35" tires with 3.73 gears

[jlindquist]

I currently have 3.73 gears pushing 35" tires down the road. I am considering upgrading to 4.56 gears but am afraid I will lose my 65+MPH highway driving ability. I was curious what options, if any, I may have to possibly add a fifth gear to my stock 4 speed manual transmission.

Any thoughts?

[SeventyOne]

split the difference and do 4.11s?

Do you not like the sluggishness off the line with 3.73?

Seems to me a trans swap to get that 5th gear would be the most work of your options.

[Lieferson]

Im running 3.73 with the sm465 and 35s, it goes pretty good for me. I agree with the above statement though. move up to 4.10s and you should be good to go

[PSYCHO_OUTLAW]

Originally Posted by Lieferson

Im running 3.73 with the sm465 and 35s, it goes pretty good for me. I agree with the above statement though. move up to 4.10s and you should be good to go

My blazer has pretty much the same setup but I am running 33s. However, I feel like on the highway the RPMs are way to high. At 65 MPH i am at 3500 RPMS continuos. Which I feel is way to high. I have thought about getting a NV4500 for the 5th gear set up. I am also swapping to 3/4 ton axles and I believe the rear is 4:10 or 4:11. I feel like that setup would be more suitable for hwy/street

[hemi43]

Originally Posted by PSYCHO_OUTLAW

My blazer has pretty much the same setup but I am running 33s. However, I feel like on the highway the RPMs are way to high. At 65 MPH i am at 3500 RPMS continuos. Which I feel is way to high. I have thought about getting a NV4500 for the 5th gear set up. I am also swapping to 3/4 ton axles and I believe the rear is 4:10 or 4:11. I feel like that setup would be more suitable for hwy/street

3500 RPM @ 65MPH ? How is this possible ?

[PSYCHO_OUTLAW]

Originally Posted by hemi43

3500 RPM @ 65MPH ? How is this possible ?

I am not sure.. but it def dont seem like it will be good for the truck in the long run.

[jlindquist]

4.11's may be the easiest, most cost effective way. Doesn't seem like much of a jump from what i have. Do you think i will see a noticeable change?

[rsavage]

Randy's calculator shows 2565 rpms at 65mph with 35" tires with 4.11 rear gear

https://www.ringpinion.com/calculators/Calc_RPM.aspx

[Mike C]

Transmission? 3.73 and 35's should be a decent combo. I run 35's with 4.10 and SM465 in my Jimmy. The Jimmy we are screwing together for my teenager is getting 3.73 with a TH350. With converter slippage, they are both probably equal in terms of highway RPM.

Maybe a cam swap to get a little more cruising RPM torque will make the difference and a lot cheaper than swapping gears in both ends. Dual exhaust, HEI and good tune.

[jlindquist]

Originally Posted by Mike C

Transmission? 3.73 and 35's should be a decent combo. I run 35's with 4.10 and SM465 in my Jimmy. The Jimmy we are screwing together for my teenager is getting 3.73 with a TH350. With converter slippage, they are both probably equal in terms of highway RPM.

Maybe a cam swap to get a little more cruising RPM torque will make the difference and a lot cheaper than swapping gears in both ends. Dual exhaust, HEI and good tune.

It’s a stock 4 speed. I have a newer crate motor with a mild cam in it now. The diffs are stock and due for an overhaul (bearing and seals), so I might as well replace the ring and pinion while I’m in there
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[Mike C]

I did ring and pinion swaps in my truck in the late 80's. I think I broke the 12 bolt in some way 8 or 9 times? My truck has a semi-float 14 bolt from an '86 3/4 ton Suburban and we just pulled a set of 3.73 geared axles from an '84 Sub for my kids project. Both of the 9.5" axles have Gov-Locks in them and we are putting a TransAm clutch posi in the front of his.


I can't see spending $1000 to re-gear your axles and less it is REALLY important to you. But you can probably find a beater Suburban and pull the 8 lug axles from it. (I paid $300 for the 4.10 equipped truck that was equipped with HD towing an TH400. The 3.73 truck had a TH700R4 and was $200.)

As you can see, if it were mine I would also be looking for a strength upgrade at same time.

[jlindquist]

Originally Posted by rsavage

Randy's calculator shows 2565 rpms at 65mph with 35" tires with 4.11 rear gear

https://www.ringpinion.com/calculators/Calc_RPM.aspx

This is a great tool thank you
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[jlindquist]

i was hoping i could get by with one of these, but with the short wheel base, the driveshaft angle would be too extreme. These add 13" to the rear of the transfer case. The NV4500 may be the best option long term.

http://www.gearvendors.com/4x4.html