Amelio

I finally got my trans rebuilt.....(M20) it needed new reverse gears, 3rd gear all new syncros and bearings.

I got it back in the car and I am fighting shifting issues......

I am running a Lakewood blow proof which I have had for years.....I recently changed to an aluminum flywheel and I am running a Center Force dual friction diaphragm clutch.

I have no problem getting the car in gear from a stop and I can rotate the drive shaft easily by hand with it in gear and the clutch depressed.

The problem is shifting from 2nd to 3rd and 3rd to 4th. Its very stiff and not smooth at all.

I just put in a new bronze bushing and once I put everything back together I noticed how far back the clutch fork sat in the bell housing.

I need to get the clutch fork moved forward closer to the pressure plate.....the only way I can see doing this is either a longer release bearing or a longer pivot ball stud.

My current release bearing is 1.25" and the pivot ball stud is about the same.

I wonder is the issue because I am running this bell housing with the engine plate? I think maybe it has moved everything further back? Also I wonder if the flywheel change has moved things as well?????

Anyone else run into this issue running different bell housings and flywheels?

Also I don't have a corvette fork.....its a standard fork and I wonder if the corvette fork has more of a bend?????

Any input is appreciated.

pauldana

i have a Quick Time Bell housing... the front shelf that mounts up to the block sets the BH back a little...you need an adjustable pivot ball McLoad makes one

GearDrive65

I used a Lakewood bellhousing when I did the SBC/auto to BBC/4sp conversion. I purchased an auto to manual kit for the C3. I had to grind 1/8" off part of the fork because it hit the floor, not letting it fully disengage.

zwede

Distance from engine block to pivot should be 4.75". You have to include the block saver plate since it moves the pivot away from the flywheel.

I have no idea how you managed to fit a regular GM fork. Those hit the floor on a C3. Get the Corvette specific fork.

I'm thinking all your geometry is off at the moment.

Amelio

Lol hey Zwede..... The fork does hit the floor! It wore a hole and I have to re glass it!

The pivot ball/stud I have is adjustable but it does not seem long enough. If it needs to be 4.75" from the engine plate then that means that the stud needs to extend from the bell housing at least 1.5-2" and it is currently not long enough for that.

I am ordering a corvette fork and push rod...... I will look at the McCloud pivot studs and see if they make one longer that 1.25" which is about how long mine is

pauldana

ok... what you need to do, is..... the Z bar, you need to water jet a second hole about 1/2" down from the hole you have now that the clutch peddle rod hooks into. This will give you a lot more throw with less peddle travel. I also had to do this... it work great...

BUT, the Z bar is case hardened steel,,, and drill bits are worthless!! so i had to have a hole water jetted in it.

Amelio

Ok I will inspect the Z bar once I get everything back together.

Having the correct fork and longer pivot may fix the issue but if I need more throw then I will look into adding a hole in the Z bar.

Thanks for the info

427Hotrod

Also look into the McLeod adjustable throwout bearings. They are really slick. Have spacers to make the bearing 3 different lengths. I've used them for years.

PN #16505

JIM

63mako

The dimension that you need to retain is 4.75" measured from the back of the engine block to the top of the pivot ball stud. This is the dimension of the GM bellhousing. The Lakewood is 4.870" plus the block plate it adds another .132" for a total of 5.002". That puts you .252" too deep inside the bellhousing. The adjustable Lakewood, Mr. Gasket, stud only gives you an extra .100' max over the short GM stud which is 1.48". So the most you can get with the Lakewood stud is 1.58". The GM long stud is 1.78", now you're over by .048. Should work. could take .05 off the top of pivot ball stud or shim washer between outside of bellhousing and flat rear of pivot stud. I had to deal with this before.
http://www.ebay.com/itm/NEW-SMALL-BLOCK-CHEVY-BELLHOUSING-CLUTCH-BALL-LONG-SBC-/290143504677?pt=Race_Car_Parts&hash=item438de68925

Amelio

Jim thank you for the part number, I will pick one if those bearings up.

Amelio

63mako that's great info thank you!

I think all the info you guys supplied should fix the shifting issue...... I will get this set back up and let you know how it turns out.

Looking at older threads it seems like this is a common issue.

Amelio

I got the trans put back in this weekend.....I installed a corvette fork and push rod.......I also installed the McCloud adjustable release bearing.

Getting rid of the standard fork for a corvette fork made a huge difference but the adjustable release bearing is what really made the difference.

The car shifts great and it seems most of the issues are taken care of.

Thanks for all the suggestion!

The only problem is shifting into 3rd....either from 2nd to 3rd or 4th to 3rd.....if you go into 3rd at very low rpm and I mean really low.....2k or below the trans does not like it......I will either get some grinding or you hear the syncro spin up.

Now when it does this I can rap the throttle a tad and it goes right in or if you shift to 3rd with a little more rpm it goes in just fine.

A friend of mine may think it needs some break in miles since the trans is brand new. Maybe that will help.....for whatever reason it does not seem like the syncro is matching the speed to get into gear at very low speeds.

Anyone ever encounter this?

I am going to contact the builder and ask him but I thought I would throw it out here also.