All right guys I need some help! Years ago there were some TH400s built that utilized a clutch as opposed to a torque converter. I’m very interested in this application and wanting to know if there’s someone that can shed some light on this subject?

Thanks!!!

David

 

what do you want to know?

 

pics, how they drive, applications?

come on!

 

What he said! I need any specific details that you can provide in order to have one built. I remember years ago in one of my old Hot Rod Mags an article on one and don't want to dig through them after over 20 years just to find the article.

Thanks,

David

 

There is at least one, but I think maybe 3, person('s) on island that did those conversions from back in the day. I cant tell you much, other than the setup was like you said, !TC and +clutch, launches were more violent like an Manual, but the rest was smooth like an Auto. If your interested I may be able to get ahold of the guy('s) here that do the conversion and have them email you, if so, send me a pm with your email addie and I'll check into it.

Charlie

 

I ran one back in the 70's it leak around the pump drive, and the car would fall on it's face on the gear changes as you have large gear spacing and no converter to keep the rpm's up.
the auto with the converter and a 4 speed both got better times at the track,
not one person I knew liked using them but at the time you got a 100 to 150 lbs weight brake in our class

 

CAT3 thanks alot and yes please do! I’ll PM you my address.

Yank, If you were using a reverse manual and shifting in a high RPM range would she still fall on her face? There are several reasons I’m considering this. I really tired of shifting and want an automatic 1st and I have a very high dollar carbon clutch that I was hoping to retro fit and the fact that a very high stall converter is very un efficient on the street and lastly the lockup converters really can’t hold the load when your hitting her with high HP. These are my basic motivations. Basically what I want to achieve is a very high HP and have a bulletproof trans that I can abuse at the track and drive the car across country if I so choose. What if a substituted a 4L80 with a Gear Vendors OD in place a perhaps a very low rear gear and just reduced the range in which the gears are separated?

Thanks for your time reviewing and responding to my enquiry!

David

 

You can't use your clutch with the turbo clutch 400's.
They use a special input shaft and a pressure plate that also drives the pump.

From what I've read the weak link was the input shaft on these since it was so small and had no converter to absorb shock from clutch dumps and shifts. I think a regular th400 with a converter would work better.

Your intended usage is a bit odd, you either want a th400 with a clutch or a 4L80E with a GV overdrive? Those are to totally different transmissions as far as cruise speed and durability.

 

The mention of the 4L80 was to achieve additional gearing only to reduce the RPM drop between gears only by using a lower rear gear only. The addition of the GV was to provide additional separation to make it drivable on the top end. I’m gust kicking ideas around, as I’m not totally committed to a TH400.

 

I think I would rather just launch off the tranny brake if I wanted a violent manual-like launch

 

the clutch turbos were mainly made by fairbanks inc. there was talk a few years ago of them reviving the clutch turbo. I never heard anything else about it.

the clutch turbo only worked with a 3 finger pressure plate and the shifts were BRUTAL since there is no converter to cushion them. I used to have one.

 

Using a trans break is one out for sure but I was looking for something more efficient for street use when you’re running a turbocharged vehicle and I would like to retain my engine breaking. Large turbos have considerable lag that is the downside to produce very high HP levels. In order to combat this high stall converters are utilized and it works very well, at the track, but not worth a flip for normal street use. I’m trying to see if I can gain the best of both worlds. I have a TH400 with a lockup converter and more than likely still use it but I want to consider all options. Looks like a tighter converter with a little Nitrous may be the ticket.

Thanks for the impute guys and keep those cards a letters coming!

David

 

I think my launches are violent enough for now, 4,000 stall, wrapped up to 4,000 off the transbrake in my Rossler TH350 But, there are a few on island that did these clutched 400's so I thought I would learn about it as well as help someone out. I personally want to get a GVOD since I will be moving back to the mainland and will be able to drive more than 70miles one way!

 

winters performance in pa. may be bring them back. one clue, if you run a clutch turbo you won't need a cooler. what does that tell you? b&m were the first to market that system. lf l did not put my head on the roll cage when l shifted to second my helmet hit the bar so hard it would almost knock me out. fantastic ride. despite what you have heard the trans needed more ratio in first not less.

 

Dave, Paul G. our now past track manager used to make these, and still has parts left in stock to do one. I am waiting for his email addie so I can hook you up.

 

CAT3, I appreciate the help!!!

 

Dave, a clutch turbo would totally suck with turbos. the problem with turbo engines is that when you are making no boost, your converter is tight because you have no torque. so most people think you need to loosen the converter up to get enough rpms for the turbos to spool. the problem here is that when the turbos spool and the engine makes the huge torque numbers on boost, the converter gets way looser. the transbrake is your greatest ally with turbos. maybe my experience can save you a little time and money.

I have a pair of t61's on my car. with the 6spd and the 2-step set to 5k, I could only get 6psi on the starting line. now my braked th400 is a different story entirely. I actually only run a 3600 converter, but I stretch it to 4500 on the tbrake. the transbrake and tight converter are exactly what you need on a street driven turbo car. I first tried the loose converter route as you are thinking. John at fuddle built me a 4800 converter with a "turbo" stator that he said would keep the engine one step ahead of the turbos. it was terrible(it wasn't John's fault. he built exactly what I asked him to.). without a tbrake, the car would only build 3-4 psi at 3800 on the footbrake and 2-step. it only ran 7.61@100 in the 1/8th on 12 psi. not to mention that the street manners sucked so badly that I nearly parked the car. then I installed the tbrake with the same converter. I learned how to stretch the converter against the tbrake and build 10psi on the line. the car went 6.40 @ 109.5mph on the next outing. it was a great improvement, but I still cringed at the idea of driving the car on the street. the converter was just so loose on the highway. I called John and asked for him to build me an upgraded converter. I told him I wanted the best of everything in it, but wanted the stall speed tightened up 1000-1200 rpms. the converter he sent me is letter perfect. I wouldn't change a thing about it. the car went 6.21@114mph with no other changes. I now use my tbrake and 2-step to control my launch boost level. I make 8psi at 4000. 10psi at 4300 and 12psi at 4500. you need the tighter converter to make the turbos spool on the tbrake. the harder you stretch the converter, the more you load the engine, the more boost you make. you can easily stretch a converter 1000 rpms or more above the rating with a tbrake. but you still have a tight converter when not on the brake and especially while driving on the street. my car is a pleasure to drive on the street now, yet gets it done at the track. get yourself a braked th400 and call John at Fuddle racing for a converter.

 

Sr71, Thanks for the input for sure and if I can’t find out that I need for the Clutch modification then I will be diffidently sending my converter back and have it tightened as well. In fact I had already planned on having it tightened up prior to coming up with the idea I proposed in this thread. I really don’t want to really go with a Trans brake as I want to retain my engine braking and my current TH400 is equipped with a lockup, which won’t work with a TB. I will more than likely just keep it in that configuration. I’m running a larger turbo and I was trying to see if I could have the best of both worlds.

Thanks again!

David

 

just remember that load is what makes boost with turbos. you will find that you just can't load the engine hard enough against the footbrake to make enough boost for HARD launches....I hope it works well for you.

 

What you just mentioned is the reason I’m looking for an alternative. If the clutch modification won’t pan out then I’m going back with my Lock-up TH400 that I already have and I’m going to send my converter back to PI and have it tightened up to about 3400. They basically have three options for my converter and that’s tight, medium and loose. Mine is presently at the mid point, which is about 38-4000, and I know I’m going to have to get it adjusted. I believe I will have to have a little Nos to assist when I want to come out of the hole without any serous bogging and if that is what I have to do then so be it. I just know I don’t want a loose converter and have issues with normal town/freeway driving.

Thanks for the response!

David