A question about speed reading at 5th gear
 

Hi.

I am a new owner of a ZR-1(1991) and am enjoying it every weekend. I am very happy now:)

BTW, please let me ask you a beginner question. I would like to know whether the rear end of my ZR-1 is normal or not.

When I accelerate my ZR1 to 7000 rpm with 5th gear, the GPS speedometer reads 223.9 km/h(about 140 mph).

Is this normal?
Is the max speed of ZR-1 accomplished by 6th gear?

I am wondering if the rear end ratio of my ZR-1 is normal or not.

*the rear tires are Nitto NT555(315/35-17).
*the original speedometer reads about 219 km/h(136 mph) at 7000 rpm with 5th gear.

Thanks in advance.

Y. Honda
1991 ZR-1

Re: A question about speed reading at 5th gear
 

7,000 in 5th gear would be about 200mph (320kph) with stock gearing. That would suggest you have around a 5:1 rear gear ratio. Some Jeeps use the D44, so there are probably some pretty extreme gears available out there.

It sounds like your speedometer has been corrected properly, though.

Re: A question about speed reading at 5th gear
 

It's possible his tach isn't reading correctly also.

Re: A question about speed reading at 5th gear
 

Wow! That would be some serious rear gears. Mine with stock 3.45 hits 181mph at 7100 rpm,s.

The right procedure for inspect the ratio of rear end
 

Thank you for your interesting replies!:-D

I understand that 140 mph at 7000rpm in 5th gear is NOT normal for ZR-1. The problem would be that the rear end ratio is not normal or the tachometer is not correct. I think I have to inspect the rear end ratio at first.

Does the method below work well to inspect the ratio?
1. lift the car up.
2. mark a dot with chalk on circumference of the propeller shaft.
3. mark a dot with chalk on the rear tire wall.
4. rotate rear tire and drive the propeller shaft.
5. count the number of rotation of the tire required to have the propeller shaft make one complete rotation.

I am not a gearheaded guy:( and do not want to make any mistakes so I ask for the right procedure.

Thank you!

Yoshi Honda
1991 ZR-1

Re: A question about speed reading at 5th gear
 

Hi! Yes that will work to get you a very close approximation of the gear ratio,

:cheers:
Tom

Re: A question about speed reading at 5th gear
 

I believe your tach is off too. You should be over 200 @ 7100 with 3.45 in 5th gear. At least mine was.

Curtis

Re: A question about speed reading at 5th gear
 

My bet is inaccurate tach :)

Re: A question about speed reading at 5th gear
 

My tach is off now. Corey even said it was off in the high direction 1000rpm's. Now it reads 8000 at 181mph which to me says 7100 is about right for that speed.

Re: A question about speed reading at 5th gear
 

Too bad you're so far way from Yokohama. I have a business trip in a few weeks so I'll be there for about 10 days. I sent you a PM on the other forum and will be meeting up with ZR-1 owners in Japan.

Craig