lol I wish the shop was that close to my house. I won't have time to drop off the car and pick it up. I will just go in for him to do the diff swap when he finishes with the gears. Hope am not disappointed by the gears after all this money that I spent lol. Thanks for all the advice man.

 

Now it sounds like you are so far away you will drive the car there and wait on him while he swaps pumpkins? Oh well, drive it 10 miles and at least stop somewhere for lunch. If he is a believer ask him if you should at least take a couple of "breaks" on the way home, like cut through a couple of towns to get some slower stop and go traffic. Read up on it and do the best you can. The reason most people claim that you don't need to do it is because you won't know for years and years if you shortened the life. If you totally ripped on it and drove for a few hours the first time 55mph you also might not make it all the way home before something went very wrong. I'd guess if you even take it a little easy you'll never know the difference in the long run. There are just some of us that do some things by the book because the manufacturer went to the trouble of telling you how to do it ideally. Find a happy medium and good luck. I think you will enjoy them too BTW if you picked them for any of the reasons listed in this long thread! I still am happy with mine 30,000 miles later...

 

Well he called me today informing me that my diff is ready with the 4.083 and everything. Now problem is this guy says he doesn't have a lift . I was under the impression that the $250 was for the swap and everything. I don't mind paying more but this sucks. So now I have to drive up there to collect my diff later today. I will bring it to another shop tomorrow to have them swap diffs.

 

I followed a break in procedure on my 3.9 fd and basically you just don't want to push it hard; do some decelleration also because it causes the other side (back side) of gears to contact, so my mechanic told me, cool down periods, do some reverse session/s like in a parking lot also (when nobody is around haha!), so I was told. I changed my gear lube after approx. 1,000 miles also just because I wanted the break in fluid and metal particles out.

One thing I always wondered about doing a gear "break in", what happens to the millions of brand new cars + trucks that are bought and just driven away? Nobody says a thing about breaking in your gears, just go easy on the engine for a while, etc. Those fd gears are also "brand new" and not much said about breaking them in. When we change fd gears now it seems like it's a big deal, may be or not. Still, I'd take it easy on them for 500-1K miles and like has been said, let 'em cool off before driving again. Good luck with your install. *It's hard to resist punching your car to test it out and I admit I couldn't resist once or twice during break in (made me smile) haha!

 

I have to say that $250 to install a new ring and pinion on the Z diff already out of the car seems scarily cheap (like no one bothered to replace any one-time use parts i.e. crush sleeve, pinion nut, all the ring gear bolts). Along with the fact that not needing all new shims to get the gears correctly meshed is about 1 in 1,000. If he has reused the crush sleeve and/or not shimmed the pinion depth and side to side carrier you can bet your going to have a loud, howling rear end that will quickly wear in the wrong mesh pattern and be permanently damaged.

I truly hope for your sake that this mechanic did everything right (actually shimmed and measured the gear backlash and pinion depth, replaced one time use parts) but from someone that has done the entire install them self, I can't see it for that price.

 

That's a pretty interesting observation you made there. lol I never thought about why the brand new cars don't need break ins. I will try my best to not test it out lol.

 

Another shop aamco transmission actually quoted me the same $250 for labor. They said another $250 to swap it on the car. A transmission shop recommended this guy because they said he would do a better job than they could. Btw the reason why both shops gave me such a low price is that I had a separate diff that was already off the car.

 

Understood that it is a separate rear end ready to be torn apart.

Did you drop this diff and gears off with any other components like shims, pinion nut, crush sleeve? Its doubtful that a shop that isn't z/g car oriented would have those items in stock laying around (dealership likely woulnt have in stock either).

Just trying to save you the anguish of losing all the $ you've put into it already. I can honestly tell you I spent over $2k on my quiafe and 4.08 gears in a spare diff pumpkin. That was doing all the setup myself with tools I already had but I replaced bearings, seals, all one time use parts. If he doesnt provide you a receipt of parts used I would not dare use it bc reusing a pinion crush sleeve, or nut is a major no no. Lots of people get away with reusing the ring gear bolts but that its advised to replace.

 

^ Good points! Yeah even the dealerships almost surely will have to order the correct parts needed as they would rarely keep shims, etc. in stock and you may need very specific sizes and any extra items like this ian99rt has mentioned; much easier/cheaper to get everything that you need at this point. This all is very critical to get the proper depth like mentioned above or it will be trouble. $250 is "extremely" cheap price and as mentioned I'd be hesitant unless I knew exactly how qualified this shop is; not just anybody that works on tranny's, etc. can do this procedure exact and it may take some trial and error; install, check, pull out ad/subtract shim size until the meshing is bueno!

 

Thanks for your concern guys. The day I dropped off the diff and gears he asked me for the above mentioned parts. I told him that I didn't have any. He sais that he would check it out and if those parts were needed he would contact me so I can order them online or he would get them for me. He contacted me 2 days later stating that everything was fine. There was a guy on here that did his swap, bmurray that didn't order that kit from z1 and had it installed at cin. So I didnt think much of it. Well picked it up today and he wasnt there so he called for me to wait till he got there. He explained what he did to it and that once installed the break in procedure that I should follow. This should be on the car tomorrow or monday. I would hope that he knows what he's doing as his shop only does gears and rear differentials, hence the name of the shop " Gears and Rears".

 

I agree with the above discussions and would be a little worried myself. I did my own because I did not trust anyone to do it right. But it is possible that if this is the only thing this guy does you could be OK! I can picture him stocking different styles of shims and crush sleeves so he is not special ordering stuff all the time but I don't know how possible that is to actually do. I know when I did mine, I took one of my shims to work and ground it down to the next size in the manual so I didn't have to spend $30 more on shims than I already had. Anything custom is possible. If anything sounds wrong at all stop driving the car and call him immediately. If you have gathered anything out of our advice you can tell that the important part is the first time you drive it. It's your first chance to either break it in or destroy it.

******See if the shop that does the swap will start it up and run it a little on the lift. Listen if anything obvious is wrong. Then have them go for a ride down the street and back if they have any experience at all with rears. Good luck!

 

Yes he had tons of diffs on shelves around the shop. I think he probably sells them too. He said he had one similar to mine. Yes I will definitely follow the break in as you guys suggested. Well going to attempt to get it done again tomorrow guys. Its so hard as I work everyday and most shops are closed when I get out

 

I special ordered my car and saw it unloaded at the dealer straight off the boat/port transport semi. It had exactly 10 miles on it from the Japan test track was what I found out. I've heard most other new Z cars had 10 miles on them. I would guess that this is part of the explanation about why I didn't have to break it in myself on that first most important run.
Then some of the other advice in the book seems to line up with some gear break in advice. Isn't there something in there about not running the same speed constantly, no cruise control? I always thought some of that advice was for brake pads but I know that those aren't real critical now. Engine could use a little care at first too.
But no drain interval listed is confusing. Must be just a little extra effort to check on it rather than be totally necessary.
And other types of vehicles I bet that once they hit a dealer lot most of them get test driven 5 miles at a time until someone buys them. And just because you know someone that would tear up a car on a test drive to see what it's got, most people do not do that. So maybe a majority of vechicles get somewhat proper break in by accident.

 

Part of our pre delivery inspection when new cars came in was taking them on a 5-10 mile test drive. Not sure if others do it.

I'm about to find out how 4.08 gears pair up with a 125 shot this spring. Waiting on a couple more odds and ends and for some tracks to open. I'll let you guys know how well or, most likely, how horrible it does. Pretty sure the stock geared pumpkin will be going back in.

 

That will be interesting to hear; mega power punch with that setup and I hope it works out well for you.

 

Finally swapped the diffs now guys. Trying to go easy on the gears in the break in stage. So far didn't really get on it so didn't really feel any difference. Going 45 mph in 4th am at 3k rpm didn't really check it before the install.

 

^You'll notice that at cruising speeds like say 70-80 or so, your engine rpms will be bumped up a couple hundred more. Nice that you got the install done and I hope that you enjoy the swap.

 

Thanks man. lol I hope I get more impressed once I get on it. Just wondering cruising stock in 4th going 45 mph about what rpm is that

 

Good to hear. I assume from the uneventfull response there must not be any concerns yet, like strange noises. I would hope a gear shop would be able to handle this for you. I would have reconsidered if there was one in my area but I like to do everything I can on my own too.
Your RPM will be 15% higher. I can remember 80mph in 6th is about 3000 vs. 3400.
If you drive lots of highway your mpg will go down because you are in 6th and higher rpm constantly, but if you are in town more you may not notice. In town you can usually drive one gear higher and it won't bog down at low rpm and you can average a lower rpm = better mpg. So for my conditions and driving habits on average I only lost 1 mpg from what I can tell. Depends on how you drive. Once you get it broken in the other benefit besides better acceleration will be being able to lug it around in a higher gear or even leave it in one gear more often around town. Do experiment with it a little because things do change with a FD swap. Continued success !

 

Thanks for your response. The installer did a great job no noise at all. And he actually gave me a discount of $30 so I paid 220 to do the gear swap. I got on it a bit and I seem to have a lot more trouble getting traction in first gear. Wider tires and a better lsd will come in the future. I am new to manual trans and sometimes I would jerk the car a bit at stop and go. Now it seems as if thats rarely happening. Much easier to move off. Is it the gears?