Hydraulic clutch on the Mighty Max bell housing

GRNDSM · Post by **GRNDSM** » Fri Feb 09, 2007 5:20 pm

Guys, I want to see some ways in which you have implement a hydraulic clutch conversion. I was considering going with this Wilwood slave cylinder:

http://store.summitracing.com/partdetai ... toview=sku

or this:

http://store.summitracing.com/partdetai ... toview=sku

But I am also intrigued by this style of TOB:

http://store.summitracing.com/partdetai ... toview=sku

In both cases, I am looking at making some sort of an adaptor, so that should even out. I like the idea of a direct bearing/slave combination. Naturally no-one makes a Mighty Max application, so I would appreciate any experiences that you guys might had.

Thanks,

Old Colt · Post by **Old Colt** » Fri Feb 09, 2007 5:56 pm

Hi Leon,
Here is a pic of the first style,

I will see about getting a pic of the second style.

Old Colt · Post by **Old Colt** » Fri Feb 09, 2007 6:10 pm

Another one,

This gearbox is apart but here is what you need to look at.
Pay attention to the different types of throughout bearings. You want one for a 7 1/4" race clutch. It will have the proper 44mm radius face to work with a Mitsu clutch. The one you have pictured is a flat face, it should be thrown out.

From production cars, maybe a Saab.Other wise it is race parts.
The one in my pic is a 38mm face, it is for a 140mm clutch.

Bill Hincher · Post by **Bill Hincher** » Fri Feb 09, 2007 7:10 pm

How easy is it to adjust the internal throw out bearing unit?

GRNDSM · Post by **GRNDSM** » Fri Feb 09, 2007 8:02 pm

Thanks for the pictures!

The one that I pictured was the first one that came up in the Summit search, I simply wanted to convey the style of the TOB that I was talking about. So what is the one that you have picture of?

Old Colt · Post by **Old Colt** » Fri Feb 09, 2007 8:09 pm

So what is the one that you have picture of?

That one is a Tilton, It is one of the shortest one I could find since this one is on a small triple plate.
I will try to get some pics tomorrow of some other ones.

GRNDSM · Post by **GRNDSM** » Fri Feb 09, 2007 11:24 pm

Looks like this Howe Racing TOB also fits the Tilton clutches!

http://www.howeracing.com/DriveTrain/In ... Racing.htm

Old Colt · Post by **Old Colt** » Sat Feb 10, 2007 6:24 am

Yup, Look into Quarter Master also.

GRNDSM · Post by **GRNDSM** » Mon Feb 12, 2007 11:52 am

GRNDSM wrote:Looks like this Howe Racing TOB also fits the Tilton clutches!

http://www.howeracing.com/DriveTrain/In ... Racing.htm

OK, looks like they have two versions of this TOB: 3/8" throw and 3/4" throw.

Does anyone have a spec on how much TOB throw, DSM clutch requires?

I know that I can always measure the slave cylinder throw and then apply clutch fork ratio, but it would be much easier if someone already did that

.

Old Colt · Post by **Old Colt** » Mon Feb 12, 2007 12:07 pm

The throw needed really matters as to what disc you run, If you use a puck type then 3/8 is fine. If you use a Centerfarce then 3/4 may not be enough.

GRNDSM · Post by **GRNDSM** » Mon Feb 12, 2007 1:39 pm

That doesn't seem to make sense to me.

Given any particular clutch system which offers different disc materials, the overall thickness of the discs is roughly the same. So, while I can see how different disc materials will have an effect on the disengagement point, once you are not touching the disc, what does it matter what material it is made from?

From what I remember, DSM slave cylinder has a throw of approximately .60”, and our clutch fork has 2 to 1 leverage, so the most that DSM TO bearing can move is around .30” (assuming that I remembered the travel correctly, can anyone confirm it?). That is a mechanical limitation of the clutch system without any regard for the type of clutch disc is being used.

Also, the difference between the 3/8” and 3/4” TOB will be double the effort, so I do not want to go to a longer travel TOB, if I do not need it.

Old Colt, do you recall what travel you had in your Tilton TOB? You mention that your 5.5" (140mm) TOB might not be right and that I need the 7.25" TOB. The problem is that this Howe TOB is being good for BOTH 5.5 and 7.25" clutches.

I guess I need to find out the actual "face" diameter.

Old Colt · Post by **Old Colt** » Mon Feb 12, 2007 2:27 pm

The part of a disc that matters is the Marcel. It is how much a disc compresses to allow for takeup at the pedal. The puck type and race multi disc essentially have no marcel where an organic disc will have .020 to .035 thou of takeup. This multiplied by the ratio in the pressure plate and then the arm to the cylinder and the other ratios in the system is what combines to set the pedal characteristics.
Generally 3/8 travel should be enough in there but then setup height is important especially if you run a clutch that will need most of that travel.
The pedal pressure has more to due with the hydraulic ratio. It may be that both the 3/8 and 3/4 slaves have the same area so there will be no change as far as pressure matters. The difference is in stack height of the assembly.
Generally the little clutches use a 38mm TOB face and 7 1/4 use a 44mm TOB, same as Mitsu clutches.
There are exceptions.
And yes about .6" sounds about right for a DSM slave and if you have had the misfortune of buying a Centerfarce clutch you will recall they use most all of that.

GRNDSM · Post by **GRNDSM** » Mon Feb 12, 2007 2:45 pm

Howe TOB has 52mm diameter at the outside of the face. Charlie, when you were listing “face” dimensions (44 and 38mm), was that to the outer, inner, or “center-line” diameters?

Old Colt · Post by **Old Colt** » Mon Feb 12, 2007 2:49 pm

There is a crown to the face, it is the diameter at the high point, call it center of the face.
I just measured 4 race type TOB and they are all .55 to .7 travel that I have here.

GRNDSM · Post by **GRNDSM** » Mon Feb 12, 2007 3:12 pm

I see, well Howe "tech support" has not impressed me today. They might be experts at something, but they do not seem to know much about their TOBs. They were insisting that everyone measures to the outside.

Anyway, it seems like this TOB has the right diameter, so I will probably take a risk and buy one of these. At $120/shipped, that isn't going to break the bank. Besides, if it I can't use it I am sure that could re-sell it on Ebay with minimal losses.

Overall, if this works, this isn’t all that much more expensive than the "conventional" clutch bearing set-up, which requires a new TOB ($25) and a fancy slave cylinder ($70).

And it shouldn’t have any of the frictional losses associated with the clutch fork shaft.

GRNDSM · Post by **GRNDSM** » Tue Feb 13, 2007 1:46 am

I was able to take a bunch of measurements:

DSM slave cylinder throw: .60" (as I thought)
After 2:1 clutch fork, this TOB travel is .30"
The face outer diameter on a DSM OEM TOB is 2.05" or around 51mm
The "crown" on that face is around 48mm

Looks like that Howe TOB just might a perfect fit! I am going to buy it tomorrow.

Old Colt · Post by **Old Colt** » Tue Feb 13, 2007 6:45 am

Have you checked the total height allowed for the TOB, some times this is an issue, I have not set up a stock style clutch with one.
I have set up the Starion with a 7 1/4 double plate and stock bearing and that was not an issue.

GRNDSM · Post by **GRNDSM** » Tue Feb 13, 2007 8:17 am

It appears that I will have to space the Howe TOB, as there is too much space! But that is fine, this will give an opportunity to make a nice adaptor for the TOB.

I forget, can it just remove the tranny "hub" that TOB rides on, by removing those 6-7 bolts?

Old Colt · Post by **Old Colt** » Tue Feb 13, 2007 8:34 am

The iron part comes right off but it is needed since it is the bearing retainer.
You will want to turn a sleeve for the new TOB to slide snugly over the guide tube, this will be used to set the height.
Then something needs to prevent rotation other than the hoses.

GRNDSM · Post by **GRNDSM** » Tue Feb 13, 2007 9:23 am

Howe recommends adjusting the TOB position by using the supplied studs and jam nuts. Depending on how much spacing I need to do, I might just drill and tap the cast housing for those studs and use their studs. How tight does the TOB has to be around the center core? Just snug enough to assure alignment?

Right now, I have 1.25” center core and 1.38” on the inside of the bearing. I wonder if I should sleeve the center core to make a tighter fit. Or if I am making an adaptor, I might make a “step” in it to give me that alignment.

Old Colt · Post by **Old Colt** » Tue Feb 13, 2007 10:03 am

I turned a Delrin sleeve for the new bearing to center over. I do use a step to set the height.
Some of the bearings the inner tube needs to slide and some it is part of the housing. This should determine the final design.
Do not try to do it Howes way, They do not work with Mitsus, If a stud is usable cool. Do not under estimate the bearing thrust loads in that front cover.

GRNDSM · Post by **GRNDSM** » Wed Feb 21, 2007 3:46 pm

I got the bearing! It is MUCH larger than what I expected! So much so, that I am not going to need much of a spacer at all! Once I assemble the clutch on the engine and take some measurements, I should know better.

Back to centering over the center core, Howe calls this bearing “self-centering”. But I am not comfortable with this and will make a sleeve. Charlie, how much clearance did you allow it after you installed that Delrin sleeve?

Also, it looks like the two Mitsu studs (3 and 9 o'clock) are a PERFECT match for the Howe bearing! I just have to remove the short factory studs and replace them with something longer!

In the meantime, I found a nice TR8 project (TR7 with a Rover V8 ) which included conversion to the '88(?) Supra transmission.

Check out his way of dealing with the TOB (week 33):

http://www.triumphcars.com/tct100307uf/

Also check out his page on a "Power Clutch"

.

BTW, what is it about his clutch that allows him to use the "OEM" style TOB (I am using race style one).

Old Colt · Post by **Old Colt** » Wed Feb 21, 2007 4:06 pm

My delrin sleeve is snug inside the TOB. Just make sure the inside of the TOB does not slide with the bearing to do this. Otherwise it needs to slide free.
Nice that you can anchor it well with two studs.

Nice setup for the Rover engine, I still have an old Olds Jetfire here. It is the 215 turbo engine. Left over from all the MGBs I used to swap.
Sure better than the Mustang box they are putting behind the old Jaguar sixes.I would sure prefer to drive with a supra box.

Many american clutches have a radius at the tip of the fingers, these use a flat TOB face. If the clutch they are using has flat fingers then they just do not know better.
I will look over that page more later when I am done with work.

GRNDSM · Post by **GRNDSM** » Sat Feb 09, 2008 2:26 am

This is my latest progress. It should work well, I guess we will see...

Robert Venable · Post by **Robert Venable** » Sun Feb 10, 2008 6:42 pm

Which TOB throw did you use??

GRNDSM · Post by **GRNDSM** » Mon Feb 11, 2008 1:03 am

Check out post # 7 in this thread.

And this page: http://www.cardomain.com/ride/2472999/5

Robert Venable · Post by **Robert Venable** » Mon Feb 11, 2008 1:59 am

Sorry, I should have been more clear. I am talking about which TOB throw did you use? The 3/8 or the 3/4"??

GRNDSM · Post by **GRNDSM** » Mon Feb 11, 2008 8:21 am

This TOB (p/n 8288) only comes in 3/8" version. DSM clutches typically need just under .300".

Bill Hincher · Post by **Bill Hincher** » Mon Feb 11, 2008 2:10 pm

do you have any idea's on preadjustment or a way to adjust the clutch after you burn it in?

the only way I see to adjust this unit is by removing the trans

Thanks
Bill

GRNDSM · Post by **GRNDSM** » Mon Feb 11, 2008 5:51 pm

That is a good question! I will try to have ~.040" gap between the TOB and the clutch fingers. As disc wears, fingers should come away from the clutch disc, closing this gap. I guess I will have to wait and see what happens

.