Rear end ratio too high

[smitty62]

My '68 currently has a 3:73 rear ratio (coil sprung) which is 'way too high for my purposes. What is the cheapest way to get to a lower ratio such as a 3:42 or even 3:08 since they won't work in the present housing? Anyone have a 3:08 to trade/sell within 100 miles of Winston Salem?

[kwmech]

Why won't it work in your housing? Swap out the gear set

[smitty62]

Series 4 housing-- 3:73 and up ---series 3 housing --3:42 and down. I have a series 4.

[kwmech]

That's right, I always get it confused with the dana 44 for some reason. Time to upgrade to a posi then

[weim55]

A drum to drum 3.08 shouldn't be that difficult to find, Especially if you've already swapped to a 5 Bolt pattern for disc brakes. If you're willing to spend the coin to have it set up in your housing, a used carrier with 308 or 342 should also be a pretty easy find. Toss a wanted ad here and I think you would get a response pretty quickly.

Steve weim55 Colorado

[RodnRudy]

I just went through the same dilemma and I ended up having to buy a posi carrier, 3.08 ring and pinion, new axles and bearings(mine were worn out). $1800.00 later and I've got a rebuilt rear! Good luck

[smitty62]

Due to expensive wheels on the truck, I need to stay with 6 lugs

[RodnRudy]

You don't need to change the housing just the carrier. That's what I did.

[jocko]

Why not stuff in an o/d trans. best of both worlds.

[smitty62]

That may be the way I have to go, Jocko. Trannys are not my strong suit- what 700r4 do I need to look for? I know there are strength and fit differences.

[ElKotze]

You are confusing housing with carrier. You just need a series 3 carrier and a ring and pinion set, I also recommend a master overhaul kit with bearings and shims to set up your ring and pinion. A limited slip carrier is about $450, ring and pinion about $200 and master overhaul kit also about $200, I like to use the one from Yukon Gears, comes with absolutely everything you need and great instructions. I just put 3.08's in my '68 and I love it. A healthy V8 has no problems pushing those gears and no need for overdrive.

[jocko]

There are plenty of vendors - personally I recommend Bowtie Overdrives http://www.bowtieoverdrives.com/cata...SUBCAT&CATID=B
If you want a mild one, it's $1250 (K-case is for 4x4s). If you want a pretty HD one, Level II might be a better choice, but shifts will be firmer. They can help with all the other junk that is required- TV cable kit, crossmember if needed, etc.

Can also go the junkyard route, but plan on a rebuild. Lotsa threads on here to help drive your choice. Btw, 3.73 with a 700R4 or 4L60 was the main rear for newer 1/2 ton trucks because it's just about a perfect gearing combo for regular street duty.

EDIT: for comparison, here's what the RPMs at speed look like for the various transmissions and gear ratios (shown for a 30" dia tire). Not sure what trans you have now, but even if a manual, if it's not overdrive, the final gear is 1:1, so the cruising rpms would be what is shown for the TH350/400/PG, etc.

If you leave as is, seems you're unhappy with cruising rpm (is that a fair statement)?
If you swap to a 3.08, you sacrifice bottom end torque at the expense of lower cruising rpm.
If you go the trans route, you get MORE low end torque than you now have and lower rpm for highway cruising.

[ct67_72]

its a bit more of an expense but it could be a good time to upgrade carriers to a limited slip. Otherwise you should be able to find a used series 3 carrier although the used ones Ive seen still arent cheap.
We have some specials on gears and limited slips right now. Let me know if I can help, or price anything for you.

[ryans69chevy]

Since you said cheapest I would just look for a whole rear end differential assembly. I bet you could find a used one from a junkyard or on Craigslist for a few hundred bucks.

Unhook your driveshaft and trailing arms and roll it out and roll the new one back in. Now you have a spare differential if you ever want to change it back.

Might just have to redo your u bolts and possibly drum brakes.

[smitty62]

That's what I would like to do but finding one around here is going to be a real challenge.

[BRL]

Originally Posted by ryans69chevy

Since you said cheapest I would just look for a whole rear end differential assembly...

That's exactly what I did because if I tried to set up my own lash pattern etc. something probably would have eventually exploded.

Went with a 6 lug :308 from a :411 removed from a truck in a salvage yard for around $250 or so.

U-bolts were a bear as I recall but it was well worth it.

Something I don't see mentioned very often is that with lower freeway cursing R.P.M.'s the engine should last a bit longer before needing a rebuild.

...and I don't get dirty looks from little old ladies passing me by while I'm in the slow lane doing 50 and the engine is screaming like it's about to come apart.

[special-K]

The cheapest way to go to a lower ratio is buy a used 3.08 rear and swap it in, sell you rear. Could break even. The cheapest way to deal with the problem of too high RPM on the hiway is slow down and enjoy the view or live with the RPMs these trucks ran since new. People didn't creep along in the slow lane in these trucks in the '70s. We are just used to everything with O/D now. I am running up and down the road every day in my '72 K2500 with 4.10s. 60 mph isn't so bad an RPM and the road belongs to all of us. If someone is driving slower in front then you have to slow down. There is no law that guarantees a person the right to drive as if there is no one else out there, nor is the speed limit a requirement. They are breaking the law driving that much "over" the speed "limit" you are traveling "under". You have the right to drive your chosen speed. They have the right to use the other lanes to go faster.

[smitty62]

????

[hewittca]

Originally Posted by smitty62

That's what I would like to do but finding one around here is going to be a real challenge.

There's a guy in Mooresville who has a ton of parts for these trucks. He posts an ad on Craigslist occasionally. I asked about rears at one point and he said he has a few. Might be worth seeing what he has. I can DM you his number if you like.

[old51sedan]

Originally Posted by smitty62

That may be the way I have to go, Jocko. Trannys are not my strong suit- what 700r4 do I need to look for? I know there are strength and fit differences.

I have the same problem with mine with the 3:73 gears. I just bought a rebuilt 200-R4 in install in mine. I went that way because it's a direct replacement for the automatic it has now. All you need to do is slide the transmission cross member back about 5" and everything bolts right back up. Driveshaft fits back in at same length and etc. You have a 4 speed overdrive.

[In The Ten Ring]

Originally Posted by smitty62

My '68 currently has a 3:73 rear ratio (coil sprung) which is 'way too high for my purposes. What is the cheapest way to get to a lower ratio such as a 3:42 or even 3:08 since they won't work in the present housing? Anyone have a 3:08 to trade/sell within 100 miles of Winston Salem?

Wow, I wish my truck was a 3.73! Mine is a 4.11 which gives me plenty of torque but a low top end. Of course, the hills in WV call for 4.11's.