Faster rear end ratio for MC5

[lostagain]

Just got back from a trip South in the 5C, it ran very well, but used a lot of fuel: 6 m/USgal.

6V92/HT740. 11R24.5 tires. 65 mph at 2200 rpm.

I would like to know if a faster rear end is available.

When I used to drive MC5s in the '70s, some of them ran at 80 mph, some only 60 mph. All had the 4 speed manual. So is there 2 different diff ratios? Or were some of the 8V71s governed higher than others?

Wouldn't it be nice, and cheaper, to rev only 1800 or so at 65 mph?

JC

[luvrbus]

JC a 3:36 will get you there sounds like you are running 4:10 ratio,my 5 had a 4:10 ratio, the ring gear and pinion are available for the drop box set up from Pro/Gear or Global Gear, you may get lucky and find a 3:33 that is the ratio I used but they are getting hard to find now   


good luck

[Ed Hackenbruch]

JC, don't know if the C is the same as the A, although i would kinda think it would be.  My A came with the 3.36:1 as standard but they did have a 3.7:1 as an optional rear end. I run 1700-1750 at 65mph and have gotten as high as 8.2 mpg at times but overall average 7.29.   

[luvrbus]

Ed, the C if a auto came with 6v71, 4:10 gears was a option for that setup it needed all the help it could get lol but a lot of Canada Greyhounds 5 A and B's had 4:10 gears I had one and the 8v71 would scream but pull like a big dog 


good luck

[lostagain]

My 5C originally came with the 8V71/4speed Spicer. The 6V92/HT740 was swapped in by the PO. I have to get under her to grease, I will look and see if I can find a ratio stamped on the end of the pinion shaft. Does sound like a 4:10 according to you guys.

JC

[luvrbus]

You won't find it on the pinion shaft without removing the drop box JC


good luck

[lostagain]

OK I'll save removing the drop box for a more compelling reason LOL.

[TomC]

If you want 1800rpm @  65mph, with 11R-24.5 tires (476rpm) 3.55's will give you 1830 @ 65mph (my gearing on my truck), 3.42's will give you 1763rpm @ 65mph, 3.36's will give you 1732rpm @ 65mph.  3.55 and 3.42 are pretty common gears-3.36 might be a bit harder to find.  Good Luck, TomC

[artvonne]

  Is the ratio anywhere a guy can find it, or do you have to jack it up and spin and count?

  On a different note, anyone know what size the lug nuts are on a 5B?

[lostagain]

Mine are 1 1/2".

JC

[luvrbus]

JC, adding to your post about a gear change the 3:36 makes 3rd gear on the 740 wicked you will love that part lol I'll keep checking with the Eagle guys may be able to find you a good take out and if you have a 4:10 one doing a change over to the B500 and Cummins may deal you straight across the board they are looking for 4:10 gears 

good luck

[lostagain]

Thanks Clifford.

JC