Going with 3.55 gears.. Need opinions...

phils89sc

Registered User
I bought a set of 3.55:1 gears for my 89 SC. Mine is a 5 speed, and already runs very quickly thanks to generous bolt-ons (70mm MAF, full Flowmaster/Dynomax/Custom 2.25-2.5-2x2.25", hi flow cats, 10% OD pulley on rebuilt SC, removed intake air silencer, and coming soon, custom Intake tube w/ conical K&N cold air intake.

When I driver her now, the stock trans shifts ok, but it seems to have quite an RPM drop between gears. I do not know what the rear gear ratio is for the factory 5-speed 89 SC's, but this causes some drop in performance because of the LAG between gears (and we all know how hard it is to speed shift an M5R2 tranny, like speed shifting an F150!!). I know the 3.55's will give me a better bottom end , but will get rid of some of this RPM fallout between gears? I would guess and say that the M5R2 tranny is somewhat of a wide ratios trans. Do you agree? Any opinions?

Thanks

Phil
 
My opinion

Having never edxperienced it first hand, I can't accurately comment on your choice of gearing, but i would say it would be like driving a close ratio toploader-im pretty sure i rad that somewhere. Do you have the stock 2:73s now or 3:27s
 
The change in the rear gears shouldn't have changed the transmission ratio gaps, only changed their position in the power band.

From this thread:
http://www.sccoa.com/forums/showthread.php?s=&threadid=16971&highlight=gear+ratios

In 89-93 the M5R2 had the following gear ratios:
1st Gear- 3.75
2nd Gear- 2.32
3rd Gear- 1.43
4th Gear- 1.00
5th Gear- .75

In 94-95 the M5R2 received some different gear ratios.
1st Gear- 3.42
2nd Gear- 2.16
3rd Gear- 1.34
4th Gear- 1.00
5th Gear- .75
 
I should have been a little more clear...

I have yet to install the gears in my SC, and the
"gap" between gears is with the stock gear, 2.73:1. Talk about a top-speed gear ratio, damn!! Anyway, I was thinking that this 3.55:1 gear should help me out, particularly in second-fourth gears as far as increasing my pull through those gears. I mostly drive my car on the local roads, and I like quick, not fast, too much stuff can happen at 150mph, know what I mean? That first gear ratio sounds really steep though, probably will have to start out in second, my gears will make first into a granny gear!! What I think would be excellent is the HD World Class T-5 BW or Tremec with a 2.95 first gear (maybe 2.97), plus it wouldn't be as hard on the tranny!!

I appreciate the help ladies and gents, keep it coming!!

Phil
 
3.55's aren't much fun. They do help your rpm drops between gears, not because they change the rpm drops, but rather because they make the most drastic ones occur at lower speeds so the effect is less. Personally, I don't think it helps much at all. I have the 3.55's, and I would not do it again. For street driving 3.08's are much better. Rather I think you'd be better off getting some better valve springs so you could safely rev the motor to 5500 or above thus allowing you to run it out more in each gear. Just my $.02.
 
Go with 3.27s

In my opinion, you're planning to trade a gear set with a useless 5th gear for 1 with a useless 1st gear. I swapped from 2.73s to 3.27s into my 5sp and all of the gears are useful and you'll be very quick in the city and you can pull any hill in 3rd without down shifting to secound because slow cars are in front of you. 5th gear becomes useful on the freeway and even pull up mountain hills without going back to 4th. Trade those 3.55 to someone with a SC automatic with 3.27s because they are dogs in my AOD. Or go ahead and put them in and try them out and trade after you find that you don't like them. Good luck in which ever you choose.
 
well

since you are looking for opinions on installing 3.55 rear end gears I offer this info. In my 89 5sp with 3.27 gears, 1st gear is very short but still useable: and at 60 mph in 5th gear the car revs just over 2000 rpm as i recall. And finally, I have beaten more than one mustang GT with my coupe, only thing other than gearing thats been done is the exaust. it also seems to be geared nicley for the turns, incase you are a tire squealer like me. I say 3.27's all the way:)
 
I had a wonderfull cruise down the freeway yesterday at 2500 RPM's going 100 MPH with my 2.73's. I would not give that up for anything. Maby 3.08's. 3.55's are only going to make it feel faster at certain speeds.

-Steve
 
gears

With a 5spd 327's are the only way to go.The car will feel like it lost 500 lbs,1st gear is still useable and it will cruise all day at high speeds.
 
355s

I set up a locker with 355s and yet to put it in , waiting to put it in , good vacation job . cant wait to pull in all 5 gears , you know it will , got 295-35-18s to hook up with . Got the 340HP kit in this car so its a fun car . Go 355 0r 327 for sure . DW
 
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