Today my friend was offering me an install kit for 3.73 gears for a 10 bolt rear. I told him that I was looking for more power (eventually doing a 350 tpi if I can ever find one in nj) and 4.11 gears. he thought that a 10 bolt would never hold up to the power of a 350 plus 4.11and that it would just blow apart immediately. I wont be driving this car daily anymore so id like to make it get-up-and-go quick but also don't want to rip the rear apart. Do you guys think a 10 bolt can hold a 4.11 ratio?

 

TPI will largely protect the rear from excessive stress, as long as no nitrous is involved.

Likewise, TPI will guarantee that the engine will not make enough power at the RPMs that 4.11 gears will force it to run at, for the car to be any faster than with a correct and reasonable gear choice; you'll end up with the situation where the car feels like it will stand up on its back bumper off the line, but will be ENTIRELY played out before it hits 10 mph, and won't even be able to pull out and pass a semi at 55 mph on a 2-lane road.

Yes they do make 4.11s for the 7.5" / 7.625" rear; so yes it will "hold" them. They fit right in. They even come stock in some applications (non F-body of course) of this model of rear.

The same basic rear comes in LT1 and LS1 cars, so if it can survive behind those motors, a TPI one will surely not be a problem. Gear ratio makes little difference to that.

 

+1

 

I have 4.56's in mine. Granted I have a 305 tbi.
Haven't had a problem out of them yet. I can tell passing at 55 is no problem at all, all kinds a power.
The problem you will have is how high your tach will be. 75 80 mph my car is pretty close to redline.

 

Dont go any deeper than 3.73s. They will live behind that motor or a 350 TPI motor. I never ran anything more than 3.42's behind an auto but I've been low 10's at over 134 with 3.42 gears, and 9.7's at 142 with 2.73 gears in a 4th gen 10 bolt. My buddy's heads/cam l98 has 3.90's and 28" tall drag radials and its living so far. Lots of street abuse and some track time as well. 60's in the 1.60-1.75 range depending.

Heavy vehicles and lots of power with sticky tires will frag ring gears/pinion gears. Higher gear ratios 3.73+ have less material on the gears and are prone to fail more so than 3.42 and smaller number gears.

 

I wouldn't go with anything pass 3.42s on a TPI/700r4 combo IMHO.

I do about 2300 RPM at 70MPH in the turd. The Z28 almost idles down the road, lol...

 

TPI based likes no deeper than 3.42 but I've seen them run ok with 3.73's...just over revving alittle by end of the 1/4 mile if you have any bolt on mods. 3.73's would be better for a miniram/stealth ram type swap where peak power is pushed up another 500-600 rpm and you have a 1000 rpm extended range to play with.

 

My 4.10's are holding up so far. I also put a Strange limited slip differential in, I have not replaced the axles but I always run radials on it so I'm not to worried about it. If I ever do go with DR's or slicks I will have to rethink all of that. I should have replaced my 26 spline axles with some 28 splines with the matching differential but it's to late for that now.

Mark.

 

ill let you know in april. i got a 450hp 331 sm block with a 3500 convertor and im spraying 125 shot outta the hole. all stock rear with 3:73's

 

Hmm..... Good luck with that!!

Mark.

 

It should hold. Mine held with alot more but 28 spline axles and 3.42's. Not sure what you have.

 

ran mine with 4.10... slicks... no problems....they were put in 17 yrs ago with at least 200 passes......best 60' 1.74

 

Thanks for the replies guys. Im thinking I may go with the 3.73's just so I don't have to pay as much in parts. Im just looking for better acceleration and speed but if 4.11's are better for something with higher redline then ill stick with the 3.73's cuz id like to just get a 350 with a cam upgrade and not too too much more

 

Also do I have to change the vss or the chip for when I changethe diff gears?

 

you can do 3.73 with the right speedo gears...... 4.10 requires a box or chip adjustment

 

so that would be the vss correct? im new to the car hobby so far. well not new but i still dont know a whole lot lol

 

as i recall the gears were 44 and 15 for the 3.73

 

Where do those gears go?

 

If you have an automatic the 4.10s will last for a long time. Manual trans well then you are asking for trouble eventually!
I had 4.10s in my bolt on M6Lt1 and i shredded the gears with a total of 9 passes 3 were on DRs then game over......

Worst part was my spare rear end was 3.23 however my new custom built 8.8 is almost done! No more 1500rpm launches for me time to leave on the limiter 6200

 

Tasty. Lots of talk about them over on 'tech.

 

get your vss calibrated right

 

I have a mild 350, pushing close to 310whp with plenty of TQ. Ive also got a 5spd, and my rear is a 10bolt with 3.73's. It handles the power fine and feels very nice.

I would say the rear will hold to around 500hp at the crank. Ive seen old rears hold less and rebuilt ones hold more.

It really all depends on the TQ. Some 350's can put out high HP and TQ 450+ at the wheels, I have seen other 350's pushing out less than 200hp and 250tq at the wheels. All depends on the way its set up