I did a search on how much the stock rear end on these cars would handle, and I couldn't find a clear answer. I have a 86 Berlinetta thats getting a 350 dropped in, it will have a performer intake, mild cam, and underdrive pulley. The problem is that I don't know how much HP its gonna make, so I cant find out if the rear end will handle it.
The question is will the rear end be ok, and when do I have to start worrying about it? I know it depends on launching, and traction, more then anything. I dont have drag radials, and I wont be launching hard very often if I can help it .

 

This is the car that you're doing this for daily-driver, long-trip reliability, right? and this is some kind of "rebuilder" motor? which means it will have dished pistons with an extra .020" of deck clearance and smogger heads; for about 8:1 compression. This is NOT going to be any kind of powerhouse, I'm afraid. 250 HP, TOPS... oh wait, 251 with the pulley.

I don't see anything in the program that spells doom for the rear. Don't worry about it.

 

Is an UDP really not worth it?

 

Usually not.

If you REALLY want to know the truth, do 2 back-to-back dyno runs, with the ONLY change being the pulley.

I suspect you'll find very little benefit... certainly not the difference between breaking a rear end, and it surviving.

That's about like some guy that used to post here alot, and the first thing on his list of "mods", was "chrome exhaust tips", and then it was kind of downhill from there. He had smoke taillight covers, white side marker lamps, stuff like that. He wanted to know how much HP his "mods" were giving him. Don't be like one of THOSE, that resemble a certain cereal grain widely grown in eastern Asia.

 

theres not going to be a certain number or a certain answer on something liek this

too many variables and so forth are involved to give a certain number as the answer

variables include not only power output to the axle but traction, spline count, drivign habits, ratio(gearset- deeper ratios have less tooth contact between the gears and thereforea higher chance of breaking a tooth) and condition of components of the axle assembly, etc.

and so on


buy a lottery ticket

run it til it ever breaks, if it does then you need a better one

good luck

 

IMO the stock rear could handle 350 up to 400 HP. That is the 10-bolt 7.5/7.625. Your not going to grenade it with what motor you look to be swapping in there. I have 420HP and 400TQ and it has yet to let go. It had noises B4 the swap was done and still does. Thats been 4+ yrs ago. But if you have any noises coming from back there it might be wise to plan an update. Maybe a posi or locker you might want , some gears if you want and go ahead and replace the bearings/races and seals. Get some Timken bearings and SFK seals and stay with conventional gear oil (80W90 recommended) for street use. Hope you enjoy the new motor. BTW the underdrive is not a major HP gainer but it will help out.

 

lol, I was just thinking of getting an UDP because it made a noticable difference on my beretta with the 3100. So I thought I'd give it a try, but I think I'll spend my money else where. Not 2 minutes ago I got off the phone with a motorsports shop around here and they start port work on heads for $100 a pair.

 

As long as you don't do something Dumb & Stupid, I don't think you are going to make enough Horsepower/Torque to break the rear axle.