2.75 Gears in a 2wd: Driveable?

[BigSky71]

I just got my truck back together and driving again. While apart I installed a Ford 9" rearend so I could run different offset rear wheels. When I had the third member out for inspection [sorry about all the Ford talk] I thought it was geared at 3.55, but now that I have driven it I know it has 4.10s which I thought was cool for about 10 minutes until I drove down the highway at 3,400 rpm just to keep up with traffic.

I have another 9" with 2.75s that I could pop in. Do you think the truck will drive ok with 2.75s and my 28.5" tires? My 350 is mild but fresh, and I don't need to drag race, just wanna cruise. Tranny is TH350.

So you think the gears would work or will the truck be so slow just getting around that I will hate it?

[jhow66]

Should work just fine. It just will not do a full block burn-out--just a 1/2 block.

[BACKYARD88]

I had a mild carbed 350 in my 88 short Chevy. Trans was a 5speed but that shouldn't make much difference. It had a 2.73:1 gear and there are folks that still talk about how quick it was. Not to mention downshifting to third at 80mph and leaving like a rocket

[davidh]

some of the trucks in the 80s had 2.73's even had somene tell me of one with 2.56. Highway runners. not bad for cruisers

[corn]

How do you tell you have 4:10's just by driving?

Oh & my truck has 3:07 gears, not a whole lot different. I think you will be fine with yours. Easy to change them in a 9" so you can swap them back and forth often if you get bored.

[Ackattack]

I had 3.08s when I first put in my 700r4. It ran OK but kind of a dog on the highway. Now with 3.73s its very comfortable. That gives a final drive ratio of 2.61 so I think you should be ok

[WorkinLonghorn]

I think it will be a dog. I had 3.08 with 33" tires once,with a very potent RV cammed 350 and a 465 truck 4spd and it really only had one good gear,2nd (3.58-1) then the shift to 3d....... end of fun. 1800 RPM at 60 in 4th. Ended up getting 10 MPG freeway,which really sucked. I don't think you'll be happy with it (the 2.75).
I say put some 33s in back and get your RPMs down AND get that sporty raked look.

[Longhorn Man]

It's right on the fence... might be too low, might not.
Pop it in and see what happens. You can always use one of the two as trading barter.

[davidh]

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I think it will be a dog. I had 3.08 with 33" tires once,with a very potent RV cammed 350 and a 465 truck 4spd and it really only had one good gear,2nd (3.58-1) then the shift to 3d....... end of fun. 1800 RPM at 60 in 4th. Ended up getting 10 MPG freeway,which really sucked. I don't think you'll be happy with it (the 2.75).
I say put some 33s in back and get your RPMs down AND get that sporty raked look.
__________________
thats comparing apples to oranges, 33in compared to 28 in tall tires, It wont be a hot rod but I bet he likes it if he cruises the highway

[Longhorn Man]

I had 3.07's with 10 inch wide 28 inch tall tires in this truck;


It still haulled ass. nothing but a cammed out 8 to1 comp 350.

[jimfulco]

You'll probably be OK with it. I have 2.73's in a '79 Suburban with a stock 350, and it's kinda doggy, what with probably 3/4-ton more weight than you have, but it's not totally undriveable, it's just kinda slow. But gas mileage increased a whopping 10% over the 3.08's, up to an amazing 11mpg.

I had 33" mud grips on my '69 SWB years ago, with an also stock 350 and what I believe are 3.07's, and it was very driveable and quicker than it looked.

[BigSky71]

Originally Posted by corn

How do you tell you have 4:10's just by driving?
Oh & my truck has 3:07 gears, not a whole lot different. I think you will be fine with yours. Easy to change them in a 9" so you can swap them back and forth often if you get bored.

I can't say for certain that the gear set is 4.10, but the vehicle I got it from came with either 4.10 or 3.55 stock, but that could have been changed in the last 25 years!

Originally Posted by WorkinLonghorn

1800 RPM at 60 in 4th. Ended up getting 10 MPG freeway,which really sucked. I don't think you'll be happy with it (the 2.75).

I think I would like it to be 1800 at 60mph, as long as it will get away from a stop light quicker than a 68 Beetle.

Originally Posted by Longhorn Man

It's right on the fence... might be too low, might not.
Pop it in and see what happens. You can always use one of the two as trading barter.

Yea, easy to change the third member out, and it will be a nearly free test, just a gasket and some gear oil.

Originally Posted by jimfulco

You'll probably be OK with it. I have 2.73's in a '79 Suburban with a stock 350, and it's kinda doggy, what with probably 3/4-ton more weight than you have, but it's not totally undriveable, it's just kinda slow. But gas mileage increased a whopping 10% over the 3.08's, up to an amazing 11mpg.

11mpg huh, that's about what I get now, maybe it will improve with the 2.75s, I can always dream .

I will clean up the other rear end, pull the carrier, throw it in and see how it drives!

[Ackattack]

oh yeah, I picked up fuel mileage when I switched from 3.08s to 3.73s....14 to 16 mpg


BTW, my corvette cruises down the highway at 60mph at 1400RPMS!!!

[edmonton72]

I wonder what the 3.42 gears in my truck would be like going down the highway. Plus who cruise down the highway at 60, 70-80 man, i got a heavy right foot.

[skokie]

Originally Posted by edmonton72

I wonder what the 3.42 gears in my truck would be like going down the highway. Plus who cruise down the highway at 60, 70-80 man, i got a heavy right foot.

My 01 GMC Sierra has 3.42s and its 2grand at 75. That is with the overdrive though.

[BigSky71]

Originally Posted by skokie

My 01 GMC Sierra has 3.42s and its 2grand at 75. That is with the overdrive though.

Yea, my 02 Sierra has 4.10s, so I drove around in third for awhile to see if the rpms at speed matched what my 67 is doing, and its real similiar.

[LUV2XCLR8]

Originally Posted by BACKYARD88

Not to mention downshifting to third at 80mph and leaving like a rocket

My "Firechicken" had the same gear ratio, pretty quick off the line,
but from 80 to 140 it was like a jet plane. Man that car was fun

[WorkinLonghorn]

Ackattack says:

oh yeah, I picked up fuel mileage when I switched from 3.08s to 3.73s....14 to 16 mpg

Yeah,there's definately something to that. I think it depends on the motor ,but mine is happy at between 2300-3000 and returns 15.5 MPG Hiwy. ( And the crowd goes WILD!) I don't know if it's the cam or the over-square bore and stroke or the heads or what but I don't think a 350 does too good under 2000 all the time.

[BigSky71]

I swapped in those 2.75s and the truck is so much nicer to drive on the highway. I did lose some off the line, but less than I expected. It is a total cruiser now, but that is what I intended to build, so I am way happy.

I recounted the gear set that I had in before which I thought were 4.10s, well they were 3.50s... sooo I think my truck stock must have had 3.07 gears, because the 3.50s in the 9" we not good on the highway and the truck did cruise nicely before with the 12 bolt, so that's my theory anyhoo...

[Jtrux]

Good choice, I would of done the same thing. A friend of mine has a 77 ford f 150 with a 468bbc and a 700r4 and his had 2.75's in it but he swapped to 3.50 and his runs great but that's only because he had the 700r4. BTW, that truck is f&^#ing fast.

[hemihead]

Lots of good opinions here....my .02...if its a cruiser and you are not looking for tire smoking performance it will work great. If you are more interested in the performance side and not about saving gas and just getting from point A to B then you will probably not be real impressed.

Had this same set-up in a 75 olds cutlass...no real impressive off the line but would hold first to 50 MPH and shift into third at 80mph. Anything over 25 MPH it was fun.

[gotchevys?]

Its a 9 inch, so it shouldn't be a problem to just swap them in and try them out. You will probably be happy with the ratio for what you want it for. If not it shouldn't be hard to find someone to trade you a better gear for your 4.10s

[1970bowtie]

my dads 72 sprint (gmc's version of the elcamino) had 273's in it when he got it, it still had power and would still light the tires.hope that helps

[BigSky71]

Originally Posted by hemihead

if its a cruiser and you are not looking for tire smoking performance it will work great.

Yes, I am quite happy with it now. Its slower from light to light, but so much more fun to drive at 70.

Originally Posted by gotchevys?

Its a 9 inch, so it shouldn't be a problem to just swap them in and try them out. You will probably be happy with the ratio for what you want it for. If not it shouldn't be hard to find someone to trade you a better gear for your 4.10s

It was a pretty easy swap, but I did have to swap the yokes, which I was worried would throw the gear lash out of adjustment, but I just torqued the yoke nut back to 175ish [my biggest torque wrench only goes to 150] then checked the pinion preload by using and inch lbs torque wrench to spin the pinion. Anyway its all back together, works great and no gear whine!

[Pyrotechnic]

I got a Turbo 350, 2500 stall converter, and 3.08 gears. The best way I can describe it would be like having a powerglide and 4.11 gears, but a gear vendors overdrive as well for a 3rd gear. For just cruising around town under 50 I just leave the shift lever in 2nd. With a stock converter, it would be a dog, but the 2500 stall converter helps a lot and it's stalled by the time I hit highway speeds.