Question about front knuckles
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Question about front knuckles
Ok this is a weird one.
As I understand it (please tell me if I'm wrong) the C4's had 3 different styles of front steering knuckles.
1st was 84 to 87 without ABS
2nd was 88 to 90 ABS sensor was in the knuckle and not the bearing
3rd 91 to 96 sensor was inside the bearing. Back of knuckle is open.
So my goal is to have wheel speed sensors on the front of my 84. I plan on using one to run my Intellitronix speedo and the other will be converted to a digital signal and then fed to my Holley ECU so it knows if I have wheel spin. That way it will shut off nitrous if it sees wheel slip between the front wheel and the VSS
So will any of the two newer style knuckles bolt onto my 84 and not change any geometry? I'm willing to bet the later (91 to 96) is probably a no go but I don't know for sure.
The other option I was wondering about is if neither of the two newer style knuckles would work, could I machine an opening in the back of my 84 knuckles so it could accept a 91-96 wheel bearing that includes the sensor? I wonder if that would make the knuckle too weak? Did they beef up the later style knuckle to accommodate the back being open?
As I understand it (please tell me if I'm wrong) the C4's had 3 different styles of front steering knuckles.
1st was 84 to 87 without ABS
2nd was 88 to 90 ABS sensor was in the knuckle and not the bearing
3rd 91 to 96 sensor was inside the bearing. Back of knuckle is open.
So my goal is to have wheel speed sensors on the front of my 84. I plan on using one to run my Intellitronix speedo and the other will be converted to a digital signal and then fed to my Holley ECU so it knows if I have wheel spin. That way it will shut off nitrous if it sees wheel slip between the front wheel and the VSS
So will any of the two newer style knuckles bolt onto my 84 and not change any geometry? I'm willing to bet the later (91 to 96) is probably a no go but I don't know for sure.
The other option I was wondering about is if neither of the two newer style knuckles would work, could I machine an opening in the back of my 84 knuckles so it could accept a 91-96 wheel bearing that includes the sensor? I wonder if that would make the knuckle too weak? Did they beef up the later style knuckle to accommodate the back being open?
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
I think the 86 knuckle is still the early geometry but will take an abs sensor. The later abs ring on the hubs fit into the early knuckle though. Not 100% certain on that. And I'd imagine the parts are probably unobtanium or nearly... thats all I know.
Source: the early front bearings all have the tone ring on them and I have it on the car at the moment.
Source: the early front bearings all have the tone ring on them and I have it on the car at the moment.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
You want '85 - '87 spindles/knuckles to take advantage of the larger caliper bolts and then those would need an approximately 60mm bore through the spindle/knuckle rear wall for the '91+ to penetrate through it. 60mm is somewhat of a WAG but there should be specifications out there with dimensions for the '91+ hub. Maybe the later F body hubs wouldn't require as large a diameter bore. Your 'local' parts guy should have hubs on the shelf I'd think to measure 1st hand!
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
You want '85 - '87 spindles/knuckles to take advantage of the larger caliper bolts and then those would need an approximately 60mm bore through the spindle/knuckle rear wall for the '91+ to penetrate through it. 60mm is somewhat of a WAG but there should be specifications out there with dimensions for the '91+ hub. Maybe the later F body hubs wouldn't require as large a diameter bore. Your 'local' parts guy should have hubs on the shelf I'd think to measure 1st hand!
That works anyway being that while I'm at it I was debating the C5 front brake upgrade.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Ok just to clarify. Your saying to take a set of 85-87 knuckles and bore the back of the knuckle out 60mm so it will accept a 91-96 hub/bearing. This will also give me larger caliper bolts. If that will work That's awesome.
That works anyway being that while I'm at it I was debating the C5 front brake upgrade.
That works anyway being that while I'm at it I was debating the C5 front brake upgrade.
There should be many images out there for a 513085 hub to get an idea of what you need to do. Maybe you use the later F-body that mounts a bit differently but could be used. The top is the '91+ and the lower is the F-body that many use to replace the '91+' The F-body is a 513090 to check your 'local' parts guys.
Last edited by WVZR-1; Jul 10, 2022 at 06:56 PM.
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Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Ok so if the 86 knuckle with ABS will fit an 84 without changing any suspension geometry could I just use an ABS sensor and wheel bearing from an 86 and not have to cut a hole?
If that would work then the next time they get an early C4 at my local Pull & Pay I'll pull a set and get a new sensor and bearing for it.
This isn't an urgent project by any means. I'll probably do this over the winter to be honest. I'm just in the planing phase trying to figure out what parts will work.
If that would work then the next time they get an early C4 at my local Pull & Pay I'll pull a set and get a new sensor and bearing for it.
This isn't an urgent project by any means. I'll probably do this over the winter to be honest. I'm just in the planing phase trying to figure out what parts will work.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Ok so if the 86 knuckle with ABS will fit an 84 without changing any suspension geometry could I just use an ABS sensor and wheel bearing from an 86 and not have to cut a hole?
If that would work then the next time they get an early C4 at my local Pull & Pay I'll pull a set and get a new sensor and bearing for it.
This isn't an urgent project by any means. I'll probably do this over the winter to be honest. I'm just in the planing phase trying to figure out what parts will work.
If that would work then the next time they get an early C4 at my local Pull & Pay I'll pull a set and get a new sensor and bearing for it.
This isn't an urgent project by any means. I'll probably do this over the winter to be honest. I'm just in the planing phase trying to figure out what parts will work.
*** You've mentioned this in the past a few times and I was confused regarding your intentions. So long as you get it ........................................ ..