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I am thinking on either changing ping/pinion to a ex. 3.77 OR an "overdrive" 5th gear. My goals are mainly to get the rpm lower at cruising speed and also a higher topspeed. 

I have tried to email RBT, but it comes back as not able to email them. Any thoughts or suggestions on where to get the parts? Are RBT still in business or does anyone have a better way to contact them?

Price difference for a 5th gear and ring/pinion? Thoughts?

Rgds 

Jesper

Last edited by JayZ
Original Post

I bought a "taller" 5th gear for about $500 (used) and I think a R&P is about $2700.  I installed the .642 gear.  I got a good deal on it.

The guy I bought the gear from was going to the 3.77 (or maybe a lower ratio) R&P for the reasons you stated.

One (minor) consideration is that if you go to the taller 5th gear, you have to mill some material off the selector shaft.  This is an incremental cost.

I was inside my transaxle already, so installing the taller 5th was a no brainer.  But I don't have the 3.77 R&P experience to compare it to.

 

I think the taller 5th only drops the RPM by about 400-500 at 70 mph.  It's not a HUGE difference IMHO.

 

Rocky

Clearance_of_2-3_Shift_Rail_For_Taller_Fifth_gear

 

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Last edited by rocky

One needs to qualify which tall 5th they are referring to there's a 0.62, 0.642 and 0.655 all taller than the stock 0.705. IMO for highway cruising at the 70-80 mph speed the taller 5th makes a big difference, it was about $1500 to add while the box was apart for a rebuild if I recall.

If you have a stroker motor or a built engine with a lot of torque, you could swap to the 3.77 and a taller 5th.

Rocky,

You bring up a great point. Some of the "drone" is dictated by what has been done to the engine along with the exhaust system. I Bought a 06 Mustang with an after market exhaust system and traded it for 2 days later for another 06 with a factory exhaust. I don't like the "drone" sound. So maybe its more exhaust than engine? Don't know, just a poor boy trying to make a living!

Ken 

I had added the overdrive 5th in my last Pantera while I had the ZF out for some other work. My engine was just over 600 hp and had 180 degree exhaust. The RPM at between 75 to 80mph went down from 2800-2900rpm to 2200-2300rpm. I did not notice any droning although my exhaust was loud anyway, but with the windows up I did not notice any noise from gear box. Gear was about $1500 from RBT.

My Bora has the 3.77 R&P.  It is much better cruising on the freeway than my Pantera.  The Bora engine has plenty of torque from low RPM so it seems to push  the 3.77 well.  In city driving it seems that all the gears are much longer than the Pantera. Makes sense.  I think it would be ideal for me if there was a medium between the 3.77 and the 4.22.  That would work much better for the Pantera IMO.

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