Drivetrain Overhaul, Need Help

SK_BlownThunder

Registered User
1990 Super Coupe 5-speed: I am pulling apart the tranny and rear end this winter for a major inspection and possible 100% overhaul. My dad and I rebuilt the engine last summer to the stock specs w/.020 overbore on the cylinders. I still use the car for day to day activities such as going to school etc..., but also would like to drag race it occasionally during the summer months.

1. I need to know where to find a set of synchros (2nd gear synchro is currently completely shot) preferably heavier duty ones for racing applications but still offer a smooth shift for daily driving.

2. I am looking at doing the final drive gears. What all is involved, what do I need, and what ratio is recommended for the 5-speed SC? (I believe the autos had a different ratio in the rear end). On my 5-speed, the diff wan't locking up this morning on the slippery wet street. My left side seemed to be getting all of the power and just spinning. Even in 3rd gear (stock setup) I was spinning the left wheel and barely going anywhere. It's never done this before, usually the diff locks the wheels together if one starts to slip.

3. Is it recommended to replace the driveshaft with an afermarket one? It would be nice to find something a little lighter yet strong enough to withstand the drivetrain forces.

4. Lastly, being the car is my daily driver, I would like to find a possibility to tweek the overdrive gear (5th) so that I still run below 2000 rpm when cruising at 64.5 mph (110 km/h).

It would be greatly appreciated if someone could give me some advice here and possibly some places to get the parts I require for this job. Unfortunately I have to get this done before my exhaust or any performance upgrades anyway. With the gas $ going up, performance mods might have to wait.

Thanks alot and I appreciate any help I can get,

Brett
 
geigerb said:
1. I need to know where to find a set of synchros (2nd gear synchro is currently completely shot) preferably heavier duty ones for racing applications but still offer a smooth shift for daily driving.

Southern Gear has the syncro's, there is no such thing as a heavier syncro for these transmissions. You simply need to hit your shifts.

Link to contact info:
http://www.sccoa.com/forums/showthread.php?t=63216&highlight=southern+gear


2. I am looking at doing the final drive gears. What all is involved, what do I need, and what ratio is recommended for the 5-speed SC? (I believe the autos had a different ratio in the rear end). On my 5-speed, the

Search on gear swaps. You'll need to replace the ring and pinion gears to change the final drive gears. It's a complex procedure setting up a rear end, if you've never done it before you should at least have help from someone that has.

3.08 or 3.27 gears are good swaps for the 5 speed. a great article is available in the members sectiion specifically on 5 speeds and choosing optimum gears.
http://www.sccoa.com/forums/showthread.php?t=31551&highlight=manual+rear+gear

As far as your diff not locking.... that's caused by worn clutch packs inside the differential. Time to rebuild it.

3. Is it recommended to replace the driveshaft with an afermarket one? It would be nice to find something a little lighter yet strong enough to withstand the drivetrain forces.

You can fit the aluminum one from the Lincoln Mark VIII. Otherwise there are companies that will make metal matrix replacements for the SC.

4. Lastly, being the car is my daily driver, I would like to find a possibility to tweek the overdrive gear (5th) so that I still run below 2000 rpm when cruising at 64.5 mph (110 km/h).

I'm not sure what you mean by tweeking it. Unless you're going to machine a new 5th gear for the transmission. You're stuck with what you get.


I'd check on the Canada forums here to finid out info on possible parts sources in the northern lands.
 
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