I went with a Centerforce Dual Friction. Engagement is smooth, pedal effort is easy to moderate, available with either a 26 spline or 10 spline disc. Rated for 529 foot pounds of torque
Thanks, Darron. I actually had been leaning toward a Centerforce of some sort. I would love to have the dual disc but its price scared me, so I was thinking of one of their lesser models. The dual friction is right at my upper price limit, and my engine can probably make 550-600 lbs. of torque but I would seldom be dumping the clutch at that RPM. Then I read some reviewers saying there were some things they didn't like about their Centerforce--pedal was harder than they thought it should be, funny noises coming out of it. So I started to consider other brands like Hays or McLeod, thinking maybe a basic organic clutch and a pressure plate that is just one step above stock is all I need. I will consider your advice, though, since I don't need to decide just yet. TKX update: Bowler wasn't kidding, the trans arrived today! So that's exactly 48 hours after placing the order that it showed up on my porch. They must have started slapping a shipping label on the box, and scheduling a pickup with UPS, immediately after I hung up the phone on Wednesday.
I would be cautious of the offset shifter stub vs a transmission that has the shifter tower physically moved and offset. From pictures of an install on a 66 or 7 chevelle (has offset shifter like ours) the owner couldn't get the rear of the trans low enough to get driveline angles correct due to the shifter tower contacting the tunnel. It looks like SST is the only vendor who sells one with offset shifter tower that is centered in our shifter hole, and it can stick up an inch or 2 and not contact any sheet metal
As per the recommendation of my engine builder he recommended going with the Centerforce DFX and going to an 11” instead of the 10.5 I should have approximately 500 HP on my small block build.
Thanks, Steve, I will look into that one a bit more. And you answered my question regarding the best clutch diameter, too. It's been 40 years since I replaced the clutch on my GS400, and I don't remember what it was. Apparently either the 10 1/2 or 11 inch will fit a BBB flywheel and bell housing, and of the two, the 11 is the better choice for hi-performance applications. I assume more contact area means better pressure plate clamping, and/or less pedal effort to release the clutch. Correct?
More friction area, but requires additional clamping, so a bit stiffer pedal. One half inch at the outer edge adds about 15 % additional friction area and that is about the same increase in HP rating of the holding potential. So, that 1/2 inch is quite a bit.
Small update: I unboxed the TKX and it looks good. Oh, and if you are confused (like I was) about which fluid(s) are approved/recommended to put in your TKX, say something and I will tell you what I learned.
Anybody have this installed and running? Curious to hear about real-world experience. Everything always sounds so good on paper (or on screen, I guess). There are lots of threads on hydraulic clutch systems - what’s the sentiment for those that have bought the TKX? Will you be running a hydraulic system?
I plan to install mine as soon as I can, which means within the next month. I will definitely give an update on how I like it. As for hydraulic clutch--not for me. Too expensive and I just don't like the idea, but others have said they love theirs.
What did you learn on fluid(s) approved/recommended? I understand. I've heard the love for them too, but I take issue with the reservoir. Looking to see if an under-dash mount might work, and there are certainly options out there, just unsure if I would really enjoy the hydraulic system that much...
American Powertrain recommends Tremec HP-MTF or GM Syncromesh. In another part of their FAQs they say Pennzoil Synchromesh, or Mobil 1 ATF. Confused yet? Modern Driveline says "If you have a TREMEC TKX or TKO transmission, there are only a few oils or fluids recommended for use, and TREMEC cautions against alternatives. The most recommended oil for TKX is Dexron III Oil. TREMEC TKX transmissions use the Dexron III or Dexron III/Mercon Spec ATF fluid. The most recommended oil for TKO is AMSOIL Synthetic Manual Synchromesh Transmission Fluid. GM Synchromesh Oil." But elsewhere MDL says "Lubricant Specifications--For all Tremec TKX 5-Speed models, the recommended oils are Amzoil ATF or Synchromesh, Tremec High-Performance manual transmission Fluid (HP-MTF), GM Synchromesh, or Mobil 1 Synthetic ATF" Holley says: "Tremec recommends its own specific formula of High Performance Manual Transmission Fluid (HP-MTF). If this is not available, then either GM Synchromesh or Mobil 1 synthetic ATF should be used." TREMEC Transmissions recommends only three types of oil or fluid for the TREMEC TKO transmission, one of which is GM Synchromesh, specifically part number 12345349 and the TR-35505sp model." But Bowler, who I bought my TKX from, says pretty much all the above, especially the GM Synchromesh or Valvoline Synchromesh MTF, PLUS Royal Purple Synchromax. I ordered the Valvoline, which was cheaper, but after break-in I plan to use the Royal Purple. I have had bad luck with the 2 vehicles I've owned that had hydraulics--'84 Z28, and 2002 F-150. They don't feel like they make the slave cylinder move far enough. Result: Grinding.
The above depicts viscosities of different trans oils. The older TKO's used brass syncro rings (ala old Muncie transmissions) so a more viscous fluid with a different friction modifier was used. With the development of the T56 Magnums, fiber lined bronze sycros, were used to allow quicker gear shift changes. Not sure, but I believe the TKX has been upgraded to these in its design, in which case you would be best suited to use a friction modified oil that is compatible. For my 6 speed T56 Magnum I was advised to only use a Dexron III fluid. In any event you want to be certain on using the right fluid so you don't glaze any fibre lined Syncro rings if that is what TKX's now have. Tom
Thanks, Tom. Here is what Holley says about the TKX's synchros: Dec 15, 2020 — The new Tremec TKX five-speed manual transmission is a new ... The TKO used brass synchro rings much like those used in Ford Top Loader . MDL says: Sintered carbon + bronze-Hybrid double-cone synchros with a non-leading edge profile direct from the T56 Magnum allowing for up to 8000 RPM shifts ...
Would seem to be an excellent plan, put a 529 lb ft rated Centerforce circuit breaker in front of the 600 lb ft rated transmission case because when you hook hard it would slip before breaking expensive trans parts. Also seems you would have to be a pretty smart dude to use other than the specified factory engineered and tested transmission fluid in a trans that you have not been driven yet. ?
After installing a TKO600 from American Powertrain over the last year with Covid delays and having it in and out 5x I can honestly say it the best improvement I’ve done to the car so far. I can say that there were plenty of snags but after taking it to a friends shop and eliminating the crappy after market cross member and modifying stock 4spd one and machining a custom pilot bushing it really runs well. Now I can do 75 on the LIE at 2100 rpms while retaining 4:10’s. Fun fun fun!!!
In my car I bought the kit from American Powertrain. The stock consellete is still in place with the 5spd. I only had to remove a slight piece of the floor under it for the new shifter. Otherwise u can’t tell. Did have to have a custom driveshaft made with the bigger u joints.
