69 4 Speed gear ratios & axle ration

[englishrodder]

Hi,
Im thinking of swapping in a late 5 or 6 speed tranny into my 69 Burb. But before I do I want to check the gear ratio's that are on the standard 4 speed floor shift manual tranny.

Does anyone know the ratio's its 69 8/350 3/4ton Custom 20 ?
Also does anyone know what rear axle ration these came with???

Thanks

[qksilver]

If it has the glove box sticker is should be on there.
If not jack it up with both wheels off the ground. Turn the drive shaft 2 times and count how many times the wheels turn. Divide the # of times the wheels turn by two.
Or you can pull the diff cover off and count the teeth on the pinion and the teeth on the ring gear, Divide the smaller # into the larger #

[oldiron]

Mine came with 4.10

[4x4Poet]

It should have an SM465 with 6.32 first gear. 4th gear is 1:1 (direct drive: no overdrive).

If an Eaton H052 rear axle, the rear ring & pinion ratio could be 4.56:1 which sometimes came in camper optioned trucks to move the power band, so to speak, to handle the extra weight. qksilver covered the various checks, well.

[englishrodder]

OK thanks for the info, Dont know the version of the rear end has 10 bolts holding on the diff cover, but doesnt look like a normal "10 bolt" Chevy rear end but rather more substantial.

Blimey no wonder 1st is almost usless at 6.32! unless I want to pull a house!

Im assuming the Borg Warner Super T10 will bolt right up to my bell housing? but I will need to shorten the prop just been offered a good one cheap...

Cheers

[4x4Poet]

10-bolt and big sounds like an Eaton. Just look at the front of the carrier and see if it bolts on. If a drop out third member, it's very likely an Eaton.
Can you post a pic of it?

Here's a link with mucho Eaton info:
http://67-72chevytrucks.com/vboard/s...d.php?t=172827

[englishrodder]

Thanks 4x4Poet. Checked out the info and its 100% an Eaton...Hmm thats going to be a pain in the neck getting parts here in the UK:-(. Mine is leaking from the pinion slightly...

What grade of oil should I use and weight etc to top it up. Does it take normal hypoid???

[Beast388]

Your 4spd should be an SM465.....

L = 6.55:1
1st = 3.58:1
2nd = 1.7:1
3rd = 1:1

[4x4Poet]

Originally Posted by englishrodder

...What grade of oil should I use and weight etc to top it up. Does it take normal hypoid???

GL-5 75-90w or 80-90w.

Randy's Ring & Pinion sells the third member gear, bearing, & seal parts though the pinion seal might be commonly available. The bearings in the hubs are available through Timken dealers like bearing sales stores we have here. As are the hub seals. Auto parts stores also sell the bearing and seals as well as all the brake parts for the 11" brakes. 12" brakes are more hit and miss. AFAIK, the original hub bearings were barrel roller bearings. Replacement hub bearings are superior tapered roller bearings.