ZF Gears

Mark I run the 3,77 Ring and Pinion and standard 5th. Its more than enough in my opinion. With 295/50-15 Tires its about 2100rpm at 100kmh/60mph. I think you will regret it if you do both unless you commute on the German Autobahn every day. My 5th is only really usefull when going fast i.e. Above 100kmh but then it is also a true pleasure. Just think about it twice is my advice.

goodroc

Thanks for your comments.

Most of my driving is track days and open road racing. At Silver State this past Sept. I averaged 149+ mph for 90 miles while using the standard ZF gear ratios. As I progress to higher speeds I would like to minimize the stress on the engine as much as possible.

Mark

Sounds like you need it. Just watch out for the barrier of sound

I have both the 3.77 and taller 5th. Too much, IMHO. Just go with the 3.77

I am sure Mark already knows,
going with the 3.77 will get his top speed from 149 up to 166
going with the 3.77 and 0.655 will get him up to 178 (with 280 hp at the wheels)

Actually the 149mph was his average. I can not even imagine what his top speed will be....

Bear in mind there are 3 different tall 5th ratios; 0.655, 0.642 and 0.62.

I have the 0.642 in my GT5 as an overdrive gear and it works really well. As the Silver State is all top gear Mark could consider the 0.62 and keep the 4.22, a cheaper option that would provide for 169 mph at the same rpm as used by JFB.

Julian

Don't forget the "taller" 5th will need machining on the shift fork shaft... But that's a minor project when you have the box all torn down anyway.

That mod will be required for any of the taller 5th gears.

Rocky

See way down at the bottom of Pg. 26 for the Machining Needed

Sorry for not getting back sooner. I've been in FL buttoning up my house there. Storm has passed and no damage. There is a posting of my SSCC run at:

https://www.youtube.com/watch?...JWE&feature=youtu.be

You will notice that my speed varies quite a bit. That is because I was having overheating issues. You can see the white temp. gauge on the A pillar. A/F gauge reads 11.3+/-. Oil pressure is above temp and is 75 psi..

There is some air in the cooling system. Need to find out where it came from.

165mph is 6200rpm.

I appreciate your comments
Mark

Have you tried to get a quote from RBT on the Parts? I am currently also in FL but on vacation, today from Redington Shores heading for Fort Lauderdale via Everglades for an Airboat ride. We had to divert our trip slightly due to the Storms but it all ended hapilly after all. It was just a bit of Wind where we were but nice temperatures still.........

My trans rebuilder is getting quotes.

My place in FL is in Melbourne. Hope you enjoyed your time there.

Mark

I have the 3.78 ring and pinion with the .620 fifth gear. I really like it as I can now cruise the freeway at under 2500 rpm.
I do have a 521ci engine so have plenty of torque.

Forest