finding information on the front chassis stuff, but maybe I'm not looking in the right places. And from what I can find, it seems the front suspension parts are mostly the same, with the exception of maybe some sway bar assembly parts, but this is where I'm not confident in what I'm finding and thought I better reach out to the pros.

Jeff Burger · Jeff Burger's Garage

Pretty sure the structures are the same but I guess I should leave that to the pros. As far as parts - go to the parts list ( https://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/originalpartscatalogue/ ) and in the far right column it will tell you the model(s) the part goes to. If you look at the front suspension most of the part numbers that say C2 also say C4

scootermcrad · 02-06-2023, 06:05 AM

Quote:

Originally Posted by Jeff Burger

Pretty sure the structures are the same but I guess I should leave that to the pros. As far as parts - go to the parts list ( https://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/originalpartscatalogue/ ) and in the far right column it will tell you the model(s) the part goes to. If you look at the front suspension most of the part numbers that say C2 also say C4

Thanks Jeff. Yeah, I think that's sort of confirming the suspension stuff.

The chassis is probably the more important question, at this point. From a manufacturing stand point, and the fact that the C4 was released before the C2 (so it seems), it feels like it would make sense that the C2 lower chassis stampings all the back to the seat pans, would be the same. But this is probably something I shouldn't assume.

scootermcrad · 10:17 AM

I did manage to find this chassis assembly dimension verification drawing. It says 964 C2 and C4. The link to the original drawing file is missing, though. That might be the verification I need. I'm going to keep looking for a download. I have large scale print-outs of all the early cars that have ALL the important dimensions for chassis repair. This one would be helpful to have with more dimensions, like the early cars.

If someone has some actual pictures of the front clip from inside, bottom and from the side area, that would be helpful and appreciated. The more the merrier.

budge96 · 02-06-2023, 11:34 AM

They are the same there are some who say the C4 has additional welds and reinforcements but
I have two 993 's and two 964's one a C2 Turbo the other a C4 and have yet to see any discernible
differences ,their could be seam welding which is not as apparent .
Why do you ask ? Thanks Bert

scootermcrad · 01:13 PM

Quote:

Originally Posted by budge96

They are the same there are some who say the C4 has additional welds and reinforcements but
I have two 993 's and two 964's one a C2 Turbo the other a C4 and have yet to see any discernible
differences ,their could be seam welding which is not as apparent .
Why do you ask ? Thanks Bert

Thanks for the confirmation, Bert! That's a great help!

I may have to source a front clip for a C4 related project and I wanted to make sure that basically any 964 would be the same. I was concerned that the C4 might have different mounting provisions or clearances for the front differential and t-tube assembly that the C2 wouldn't have. Sounds like that is not the case, though. That is great news. Thanks again!

EDIT: I somehow missed this thread about chassis differences between C2 and C4. Not sure how I missed this. Seems to confirm the chassis are the same.

964 C2/C4 chassis differences?

LM964 · 02-08-2023, 01:47 AM

The only thing in my case that recently springs to mind being the different stabiliser front drop-links I installed necessary with the C4 front drive shafts.

Chassis the same all round as far as I am aware but different components attached or fixed to the chassis that make it a C4/C2/Turbo (minor chassis mods possibly to accommodate these differences).

scootermcrad · 02-08-2023, 05:33 AM

Quote:

Originally Posted by LM964

The only thing in my case that recently springs to mind being the different stabiliser front drop-links I installed necessary with the C4 front drive shafts.

Chassis the same all round as far as I am aware but different components attached or fixed to the chassis that make it a C4/C2/Turbo (minor chassis mods possibly to accommodate these differences).

Yep! The drop-links have been the only major difference I've seen! Good call! Thank you for mentioning that!

scootermcrad · 06:40 AM

I'm coming up completely dry on my quest for dimensional drawings that would show X, Y, and Z reference dimensions for 964 chassis repairs, pertinent suspension pickup points, etc. That picture I posted early has only a couple reference dimensions and wouldn't help much. I know there are dimensional drawings/schematics for the early cars. I basically need the type of information that's in this early LWB drawing dimensional thread:

1969 Porche 911 blueprints

It seems like this information would be important for fixturing with Celette or Blackhawk fixtures, but I don't see anything. Does anyone have any recommendations on where to find this information?

Ralph3. · Ralph3.'s Garage

Factory work shop manual has dimensions

scootermcrad · 02-09-2023, 04:24 AM

Quote:

Originally Posted by Ralph3.

Factory work shop manual has dimensions

Aaaaa! Okay. Thank you for sharing that.

Cobalt · Cobalt's Garage

I have a few C4's converted to C2. I haven't seen anything that stands out.

The PET lists the body in white as the same for C2/C4. Other than drop links and slightly stiffer rubber bushings on the inner tie rod I can't think of anything. Although sway bars vary from model to model but those bolt up in the same place. The C4 uses an electro hydraulic brake boost eliminating the Vacuum boost canister making room for the front diff.

Stock C2 The canister would be replaced with the transfer case. The longitudinals of a C4 will not be drilled for the mountings of the vacuum and brake master. The differences are primarily when comparing 964 to 993 and will vary marginally in some cases. I use the 993 longitudinals on the front end of my widebody converted C4 to C2 and it pushes the front suspension out by 12.5mm per side iIRC.

scootermcrad · 02-10-2023, 11:19 AM

Quote:

Originally Posted by Cobalt

I have a few C4's converted to C2. I haven't seen anything that stands out.

The PET lists the body in white as the same for C2/C4. Other than drop links and slightly stiffer rubber bushings on the inner tie rod I can't think of anything. Although sway bars vary from model to model but those bolt up in the same place. The C4 uses an electro hydraulic brake boost eliminating the Vacuum boost canister making room for the front diff.

Stock C2 The canister would be replaced with the transfer case. The longitudinals of a C4 will not be drilled for the mountings of the vacuum and brake master. The differences are primarily when comparing 964 to 993 and will vary marginally in some cases. I use the 993 longitudinals on the front end of my widebody converted C4 to C2 and it pushes the front suspension out by 12.5mm per side iIRC.

OH! That's very interesting! And thank you for sharing that picture. A really big help!

It's amazing just how much changed from it's previous early roots.

scootermcrad · 02-10-2023, 11:29 AM

A little off topic from even my own questions, but on a tangent, would anyone happen to have an early car steering rack (center drive) and a later 964 steering rack sitting side by side with tie rod ends on it that they could share a picture of? I'm curious just how different the overall width is from tie rod end to tie rod end.