Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part August's Ride of the Month Challenge!
1 - 19 of 19 Posts

·
Registered
Joined
·
63 Posts
Discussion Starter · #1 ·
Hey guys,

Upgrading my 3-speed to a T5, MDL quoted me about $4k for the complete conversion and Currie the same for a rear end.... $8k seems a bit steep so I've been doing a bit of digging.

And I've sourced a good 8.8" Explorer 3.73 31 spline rear end and a world class Borg Warner T5 for a tenth of that cost. Before I pull the trigger, I'd like any and all advice. I've read through quite a bit of these conversions but I'm not sure how unique my situation is because of replacing the front and rear simultaneously and also having a 200 i6. If there's very little between difference between my situation and every other 6cyl conversion then I apologize in advance!

For the rear end, I'd need to remove and reattach the leaf spring brackets, but that's about it, right?

And for the T5, I'd need a whole lot of stuff, I'll probably need an adapter plate to my 6cyl 200 but where should I go looking for those, are all T5s built the same or is BW very different from Tremec? What else should I be thinking about, is there anything I can reuse from the 3 speed?


Does this about cover it?

Thanks for the patience, I'm pretty new at this whole thing.

For what it's worth- it's a '67 as well.
 

·
Dimples
Joined
·
7,395 Posts
If you’ve done your research, you’ve probably found this thread on the 8.8 swap:

As far as 6cyl-specifically, I would imagine that the only difference may be the driveshaft? I’m not sure about that one.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #3 ·
If you’ve done your research, you’ve probably found this thread on the 8.8 swap:

As far as 6cyl-specifically, I would imagine that the only difference may be the driveshaft? I’m not sure about that one.
Yeah I came across that one, the rear I'm looking at already has brakes attached and I've got a '67 so hopefully I can avoid a couple of those costs.

I assumed the driveshaft's gonna need something, which is why I figure let's do the rear end and the transmission at the same time. Install twice cut once.
 

·
Dimples
Joined
·
7,395 Posts
Yeah I came across that one, the rear I'm looking at already has brakes attached and I've got a '67 so hopefully I can avoid a couple of those costs.

I assumed the driveshaft's gonna need something, which is why I figure let's do the rear end and the transmission at the same time. Install twice cut once.
Good call. I did the T5 first and had to cut an inch out of the driveshaft. Did the 8.8 and had to cut another inch.

The thing I’m ignorant of is if the 6cyl driveshaft is lighter duty and if it would be worth upgrading while you’re in there. The idea of finding the right size out of a Ranger or something is attractive.
 

·
Registered
Joined
·
6,008 Posts
I would think that a non-Z spec T5 combined with a 3.73 rear end would give you a granny type 1st gear ratio,
 

·
Premium Member
68 Mustang Coupe
Joined
·
6,295 Posts
There's an explorer driveshaft you can use. I can't remember if it's the 2wd 2 door version or 2wd 4 door... there's a thread or two on here.
 

·
Registered
Joined
·
1,122 Posts
There's allot of little things that really improve the entire T5 upgrade. Start by taking your pedal assembly and put in roller bearings, common upgrade. I prefer an external slave cylinder for the clutch because it easier to replace if it leaks. MDL has good stuff, but most you can make yourself for a fraction of the cost, like the crossmember, if you have the tools and welder. Use their clutch master cylinder, but pay very close attention to the install process. As for the 8.8, again, if you have a welder, you can save a bunch of $.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #12 ·
There's allot of little things that really improve the entire T5 upgrade. Start by taking your pedal assembly and put in roller bearings, common upgrade. I prefer an external slave cylinder for the clutch because it easier to replace if it leaks. MDL has good stuff, but most you can make yourself for a fraction of the cost, like the crossmember, if you have the tools and welder. Use their clutch master cylinder, but pay very close attention to the install process. As for the 8.8, again, if you have a welder, you can save a bunch of $.
I did the roller bearing upgrade and shifter rebuild kit at the same time (my old shifter would sometimes wiggle itself into neutral) and you're right, it felt so much better to drive.

Granted, my clutch also had bored a hole in the pedal assembly and twisted itself so it would gouge into my steering column so shifting was already unbearable. No idea what the previous owner was doing...

I don't have a welder unfortunately, but there isn't too much welding with this project, or there doesn't need to be... right? Aren't leaf spring brackets and the driveline being shortened the only "modifications?"
 

·
Registered
Joined
·
6,008 Posts
That's interesting, could you expand more on that?

Most of my reading said best highway rear gears are 3.55 to 3.73, but that's all it was- reading.
Here's an explanation from Google: "If your Mustang has a 3.35 First gear and a 3.55 rear gear, the overall First-gear ratio is 3.35 x 3.55 = 11.89. Anything greater than 9.5 could be considered overkill for the street. Ever driven a Mustang with a 3.35 First-gear trans and a 3.73 rear? First gear is virtually useless, since the overall ratio is 12.49".
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #15 · (Edited)
Here's an explanation from Google: "If your Mustang has a 3.35 First gear and a 3.55 rear gear, the overall First-gear ratio is 3.35 x 3.55 = 11.89. Anything greater than 9.5 could be considered overkill for the street. Ever driven a Mustang with a 3.35 First-gear trans and a 3.73 rear? First gear is virtually useless, since the overall ratio is 12.49".
Hm, my current gears are 3.20 so if that's the case should I swap the rear end at all? The guys at MDL said 3.20 won't be as fun to drive (as 3.55 but 3.73 was their recommended) and I'll rarely be going fast enough to need the 5th gear. Maybe that was with their Tremec T5 though and the BW has different ratios?


EDIT: Just looked up the serial number of the BWT5, it says my first gear is 3.35. 3.35x3.20=10.72. Even without upgrading the rear end I'm overkill evidently.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #16 ·
I put a Foxbody 8.8 into my 68, not sure how much of the info will help on the Explorer variant but here's the thread - Foxbody 8.8 Swap into 68

You'll also need to change your master cylinder to handle the rear discs, as well as adapting the parking brakes.
Got discs up front so I think it's just a matter of deleting the proportioning valve.

That's a great write up. If the worst part was grinding then I feel a bit more confident.
 

·
Registered
Joined
·
1,892 Posts
I'd buy an 8" and swap it in, way cheaper.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #18 · (Edited)
I'd buy an 8" and swap it in, way cheaper.
I've been looking all summer for an 8" (that's what she said) from a Maverick but no luck.

Craigslist had a few lemons in 8 and 7.5".
Ebay has exorbitant shipping costs, and generally not complete 8" rears and piecemealing something together puts it up toward the same cost.
Found some luck with Shoppok but only 8.8s.
Scrap yards had 8.8s, but like I said, if I'm going through the wait of finding a rear end anyway I should hold out for a good one (3.73 / 31 spline). Although, it may seem that 3.73s are overkill?

Do you know anywhere I should be checking? I'm happy to get the easiest rear end, but I'm happier to get the least expensive one (after total cost of mods). At this point I'm wiling to spend up to near $400 or maybe even $500 on a rear end because I can't seem to find one.
 

·
Dimples
Joined
·
7,395 Posts
Got discs up front so I think it's just a matter of deleting the proportioning valve.
You wouldn’t delete the proportioning valve, you would remove an external residual pressure valve or if it’s internal on the master cyl (depends on what master cyl you have), you would switch to a master cyl that doesn’t have a residual pressure valve.
 
1 - 19 of 19 Posts
Top