I was trying to tackle the ".63 O/D with 2.80 gears" issue with an upcoming T5 swap, and I noticed Modern Driveline will put a .73 O/D in a T5 for me for an extra $170. That's a hell of a lot cheaper than replacing the gears out in the rear end like I was looking at doing, and it would put my RPM at 70 MPH at right about 1911 based on my tires/rear end setup. What do you all think? I've got the standard 2.80 gears in there right now running 215/60R15 tires. I either swap out the gears, or I pay extra for .73 O/D, or I never see 5th with the T5. Of all the reading I've done on the T5 swap, I've only heard of everyone talking about swapping out the rear end. I've never heard anyone mention the possibility of just changing out the O/D gear.

I've been using the following RPM calculator... great tool!

http://www.allfordmustangs.com/Detailed/608.shtml

 

I think that would be wasting a 170 bucks.

although 1st gears are similar 2.46 vs 2.95 c4 and t5 respective and you would be getting the benefits of a 2000 vs 2700 at 75 mph you are really only getting half the benefits depending on how you drive the car maybe thats all your looking for...

But for about 200 bucks more you could get the benefits of running a 3.80 rearend and having the .63 OD...Having your cake and eating it too. This makes a big difference in acceleration plus you can also cruise down the freeway at 90 mph @ 3000 rpm or 75 mph at 2500 rpm (bout optimal efficiency rpm right there)

Do you really want to go through all the trouble of the t5 swap and miss out on the other half of the picture?

Thats up to you.

You could install the t5 as is then swap the rearend when you have funds. Thats what I did.

-Gun

 

Really? Only $400 to put in 3.80 gears? I've only been seeing rear end gears for over $1k, and that doesn't include installation (I'm not opposed to doing it, but I've never messed with a rear end... that sounds wrong). I must not be looking in the right place, or maybe I'm looking for the wrong item (been doing a search for 3rd member on jegs). Should I only be looking at the ring and pinion gear? Approximately how much would it cost to buy my own gears, and then drop the car off at a shop to have the gears put in? I know nothing about rear end gears, setting backlash, axles, and whatever else applies.

I didn't consider 1st through 4th and how that would feel. with the T5 gears. This car is my daily driver. I baby it. It's a cruiser, not a track car at all, and I have no intention of driving it anywhere near 90. Probably 75 on the freeway is the fastest I'd ever drive this car.

 

No..NO no no...you got it all wrong.

You dont need a new 3rd member.

All you need is a ring and pinion gear and bearings.

http://www.summitracing.com/parts/SUM-740802/


Getting them to mesh properly is a task I didn't not want to attempt so I had a shop install them. With the new bearings and the install of the gears its simply 50ish or something for bearings and shop labor...All said and done cost should not exceed 400 for everything.

The shop will handle bearing purchases at least in my case.


If you feel froggy now would be a good time to install a limited slip differential

http://www.summitracing.com/parts/DTL-912A580?autofilter=1∂=DTL-912A580&N=700+115&autoview=sku

This system allows for equal power to both rear wheels but unlike lockers its totally transparent to the driver it doesn't clank, pop or chirp tires and functions just like your open differential does now...until one tire starts to slip then power is transferred to the gripping tire...so now it leaves two stripes when you peal out and finally unlike common LSD systems this one is totally gear driven so there are no clutch packs to wear out...I think the proper term for this system is a torque sensing differential.

I dont recommend this upgrade in your case...I dont think its applicable...I daily drive my car and love my tru track...So I figured it was worth mentioning to you.

One more thing.

With the lower 3.80 gear you will reduce torque stress on the t5 and Im pretty sure you'll get better fuel mileage around town as effort required to start the car moving is less.... just like its easier to get a bicycle moving in the low gears as opposed to trying to start off from one of the higher gears (like 5th on a 10spd bike)

-Gun

 

Got it, thanks! I suppose it would be smarter to just spend the little extra and get new rear end gears eventually. I see the ring and pinion gear sets are FAR less money. Thanks for pointing me in the right direction! Like you said, I can just upgrade to the 3.8 gears later down the road. Good analogy with the ten-speed bike. That makes perfect sense.

 

The ring and pinion you have in there now is probably about worn out. Mine had chipped teeth and questionable bearings...its like 45 years old what did you expect right?

So thats one more reason to swap gears as opposed to changing the t5 ratio.

How lame would it be to change the t5 gear then have the carrier bearings fail in the diff and realise that 10 teeth are chipped as well on the ring gear...and then say "Damn! I could have installed 3.80 now for the same cost as another set of 2.80s but 3.80s are unusable now with my .75 od"

-Gun

 

Great point. That would definitely be no good. That would be just my luck, too. That plan will actually help to ease the pain on the wallet for the swap. Like I said, I'm pricing everything out to be around $3500 with a new T5. I don't mind spending it though if it's such a good upgrade and the parts are quality and sure to last me a while.

I can upgrade the rear gears after the wifee has had some time to "cool off" after hearing how much I spent... haha.

 

Yeah its a great upgrade. I did fight a vibration that occurred after the swap. I think it turned out to be a combo of old crappy driveline + worn slipyoke + worn tailshaft bushing. Replacing all those minus the crappy driveline yield a usable result. I think switching to a 3" aluminum driveshaft is in order for me but its actually working great most of the time.

With an all new T5 (totally new or well rebuilt) you should have zero problems and it should be pretty easy. Word of advice go for the hydraulic clutch. The cable is a total pain to install and the hydraulic system is smoother. You can talk to JamesW about getting a complete hydraulic system from Daze (who is a member here but hasn't posted lately) Im pretty sure JamesW could point you in the right direction for the hydraulic setup if you dont already have one lined up. (cost was way less than what you see in catalogs)

Good Luck

-Gun

 

I'm actually pretty set on the cable clutch setup. I plan on going with the complete mustangsteve pedal assembly/cable clutch/brake booster setup. It appears to be a pretty simple mostly bolt up assembly that I think will help with my power brake upgrade as well. The only issues I've ever read about with his setup are...

1. Clearing the cowl for the quadrant. I'm not too worried about this though. I'm not afraid of a little elbow grease and a 5lb sledge hammer. My cowl already leaks anyways, so I can't imagine doing any more damage. I've also read about a bottle jack method that made it even easier.

2. Clutch cable routing/melting. I'm not too worried about this either though. EVERY single instance I've read about where someone was having issues with the clutch cable, it ended up having something to do with exhaust/header setup. I'm planning on shorty's, the 86-93 bellhousing, and the longer SN95 adjustable cable that routes all the way past the oil filter before looping back around. I'll also make sure to use plenty of heat wrap where necessary, and I'm not having the exhaust installed until the cable has been ran. That way the technician can take the clutch cable setup into account when connecting my headers to the mid-pipes.

I know cable clutches were used for many years and can be good for ten's of thousands of miles if not more. I truly believe it's all in how you route the cable and take the time to make sure it's free and clear of any kinks and hot exhaust pipes. Like I said before, almost every issue I read about had something to do with the owner not wanting to get rid of their long tubes or something similar.

 

I used that same system.

1) There is no room to swing a hammer with enough force to bend anything (epic fail) Couldnt get the bottle jack to fit either. The solution was to have a helper heat the metal red with torch by sticking torch through clutch hole in firewall and then beating the crap out of it from the drivers floor board using a small hammer and a foot long brass rod one little spot at a time.

2) Have shorty headers and cable route works okay does require insulation at at least one point.

That said the mustang steve cable system does work well. I found the hydraulic system had a slightly smoother feel and a bit less pedal effort. Hydraulic setup also eliminated the flex at the firewall that occurs when the clutch is pressed in. There is a huge amount of force applied to the adjusting block which is bolted to the firewall this flexes the mounting location on the firewall each time you press in the clutch an obvious amount. Other than it looking painful Im not sure of any issues that it causes.

Finally both clutch systems require far more effort to engage than you are use to (especially the cable) I run the 10.5 king cobra clutch at first you are like "wow you gotta really stomp on it" but I never considered it unreasonable and you dont even notice it after about a week It teaches good habits like shifting to N at stops rather than beating the crap out of the throwout bearing.

-Gun