BRM 4.08 rearend swap now available!

[HeavyDuty]

I would if I could get a supplier for the bar itself - it needs to be aluminum, adjustable and have nice Heim joints...

Hey, if we're looking at modifying another application, let's pick one without rod ends & no adjustment, like the Cusco bars on my B13.

Seems to me those type of bars are designed to make up for a lack of precision & serve only to change the pivot points in the tower flex. Something like a Cusco or Comptech brace would be far superior.

[Q45denver]

I'm definitely interested. Just wondering how this upgrade compares with the cost of rebuilding a LSD and what the standard life expectancy is for an LSD? Also does anyone know if a 1996 driveshaft will work on a 1993 Q45? I'm thinking of replacing the driveshaft and transmission on mine with about 160K miles with a brand new one from a 1996 Q45 that I bought on eBay. Assuming I also replace the LSD with the 4:11 unit, how would I go about calibrating the speedmeter. Could I have this work done by a speedo shop? Will I need to get a 1994-1996 TCU to work with the 1996 transmission or will my 1993 TCU work ok? To add another monkey wrench to the mix, I also plan to install slightly taller (225/60x16) tires vs. the 255/50 that I am presently using.Sorry for all the questions. While, I am fairly certain all the above is doable, I just wanted to get an expert opinion as to how practical.

[maxnix]

1996 is OBD II, so good luck is all I can say. Transmission ratios are different, so a better match may be a 1994-1995 TCU.

Speedometer is not calibrated per se, but the speed sensor should be driven by the correct gear ratio matched to the differential.

225/60-15 are tall tires. May work well with the 4.08 rear end, but check clearances. I think there are some posts by Q45tech on this size being barely servicable on G50 Q45.

[EWT]

If I keep my 95 (which is looking more likely), I'd be interested. Is reprogramming of the TCU required to make things shift when they're supposed to?

[maxnix]

Not with the correct drive gear for the speed sensor.__________________Brian1995 Q45 & Q45t & 2000 Q45

Discover the power of the button!

[Q45denver]

AZhitman:

Did you give up on your Q45 / 300ZX rearend swap project?

[AZhitman]

Since this? Yes.

[HeavyDuty]

Q45D: "I'd you give up on your Q45 / 300ZX rearend swap project?"

AZ: "Since this? Yes."

Well if you're regearing Q diffs, then why shipped without stubs?

I'm game, AZ, I'll have to work on the timing, but mine's going south fast. Pardon the stupid question for those in the know, but are the stubs just retained with internal spring clips in a reveal cut in the spline of the stubs? Or a C-Clip type mounting? Something else? If so, leaving the stubs from the donor carcass would be a plus as well for the DIY'er. FWIW, of course.

Also, as Max mentioned, I'm curious about the balancing with respect to the OE (balance or imbalance) paint alignment marks on the driveshaft & pinion mating flange? Muy importante. :pface

Make sense?

[AZhitman]

Not shipped w/o stubs. Stubs will remain.

Swapping stubs is a PITA. (Z-car has 5 holes, Q has 6)

Plus, for this price, new innards is a nice option.

[HeavyDuty]

This would include new r&p, carrier bearings, pinion bearing and seal, axle seals. Keeps your original axle stubs. You add the fluid (shipped dry) and install.

Then I misread that. My mistake. It sounded like one would receive a setup diff minus stubs that one would swap from the original.

Sounds like the 300Z diff is out anyway so as not to confuse the 5 hole stub statement.

Balancing?

[AZhitman]

Not sure on balancing.

I have a new driveshaft, but I'm not familiar with the need to re-balance when changing out the rear diff. I'd like to hear Dennis/Scott's thoughts on this.

[maxnix]

Seems like all rotating masses must be at least statically balanced before assembly.__________________Brian1995 Q45 & Q45t & 2000 Q45

Discover the power of the button!

[rsiwicki]

Yeah!!!!....I have just won the ebay aution bid on the 94 rearend!!!! I got it for $59.52 + $65 shipping = $124.52. I will be working with Hitman on where he wants this shipped to begin the work. So we now should have one rearend in the pipeline to start the chain moving. There is a user named "junkyarddog" that has found a 90 Q45 in a salvage yard and if necessary, we could all maybe get that rearend also if needed and if they price is right. I can't wait to get our cars really moving....

Hitman...send me an email and let me know where to send the rearend so I don't have to pay twice for shipping...Thanks, Rob

[QShip]

Seems like all rotating masses must be at least statically balanced before assembly.

Makes sense to me.

[AZhitman]

UPDATE:

I have good news and bad news.

Apparently, the company that was doing these for Rex back in the day will no longer sell the gears to another shop to do the work. Their bench fee is nearly twice the rate Rex had negotiated.

Also, since then, the conpany that made the spacer plates for these has since gone under, and the spacer plates muct be fabbed by the installer (which they can do just fine, but it will bring the cost up, closer to $1100.)

I will be making some more calls tomorrow to see if I can salvage this deal. If nothing else, I will be inquiring as to the interchangeability of the Q and Z stub axles. If they will interchange, we'll just do things a little differently.

Rob, hold off as long as you can. I won't let you get stuck, even if I have to pay for the diff myself. Hold tight.

[rsiwicki]

Thanks for the update Thanks for offering to help recover the costs on the diff I bought and maybe we could just split the difference or something like that. I will ask the seller to hold off on shipping the rearend until we find a new home for it.

I had called Stillen and Z1 motorsports today and both said that they used to do the swap but don't they all don't have the contacts anymore to do the swap.

Hitman....keep on looking for us as I really want this mod done to my car and we will find someone willing take our business & our monies....

Here is an article that I found on Z1's website that may or may not help, but it describles the 300zx swap.

1990+ Nissan Z specialists770-562-8668http://www.Z1motorsports.comTT -> NA Rear Differential Swap

Common modification to get the TT off the line quicker. Installing the NA rear diff with a lower gear ratio of 4.08 compared to 3.67 in the Turbo diff makes a shocking difference in the first few gears, but does take some away from top end. However it is not as easy as just changing out the rear diffs alone. We often perform the swap here at our shop and can also just sell and ship the parts to do it with. The TT diff is larger and the mounting points are positioned differently compared to the NA. The halfshafts also have a 6 bolt flange at the diff on a TT as compared to 5 on the NA as well as different splines and diameter where they go into the hub/wheel bearingassembly. You will need the NA rear subframe, differential, halfshafts, spindle/hub/knuckles, and a couple of suspension links, all which are different for the NA ($650). You have to drop the whole rear suspension and change it out with the NA setup.We recommend installing Energy Suspension differential mounts ($32), since the stock ones are often bad and 2 qts Redline 75-90W in the NA diff ($18). Some choose to install the 4 performance or solid subframe bushings since the rear subframe has to be changed and will be out of the car. We also have some subframe stiffeners for $40 that will compress the rear subframe bushings reducing wheel hop. You either need the back half of the NA driveshaft ($60) or better yet a one piece driveshaft (which we have for $250), because the TT one bolts up in a different pattern and the length of the TT diff is different.Since you will be eliminating HICAS the best idea is to remove with the larger 2 chamber TT pws pump (more drag on motor), HICAS solenoid, extra lines, etc. Removing all of that really cleans things up and removes a lot of excess junk. As replacement we sell a NA pws pump (that we rebuild here using all Nissan internals), mounting brackets to the block with bolts, pivot bolt, Adjustment bracket, reservoir, and belt for ($325). You will also need an NA speed sensor pinion gear. ($20)

[AZhitman]

After reading the Z-car info that Rob posted, it looks like even more work.

Grrrr.

Let me do some research tomorrrow and place a few calls.

[HeavyDuty]

$800 sounded like a steal.

If someone will send me or sell me a core, I'd be willing to help this along.

We regularly setup even the most finite of final drives. Even the incredibly tight tolerance S2000 diffs. And I'd be willing to do it for BRM.

Not looking to steal thunder here, Greg, just wanting to get *something* moving in all of the ambitious undertakings you're currently engaged in, (headers, exhaust, supercharger, diff)

Hoping I didn't offend,

HD

[rsiwicki]

Below is the info on who Unitrax is....

This is all confidential of course as I got Unitrax's info from a very reputable unnamed source, but Unitrax has done many Q45's swaps for a well know performance company that outsourced the rearend swaps to their shop. Email me and I will tell you who it is that they did the work for, but you all probably can guess who it was anyway. I talked to them and they can do the whole job for about $1025 which includes everything (all new with OEM or better) with a 4.08 gear. I asked about doing other ratios and they said that they would only do the 4.08 swap and have not tried any higher gears with the Q45. They said the difficult piece was the ring gear bolts and that they were only custom made by a specific company that no longer makes them but they can still get them. This sounds like a good deal as well and they can do the speedo calibration, but they said that there was a trick to it that needs to be done to get it working correctly and that they can have their tech guys talk to who ever is doing the job to get it done right.

Here is the website.... http://www.gounitrax.com and the phone number is 800-622-4327

I talked to Debin (spelling?) and he was very helpful and seemed very interested in a group buy type project.

I am a novice at this stuff, but becoming a fast learner. I think that it would be best if someone such as Hitman or another member contacted both shops to figure out who to go with. I already have the extra core so there will be no down time as long as we keep the chain moving with people sending in the old cores back.

We are on our way!!! Rob:)

This project is very alive and well. I will be sending the core to either place within the next week to start the chain. Please contact Hitman if you are interested as he started this thread and has a list already compiled a list of who is interested.

[AZhitman]

Unitrax may be out, as they'd be nearly $1200 after shipping.

HD, no offense taken - I'm glad for the help.

[AZhitman]

Stop the presses - We are all set now.

As far as swapping a Z diff goes, it's a no go. While the twoa re visually identiacl and theoretically interchangeable, the Q45's stub axle splines and shaft are significantly thicker than the n/a Z-car axles.

As regards doing the 4.08 gear swap, Kevin has agreed to do them for BRM for a great price, which I will confirm with him on Monday.

Rob, your differential is heading for sunny California. I'll email you the address.

We could use a few more diffs to send him so we don't have to have any "down time", so you guys be on the lookout for junked Q45's with under 100K.

p.s. He had one already done, I just bought it. It'll be here in a week.

:fruit

Sorry guys, the big dog eats first.

[rsiwicki]

Ahhh Muy Bueno Senior....

I am glad that Kevin could come through for us. I don't know exactly what kind of shop he is running, but he said that he goes through a ton of gears every month and actually uses the Q45 gears to build a top end car for racing...thus his familiarity of the Q45 setup. I will send the differential over to Kevin and check my mail for the address. I can't wait till I/we get our cars moving.

Hitman.....Thanks for doing all the technical talk with Kevin and the others as I really don't know much about this stuff...it took a while but I guess the search finally paid off.

:ylsuper

[AZhitman]

Well done, Rob.

Glad to have members like you on the board.

[dgoodno]

. . . also said that he can stick a 4.36 gear in the rear as well if anyone wants to get really crazy.

What is the up and down side of doing 4.36? Remimber that my application is different from your. More power off the lower gears maybe a small loss at the top end -- that is never reached on track?

[AZhitman]

Can't think of a "downside" for your application, Duaine.

Other than difficulty using 1st gear for any appreciable distance, it should be great for squirting out of the hole when exiting turns.

Kevin will be glad to do it!

[sultan]

this might help dgoodno or other people:

using the formula (rpm x tire diameter in inches)/(diff ratio x trans ratio x 336.135) and 94-96 trans ratios to 3 decimals and stock tire diameter this chart should be correct, sorry for formatting. actual indicated tach and speed readings seem to be lower than this chart says(due to: drivetrain loss? fluid thickness? tach that reads higher than actual? tire diameter different than stock?)

speed in mph at 6900rpm in each gear with different ratiosthe last number is rpm at 70mph in 4th gear (approximate) ratio 1st/2nd/3rd/4th

3.538: 58.73/102.0/150.85/217.37 2250

4.083: 50.88/88.38/130.72/188.35 2565

4.363: 47.62/82.71/122.33/176.26 2750

[rsiwicki]

these are the figures I get as well using the little calculator that I posted the link to on the first page of this thread. I shift at about 91 mph from 2-3 under WOT and at max rpms (7200?)...there is no way I could get my car to do 102mph without it shifting into 3rd

[HeavyDuty]

Stop the presses - We are all set now.As far as swapping a Z diff goes, it's a no go. While the twoa re visually identiacl and theoretically interchangeable, the Q45's stub axle splines and shaft are significantly thicker than the n/a Z-car axles.

I went to a premier "driveline only" shop this afternoon & was informed of the "carrier crossover" point on these diffs. So, amen to the stub diameter issue.

p.s. He had one already done, I just bought it. It'll be here in a week.

:fruit

Sorry guys, the big dog eats first.

I always kinda thought AZHitman looked like Aww$hitman to me.

Fuh-Qer

hurry up, dammit!

PS, PLEASE ask about a 3.80 config for me while you're at it.

Signed, "Man without an experimental core."

[AZhitman]

LOL @ HD... Start scouring the local wrecking yards!

I'll ask about the 3.80's...

[Q45tech]

You are forgetting tire growth above 100 mph which can make the effective rolling diameter UP to 10% greater depending on tire construction..........whether or not the tire has a nylon/aramid cap.........even the best non racing certified one [Michelin Pilot Sports] grow 4-5%.

A 3.538 might act like a 3.36 a 4.083 like a 3.88.

Don't assume that most tires with V, Z, W rating don't grow significantly.