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Volvo B20 T5 Trans Swap Questions

hensh_ma

New member
Joined
May 20, 2024
I have a '65 Volvo 122s with a B20 swap. Engine is getting mildly rebuilt, and now I'm focusing on M40 trans which feels like shifting through a bunch of rocks. Because of rarity/cost, seems like M40/M41 is a nonstarter these days. And I don't want to deal with an electric overdrive/"fake 5th gear".

Enter the T5 swap.

I've dug through a ton of articles talking about this swap, and I have most questions answered, except for the T5 transmission selection due to input shaft/bellhousing/gear ratios.

Seems like you can swap a few different Ford Mustang T5's on a B20 (with adapter plates, bell housing mods, pilot bearing changes, etc):
  • BEST: '85-'93 Mustang 5.0L v8
    • Input shaft length matches (7.14")
    • Gear Ratios: 3.35, 1.93, 1.29, 1, 0.68 (tall 5th gear annoying but otherwise ok)
    • Torque rating: 300
  • DECENT: '94-'95 Mustang 5.0L v8
    • Input shaft length longer (~7.8") requires a thicker adapter plate, input shaft swap OR trimming 5/8th off the end
    • Gear ratios: same as above '85-'93
    • Torque rating: 300
  • QUESTIONABLE: '94-'98 Mustang 3.8L v6
    • Input shaft length: ???
    • Input shaft tooth compatibility: ???
    • Gear Ratios: 3.35, 1.93, 1.29, 1, 0.73 (seems like better gearing for B20?)
    • Torque rating: 265
Is this information accurate? With a '65 122s rear drive ratio of 4.1 (I think) I'm getting confused about gearing...I'm also going to run smaller tires than stock (195/60r14) for now...the Mustang v6 transmission is the most available near me (and the cheapest) so hoping to figure something out.

If anyone has some input on this swap and the type of T5 to choose based on experience, would love some input...thanks!
 
I believe that all available adapters use the longer input shaft. There are shafts available to suit almost all flavors. My plate uses a stock b18-20 bellhousing, so you can keep your hydraulic clutch. Some adjustments To the throw out fork are required, just a little polish down till it slips around the bearing. Uses an off the shelf mustang TOB and pilot bearings. Might require some shimming of the clutch pivot.
 
I believe that all available adapters use the longer input shaft. There are shafts available to suit almost all flavors. My plate uses a stock b18-20 bellhousing, so you can keep your hydraulic clutch. Some adjustments To the throw out fork are required, just a little polish down till it slips around the bearing. Uses an off the shelf mustang TOB and pilot bearings. Might require some shimming of the clutch pivot.
Do you make an adapter?

The only ones I've seen are from Deeworks, BNE or through John Parker @ VPD (who, from what I've read, is to be avoided)
 
What is the measurement from the transmission face to the centreline of the gear stick for your 122S' present transmission?

Dave Barton's pages have much T5 goodness.

IMHO you'd be best off with a T5Y ratio set with a box that has a V8 cluster set, takes a V8 input shaft with a tapered pocket bearing (stronger) and a 28 spline output shaft.

Then either using a shorter diff ratio, or finding a suitable pair of 28-spline 5th gears to give you something shorter than 0.68 in 5th.

T5 gearboxes are a bit like Lego - many combinations are possible.
 
@cwdodson88 awesome. Those bad boys are thick -- so they work with the 7.85" input shaft?
They’re 1” thick, with a built in spigot for the bellhousing side. At the moment, I have the ability to run them on a 2wk turn around.

They require the 7.85 input shaft. I also have a core t5, 3.35 1st, 0.72 5th that I can let go. It probably would be fine for a medium power b20 or rebuild it and it’ll take some more abuse.
 
@cwdodson88 appreciate it, but I actually found a spare M40 on facebook marketplace with good gears this weekend for cheap -- so I may try to make the M40 work as I have some spare parts now.

@spock345 yes, I know that, although the extent of the removal is a little unclear. Seems like it's mostly where the bellhousing part of tunnel meets the firewall area. Plus figuring out the shifter relocation. I see your old(er) posts all over these boards with both engine and transmission swap questions - what do you have these days?
 
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