hey i was woudering if i can use a lsd/diff out of a automatic and throw it in to a manual rear end? i have a base model s4 and i might get a auto gxl diff/lsd.

 

Yes.

The gear ratio will change however from 4.10 to 3.90. You can always swap over the ring gear while you're in there.

Good luck

 

how hard would that be??? is it something i can do or do i need a shop to do it?

 

You'll likely want a shop to do it in order to set the backlash. Otherwise, you risk destroying the r&p, which could either happen quickly or over time.

 

about how much are we looking at?

 

by that i mean is that something that takes a like an hr or are we talking about a few hrs of labor?

 

Under an hour to set backlash.

 

My car was an auto and I put a manual tranny in it but I kept the auto rear. I figure its not that huge a difference between 3.9 and 4.1. If I were going to go through the effort to change it I'd go with the 4.33 from a GTUs, though they might be harder to come by.

 

Should pony up some money and get a 4.88 or a 5.12

 

Who makes a 4.88 that will go in our diffs?

 

i personly would rather stick with my gears now because i am used to it. i plan on drifting this car so i just dont want to keep on dumping money and wind up killing my car because i dont pratice. once i get it down better i might bump to an after market r&p set up

 

I'm pretty sure there is no such thing as an automatic LSD rear...

 

lol hey alex i was talking about a lsd rear end out of a automatic car. not a automatic locking rear/lsd

 

if i am going to keep my gears the same but use just the lsd doesn that mean i will have to buy any thing new ie barrings..... internal stuff?

 

ISC Racing used to.....but they were expensive

I think $2.5K for a new LSD setup outright?

 

If you are going to drift you for sure don't want to use an auto diff. the 3.9 to 4.1 ratio is a big change you will need more RPM to keep tires spinning making your motor work harder than it is already. it would be easier to drift a car with a higher gear ratio since at a lower MPH you are at higher RPM 4.33 GTUs diff is sweat just a comparison with a 4.10 stock diff at 80MPH you are at 3000 RPM with the 4.33 GTUs at 80 you are at 3500-3600 rpm so figure it out.


my boy has a 4.33 one in his ford V8 swap with a stock AOD and that thing drifts like a beast he spins out more than drifts but when he gets it right ohh boy

 

That's also because the GTUs has a different 5th gear. If they had the same 5th gear, you'd only see 3150 rpm at 80 mph.

There are two reasons why you want a higher final drive gear. First is that you have more acceleration in every gear. Since our cars with stock power come nowhere near what the gear top speed is, you can increase the final drive significantly before you run into any problems. For example, you could have a 5:1 gearset in the back and you still wouldn't top out the gears. The 2nd is that at any given speed in the right gear, you're more in the power band with a higher gear, than a lower gear, allowing you to control the drifts easier with the gas pedal.

 

i was under standing that i could just use the lsd but keep my r&p it would keep my gears the same this true?

 

?

 

yes about the r&p......for clarification, auto's didn't come with LSD, unless they were j-spec, even that I'm not sure about. NA-spec autos came with an open differential.

 

I'm using a diff from an AT in my manual. Like has been mentioned before, you wouldn't want to use it for drifting. It's better for high speed driving and better gas milage. I swapped in an LSD from a GTU, but it was so worn out that it didn't make a difference. I'd recommend putting a torsen in instead. If you're going to drift, you'll prolly wear out the stock LSD clutch pack often.

 

^

OP is using his old r&p, so no benefit for cruising or highway driving.

 

I know. What I meant was that I didn't think that there was an automatic FC offered with a 3.9 LSD rear as an option.

 

o i see sorry alex i missunderstood you. thanks guys. i guess this forum is pretty much closed i think.....

 

Looking at the options sheet for 88's it seems that you could get a GXL (which has LSD standard) and get an optional automatic transmission. Still, I've never heard of 3.9 LSD's on these cars. Anyone else know if any autos came limited slip 3.9 or did they get a 4.1 too?