"Z51" on the ZR-1...

[Aurora40]

Instead of hijacking Johnny's for-sale thread: http://zr1netregistry.com/forum/showthread.php?p=65876

I figured I'd continue my question here. My reply is as follows:

Our '90s do have the "Z51" rpo. However, the steering rack is most definitely not the fast 13:1 rack. If you've ever driven one (I had an '87 Z51), you'll know what I mean. The difference is quite clear. The fast rack feels insanely quick. Like if you sneeze, you'll probably stuff the car in a ditch quick. Also, the fast rack was about 2 turns lock-to-lock. You can confirm this on our cars by turning the wheel from one end to the other, I believe it's closer to 3 turns.

We also don't have the Z51 springs, sway bars, or HD bushings. Apparently Z51 with FX3 meant base springs and swaybars. I think all we really have is the power steering cooler, since the Z51 oil cooler was different, we don't have the rack or suspension, and the ZR-1 had a completely different exhaust (Z51 had the "free flow" mufflers good for 5hp).

[phrogs]

well I don't know for sure I know what my RPO codes says but I had a 87 with Z51 and I can not remember how fast it was compared to this one.
From what I have seen you either have a base or the fast rack and pinion I do not think there was another option.

I do know why our spring rate was different its becuase of how much the engine weighed compared to the L98.


check this out

corvette forum.com/c4-general-discussion/1649123-interesting-fx3-tidbit-long.html

[-=Jeff=-]

From what I thought.. fast ratio rack was not on the ZR-1

[XfireZ51]

The 84 was the quickest. 2.5 turns lock to lock. A manly steering rack.

[Scrrem]

Our '90s do have the "Z51" rpo. However, the steering rack is most definitely not the fast 13:1 rack. If you've ever driven one (I had an '87 Z51), you'll know what I mean. The difference is quite clear. The fast rack feels insanely quick. Like if you sneeze, you'll probably stuff the car in a ditch quick. Also, the fast rack was about 2 turns lock-to-lock. You can confirm this on our cars by turning the wheel from one end to the other, I believe it's closer to 3 turns.

We also don't have the Z51 springs, sway bars, or HD bushings. Apparently Z51 with FX3 meant base springs and swaybars. I think all we really have is the power steering cooler, since the Z51 oil cooler was different, we don't have the rack or suspension, and the ZR-1 had a completely different exhaust (Z51 had the "free flow" mufflers good for 5hp).

Wow..I guess I am really confused about these Z's now. I had to get my build sheet out and take a look. Mine has the FE7 option which is the H.D. F&R suspension (Springs or Sway Bars???) Mine also has FX3 Selective Ride Control, and the Z51 Handling Package. I guess I'm puzzed as to what the Z51 is if its not the 13:1 rack :icon_scra
Rich

[1991ZR1]

I had an 86 with Z51 just before I got the ZR-1 and the steering was faster on the 86. I really liked it for driving around town.

[gbrtng]

I had an 86 with Z51 just before I got the ZR-1 and the steering was faster on the 86. I really liked it for driving around town.
My 86 Z51 car was 2 turns lock to lock; the ZR-1 is about 2-1/2 turns.
Actual ratios ???

[Aurora40]

I'm going from memory, but I'm pretty sure the Z51 rack was 13:1 and the standard was something like 14.9:1?

[batchman]

I can confirm our 91 had the slow rack, in fact I had to undertake an 18 month long argument in order to get SCCA rules changed to allow me to swap in the quick rack.

The 2.0 turn rack makes a big difference when you're running a 1.5 mile course with 70 turns.

Later,
- Jeff

[gbrtng]

I can confirm our 91 had the slow rack, in fact I had to undertake an 18 month long argument in order to get SCCA rules changed to allow me to swap in the quick rack.

How does the SCCA discover an illegal rack?

Also, it's clear that the Z51 option content differs by model year and also (probably) by model.
However, both my 91 ZR-1 and 91 L98 cars have the same rack.

[batchman]

How does the SCCA discover an illegal rack?

In autocross it would be noticed by a competitor, who would only have to observe the 2.0 turns lock-to-lock. At big events everybody is putting in no small effort, in expectation that everyone has prepared to the same rule book. Impound is held after a run group, such that competitors can scrutinize each others' cars and challenge if something is inappropriate.

Anyway it's legal now, all year/model C4s can swap parts in Street Prepared; previously the ZR-1 was seperated from all the others.


- Jeff