Mike J

In my quest searching for a C2 that meets my expectations I have also seen a very clean very low mileage C4. I have not driven it yet and am a 911SC owner at the moment so I have not exprience with the 4 wheel drive system on these cars.

Specs are:
- 1989 C4
- engine updates have been Porsche done
- LUK flywheel
- distributor vent kit
- 24,000 miles
- original owner
- no accidents
- PPI it totally clean
- updated A/C to 134a

I have heard a lot of negative talk about the complex mechanicals of the C4, the pump goes, and the weird handling, they are too complex for the DYI, etc.

What is the list's opinion about this or is this a personal thing? I searched through the archive which is peppered with various opinions. I have not considered a C4 so I am curious to see what the list thinks.

Cheers,

Mike

Adrian

Dear Mike,
I am not entering a C2 versus C4 war anyway. The C4 is best so what is the point of arguing (TIC).
A 1989 model C4 cannot have a LUK flywheel fitted. This must be a 1990 model. The 1989s had a single mass flywheel installed.
You purchase what you feel you need. If you want to drive all year round including in the snow and ice, the C4 is the 964 to have.
Complicated, yes they are. Heavier, yes they are. Do they need a little more understanding, yes they do. Surrounded by false myth and legends, yes.
If you can use AWD a C4 is great. If you do not need AWD then a C2 may be better.
Ciao,
Adrian
911C4

PS: One point of note. The basic C2s (narrowbodies) were fitted with vacuum boosted brakes. The C4s and certain C2s (widebodies, Speedster, 964RS, Carrera Cups) were fitted with a hydraulic pump for hydraulic boosted brakes. These pumps are very reliable.

neil williams

Hi Mike,

I too had an SC (81 UK sports model) and now have a 90C4.

A C4 does not have weird handling just different, but once you get the hang of it it is FUN! Okay so you can't hang the back out like on an SC, but get it right and the C4 goes around a tight corner like it is on rails. So there is a challenge to it.

One of the guys on the smartgroups site has posted an article from 1992 Excellence Magazine (I think it is 92). It gives a very good insight into how to drive a C4 fast and how to setup the suspension.

But if you want those rear-end powerslides get a C2!!

Just my 2 cents.

cheers

Neil

Bill Gregory

Mike,

Adrian and Neil made some good points. I've owned an SC, and just recently bought a C2. One reason I didn't look at C4's was the added complexities the "4" brings (I do most maintenance myself). Look at the brake system, for example: On a C2, I can bleed it myself (and do many times a year, due to track usage). On a C4, you need a $5K Bosch tool to bleed it (Different systems as Adrian pointed out). So, for me, the C2 was the choice.

I don't think there's a war to be had...you find the Porsche that fits your needs and desires, and go for it!

Mike J

Hmmm, Thanks Adrian I will have to checkout the flywheel. I might have misunderstood my contact when we talked about the clutch.

I think that Bill has a killer point for me. I do all my own maintenance from brakes, suspension, clutches, whatever. I take pride in doing it myself. I am even taking Anderson's engine rebuilding course in December just so I know how that works. So, if I truely need a 5K took to bleed the brakes, then I need to think about it. Is this this "hammer" that I have seen in a couple of posts?

I drive the car 3 seasons a year, and have quite a contrasting vehicle (a 94 chev 3/4 ton extended cab 4x4!) for winter. I want to keep the truck for camping anyways so I don't need the car for winter. I am also used to driving a 911 rear-wheel drive on the track. However, I am interested because the car is very clean but honestly have not seriously looked at the C4s.

What other differences are there that would affect a DYI type of person?

Cheers,

Mike

GeoffD

Howdy,

I have had an 1989 C4 for about a year and a half and have driven it the whole time, including the snowy winter we had in Ontario last year (I have snow wheels and tires for it and higly recommend them). I have the distributer vent kit and do not have the cyl head update but my car doesn't leak from there although it does leak from between the case halves.

One of the major things I was worried about when I bought the car was all this dreaded C4 understeer stuff you read about. My car has the suspension mods from the Excellence article. Eibach springs (lowered and levelled) and koni yellows. It also has 7 1/2" front (from a 944 S2) and the stock 8" rear wheels with 225/16 front and 245/16 rear tires. The suspension set up stops the car from pitching and keeps the front from loading up too much. This, and the wider front rubber presumably helps combat the understeer. I have read that the reason that Porsche put those ridiculous 6" front wheels on the things was to promote understeer to mitigate liability. Apparantly insurance comapnies don't like cars that leave the road backwards as much as ones that leave it still going forwards!!

I know a little bit about vehicle dynamics, I club race a 924S and I instruct for the PCA, so I feel I can recognise problematic handling. So the verdict is.....on the street, my car feels totally neutral, like a 944, and in the winter, you can definitely get it to oversteer and hang the rear out as far as you want ( I generally restrict this to parking lots). Although I didn't buy it to drive on the track (I already have a race car!) I took it to Shannonville for a PCA weekend last summer and my brother in law and I did double duty in the car over the weekend. In order to deal with potential understeer in the track environment, I put 8" wheels with 226/16 yoke A032's on all four corners and the car was absolutely amazing. Perfectly balanced. Boy it was fun to feel the four wheel drive working under you!

I bought the car with 106,000 km on it and now have 150,000 km. I've adjusted the valves once, changed the oil 4 times, replaced the battery, and changed the brake fluid when I put new pads and rotors on it. I've had none of the complexity related problems you hear about. As a daily driver, the car has been stone cold reliable. Including a pretty comprehensive repaint, I have $40 K CAN in it, or about $27 K US. I can't imagine a better car for the bucks.

This is my first 911. I have my 924S and had a 968 which I thought was the pinnacle and which was a great car. My wife, who is a good driver and has no biases between Porsche types, likes the C4 the most by far.

One point in closing, I think the 964 C4 has taken a bit of a bashing over the years from traditionalist rear wheel drive types, many of whom wouldn't even recognize the handling traits that they accuse it of having.

If you go to Whistler on the weekends this is the car for you!

Jay H

Mike:

I can offer a few other small points on the C4/C2 issue.

My trusted mechanic told me (while I was searching for a 964) that to change the clutch/flywheel on a C4, both the motor and trans have to drop. On a C2, he could sneak the trans out without dropping the motor (therefore less labor costs).

Bruce Anderson just wrote in the December 2001 issue of Excellence (Technical Notes section addressing early 964 reliablity) that "we have also seen some front wheel drive mechanisms for the all-wheel drive 911 Carrera 4 wear out after 100,000-125,000 miles". Though, I have yet to read a post on this board of anyone complaining or posting about their C4 having any drive problems. Who knows how the cars with over 100k miles and failing drive components that Bruce has seen were driven or maintained.

I also remember Bruce writing in previous issues of Excellence that he felt the C4's AWD system was complex, but very robust. I'm sure Porsche over-designed that system (so it wouldn't fail) in the late 80's when they were betting the farm for their future success with the 964.

I certainly wouldn't pass up a nice C4 (just because it's a C4) if it's a great car. Nice 964's are hard to come by, period.

Good luck!
Jay
1990 C2

Bill Wagner

Mike:

What you NEED to do is drive, and I mean DRIVE a C4. I'm not talking about taking it for a mild cruise down main street, I'm talking about taking it out and pushing (within reason for a test drive) the limits of the car, particularly around a curve.

If you take a curve at fairly high speed, often the front differentials will lock (a little light on the bottom console will flash when this happens) and the steering wheel will act like it's fighting you. This is very unlike a 2WD car, where, under similar circumstances, the tail may start moving out from under you. I suspect that this is the reason many "purists" say the 964 C4 acts like a front wheel drive car. The feeling the steering wheel gives you is similar to the torque-steer condition on FWD cars, but it's NOT the same. It takes some getting used to, and quite honestly a bit of practice to master, but it can be mastered.

You need to drive the car under such conditions to see if it suits you. In bad weather conditions, you can do things with a C4 you wouldn't even consider in inclement weather (for example, you can STILL drive it like you were on dry pavement...within reason, of course).

From what I've been able to tell from my own research about C4s before getting mine, the transmission is EXTREMELY reliable.

Good Luck,

Bill Wagner

1AS

I've had both- 90C2 and 91 C4. If you want to drive in snow, the C4 is the only answer, and it's delightful. With all weather tires, anyone can make it do anything in the snow. Grip is great, power on understeer in slippery conditions can easily be tamed by lifting in mid corner, or by simultaneous brake and gas. Whatever you like about the car in the summer, double that in the winter. If you lock the front diff, I think it would climb a tree.

Adrian

Just to make a couple of clear points with the AWD function of the C4.
Understeer on the C4 is a problem when the traction control system activates. This can be almost eliminated by installing a 21mm 1990 C2 rear sway bar.
Now the US versions ride highter than ours here in Europe so lowering just to standard Factory Spec will improves things. Going to 964 RS specs, well even better but may not be for some owners tastes.
The traction control works as follows.
Rear Wheels can be locked together via a differential lock mounted in the rear diff.
Both rear wheels can be locked to both front wheels and vice versa via the differential lock mounted in the centre differential. It actually locks the drive shafts together. If you ever get to see the centre diff, disassembled, it is a wonder of engineering.
The front wheels cannot be locked together side to side.
The little led on the console only comes on when the rear differential lock is energised. If you look at the symbol it only shows the rear differential ( the only caveat is that this may be different on US models). I do not have the programming data for the 1991 upgrade. The centre differential locking is not monitored on 1989 and 1990 PDAS/BS control units.
Drive is 31% front and 69% rear. The load or torque transfer from rear to front only takes place when both rear wheels spin up. Naturally vice versa. I have never been able on the road to get my front wheels to slip or spin up. Damned hard getting the rear to as well.Torque transfer will also only take place whilst accelerating. It is hard to tell it is happening. Take a drive in a Audi RS2 (built by Porsche) it has a similar system and that feels very funny and somewhat dangerous when the torque transfers from front to rear being primarily FWD.
This other stuff about failing front differentials is well unsubstantiated. From all my contacts with repair shops all over the world and asking them of 964 repairs they have done, I have never heard of a failed front differential. They will fail eventually, they are mechanical. However I suspect they were designed for far more miles than a certain person is claiming.
Ciao,
Adrian
911C4