12HT standard vs heavy duty clutch, application and pedal stiffness (1 Viewer)

[Br3ntfire]

I drive an 87 JDM HJ61 with the 12HT/H55F, and unfortunately my transmission just up and died out of nowhere, so I'm replacing it with a new unit, and obviously will drop a new clutch in as well while I'm in there. My question is, would the standard or heavy duty clutch be a better choice? Likely purchasing from @cruiseroutfitters. This is one of my daily drivers, and more of a road trip and camping vehicle than a crawler for me, although I do get down some mildly gnarly forest service roads etc from time to time.

I've never had issues with my current clutch, although I don't know whether it's the standard or HD as it hasn't needed any work since I've owned the truck. I'm inclined towards the heavy duty option because beefier is usually better, but I spend enough time stuck in ski/hiking traffic on I70 that I'm slightly worried about the potential for a much stiffer pedal. Does anyone have any guidance on this issue? Haven't been able to find an answer to the clutch pedal stiffness on the forums so figured I'd start a thread to make the info searchable for others.

I'm on 33s with no plans to go larger, 3.7 gearing and am doing the 10% overdrive option on my new H55 unit that I'm buying from @cruisermatt. I've also added a boost controller and am running ~12psi for the increased power and decreased EGTs especially up the steeper grades on I70. My rig is fairly stock, no giant bumpers or roof racks weighing it down more than the giant lump of steel came from the factory . I occasionally tow, but just around town picking up plywood etc.

 

[drenmaster]

Just get the standard aisin clutch and stop thinking about it.

Edit for clarity. The OEM clutches have lasted for 100s of thousands of miles with no issues. Aisin clutches are pretty much the oem clutch now for these. In my opion the 12ht will never be able to produce enough power the where the stock clutch would not last.

Aisin clutch + Japanese bearings can’t really go wrong.

I have never used a heavy duty clutch so i can not compare, but I always go with what I know works.

 

[cruisermatt]

I would like to hear @cruiseroutfit thoughts on this, I don't hear of many running the HD clutches?

 

[cruiseroutfit]

The only customers we have running the HD variant clutches are those with extremely tuned/tweaked motors. I’m not talking about turned up fuel rather larger turbos, injector upgrades, exhaust and intake mods, etc resulting in power output significantly higher than even a traditionally tuned diesel. Far lass common here in NA compared to what users in Aus do to them. For the other 99%, the AISIN kits we build in house (all using OE Koyo or NSK bearings) are perfectly suited.

 

[Br3ntfire]

@drenmaster thanks for the edit... Much more helpful than the original version lol.

The only customers we have running the HD variant clutches are those with extremely tuned/tweaked motors. I’m not talking about turned up fuel rather larger turbos, injector upgrades, exhaust and intake mods, etc resulting in power output significantly higher than even a traditionally tuned diesel. Far lass common here in NA compared to what users in Aus do to them. For the other 99%, the AISIN kits we build in house (all using OE Koyo or NSK bearings) are perfectly suited.

This is exactly the info I was looking for, I'd seen some rumblings from other threads about larger tires + more torque potentially causing slippage but sometimes it's hard to know if that's just typical cruiserheads overdoing everything or actual important information. I'd love to tune the truck more eventually but the import emissions laws in CO are pretty strict, so looks like it's standard duty for me.

Thanks @cruiseroutfit!

 

[drenmaster]

@cruiseroutfit the kit they are talking about is what I put in my 61 and works flawlessly. My OEM clutch did not need replaced but I had a bearing chirping so with the tranny out the right move was to replace everything.

 

[drenmaster]

@Br3ntfire sorry about the lack of info. I just put it out there with the intention of coming back and adding to it.

I helped tow a FJ55 up a decent incline a couple years ago in CO. Even with a clutch dump and clutch smells, no slipping and just kept pulling.

 

[Br3ntfire]

@Br3ntfire sorry about the lack of info. I just put it out there with the intention of coming back and adding to it.

I helped tow a FJ55 up a decent incline a couple years ago in CO. Even with a clutch dump and clutch smells, no slipping and just kept pulling.

View attachment 3283581

Haha no prob. I saw it while driving and was like wtf... But when I came back for my snarky reply, lo and behold, there was a useful post

I'm impressed you even smelled clutch, I've smelled a lot of smells from the cruiser but never even a hint of clutch no matter how i was abusing it. I'm in the boat of having to spend a ton of money I didn't expect to spend replacing my transmission so I figured I'd better make sure I was making the right choices so I don't have to redo a bunch of work sooner than I want to. Mud always pulls though!

 

[FJBen]

Good info. I’m trying to decide whether to upgrade my 13BT clutch.

@cruiseroutfit
I’ve got upgraded turbo, 20psi, fuel slightly turned up, and 34” tires. Seems like upgraded clutches are about double the price. I’m not sure I need it with my setup. I will intercool eventually but doubt I will turn the power up much more. Do you think the stock Aisin will hold that?

 

[cruiseroutfit]

Good info. I’m trying to decide whether to upgrade my 13BT clutch.

@cruiseroutfit
I’ve got upgraded turbo, 20psi, fuel slightly turned up, and 34” tires. Seems like upgraded clutches are about double the price. I’m not sure I need it with my setup. I will intercool eventually but doubt I will turn the power up much more. Do you think the stock Aisin will hold that?

I do, we're not seeing issues with standard upgrades. I think it will be fine.

We do offer a 13BT upgrade, as noted it's about double the cost.

 

[FJBen]

I do, we're not seeing issues with standard upgrades. I think it will be fine.

We do offer a 13BT upgrade, as noted it's about double the cost.

That’s what I figured, my clutch is slipping because of the leaking input seal. I’ve got one more seal change before I have to find or repair my B input shaft.