Has anyone tried changing out the rear gear on a manual before? I want to get swap in an SRT rear end to hopefully get first gear back with the v8 lol. I am wondering what I need to do to the computer to not have it throw codes and to make sure the speedo reads right.

 

I figure that a 2.67:1 would be just about perfect but have not found one or anything close.

 

I thought I would just try the SRT 6 gearing to see how I liked that, maybe find something else later if it isn't enough. I heard rumors that you can modify a charger or challenger rear end to fit the crossfire, might open up some more options on gears. It won't matter much what is in there if the car stays in limp mode though

 

You won't have to worry about the speedo or limp mode. You'll give me a call and I'll walk you through it in DAS

It'll have to be a Benz diff, or a ratio that a Benz had in the same generation. The SRT gearing would be perfect. Swap in the whole shebang, that's what I'm doing lol.

 

Ok awesome!

Yup that's what I was thinking too. Get the whole housing with the gears and swap it in. Now I just have to find one for the right price. I would love to get one with the Wavetrac already installed, but surprise surprise no one seems to want to get rid of theirs.

 

I just sold a srt diff with the 307 with wavetrac and tcu, I can get you a 307 with wave-trac for around 2600.00 + shipping.

the wave trac has never been in a car. (it's new),,, diff axle bearings ,,new.

I'll brake it down for you.
wave trac 1350.
axle bearings 150.
307 srt diff 800.
labor to build 500
total 2800
discount 200
as said above 2600.00 +shipping

if you need tcu for auto trans add 700.

 

The 307 from the srt would drop rpm around 200 rpm at 75 mph.
I would like around a 2.88, giving the power band of the 3.2

 

I think some of the older diesels have 2.88 gears. You are right, I am not sure that the SRT gears are going to have enough of an effect. But for what is available for our cars I am not sure if there is a better option.


I will have to get back to you on that. It's a little out of my budget right now.

 

If I new it would work I would already have one.
Yes the older diesels had around the ratio I was looking for.

 

2000clk430 has a 2.87 ratio and the rearend looks identical, if it is the same, would be great gears for a 6spd, great 1st gear take offs and interstate cruising.

 

I think a 2.67 would be about perfect to make 1st usable and 6th a real OD (stock 1st will go straight up the side of a wall and 6th is the same as my old Fiero 4th).

If anyone can find a supply of 2.87s that would be much better than what I have. (and I have dial indicators so just ring and pinion would be great)

 

Have an E250 diesel and the axle ratio is 2.23...1600 rpms at 72 mph. Probably way too low for the Crossfire though.

 

Big difference in power band between the two

 

Personally, I think all the attempts at procuring a taller gear ratio for the stock NA's are going to lead to lot of disappointment.
When those of you getting tired of the short 1st. gear find out that your new ring and pinion only offers about a 5mph increase in first gear (that's about 40mph) your going to notice it's harder to stay ahead of those sporty 4cyl, Japanese hatchbacks at every traffic light.
The others who want their engine to be idling down the highway around 1700 RPMS at 75mph are going to discover that the Crossfires MPG "Sweet Spot" seems to be somewhere between 75 and 80 mph with the stock 3.27:1 differential.
So unless you are a frequent flyer on the Autobahn, chances are you will never realize an improvement in mileage. Because you will have to be traveling so much faster to reach that perfect RPM, the wind resistance you will encounter at that high speed will take more fuel to punch a hole into it.
But on the other hand, it's always good to dream.

 

I would just like to lower interstate cruising from 2600-2700 down to around 2200 rpm, for alittle less stress on engine with the cruise set for 2-4 hours twice a week.

 

Speedy, the Crossfire's peak torque is reached at 3000 RPM's, this also seems to be the RPM range where many drivers have discovered their best MPG readings.
I assume that is because the engine is neither laboring, or over extending its capabilities.
The Crossfire will run at 2200 RPM's at highway speeds staying with traffic all day long. But by doing so (even though you wouldn't realize it) you're actually putting more stress on the engine by "lugging" or "taxing" the engine. Simply because it's not operating in its most efficient power zone.
3000 RPM's is exactly 1/2 of the engines redline. I would imagine a "stock" Mercedes engine could probably run continuously (at 3k RPM's) on a dyno, with nothing but fresh oil and fuel, at proper running temp for a 1/2 million miles with very little maintenance, besides some new spark plugs, and coils. Just my opinion.

 

I run 75-78 mph on interstate for hours.
Cruising at 60 mph it is great.
I do mainly inserstate, why I would like to get it around 2200.
Not saying I want 1500 that is to low for this car.
With stock ratios I still would rather start in 1st rather than 2nd, which lugs engine and most ppl probably slip the clutch starting in 2nd..
For maintenance I always stay ahead of schedule.
And I drive flat interstate not alot of hills, or mountains.

 

I agree, Fiero V6 was an archaeic iron block, valve in body. Crossie 3.2 is a much more modern engine with a wider power band. Besides I kept looking for a gear beyond top in the Fiero also. Sweet spot for a gas engine these days is 1900-2000 rpm at 70 mph. That's about what the 3.6 in my Jeep GC (aka barn door) turns. A modern engine can pull a gear that tall without getting into PE and minimizes IHP/pumping losses that increase with the square of the rpm.

BTW my Jeep peaks torque at 4800rpm (hp is redline limited) but maintains 90 percent of its peak value from 1,600 to 6,400 rpm. 2k cruise is NP. Peak is really irrelevant, it it the torque curve that matters. 3.2 is a lot peakier but is still making 221 lb-ft at 2k. Anyone have any BSFC curves ?

ps I would rather start in 1st myself, but is so low and the gap to second so large that the only smooth way is a WOT speed shift. I have not found anything else that feels smooth. Starting in second is just much easier.