Chevota clutch issues

[Jerzfj40]

I've got a '77 fj40 with a '72 SBC mated to a stock '77 4 speed Toyota tranny. This V8 conversion was done by the previos owner in 1982 using a fabbed adapter plate that offsets the trans from the Chevy bellhousing by .580 thick. When i rebuilt the motor in 2001 i went with a Centerforce Chevota clutch from Downey Offroad.This Cruiser has not been my daily driver up until 3 months ago and now im having issues with the clutch .
Problem: A few weeks ago, i started having trouble shifting into reverse. The clutch felt like it wasnt disingaged enough and the gears were grinding. I adjusted the clutch slave pin enough to allow the stick to shift without grinding, but then i would get a terrible low rpm shudder/vibration that im assuming is the throwout bearing not disengaged and riding on the pressure plate. I can even hear a difference in sound when i am in neutral engine running, and release the clutch pedal from the floor, you can hear something turning/ like the throw out bearing not releasing. I'm prety sure the clutch disc is not worn out because i dont have enough miles on it and also my clutch grabs enough to lay down rubber
I'm wondering if the previos owner used the wrong offset ( .580) with his adapter plate and since ive got to pull the clutch maybe i should buy the Advance adapters conversion bellhousing. Does anyone know what the correct offset shoud be for this conversion?

 

[Bennett]

There is always several opinions on how to solve this ... here i what worked for me from the Guru: Mark Whatley on Chevy clutch issues.
I fought the clearance issue for 5 years before I got it right.
Seem like most SBC guys have had the issue at one time or another and the centerforce is not the answer in my opinion. ( use it but add the 69 brake master for the extra slave throw and be done.. lots of adjustment room and no more T/o bearing touching the clutch disc)
...........
https://forum.ih8mud.com/40-55-series-tech/418205-what-clutch-have-i-got-need.html

What I did.. i have the sbc setup and had to pull my motor several times before I got it right.
Chev clutch disc splines are cut different than a Toyota . (The difference is straight cut splines on the Chevy verses an angle cut spline on the Toyota.
I tore the center hub out of my clutch because it had worn on the input shaft.)

I tried a Toyota disc( with rubber instead of springs) and the inner hub would rub on the pressure plate. ( It was facing the correct side)

I had a toyota ( spring type) splined inner Clutch disc hub mated to a chevy clutch disc. Custom deal but no problem for any good clutch shop and same price. I used the chevy diaphram type pressure plate because it takes less throw from the slave to operate and chevy T/O bearing. I also used a curved cast clutch for to get the position closer to the slave as I used a AA slave bracket on the Chevy. Make sure you have good tight connections and no free play, with a good strong clutch return spring pulling straight back perpendicular with the fork. it will save you alot of time. Ask me how I know.



Like I said ... I researched the lcml archives and found a zillion opinions. I have run into tons of chevy guys that are always crawling under their rig and fiddling with the clutch adjustment. It just made sense to me to use the Toy center splined connection hub on a Chevy outer disc material.)

https://forum.ih8mud.com/40-55-series-tech/360991-bore-size-clutch-brake-master-slave-cylinders.html

https://forum.ih8mud.com/40-55-series-tech/51460-chevy-v8-toyota-4-speed.html

https://forum.ih8mud.com/40-55-series-tech/44288-350-swap-clutch-issues.html

https://forum.ih8mud.com/40-55-series-tech/37907-v8-clutch-issues-4-speed-lc.html


What I forgot to do was put in a new chevy ball pivot $10 on the inner bellhousing. Mine was worn and caused lots of end play when the fork would pivot and try to "walk".
Ball Pivots wear and cause longer throws than needed, small Item that gets overlooked. You need all you can get .. I have seen many a sbc conversion throw out bearing spinning away cause they are too close to the clutch fingers and touch and begin to spin and sing to you.

Lastly I used a pre 69 brake master cylinder ( as per Mark Whatleys years of experience ) to give me longer slave throw. Pre 69 Brake master( yes brake master cyl( bolts right up and to the clutch mount .THe diameter slightly larger than the slave diameter resulting in about a 1/2" to 3/4" more throw when the pedal is depressed.


Ps ... IIRC you need to flip the slave so the bleeder is on top = air rises...correct me if I am wrong.

 

[Jerzfj40]

Since this is already a " Chevota" low profile clutch ,would it be possible that by just replacing my clutch master to a pre 70, it would solve my issue? At least i wouldnt have to pull the tranny or motor at this time

 

[Bennett]

Since this is already a " Chevota" low profile clutch ,would it be possible that by just replacing my clutch master to a pre 70, it would solve my issue? At least i wouldnt have to pull the tranny or motor at this time

I would try it... the pre 69 Brake master is a direct bolt up . From the pics you have the right fork and the throw out bearing.

some copy and paste highlits from a few of my post's

The pre 69 brake master is 1" bore and the slave is under that ( 3/4" IIRC)..... thus more movement by nealy 5/8" for me or 25% more. The pedal is a *little* stiffer but works absolutely perfect.
I actually had too much movement and needed to adjust my slutch slave rod down The Master bolts right on in 2 miuntes ... hooked up and bled and shazam.. great clutch movement.
I guess you could over extend the slave but it did not happen to me.
I took care of that by adjusting the slave rod almost to to it's shortest position.
I pulled the rubber cap and watched the slave movement and I was not close to coming out at full pedal.
Also you need to have your throw out bearing not touching the fingers of the plate ..
mine is about 3/32" away. no spin on the t/o at all now with the new setup and no grinding gears. Works great IMO.

 

[Jerzfj40]

Thanks for all of the great info. I'm going to buy a early brake master asap and get my DD back on the road running right this time. That spinning throwout bearing noise has always had me wondering if something was done incorrectly....now i know!

 

[Bennett]

The pre 69 will have the big nut on the end....

examples

65-70 Toyota Land Cruiser Hilux Brake Master Cylinder: eBay Motors (item 350345726946 end time Nov-20-10 16:07:04 PST)

Beck/Arnley 072-2900 Brake Master Cylinder: eBay Motors (item 290490345942 end time Nov-19-10 17:29:28 PST)


fwiw... since you are going to a larger master to a smaller slave the clutch pedal will feel stiffer. After one day driving I didn't notice.

you will need to adjust the pedal to master rod to take up free play. I had about 1/4" of free pedal before the pedal rod would make contact with the pocket in the brake master. Using the right clutch return spring is really important ... I'll post a pic later on this.

good luck

In the pic the clutch return spring fits between the bracket and oil filter .. my reason was more torque on the spring the closer to the pivot point... worked for me and got it out of the way.
notice the bleeder on top the slave for easier bleeding. Ther orange high heat wrap was for a previous rear dump exhust manifold that is gone.
I went rams horns and best mod so far on the motor.

jsut noticed my jam nut is loose in the last pic....whoa

 

[Jerzfj40]

Just ordered an OEM Toyota Brake master cylinder from SOR. When i get everything changed over , i'll post pic's and let you know my results.Thanks for the pic of the spring return, that helps.

 

[Jerzfj40]

Finally got through the " Honey do's " and started the clutch master swap for the brake master . I bolted up the new brake master in mere minutes, but cannot get the brake line threaded into the tapped hole on the master. It looks to be the same fine threads as my old unit, but maybe i needed to change the threaded brake line piece?
Anybody know the metric thread size for this 11MM part in case i need to clean up the threads with a die?

 

[Bennett]

Pre 69 is 9MM and later was 10mm IIRC


here is a thread about a similar dilemma
https://forum.ih8mud.com/40-55-series-tech/245036-review-new-9-mm-brake-lines.html

Since it was a clutch and not brake I used a brass fitting that I got at a hose supply but I use a mini truck brake line that was 10mm on one end and went 9MM on the master end . I wanted the rubber hose for flex as I instructed by someone more in the know than I.
. Somewhere here on mud is the whole story.. got to be 4-5 years ago now.

 

[Bennett]

Here is an old post that looks like the simple solution

https://forum.ih8mud.com/40-55-series-tech/117559-69-older-9mm-brake-line-adaptors-faq.html


looks like Napa still has em'
http://www.napaonline.com/Search/Results.aspx?Ntt=BK 6415023&Ntk=Keyword&Nty=1&N=0

use part no. BK 6415023

 

[Jerzfj40]

More clutch issues

It's been awhile since i have had the time to finish fixing this clutch issue.I finally put the 9mm fitting on my brake line and screwed it on to the new "Brake Master" im using in place of the clutch Master.
New problem: As i was pumping the clutch pedal to bleed the line, the pin and plunger shot all the way out of the slave cylinder and shot fluid all over, also damaging the rubber seal around the plunger. I replaced the seal, and backed the adjustment of the pin to start off deeper in the slave to allow for more travel, and as i was bleeding the line again, pop! same thing happened again.
A friend of mine thinks that the proportioning valve inside of the( pre 69) brake Master should have been removed before set up. His reasoning is that the brake master is set up to maintain 9 lbs of constant pressure in the system and to use it for a clutch master would build up too much pressure, thus causing the slave pin to get pushed all the way out.
Has anybody experienced the same problem with the slave as me? I could use some advice on this soon.

 

[Bennett]

Never had a problem with mine .... I followed Mark Whatleys from the TLCA BB info and just put the master on, bled adjust and away I went. one thing I did do was adjust the pedal throw so it could not push the slave rod out. I also adjust the amount on the slave rod as well. I set both so I could not push the rod out...I gained another 1/2" over stock and solved my problem.

Not sure if a pre 69 mc had a prop valve do they?

 

[Jerzfj40]

Its right behind the big brass nut on front of the master.It sets between the nut and the internal spring.I guess i'll try again and double check the adjustment on the slave and pedal.
Thanks

 

[bikersmurf]

I think you mean "Residual Valve"... All of the other newer masters have them, so I'm sure a 69 would also. For a clutch, there is no need for one, so I'd remove it and set it aside.

If you can, also try a vacuum bleeder to bleed the system. They are much easier and faster.

 

[Jerzfj40]

I think you mean "Residual Valve"... All of the other newer masters have them, so I'm sure a 69 would also. For a clutch, there is no need for one, so I'd remove it and set it aside.

If you can, also try a vacuum bleeder to bleed the system. They are much easier and faster.

Yeah, thanks, Residual Valve is what he said. And i will try the vacuum bleeder this time as well.

 

[65swb45]

If you back off the pushrod of the master cylinder far enough at the pedal, you will not have any residual backpressure. Conversely, you can remove the residual check valve and still build up pressure if the pushrod is misadjusted.

Also, FWIW, the slave cylinder is not supposed to stay attached to the clutch fork by it's own resistance; that is the job of the return spring...which I don't see in your pic.

Best

Mark A.

 

[Bennett]

Also, FWIW, the slave cylinder is not supposed to stay attached to the clutch fork by it's own resistance; that is the job of the return spring...which I don't see in your pic.

Best

Mark A.

Good point Mark.. The clutch return spring is very important.. I went through several before I found the right weight /pull for my satisfaction.
If you go back up to post #6 you can see it in the 2 pics ( yellow arrow) I snaked it behind the slave plate and oil filter to get a direct straight pull .





*edit*... post #1 has no return spring ( original poster) ... my bad for buttin in.. thought you replied to me