TKX gear ratios and other questions, Newbie mk5 build. Be Kind

[Ejzajac]

Coyote Gen 4X, IRS, 3.55 rear with 315 x 35 x 17 rear tires. Build is for street use only with limited long highway trips and no track.
1. Suggestions for selecting from multiple TKX ratios? Best to match with my set up and Coyote 4X
2. Bellhouse choices. steel vs aluminum?
3. Clutch choices. Kevlar vs ceramic?
4. Flywheel. cast vs milled?
5. What has been the experience with Modern Driveline, Idaho?

Thanks

[Jeff Kleiner]

With a 3.55 I’d go with the TCET17765 which has a 2.87 first gear and .68 fifth. Street use the aluminum bell will be fine but check flywheel clearance during assembly—-some need minor grinding to avoid interference. Can’t speak for Modern Driveline but I suggest that before you commit to anything you should speak with Mike Forte.

Jeff

[rich grsc]

agree with Jeff on tranny
aluminum
neither one
cast
none

[gbranham]

I went with the .68 ratio TKX at Jeff's suggestion, after playing around with online gear ratio calculators. While I have the 18" Halibrands and the kit-supplied 3.55 IRS diff, this chart gives you an idea of the RPM you could expect at different speeds and different gears. In 5th at 70MPH, for example, I can expect to be turning around 2250RPM. I'm not on the road yet, but I feel this is a good setup.

TKX Chart.jpg

[Valkster]

Hi, I am currently building a MK4...almost done, I hope. My engine is different than yours, a modernized old-school FE, but I have that same TKX in my build that Jeff suggested. I also have a 3.55 rear IRS that I got used for my build, and the same rear tire size as you (Nitto NT555 G2s). I have a McLeod ceramic/organic clutch plate with Mcleod pressure plate and hydraulic clutch bearing to go with it. I have a milled flywheel, but I think it was due to availability of parts for me during post-covid times. A fellow named Brett Lykins in Kentucky helped me spec much of it out (he has a nice YouTube presence for Ford engine enthusiasts). I too am building for street use with some longer highway trips planned. I am just go carting the car right now, but even with much lower top-end RPMs than you will be able to take advantage of, I am at highway speeds with a lot of engine left. At the same time, at 1/2ish throttle, the low rpm torque on my engine will spin the car round-and-round in circles with this setup, lol. I'd have gone with an aluminum OEM bell housing if I could, but I could not find one for my engine/tranny combo and had to use a Quick Time steel bellhousing. You should be able to find an aluminum one though, and it would be more than adequate for street use. Good luck with your build!

Mark

[OB6]

I have an LS3, but the principles are the same. I have the 3.55 and the .68 TKX. Stock organic clutch to keep things quiet and smooth. And a Quicktime (steel) bellhousing. All of this was recommended by and sourced from Mike Forte (except the 3.55 Torsen which I bought locally). Definitely give him a call.

You'll want to consider which type of throwout bearing to use. I'm a fan of the internal hydraulic units from Tilton, but lots of people prefer the external setups, and Mike is the go-to for that.

[BUDFIVE]

Ejzajac,
Welcome and we all were Newbies at some point. Excellent points above from guys I have learned a lot from. I have the same rear gear and tire sizes as you but with a 347 SBF and a bit of an old school MK4 build.
1) I made a different transmission choice (18084) with the same 1st-4th but a 0.81 5th instead of 0.68.
I point this out only because it highlights the question how you really want to drive the car and what RPMs your engine wants to run—someone on the forum may benefit. If your “limited long highway trips” are at 70+ mph it makes sense to consider the 0.68 as suggested, especially with a torque motor like Valkster’s. Plus your coyote will probably be happy at even 1700-1800 RPM. But, If “street use” includes poking around country roads with 55-65mph speed limits and your motor is happy above 2000 RPM, that’s why I picked the 0.81–these roads are the joy rides in my Vette while I build the Roadster. Gbranham’s chart illustrates the non-linear jump from 4th to 5th with the 0.68 gear. This is fine if you run it up to 65 or 70 in 4th on the entrance ramp then hit 5th. The 0.68 hits 62.8mph at 2000 RPM where the 0.81 hits 52.7mph. So I can run it up to 55 in 4th, hit 5th and cruise at 55-65 on my country roads, still above 2000 rpm where my motor wants to be. Most folks pick the 0.68 as suggested above and consider the 0.81 option to be for track use. I picked the 0.81 to make 5th more useable at slower speeds. By the way, on my GoCart 3.0 last week I ran the car up through the gears to 55 and hit 5th, sweet
2) I went with an aluminum bell housing from Tremec—the measured flywheel to bell housing runout (critical on the TKX output) was in spec.
3) I have a McLeod Organic/Ceramic with a mechanical throwout and quadrant with Ford Performance cable. I like the set up so far.
4) My flywheel is a 25lb billet steel unit from Ford Performance. It seems heavy enough to get the car rolling but still lets it rev.

Enjoy your MK5 build and learning+contributing on the forum. I look forward to reading your updates.

[weendoggy]

Coyote Gen 4X, IRS, 3.55 rear with 315 x 35 x 17 rear tires. Build is for street use only with limited long highway trips and no track.
1. Suggestions for selecting from multiple TKX ratios? Best to match with my set up and Coyote 4X
2. Bellhouse choices. steel vs aluminum?
3. Clutch choices. Kevlar vs ceramic?
4. Flywheel. cast vs milled?
5. What has been the experience with Modern Driveline, Idaho?

Thanks

1. The TCET17765 will be fine for your use, especially hwy.
2. Aluminum stock is fine (I use it on my '02 Coyote swapped Mustang)
3. I like the Centerforce DF clutches myself. Using them for 30+ years.
4. Look into the ATC flywheel. Close to aluminum weight but all steel.
5. MD is great to deal with and they're a dealer as well.

jmo