Anyone added 3.55's to thier LFX?

[C-redfly]

Trying to see what kind of difference it will make to go from the 2ls 2.92's to the 3.55's. Share some results if any.

[KMPrenger]

2LS ratio to the 3.55s would probably yield some pretty noticeable results.

But the 3.27s on the rest of the cars to the 3.55s isn't much of a jump...but still an improvement. I'd rather have 3.55s on mine than the 3.27s, but at the same time there is no way I'd pay that much for that small of a gain. 3.73s would be nice if available, but at that point the cruising rpms will start to go up a bit high...probably between 2,300 and 2,500 rpm. 4.10s great for the strip in an automatic, but I'd never consider it for my car.

[C-redfly]

Yea exactly. I got those 2.92's so I'm yearning for some 3.73's. I read in the ss a6 with 3.73's, you cruise at 2,050 and with 4.11's 2,250. Not sure how true it is but 2,050 is smooth on the highway with our LFX's. So I'm gonna do a rear swap soon to get the 3.73's

[etmx183]

Is your car an Automatic? If so let me know what you are doing for the swap out. My understanding that there is no easy swap out for the automatics due to the A6 driveshaft couplings Vs differential pinion flanges on the M6/SS rear. Thanks for any feedback.

Originally Posted by C-redfly

Yea exactly. I got those 2.92's so I'm yearning for some 3.73's. I read in the ss a6 with 3.73's, you cruise at 2,050 and with 4.11's 2,250. Not sure how true it is but 2,050 is smooth on the highway with our LFX's. So I'm gonna do a rear swap soon to get the 3.73's

[C-redfly]

I'm gonna look into it to get more details but ppl have definitely already completed the swap.

[butters]

3.73 for sure!

[lscamaro]

If the LFX is very different in the rear from the LLT then no one has attempted it. But if its the same, many have already swapped out their rear for the M6 from an SS. The person I remember doing it is member Asanti. He has a thread on how he did it and what parts he had to buy. If I remember right, he spent like 2000 dollars in parts. He did all the work himself so it might be more if a shop does it for you.

[BlackoutLFX]

The richmond 3.55 ring and pinion did not fit my LFX rear!!!! Ring gear is 1/4 inch thinner than stock and they don't make a shim kit to correct this.. I have a feeling it is a different series carrier. Jegs is taking everything back. Richmond called today but I was busy and missed the call. I should know something tomorrow. I went ahead and bit the bullet on the ss rear stuff for the swap. Meanwhile my wallet is 500 dollars lighter for getting my old gears put back in. Not happy with having to pay for the installation of a defective product. I bet they probably did not even look at a lfx differential before slapping a 2010 and up label on it. I feel I should get my money back for tthe mechanics bill..

[lscamaro]

The 3.55 wouldn't even have made a difference. I would of just have done the ss rear swap from the beginning.

Btw, damn a year old thread!

[Jason@JacFab]

Originally Posted by BlackoutLFX

The richmond 3.55 ring and pinion did not fit my LFX rear!!!! Ring gear is 1/4 inch thinner than stock and they don't make a shim kit to correct this.. I have a feeling it is a different series carrier. Jegs is taking everything back. Richmond called today but I was busy and missed the call. I should know something tomorrow. I went ahead and bit the bullet on the ss rear stuff for the swap. Meanwhile my wallet is 500 dollars lighter for getting my old gears put back in. Not happy with having to pay for the installation of a defective product. I bet they probably did not even look at a lfx differential before slapping a 2010 and up label on it. I feel I should get my money back for tthe mechanics bill..

That's very interesting... I wasn't aware of this as I had also purchased a set of Richmond 3.55 (which I currently have listed in the classifieds as I am changing directions, and bought them prematurely)... I am not aware of any difference in the GM 7.6" IRS rear end from 10-11 to 12-14. I purchased a 2011 3.27 rear from an LLT car to swap into my car (w/ the 3.55's), but now... wtf?

I'll report back on what I find once I jerk the stock 2ls rear out. Would be a shame if the 3.27 geared 2011 LLT rear end didn't fit for some reason.

Perhaps I will pull the cover off the back of the LLT rear and hold the 3.55 ring gear up to it for pictures. LFX rear comparison? That may have to wait a bit.

However, thinking back (not too far mind you)... You can/could purchase ring gear spacers for the old chevy 10/12 bolt rear ends. If the Richmond ring gear is indeed shorter than the LFX ring gear, for whatever reason, I would imagine a ring gear spacer may fix the problem.

Originally Posted by lscamaro

The 3.55 wouldn't even have made a difference. I would of just have done the ss rear swap from the beginning.

Btw, damn a year old thread!

It's worth reviving if there is some difference between the LLT and LFX rear that doesn't allow THE ONLY aftermarket "performance" gear that was made for the a6 v6 rear end that will allow it to work for one, but not the other. I bought the 3.55 thinking it would work... If it won't, but yet it's advertised EVERYWHERE that it does... That's kind of a problem.

[BlackoutLFX]

I am positive there is a carrier break and that they are two series. When they switch to the 2.92 on the A6 v6 they changed carriers as well. THis is from GM, and Richmond(Richmond just found this out yesterday. I am sure they are a decent product for 2010-2011, but why would you change from a 3.27 to a 3.55? Anyway the guy at Richmond hung up on me when I asked about being reimbursed for labor...called back voicemail...I'll pick ths up again monday...

ON A GOOD NOTE!!!!!! EVERTHING ORDERED FOR THE SS LSD REAR SWAP

[BlackoutLFX]

Originally Posted by BlackoutLFX

The richmond 3.55 ring and pinion did not fit my LFX rear!!!! Ring gear is 1/4 inch thinner than stock and they don't make a shim kit to correct this.. I have a feeling it is a different series carrier. Jegs is taking everything back. Richmond called today but I was busy and missed the call. I should know something tomorrow. I went ahead and bit the bullet on the ss rear stuff for the swap. Meanwhile my wallet is 500 dollars lighter for getting my old gears put back in. Not happy with having to pay for the installation of a defective product. I bet they probably did not even look at a lfx differential before slapping a 2010 and up label on it. I feel I should get my money back for tthe mechanics bill..

2.92 TO A 3.55 will make a small difference. 2012 a6 have 2.92 to help get 30mpg rating

[BlackoutLFX]

Originally Posted by RacnJsn95

That's very interesting... I wasn't aware of this as I had also purchased a set of Richmond 3.55 (which I currently have listed in the classifieds as I am changing directions, and bought them prematurely)... I am not aware of any difference in the GM 7.6" IRS rear end from 10-11 to 12-14. I purchased a 2011 3.27 rear from an LLT car to swap into my car (w/ the 3.55's), but now... wtf?

I'll report back on what I find once I jerk the stock 2ls rear out. Would be a shame if the 3.27 geared 2011 LLT rear end didn't fit for some reason.

Perhaps I will pull the cover off the back of the LLT rear and hold the 3.5 ring gear up to it for pictures. LFX rear comparison? That may have to wait a bit.

However, thinking back (not too far mind you)... You can/could purchase ring gear spacers for the old chevy 10/12 bolt rear ends. If the Richmond ring gear is indeed shorter than the LFX ring gear, for whatever reason, I would imagine a ring gear spacer may fix the problem.



It's worth reviving if there is some difference between the LLT and LFX rear that doesn't allow THE ONLY aftermarket "performance" gear that was made for the a6 v6 rear end that will allow it to work for one, but not the other. I bought the 3.55 thinking it would work... If it won't, but yet it's advertised EVERYWHERE that it does... That's kind of a problem.

Ring gear is 1/4 inch thinner than stock gear, Richmond does not have a solution...yet to this problem, because they only found out about it thursday....Not happy with Richmond.

[BlackoutLFX]

Originally Posted by BlackoutLFX

Ring gear is 1/4 inch thinner than stock gear, Richmond does not have a solution...yet to this problem, because they only found out about it thursday....Not happy with Richmond.

Works on the 3.27 carrier only. so 10-11's should be fine....