Final Drive Swap Break-in
 

So I just got my final drive swap. I'm currently doing my break-in atm

First one was drive for 15-20 mins and sit for an hour
Second drive was about 30 mins and sit for an hour
I really had to get home so I drove in traffic for an hour and a half.

Question is, is the traffic bad for break-in when you swap out your ring and pinion? I still have my torsen LSD, only did a final drive swap. How high should I rev? Should I shift at lower rpms than 3k?

As far as I know, differentials don't need any special break in.

Least wise, back in the day, they didn't.

humfrz may be wrong on this .....:bonk:


humfrz

Would still love to have everyones opinion :x

The people @ corner3garage were like yeah you don't need to break anything in you can go hard it cause I didn't swap out my LSD and only did a final drive swap. It sounded really sketchy..

as I'm driving I hear some chattering noise while accelerating slightly, I also hear a slight howl when I turn right =/. I'm not sure if it's just me being paranoid or there really is something wrong. I feel as if the shims are loose and shaking

Get it looked at. I did a 500km break in period where I just didn't push too hard.

Mine has made no noise and has been perfect from when I drove it away after the swap. Diffs are pretty specialist work. If you used a mechanic that has hardly done any they may not have done it well.

Did you have the pinion bearings replaced at the same time?

they work on nissan diffs a lot and apparently the FR-S is 20x more work. I honestly had a gut feeling that it wasn't gonna go well either. I'm now around 50 miles.

Anyone in socal that did the swap wanna compare sounds so I can have a peace of mind?

Here is some more information ...... see, I told you ol humfrz was not always right ...... :(

https://www.marlincrawler.com/tech/d...re-information


humfrz

PS - after further looking into this ....... I figure your differential is mostly broke in by now.

However, you may not want to climb up Pikes Peak with your new differential for another 500 miles.

yup, I read that as well. I'm still scared as shit lol this is definitely a specialist

Ahh....I suggest you relax and enjoy your new differential. After all, the ring and pinion come as matched sets and as long as the tech put them in straight ..... they will get used to each other just fine ....... especially transferring less that 150 ft lbs of torque.


humfrz

The chattering noise could have something to do with the backlash between the ring and pinion gears.

It shouldn't make any more noise than stock other than engine revving higher.

No more clunks, whines etc. If it is it has been done badly IMHO.

I didn't trust my dealer and had a race car builder do my swap.

Let's just hope the extra sound is just paranoia

I wouldn't think you would hear noises any more than the OE diff since you still have a torsen. If you are hearing noises it is probably because the backlash is not right. The ring and pinion has to be shimmed to mesh properly, and its not a simple thing to do. Guys that have been doing it for 30 years can do it by feel. Us normal plebs have to use feeler gauges and a lot of patience. Either way clunks and whines should be the same as your OE diff.
Break in is way more involved on a clutch pack diff, torsen diffs still require break in, but at least you can break them in on the street. Figure 8s while breaking in a clutch diff is pain in the ass.

What company did you get the final drive from? I remember there being comments about one of the companies (m-factory?) FDs that have a slight noise to them.