gear ratio ?

[jakeblues652]

so ive had my 67 for a couple of weeks now, and you can't get that thing over 60. when i say you can't, the needle wont go a touch over. its a 4 speed. any way of getting the gar ratio without going into the housing? i was at the parts store today..15 bucks a quart for synthetic gear oil. also, the previous owner told me it was posi if that helps.

[bfay17]

If it were mine i would spring for the gear lube and pull a cover just to check everything out and count some teeth. (Did this in my 70 and found 4.56's) May cost a little bit but then you know exactly what you have and the shape its in Just a little peace of mind

[jakeblues652]

thanks for the advice. the problem is if i do it in the back, i want to do the front too (4 wheel drive gets used a lot around here) and you figure 2-3 qt per case and you got 90 bucks each, so 180 just for gear oil, before the gaskets. a little pricey if you ask me.

[donut]

Jack up the rear (neutral). put a mark on driveshaft and one on a wheel. rotate the wheel once and count how many times the driveshaft turns. iirc this should give you the ratio.

driveshaft just a tic over 4 turns, 4.10. 41/2 turns 4.56. This is going off memory, personally I haven't done it in a few years. Ideally, you'd count teeth.

[Stocker]

$15 is too much for a quart of synthetic gear oil -- look for a different brand, check at other stores, or just go with dino. Probably worth changing since you recently got the truck and don't know when it was last changed.

As to gear ratio, this is the method I use -- I'll quote board member raycow from a previous thread.:

Re: How do you calculate your gear ratio?
You don't have to take off the cover unless you really enjoy draining the oil, getting yourself greasy, scraping off the old gasket, etc.

Put matching marks on the pinion yoke and differential housing. Jack ONE rear wheel off the ground, put the transmission in neutral, and the parking brake off. Turn the wheel exactly TWO revolutions and count how many times the driveshaft turns, estimating any fractional turn as closely as possible. That number is your axle ratio.

If the wheel is difficult or impossible to turn, you may have posi. In that case, jack both rear wheels off the ground and turn either of them only ONE revolution. Count the driveshaft turns the same way as for an open rear.

Ray

[bfay17]

Not trying to be a A$$ here but your looking at 6 quarts of lube which at 15 a quart would be 90 for the front and rear axle. I was always taught to just use black rtv for the gasket. I'm not saying that my way is golden or that you shouldn't use the gasket I'm merely saying what i was taught. Even with gaskets you shouldn't be much over 100 for it all i wouldn't think. Like Stocker said though 15 a quart is crazy even for synthetic. Not trying to start a fight here either so If i offended you I'm sorry and i will delete my post.

[jakeblues652]

yeah, i just thought 90 bucks was a little crazy...and i was always told to never reuse the gaskets, and use gasket sealer sparingly on them just for the best seal. but it changes from person to person i guess. and this truck, i want to cut as few corners as possible.

[Redcap]

Originally Posted by jakeblues652

yeah, i just thought 90 bucks was a little crazy...and i was always told to never reuse the gaskets, and use gasket sealer sparingly on them just for the best seal. but it changes from person to person i guess. and this truck, i want to cut as few corners as possible.

Use RTV instead of gaskets and get a decent quality dino oil.

[bfay17]

I completely understand not wanting to cut corners. If you use the black rtv you dont even need a gasket it will set it up very nicely. I just use a 1/4 to 3/16 thick bead around the whole cover and i havent had one leak yet. Again im not saying its the only way to do it.

[jakeblues652]

well, its posi. found that out today. and also did a little test. 10 miles per hour maybe 13 if you really rev the pi** out of it. thats in second.so im thinking either 4:10's or 4:56's. either ratio, im happy.

[Mike C]

Are you saying your motor is done at 60 mph? And you have 35" tires? With 4.10 gears in my Jimmy and 36" Wrangler RTII (exact same height as the 35" BFG's I took off) I do 2500 rpm at 60 mph. Do you have it stuck in low range or something? That would seem likely with 5000 rpm at 60.

[jakeblues652]

the speedo reads 60, which is closer to 65 with the tires. its about 5 mph slow with the mechanical speedo. and i bet its at 3200-3500, but thats the top end for me at highway speeds. i dont like cranking out that many revs with an old motor.

[oldblue1968chevy]

Gee with stock tires at 60 mph im EASILY running 3k + lol This is on a C10 (2wd) I just discoverd this board so I thought id post

[Stocker]

Originally Posted by oldblue1968chevy

I just discoverd this board so I thought id post

[jakeblues652]

Originally Posted by oldblue1968chevy

Gee with stock tires at 60 mph im EASILY running 3k + lol This is on a C10 (2wd) I just discoverd this board so I thought id post

do you know your ratio, cause that sounds like my truck, but luckily i have 35's