Rear Differential Ratio

[whomadewho]

Have a 1993 Toyota pickup regular cab- 22re engine - 5 -speed with abs brakes. Aim running 10 wide -aluminum wheels,with 265x 75r 15 inch tires. THE QUESTION - What gear ratio is everyone using with over sized tires?? Aim not positive,but I think I have a 4:10 ratio. The vehicle is for highway - No off road use. Aim looking at going with a 4:56 ratio. - Looking for some feedback. The vehicle has front lock outs and I have not used - 4 wheel drive for along time,so for the immediate future,I plan on only changing the rear differential until I get the correct ratio. The issue Aim having, besides the speedometer reading 10 MPH ( slow) is the overall performance is lacking,and at 60-MPH the engine is laboring, the vacuum is at 11-13 inches. - Thanks in advance for any input.

[DeadlyPeace]

The tires you're using are only about 30.5" (if I recall correctly). You should be fine even with 4:10 gear (up to 32"). Don't remember the gear options for 93's. Did you just put larger tires on it? If you're having performance problems then you might want to check into the engine. How does it run?

[whomadewho]

Thanks for your quick response and input. The vehicle has 130k actual. The engine has 1200k on a complete overhaul - Ross pistons -bored .020 over -block resurfaced - head rebuilt with over sized valves - mild cam -headers - head studs -cam degreed ect. I moved the knock sensor because of the racing pistons. I realize the 22re engine is a truck engine, and with all the emissions and the poor quality and low octane fuel that I am pretty limited,but I was expecting better results. The engine runs great. The timing is set right and after hours of work,I finally got all the engine code issues resolved. The tires are only around 30.5,thats why I did not give it a lot of thought when I purchased them. That is the reason for the gear ratio upgrade,I feel I have reached the max. horsepower and output of the engine. The only other upgrade I can think of is the exhaust system. I have a performance muffler,but a stock catalytic converter. In your opinion, do you think I will gain anything by doing this. Is there any other upgrades you can think of that will help. Open to any ideas advice or opinions. Thanks in advance.

[DeadlyPeace]

What size exhaust do have now? 2.25"-2.5" works good. No bigger or you loose the back pressure that 22R needs. Your cat could be plugged up so depending on the condition and age of it you could replace it with a new high flow one.

[whomadewho]

THANKS again for your response. I have Pace Setter Headers with a 2.25 flange. The catalytic converter had a hole in it,so I replaced it with a non performance converter. The muffler is supposed to produce a deep sound but the exhaust is totally quiet. - Maybe to much back pressure? What is your opinion going with the 4:56 gears??.I found a set - front and rear for $250.00. My only concern would be going to LOW which would effect the top end speed. I running out of ideas. Aim almost ready to see a doctor and get a prescription for sleeping pills ,so I don't lay in bed at night thinking about ways to improve the vehicle performance.

[fourwd1]

The cost of regearing for 30-31" tires hardly seems worthwhile.
Your talking $500-750 for parts, maybe 2 hrs labor ea at about $100/hr.
And that's if you pull the 3rds and carry them in. If you have the shop pull and reinstall the diffs add 2-3 hrs labor each.
Now if you locate some used 4.56 3rds and do the install yourself it's a whole different story.

[whomadewho]

I found a set of front & rear carrier assemblies with 4:56 gears out of a vehicle from the government clunker program for $250.00. I can do the R&R myself. The end result is the issue. What I am looking for is information and opinions from someone who has - 30-31 tires with 4:10 gears and switched carriers to a 4:56 ratio,or someone thats running - 4:10 - 4:56 ratios with over sized tires, to get opinions and input on issues like low and top end performance,and what they would do or would have done different. Right now the master plan is to purchase and R&R the rear carrier only to see if this makes any difference. Thanks I appreciate any and all of the input and opinions.

[fourwd1]

4.56 is the ratio Toyota used for the factory 31" tire package. So yes, it will help.

[whomadewho]

Thanks for the input,I kind of thought it was. I purchased the rear carrier today. I am going to roll the dice and see what the change does. What is really frustrating I have close to 2 grand into the engine alone, my wife has the total amount from body work and the engine plus tax right down to the penny,she reminds me every time I open the hood. The engine runs great, but lacks performance. Changing the carriers is going to be the last thing left to try.

[DeadlyPeace]

Duct tape does wonders on a woman's mouth.

If the cats new then definitely go with the new gears, especially for that price.

[whomadewho]

YEAH I thought about using duct tape years ago, the problem is looks would kill before I got the job done, and after years of looking I still have not found any duct tap wide enough.

[whomadewho]

I changed the rear differential from the 4:10 to the 4:56 ratio this weekend. There is a totally remarkable change in performance. I drove the truck around for a half hour,and about a mile from home it developed a bad miss. I had a sick feeling when I drove in the drive way. I don't know which was worse,the miss or explaining to my wife that the engine needs to be torn down. I sat in the truck thinking the worst. I finally got the courage to open the hood only to discover a plug wire came out of the distributor. I found a front differential,so the next project is changing it out. What is everyone using for gear lube? I have been using Valvoline syn power in the differentials and transfer case. In the transmission I use ac delco synchromesh transmission fluid.