M29 + 4.10 = TEH SHIZZNIT!!

Okay... count the suck:

1. Convert car over to M28 / 3.73 T56. Get sick during the install, delayed one week.
2. Drive car, no third.
3. Install 2nd M28 trnas. No fifth. Don't give a shit. Car runs fine, drive to Detroit and it starts to howl. Big time. Decide I better not risk damage to M28 #2 since parts for them are very hard to find.
4. Install M29 trans that I bought from Bewbz. Not the greatest for 3.73s but what the hell. Howls like a mofo. Decide maybe I just need to install a shift boot and some sound deadening.
5. After installing the deadening, the noise is obviously coming from the newly-installed 3.73s. Pinion nut backed out.
6. Take car back to gear installer, he completely re-sets up the rear. Nice pattern, yadda yadda. Still howls like a SOB. Must've worn a noise pattern into the gears during the several hundred miles that I thought the tranny was howling.
7. Yank the rear axle out of my DCM '95. It's a 4.10, should be the sweetness with the M29.

Wait... 7 doesn't suck, except I now have to build a rear end for the DCM. The car is FANTASTIC to drive. That close-ratio M29 is the hot ticket, boys and girls. Damn, what a blast. Very little drop between gears, pulls like a bandit!

Anyway, just wanted to share. This one's been fighting me, but as of now it is the best running combo I've tried... and I've tried 'em all!

I think the next step is to just build a 4.56 rear end disc brakes for the '95. It already has a bullet-proof T56 in it, the later kind. It'll be geared very similar to this M29 / 4.10 car but a little longer legged on the highway. Should be sweet. Plus I already have a Denny's shaft for that car.

Oh... and the biggest surprise is that the stock shaft on this car doesn't vibrate a bit even with the 4.10 gears. WhooHoo!

Congrats But...V_I_D_E_O is needed!....lol

brokecello wrote:

Congrats But...V_I_D_E_O is needed!....lol

Ha! I don't have the mad video-making skills you do.

Plus, I don't have a tach so I can't demonstrate the shallow gear drops. All I can say is this thing is a real sweetheart to drive. Made the morning commute much more enjoyable!

Remind me the differences between M28 and M29?

sherlock9c1 wrote:

Remind me the differences between M28 and M29?

Gears 1 and 3 are different:

Year 1993 (M28) 1993 (M29) 1994+ (MN6)

1st: 3.36 2.97 2.66
2nd: 2.07 2.07 1.78
3rd: 1.35 1.43 1.30
4th: 1.00 1.00 1.00
5th: 0.80 0.80 0.74
6th: 0.62 0.62 0.50

More of a drop between 3 and 4 for the M29... but for the most part at a less critical time. With 1, 2, and3 spaced closer together, the car just seems to stay in the power range better. IMO the 4.10s are perfect with the M29... highway RPMs in 6th are about the same as a 4L60E with 3.73 gears.

Another way to look at it is the drops between gears:

Year 1993 (M28) 1993 (M29) 1994+ (MN6)

1-2 1.29 0.9 0.88
2-3 0.72 0.64 0.48
3-4 0.35 0.43 0.3
4-5 0.2 0.2 0.26
5-6 0.18 0.18 0.24

Looking at the drops, the M29 is closer-ratio than the M28 for gears 1-3... but when compared to the later MN6 trans, both the M28 and M29 are wider ratio in the lower gears. For some reason my SOTP impressions didn't suggest that... but I had just driven it as an M28 and I've never had the 4.56s behind my MN6 car (probably will happen this spring). My guess is I'll like the 4.56 / MN6 car even better but the driveshaft will be spinnin' pretty fast.

I don't understand all the numbers

How about I just drop my car off......... and pick it up when you are done

Wagon Collector wrote:

I think the next step is to just build a 4.56 rear end disc brakes for the '95. It already has a bullet-proof T56 in it, the later kind. It'll be geared very similar to this M29 / 4.10 car but a little longer legged on the highway. Should be sweet. Plus I already have a Denny's shaft for that car.

Sorry to hear about all your issues. I have an MN6 sitting in my garage along with 4.56 gears, Tru-Trac posi and lots of other related parts for my swap. Your post has gotten me motivated to check my list twice to see if there are any parts I need to add to my list for Christmas.

Below is a screen shot of a spreadsheet I did while going through the gear selection process. You are correct that the MN6/4.56 setup will be very close in performance to the M29/4.10 combination as shown on the graph.



I will post the info for the spreadsheet in the Technical section and will be glad to send a copy to anyone that wants to play with it.

ArlingtonSS wrote:

Below is a screen shot of a spreadsheet I did while going through the gear selection process. You are correct that the MN6/4.56 setup will be very close in performance to the M29/4.10 combination as shown on the graph.

Cool that our number agree - but you got some mad spreadsheet skills going on there.

When you get a chance, plot the M28 / 3.73 combo - that one is closer to the MN6 / 4.56 on the 6th gear end, and very close on first as well. Be a good combination for those who might already have a 3.73 rear end...

m28's are fine for their low 1st n 2nd,. but drive like an old muncie wide ratio,..
I really like the quick 4 that the m29 gives,
I,m thinking i'll be down your way, and we'll try 4:88's with the m28,. see how hard it launches in 1st,.

Nick

Wagon Collector wrote:

When you get a chance, plot the M28 / 3.73 combo - that one is closer to the MN6 / 4.56 on the 6th gear end, and very close on first as well. Be a good combination for those who might already have a 3.73 rear end...

Here ya go...MN6/4.56, M28/3.73 and 4L60E/3.73. If you want an interactive copy of the spreadsheet, PM your email address to me....you can then try out all types of combinations.

ArlingtonSS wrote:

Here ya go...MN6/4.56, M28/3.73 and 4L60E/3.73. If you want an interactive copy of the spreadsheet, PM your email address to me....you can then try out all types of combinations.

Excellent! PM Sent...

phantom 309 wrote:

m28's are fine for their low 1st n 2nd,. but drive like an old muncie wide ratio,..
I really like the quick 4 that the m29 gives,
I,m thinking i'll be down your way, and we'll try 4:88's with the m28,. see how hard it launches in 1st,.

Nick

Yeah... that 2-3 drop is big, and for the brief moment I had an M28 in that car it was noticeable. Still a decent way to go with 3.73s, though.

An M28 with 4.88s... I'll have to get faster at shifting for that combo!

Spreadsheet sent via email to Wagon Collector. Let me know if you have any questions or suggestions for improvements.

Great spreadsheet - thanks!

Took this one on it's first road trip this weekend. Drove to Moultrie, GA and back. Total drive time = 28 hours, done in about 38 hours.

The M29/4.10 combo is killer on the highway, but I didn't get the gas mileage numbers I was hoping for. 21 MPG all highway. Still not bad. My MM6/4.10 setup got more like 25 MPG. That one was nowhere near as fun to drive, though.

6th gear works almost always above 70 MPH, and has zero problems climbing the mountains on the I75 corridor through Tenessee. Granted, these mountains ain't steep, but the car still pulls very nicely in 6th gear at 70 MPH and above. Downshift to 4th and nail it and you're in the triple digits pretty damn fast. Truly a blast!