bajaiman

I was planning to change my final drive ratio from 3.27 to 3.9 ….. I was just wondering if anybody has done this mods??…any thoughts?. The shop told me that I can get 1 second off 0-60 time but with a downside of losing 20% of top speed. They also told me that there is no reliability issue for this type of mods. I won’t mind losing 20% of the top speed cos I won’t see myself doing more than 110 at any given time.

Would the dealer notice that I’ve got this type of mods when I’m going for service??, any other downside apart from losing 20% top speed?. Any suggestions/input/thoughts are welcomed!

Cheers.

dswildfire

20% increased engine wear compared to stock setup, and they'd notice if they took it for a drive

Iceman's C230

Who sell's 3.90 for the C230? In my stang i went from 3.27 to 4.10's and you could feel the power at the track but i wonder if you would feel the same power on the C230 going from 3.27 to 3.90's? My stang was Supercharged and was putting out over 400HP And over 400Pound feet of torgue... I don't think i would change gears on a stock 230. If it was moded maybe but with the amount of torgue it has stock, i don't know if your going to feel any power. And i don't know about getting 1 second off 0-60 that seems a little too much on a stock car with just gears? I would save the money on other mods first. But thats my .02 cent's.

Buellwinkle

That's great, where do you get a 3.9 gear? I know in some countries they have the 3.67 gear. Do it, you'll love it. I went from 2.73 to 3.45 on a '98 V6 Mustang combined with a dual exhaust and K&N filter and my 0-60 dropped 2 seconds with no noticible difference in gas mileage, drivability or freeway driving noise. The car just snaps off the line, even with the automatic.

bajaiman

Well I live in Sydney, Australia. I've called a tuner shop that can source a 3.9 final diff ratio for my car (C200 Kompressor sedan with auto tranny). I know that Australian C180 has a final drive ratio of 3.67.
I'm still undecided which one to get...the chip or the diff ratio, so thats why in need input from you guys . But so far the diff ratio mod is really tempted cos it doesn't cost as much as i thought ... i might be able to get it done for about US$900 including labour. Would i be able to get 1 second off too for my 1/4mile time??

Buellwinkle

Seeing that you already did a pulley, a gear ratio change will give you a better snap off the line and that's about it, it won't do much for passing people at high speeds or for top speeds. The chip will give you more power throughout the rev range and you are probably running too lean anyway so a chip may fix that. A good chip can probably get you 10-15hp. Going to an alloy pulley over the ring may give you 8-10hp. A good intercooler would probably get you 10-15hp. Surprisingly from what I've seen a good airfilter like ITG has the potential of 6 more WHP based on a dyno I did without an air filter on my C230 coupe. Also, because the car runs lean with a pulley, cooler spark plugs may get you some more HP (I've seen 12 extra wheel ponies on a SLK230 just from cooler plugs).

bajaiman

I've got my a/f ratio when i did the dyno 1 week after i did the pulley. i've got 12.9:1 - 13.1:1 at WOT from the dyno....
I think i'll do the chip and diff ratio mods as far as the engine modification mods...well thats what my wallet permit at this time

Do you any recommendation on which cooler spark plugs to use?..which brand and model??

KJ-TypeR

The shorter final drive would be a great mod.

Unless you can hit the rev-limiter in 6th gear, I don't think your Top-Speed would be affected much (if at all).

The mod will increase your ability to pass people at ALL SPEEDS and will definitely be a mod you can feel.

The best part about it is that you won't have to worry about the mod not working out. It's a GUARANTEED acceleration increaser.

Whether or not you can put up with increased rev's on the highway is another question.

You'll probably be crusing at approx. 20% higher rpm's (at the same speed as before). You can calculate your RPM's at xxx speed to see if it will be tolerable for you.

TimmyC230boy

I agree with KJ. the final drive ratio would be great. Then as your wallet increases you can do a chip too. if my memory serves me right the manny transmision cars can hit the rev limiter in 5th gear.

I have a friend that has a Pontiac Firebird Formula. It had a 4 speed auto with a 2.73 rear-end ration. he changed it to a 3.83 and picked up .65 in the quarter and only changed his highway rpms by about 600rpm. His 0-60 time dropped about .4 tenths too. as far as the butt dyno goes it felt WAY faster even though the real dyno would say little if any increase in HP

KJ-TypeR

Another plus is that your car is RWD, so changing the final drive is a snap. If it was a FWD car, you'd have to take apart the whole tranny to change the final drive!!!

When you sell your car, you can put the stock Final Drive back in and no one could tell!

renncpe

I changed from the 3.27 to the 3.67 it made a big diffrence I have now gotten my 0-60 times below 6.5 with the new dif.

Randy

Buellwinkle

I can't speak for how it would work specifically on a Coupe but on a Mustang your top speed is severely limited. With my conservative upgrade to 3.45 gears on the Mustang I can only get to about 108 mph. With 3.73 gears the top speed I heard from those that have done it to be about 95 mph. I've heard that the 4.10's got to only 85 mph. It's the speed limiter and not the rev limiter that it hits but MB might be different. It did have an impact on the auto trans because it allowed me to rev higher before it shifted. On a manual trans car it would not make a difference, just downshift to get the same effect. The funny part about Renncpe's 0-60 times is that he did it in 2nd gear launch for the best times. If you have a manual trans and truley want the best 0-60 times it would be best to go the other way to a 2.9 gear like the BMW 330. Based on Renncpe's results, a dragstrip launch in 1st with the 2.9 gears would improve and you wouldn't have to hit 3rd just before 60 mph.

renncpe

My first few trys were best in second gear. Later I has able to get the best times with first gear starts. I had the misbleif that I would not get the best times if I had wheel spin. I was wrong, too much wheel spin is no dought bad for your times but a small amount of slippage seems to work the best. I think a 2.9 rear would be a poor chioce, I'm changeing to a 3.07 with the new engine set up though.

Randy

bajaiman

Did you have to change your computer setting when you changed the final drive ratio??, did you have to calibrate your speedo??... will the ECU adapt by itself?... oh btw...what was your original time 0-60 before the final diff upgrade??

Thanks

JDM_love

Did anyone change their final drive?

phister

I have a rear diff that I have waiting to be swapped out that has different ratios. Forgot what model it was out of but Cale an old member on here had the specs on it. I'll have to see if I can find his thread.

LILBENZ230

I don't think any of the people who posted in this thread 11 years ago will be available to answer. But yes, Cale did dabble in that.. I'm not sure if he ever actually replaced it, though.