And when those pieces go thru the ring & pinion gears....
CK5
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Need advice
- Thread starter Kyle1983
- Start date
rampage
3/4 ton status
Purely cosmetic. Just a flesh wound.
So the workshop confirmed it 2.73 gears.
Damn. 2.73 gears. 35 inch tires. Stock 700R4 tranny. And a 383 stroker pushing 350 to 400 HP.
Step 1. Replace both axle gears to 4.50. Can they remove the gov lock completely when they replace the gears?
Damn. 2.73 gears. 35 inch tires. Stock 700R4 tranny. And a 383 stroker pushing 350 to 400 HP.
Step 1. Replace both axle gears to 4.50. Can they remove the gov lock completely when they replace the gears?
bsgreen
1/2 ton status
Yes. They can just swap it to open carriers. IMO 4.56 gears will be perfect for that truck
The lower first gear of the 700R4 will help a lot with 2:73's,it wouldn't be as harsh on the transmission compared to a TH350 or TH400 with a much higher first gear ratio..but it is still hard to get a heavy vehicle moving with such high diff gears..good for highway cruising and better mpg at higher speeds,but low speed & pulling power suffers a lot..
I never realized the higher ratios like 2:73's and 3:08's that were probably the most popular "stock" gears had more teeth on the pinion and that equals more in contact with the ring gear,so that is probably why you rarely see a stock diff with any ring & pinion issues...the lower ratios have more torque to the axles and case and the pinion is not quite as beefy having less teeth,but it is still pretty rare to hear of one failing that wasn't related to bearing failure..
I never realized the higher ratios like 2:73's and 3:08's that were probably the most popular "stock" gears had more teeth on the pinion and that equals more in contact with the ring gear,so that is probably why you rarely see a stock diff with any ring & pinion issues...the lower ratios have more torque to the axles and case and the pinion is not quite as beefy having less teeth,but it is still pretty rare to hear of one failing that wasn't related to bearing failure..
Bummer, sorry. I went to 4.10's because I found an 89' 3/4 suburban with that gearing in junkyard. Took the front axle and rear axle, and swapped them in. Cheaper than re-gearing for sure! I have the 10 Bolt up front and 14 SF in rear.
If you are going to pay for new gears, I'd go 4.56's.
Any junkyards in Sweden?!?
Wow. That should go over 100MPH in 2nd gear! 55MPH in 4th gear is about 1000RPM (i.e unusable). Might as well leave it in 3rd at 1500RPM. Who needs overdrive?
Dropping to 4.56 is literally 2/3 more torque.
Dropping to 4.56 is literally 2/3 more torque.
CrpMag122
1/2 ton status
Sounds like you would be okay without a locker, but if you decide you want a locker or more of a limited slip I would suggest the eaton truetrac.
bsgreen
1/2 ton status
Yeah, that gear change is gonna be like driving a new truck
My 87 blazer had 2.73 gears with 31s. Would pull first gear to 40 mph if I stayed mashed on the skinny pedal.
I have 4.56 gears in the jimmy with 35s. Stock engine. Hunts 3rd and od at the smallest grade at 65mph. Wish I would have gone 4.88s.
I have 4.56 gears in the jimmy with 35s. Stock engine. Hunts 3rd and od at the smallest grade at 65mph. Wish I would have gone 4.88s.
My '81 G-10 van originally had 3:08's but the diff case got hogged out--it now has 2:73's with a TH350...
I have wound it up to 60 mph in first more than once..
Second gear will get you up to about 75 mph...when it goes into third,the 307 struggles to get it to go much over 80 though..
At 65 mph its only revving about 1800 rpms ..putting 235/75/15 tires on it made it even doggier...acceleration is about the same as my 6.2 diesel getting up to 65 on an interstate unless you wind it out and hold it in first & second manually..gas mileage suffered some,as the engine is always lugging,and not in its "sweet spot" as far as torque..
I have wound it up to 60 mph in first more than once..
Second gear will get you up to about 75 mph...when it goes into third,the 307 struggles to get it to go much over 80 though..
At 65 mph its only revving about 1800 rpms ..putting 235/75/15 tires on it made it even doggier...acceleration is about the same as my 6.2 diesel getting up to 65 on an interstate unless you wind it out and hold it in first & second manually..gas mileage suffered some,as the engine is always lugging,and not in its "sweet spot" as far as torque..
But he’s got Stroka Powa!
Still going to hunt between gears. That burns a transmission up fast.
Never had a problem with mine on slight grades looking for third at 65.
I am no expert just giving my .02 I've had dealings over the years with multiple trucks that had 35" tires and 700r4 transmissions with 3.08, 3.73, 4.10, 4.56 gears in them . If I was paying to swap gears minimum would be 4.56 and as said above I would also agree going 4.88 . I have one now with 33's and 4.10 I am swapping in a set of 4.88 axles I already had built for another project,at some point knowing the next set of tires will probably be 35". I would personally be only driving that 700r4 out of OD with those gears and tires .
sfazekas
Registered Member
My ‘72 Blazer has 35” tires, carb’d 350 w .30 over, headers, pretty sure 3.73 gears and a hydraulic lockup on 4th on my 700r4. I just got it back Thursday (had done the trans swap w/upgrades and 2000-2200 stall) and took it for a test drive - it ran and drove just fine initially during stop and go traffic - then it seems the throttle valve body inside seized up after I got it up to 50 mph...
Troubleshooting on the governor was done by the installer and determined the issue was internal and not up shifting. I tried a few suggestions on freeing the valve body. I’m taking it to the trans builder next week. After I get it back and shifting again, I can tell you all how it does cruising...
I don’t plan to off-road it at all, so I think the gearing is ok, but based on the thread responses, I’ll consider doing the gearing update to 4:10, 4:56 for better torque.
Troubleshooting on the governor was done by the installer and determined the issue was internal and not up shifting. I tried a few suggestions on freeing the valve body. I’m taking it to the trans builder next week. After I get it back and shifting again, I can tell you all how it does cruising...
I don’t plan to off-road it at all, so I think the gearing is ok, but based on the thread responses, I’ll consider doing the gearing update to 4:10, 4:56 for better torque.
Thanks for all the help guys, you are truly a big help. So the workshop will swap the gears to 4.56 or 4.88 but it will be close to $2k. Parts and work hours.
Then I will pay to have a lockup Harness kit added so the vehicle can go to overdrive. And a transmission specialist will add a new pressure spring in the transmission. Looking at about 2,500 for all that. He said he can do a couple cheap upgrades in the tranny and I won't have to worry about destroying it.
I never knew when you switch the back axle gears you had to do the front as well. But I'm also new to all of this.
Any idea how to tighten up the steering? I feel like I'm driving a bumper kart trying to keep it straight on the road.
Thanks again!
Then I will pay to have a lockup Harness kit added so the vehicle can go to overdrive. And a transmission specialist will add a new pressure spring in the transmission. Looking at about 2,500 for all that. He said he can do a couple cheap upgrades in the tranny and I won't have to worry about destroying it.
I never knew when you switch the back axle gears you had to do the front as well. But I'm also new to all of this.
Any idea how to tighten up the steering? I feel like I'm driving a bumper kart trying to keep it straight on the road.
Thanks again!
We have to see what you have as far as lift and ask you to do a few tests and we can steer you in the right direction.
Pun intended
Both of my K5s are manual trans. The '77 has 3.73 with 33inch tires, the '79 has 2.76 with 32inch tires. The '79 ratio is terrible in the mountains and am planning to swap front/rear axle/diff and springs soon. Most of the time I start rolling in low (not 1st) unless I'm headed downhill or it's really flat.
