Congrats. Glad you got it to fit.

 

Excellent, Kevin! I'm glad for you, and now assured for me.

We have helped to unlock the key components for the strongest lockup.

I'm next. Car is dropping off for monday, as I've been promised.

Props!

Coop

 

Sorry for the short post last night, I had to get to bed and am headed off to work again but it worked like a champ. I'll post my mod later after I put the car back together which won't happen until Wednesday. But the good news is that the rear half of the manual driveshaft works with the front half of the automatic driveshaft and mates to the rearend with an exact fit. I didn't have a chance to torque everything down per spec yet but it's there. I can't wait until Wednesday to put it all back together.

 

We've had success. I dropped the car off, the guys removed the exhaust and the driveshaft.

I came down with my inch-pound lever torque wrench and we measured the rotational force to rotate the diff from the flange nut: 18-20 inch lbs. This is with correct specs inside.

They blasted off the nut and used a slide hammer to pull off the three bolt (auto) flange. Then they put the four bolt (manual) flange back on.

Jimmy cranked on the nut and measured: 12 inch lbs. He put a stopper on the flange and tightened it twice again to reach 18 in lbs. Done.

I left them to drain and renew the diff oil now that I've got 500 miles on it, and reassemble with rear section of the manual driveshaft I bought.

I just got a call from him after a test ride: NO vibration, smooth as it should be.

I'm awaiting tires for the 18" Enkei rims, but this task has been solved.

News from the cockpit soon.

Coop

 

I get butterflies in my stomach reading posts like these. Great stuff man.

 

The car is in my driveway, finished.

Just as they allowed the swap made ALL the difference with my HP/torque level. NO vibration at the peak torque levels.

If the OEM rubber coupling distorted only 3mm (1/8") that would send the rear shaft way out of balance. Which it did.

I am back on my wider 18" tires, and I can't tell you how much I enjoy the softer ride of a wider sidewall. (Well, I just did!)

All-in-all this swap took some work and a bit of discovery, yet it worked out great. I'd love to know that the OEM diff would accept 4.08's with mods, but we'll have G37Sam report back on this trial.

Interesting that the G37 convertible has 3.91:1 gearing? THAT would also have the OEM long pinion. That's a halfway mark from 3.69 to 4.08, and if you had a 7AT, it might be almost too aggressive. Least expensive method would be to simply order & install those gears, or find a whole diff to swap (rare).

Option: 7AT (3.36:1) convert to a used 5AT diff (3.69:1).

Happy trails!

Coop

(I edited the first post with a synopsis of the thread's findings. It should not replace reading, yet it states the problems and solutions in a nutshell.)

 

I think for 7AT a swap to the 5AT is ideal. I once swap 3.27 to 3.55 on my old 5.0 Mustang and it ran like crap.

 

Is this a photo of the 5AT front driveshaft piece attached to a 6MT end driveshaft piece? The photo isn't there anymore.