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I will be straight up honest and say that I do not have fabrication experience and I'm concerned of making the rear-end my first go around haha
If I didn't have to have the car functional in 30 day intervals (breathalyzer calibration unfortunately) I'd be willing to give it a shot, but not on the rear-end this time. Seriously appreciate the insight and you have an awesome thread going!
Old racer,, "you have a better chance of winning with a mild motor and great suspension than a monster engine and crap suspension.. " Oscenities removed...
Guy had run cars at Indy in the 50's so he always had some good tag line..
That's actually a great quote, as of now since my suspension is absolutely shot, I couldn't agree more haha
Im comparing some suggestions and still reading threads on the wheel and suspension setup before ordering the 9" rear-end but this will all likely be ordered here in next 2-4 weeks if I can get the answers and piece this puzzle together fast enough.
No matter what rear the gears are in, stock, 9", 12 bolt, or a S60 they will act the same if all using the same ring and pinion ratio. It's the transmission gearing that makes it different from later years. 3.73's in any rear in your car will act as 4.10's.
Okay now Im following! Thank you for clarifying! Sounds like 3.73 is the highest Ill go then since it will be converting to 4.1, would 3.5 then be the proper gearing to convert to 3.9 on the 1993 T56? If I plan to make 400-500HP & TQ would now be the time to look into transmission before I break the 1993 T56?
I haven't read very much that suggest the T56 won't be adequate but definitely would appreciate some insight here before swapping the rear-end with 3.73 or lower gears only to have to swap them later for 3.9 in the new trans once cammed.
Originally Posted by Catmaigne
The calculator that was posted for gearing is going to be invaluable for choosing the ratio. The most important variables you have to consider are tire size, redline, and a tentative trap speed. Also, if you plan on running bias ply slicks, keep in mind that diameter grows slightly at high speed and will effect your mph @ shift.
I'll just throw some numbers out as a guesstimate. Let's say stock tire size on the rear at 25.6" with no growth (street drag radial), a h/c setup on a stock bottom end with a medium sized cam for longevity, low-mid 400's whp, a shift point around 6.4k and a trap speed of 115-120mph at sea level. Knowing all this, you want the shortest gears you can get that will avoid the 4-5 shift at the strip and have reasonable engine RPM at highway speed. Some examples from the calculator:
3.73: 131mph at the top of 4th, 2100rpm at 70mph in 6th
3.90: 125mph at the top of 4th, 2200rpm at 70mph in 6th
4.10: 119mph at the top of 4th, 2300rpm at 70mph in 6th
If your endgame is larger bias ply tires and/or h/c stock shortblock, I'd do 4.10's all day. The 3.90 would allow more power in the future and is a nice compromise for the street though.
And for the rear end, I wouldn't conflate price with quality. I have a Moser 9" in my car that I got through Brute Speed and it fits like garbage. Torque arm mount tubes were welded misaligned, the cast torque arm bracket is too undersized and needed a shim, LCA brackets are too wide and needed washers to take up slack, sway bar mounts aren't low enough, etc. Also, Moser axle splines seem somewhat undersized and the fit into my Wavetrac is very sloppy. All of this is a lot of bullshit for something that's marketed as a premium "bolt in" solution. I haven't heard many bad things about QP and their quality is supposedly good, so do some research on them. I know MWC's quality is allegedly top notch, but I have heard some sketchy things about wait times and customer service.
As far as the carrier and driveshaft are concerned, I'd just stick with a regular clutch posi (33 or 35 spline) and grab a larger diameter aluminum ds. I'm currently running a 3.5" PST.
Im definitely leaning towards the 3.9 ratio as this car is a daily driver. Still reading about good tire sizes, do you have any recommendations? Strictly talking street tires, not considering strip/track use at this time. Overall the stock size is way to skinny and just looks awful since the fenders stick out quite a bit past the tire.
Im more worried about going too big and rubbing the top or inner area of the fender or just looking plain goofy. Would at the very least like to get the wheels/tires aligned with the fender (this may be more of a wheel offset question?)
Can you help me better understand the 31-35 spline difference? Im fixing to call quick performance on Monday and find out their posi options and also see if they sell quality rear disc brakes with their 9" setup since they werent listed.
I really appreciated your honest feedback on your brute speed/Moser experience, that was "brutal" but awesome of you to be straight up truthful to help others save money and progress faster on other build items.
Okay now Im following! Thank you for clarifying! Sounds like 3.73 is the highest Ill go then since it will be converting to 4.1, would 3.5 then be the proper gearing to convert to 3.9 on the 1993 T56? If I plan to make 400-500HP & TQ would now be the time to look into transmission before I break the 1993 T56?
I haven't read very much that suggest the T56 won't be adequate but definitely would appreciate some insight here before swapping the rear-end with 3.73 or lower gears only to have to swap them later for 3.9 in the new trans once cammed.
Im definitely leaning towards the 3.9 ratio as this car is a daily driver. Still reading about good tire sizes, do you have any recommendations? Strictly talking street tires, not considering strip/track use at this time. Overall the stock size is way to skinny and just looks awful since the fenders stick out quite a bit past the tire.
Im more worried about going too big and rubbing the top or inner area of the fender or just looking plain goofy. Would at the very least like to get the wheels/tires aligned with the fender (this may be more of a wheel offset question?)
Can you help me better understand the 31-35 spline difference? Im fixing to call quick performance on Monday and find out their posi options and also see if they sell quality rear disc brakes with their 9" setup since they werent listed.
I really appreciated your honest feedback on your brute speed/Moser experience, that was "brutal" but awesome of you to be straight up truthful to help others save money and progress faster on other build items.
A common wheel setup for these cars is 17x9.5 front, 18x10.5 rear. Most guys go with Corvette reps from OEWheels because they're cheap and decent quality. There's occasionally some pounding involve fitting them on the rear if you go with a wider tire, look up the BFH mod. I run 275/40r17 front and 315/35r18 rear to keep the sidewall height the same. You can run a shorter rear tire though to keep the stock speedo calibration correct.
As far as street tires go, I haven't had much luck with regular high performance summers and low 400's whp when my car was NA. I was running a 295/35r18 Mickey Street Comp which is 300 treadwear, but the lack of 2nd gear traction got old really quick (even with a 1" taller tire and 3.90 gears). A Toyo TQ or NT555r will do it for you, but they are soft sidewall street drag radials and won't handle something like autox. Your best bet is to buy a 2nd set of rear wheels and have both tire types depending on use.
And the axles with more splines will be larger diameter and stronger. 31 will be fine if you're not going serious drag, but I don't remember there being much of a price difference between the larger setups. 35 would be overkill, 33 is probably ideal. The larger spline axles will be heavier. Also, dunno about aftermarket brakes, but I'd stick with a stock style setup if you ever plan on doing something like autox. I'm running LS1 era rear brakes.
The calculator that was posted for gearing is going to be invaluable for choosing the ratio. The most important variables you have to consider are tire size, redline, and a tentative trap speed. Also, if you plan on running bias ply slicks, keep in mind that diameter grows slightly at high speed and will effect your mph @ shift.
I'll just throw some numbers out as a guesstimate. Let's say stock tire size on the rear at 25.6" with no growth (street drag radial), a h/c setup on a stock bottom end with a medium sized cam for longevity, low-mid 400's whp, a shift point around 6.4k and a trap speed of 115-120mph at sea level. Knowing all this, you want the shortest gears you can get that will avoid the 4-5 shift at the strip and have reasonable engine RPM at highway speed. Some examples from the calculator:
3.73: 131mph at the top of 4th, 2100rpm at 70mph in 6th
3.90: 125mph at the top of 4th, 2200rpm at 70mph in 6th
4.10: 119mph at the top of 4th, 2300rpm at 70mph in 6th
If your endgame is larger bias ply tires and/or h/c stock shortblock, I'd do 4.10's all day. The 3.90 would allow more power in the future and is a nice compromise for the street though.
And for the rear end, I wouldn't conflate price with quality. I have a Moser 9" in my car that I got through Brute Speed and it fits like garbage. Torque arm mount tubes were welded misaligned, the cast torque arm bracket is too undersized and needed a shim, LCA brackets are too wide and needed washers to take up slack, sway bar mounts aren't low enough, etc. Also, Moser axle splines seem somewhat undersized and the fit into my Wavetrac is very sloppy. All of this is a lot of bullshit for something that's marketed as a premium "bolt in" solution. I haven't heard many bad things about QP and their quality is supposedly good, so do some research on them. I know MWC's quality is allegedly top notch, but I have heard some sketchy things about wait times and customer service.
As far as the carrier and driveshaft are concerned, I'd just stick with a regular clutch posi (33 or 35 spline) and grab a larger diameter aluminum ds. I'm currently running a 3.5" PST.
I'm sorry you had so many problems with your Moser rear, Michael. I have sold a lot of these rears since you bought your rear back in 2013, and I haven't had many problems with them. If I did, I wouldn't be selling them. Thanks. Bob
__________________ ATI ProCharger and Moser Sales 260 672-2076
No matter what rear the gears are in, stock, 9", 12 bolt, or a S60 they will act the same if all using the same ring and pinion ratio. It's the transmission gearing that makes it different from later years. 3.73's in any rear in your car will act as 4.10's.
Bump on this post, in a 93 firebird M6 with M28 T56 trans, what gearing would I get to achieve 3.9? Would I go 3.5?.
I think 3.73--> 4.1 will be too much for a daily driver.
Bump on this post, in a 93 firebird M6 with M28 T56 trans, what gearing would I get to achieve 3.9? Would I go 3.5?.
I think 3.73--> 4.1 will be too much for a daily driver.
If this post is correct: https://www.firebirdnation.com/threa...erences.12302/ the 3.36 1st gear would be pretty steep for 4.10 gears. The good news is, the .62 6th makes highway easy. There are plenty of links online how to calc your rpm for a given speed with trans/rearend/tires.
I think the 3.73 is still a good fit. 1st gear multiplication would compare pretty similarly to what a later model L99 Camaro automatic would have had with it's taller tires (3.27 rear, 4.03 first). And thanks to your double overdrive, should be very highway friendly.
If this post is correct: https://www.firebirdnation.com/threa...erences.12302/ the 3.36 1st gear would be pretty steep for 4.10 gears. The good news is, the .62 6th makes highway easy. There are plenty of links online how to calc your rpm for a given speed with trans/rearend/tires.
I think the 3.73 is still a good fit. 1st gear multiplication would compare pretty similarly to what a later model L99 Camaro automatic would have had with it's taller tires (3.27 rear, 4.03 first). And thanks to your double overdrive, should be very highway friendly.
I seriously appreciate the insight, I'm going to stick with the 3.7 gears then since I have the oddball M6 M28 trans.
Update:
- Talked with Solomon, (what a nice guy) and will be going with him for tuning purposes.
- Currently finalizing order details with MWC for their Fab 9" to install in December
-Drump Juan wins, I ended up ordering wheels before the rear, haha you called it!
I seriously appreciate the insight, I'm going to stick with the 3.7 gears then since I have the oddball M6 M28 trans.
Update:
- Talked with Solomon, (what a nice guy) and will be going with him for tuning purposes.
- Currently finalizing order details with MWC for their Fab 9" to install in December
-Drump Juan wins, I ended up ordering wheels before the rear, haha you called it!
Nice plan! Solomon tuned by LT1 when just bolt-ons and is currently tuning my LE2 24x setup. Great customer service and he is taking the time to get everything right, you'll be happy with the results.
Nice plan! Solomon tuned by LT1 when just bolt-ons and is currently tuning my LE2 24x setup. Great customer service and he is taking the time to get everything right, you'll be happy with the results.
Thanks man! Honestly its feedback like this that made choosing Solomon for my OBD1 tune a no-brainer because better customer service with a tuner goes a very long way. Ive never had a car tuned nor put as much time or money into a car as this bird but had a fair amount of experience in the past with street bikes (specifically Buell Firebolt, R6, and CBR). When it came time to tune the Buell, customer service made the difference between a good tune and a better tune.
**On a side note, I have a question that seems relative in this thread if some folks would like to chime in. Should I be concerned or at the very least planning on a different clutch for the M28 T56?
It seems like the transmission is the least of my worries right now until I make more power but I'd like to get some insight to better understand some of the trans weak points once I get to the Heads & Cam down the road. Again end all be all power goals are in the 400-500 hp & tq range while staying NA but will likely take another 24 months to get there.
Thanks man! Honestly its feedback like this that made choosing Solomon for my OBD1 tune a no-brainer because better customer service with a tuner goes a very long way. Ive never had a car tuned nor put as much time or money into a car as this bird but had a fair amount of experience in the past with street bikes (specifically Buell Firebolt, R6, and CBR). When it came time to tune the Buell, customer service made the difference between a good tune and a better tune.
**On a side note, I have a question that seems relative in this thread if some folks would like to chime in. Should I be concerned or at the very least planning on a different clutch for the M28 T56?
It seems like the transmission is the least of my worries right now until I make more power but I'd like to get some insight to better understand some of the trans weak points once I get to the Heads & Cam down the road. Again end all be all power goals are in the 400-500 hp & tq range while staying NA but will likely take another 24 months to get there.
I had a Solomon tune. (Former 97 WS6 owner) It absolutely made the car better run better. Better mpg, ran cooler, picked up some power...etc You'll love the results. As for the T56 and the clutch, I've never had issues with the stock clutch not holding power but I wasn't one to beat on the car and I wasn't close to 400whp/tq. As long as your tires are slipping first the clutch should be fine. Budget for a decent replacement but for now, if it ain't broke don't fix it.
figured I'd give you guys an update since I've made some progress.
-My Dad's friend gave us a set of slotted and drilled front rotors, new stock clutch, slave cylinder, and throw out bearing. Legitimately it was a miracle that he had lying around from his old T-56.
- Installed Strano Swaybars front and rear and holy smokes... what a massive difference when running them with Strano springs and Koni shocks!
- BC Forged wheels are on with Michelin pilot all season, I also graphene coated the wheel face with Adam's polishes advanced coating.
(used a scale at home and wheels are 19.8lbs each!)
- Now running drilled and slotted rotors all around (nothing fancy but a nice refresh after 28 years)
- Strano Master Cylinder Brace installed, I chose to grind down the spacer a bit to get it more level. Also replaced the shock mount bolts to be longer for an easier install of the master cylinder brace. The new bolts are not pictured, picked them up from ace hardware with a set of lock nuts as well, went with grade 8.
