Author Topic: My Black Bitza (Read 79825 times)

wabco40 · « **Reply #80 on:** September 16, 2015, 03:19:57 PM »

I don't know why they would say an air gap between the bearing at rest and the clutch fingers when the bearing at rest is compressed against the clutch fingers to within 1/8" to 3/8" of bottoming out.

For sure, make the spacer between the tranny and bellhousing.

You got me worried about mine so went out to the shed and measured between the compressed bearing face and gearbox case. Mine comes to 60mm which if I was using the same flywheel and clutch as you would give me about 3/16" clearance. Problem is I am using a relatively thin flywheel and centre force clutch. Guess I will have to wait until the weekend to set it up and check.

Scott · « **Reply #81 on:** September 16, 2015, 03:42:15 PM »

My CSC has no spring pushing it in either direction, so once it's compressed, it stays that way and there is an air gap between the bearing face and the clutch fingers.

bfit · « **Reply #82 on:** September 16, 2015, 06:02:42 PM »

Scott
Reading this is Confusing
You will need to make sure you have sufficient room to allow for the wear in the clutch.
As the clutch wears the fingers will move back towards the gear box .
In setting the slave cylinder up its important to get it correct .
If there is not enought clearance at set up then some time as the clutch wears it will start to slip

There should be a shim pack under the hydraulic throw out bearing .
I would like to read the instructions
Bfit

bfit · « **Reply #83 on:** September 16, 2015, 06:24:21 PM »

Scott
I read your posts on setting up the bellhousing . I have been working on engines and gear boxes for 50 Years I have never done this procedure and never had a gear box fail.
But each to There Own

I would point out one fact
Chev engines have 0.0025" to 0.005" clearance in the main bearing which means at rest the crank will sit down in most cases 0.0025 "
This should be taken into consideration if you really want the bellhousing centred accurately .
Bfit

Scott · « **Reply #84 on:** September 16, 2015, 08:51:10 PM »

Link to instructions below. As you said, normally you measure the gap to allow for clutch wear, then put shims under the bearing until you get the right clearance.
Due to the size of the hyd bearing, and the shallow depth of chev bellhousings, there is insufficient clearance to start with. So to gain the correct clearance I need to move the clutch (attached to the engine) away from the bearing (attached to the gearbox). The only way to do that is to add a spacer somewhere between the engine and gearbox.

http://americanpowertrain.com/attachment/38310-.pdf

bfit · « **Reply #85 on:** September 17, 2015, 07:27:59 AM »

Interesting read
It does seem to cover the setting up in detail.
Have you thought of machining the flywheel
Bfit

Scott · « **Reply #86 on:** September 17, 2015, 08:06:58 AM »

I hadn't thought of that. Still, 3mm is a lot of material to take off. I'll stick with the spacer between the box and bellhousing. the bellhousing is located by the front bearing retainer anyway and has much more than 3mm engagement, so there isn't any issue with things moving or being out of alignment (hopefully).

bfit · « **Reply #87 on:** September 17, 2015, 10:09:05 AM »

The original flywheel is 28lb. Chev did supply a flywheel for a 10.5" clutch that was 15lb.

as long as there is sufficient clearance in the flywheel retaining blots and at least 7/16" of thread on the clutch retaining bolts. I would think it would be a good option.
Bfit

Scott · « **Reply #88 on:** September 17, 2015, 03:08:04 PM »

I'm running a 400, not a 350, so externally balanced. Not sure if that makes a difference.

bfit · « **Reply #89 on:** September 17, 2015, 03:28:21 PM »

Quote from: Scott on September 17, 2015, 03:08:04 PM

I'm running a 400, not a 350, so externally balanced. Not sure if that makes a difference.

I think that's one of those cases best left alone.

How much meat is on the back end of the throw out assembly
personally I'm not keen on spacers , but sometimes they are unavoidable.

bfit

Scott · « **Reply #90 on:** September 17, 2015, 04:15:29 PM »

I'm not super keen on spacers either, but the bellhousing will be aligned on the bearing retainer and I'll loctite the bolts, so there shouldn't be any issues with movement.

bfit · « **Reply #91 on:** September 17, 2015, 04:26:47 PM »

Scott
How much torque will is the engine making.

( I'm glad I when with a 6 speed magnum less problems and handles more torque )
Bob

Scott · « **Reply #92 on:** September 18, 2015, 08:05:44 AM »

Considering it's a stock 400 with a performer manifold and a set of shorty headers, not a huge amount. Realistically, the gearbox is rated to 600lbft (with a considerable safety margin). The tyres won't hold that much torque on the street anyway. The spacer will put a tiny more amount of stress on the bolts, but not enough to be any worry to anything. The clutch will still be the weak link in the system. So I can't foresee and mechanical danger of using a 3mm spacer.

Scott · « **Reply #93 on:** October 12, 2015, 09:57:17 AM »

I used the Bathurst weekend as a good excuse to disappear into the shed and get some stuff done. Luckily I have a borrowed telly in the shed for such occasions.

Also had my No.1 helper on the job.

After making and fitting my bellhousing spacer, putting the hyd. throwout bearing on and adding the lines, I hoisted the box up, then spent 15 or so mins adjusting angles and heights before everything slipped smoothly into place.

I spent more time trying to nudge the crossmember into the right place so I could bolt it to the chassis, and then tightened up the tranny mount bolts. After that I spent some time looking at the angle of the box and thought to myself that can't be sitting right...

I checked with a straight edge and the cross member doesn't look bent, but who knows. I know the engine is sitting a little high, so I'll fix that up and then try measure the angles of the box and diff. I'll throw int he tailshaft as well. Hopefully I can get the angles right by shimming things up and down. Otherwise, the vibrations will be killer.

bfit · « **Reply #94 on:** October 12, 2015, 11:32:36 AM »

yes it does look to be at the wrong angle .
the engine should be set around 3 deg downwards towards the diff
and the rear of the box must be above the diff input.
you should find your diff will be set vertical at the yoke that goes against all the advice you will read , however I believe that is the factory set up.
Id ne interested to know if you check your diff and find it is set differently
Bfit

wabco40 · « **Reply #95 on:** October 12, 2015, 12:23:44 PM »

Hi Scott,
How far can you jack the back of the box up before it touches the tunnel?

Also is the bottom of the floor parallel with the cross member or is it sagging in the middle?

Scott · « **Reply #96 on:** October 12, 2015, 02:44:52 PM »

The floor looks pretty much parallel with the x-member. I remember you put the rubber blocks in your to lift the floor. I can probably lift the rear 5-10mm, and drop the engine 5mm. I should be able to lift up the front of the diff a little too. I called it a day after the box was bolted in and watched the last 10 laps fro the comfort of the couch. Tonight I'll pump up the rear tyre and accurately measure the angles with the anglemeter on my old nokia phone.

Scott · « **Reply #97 on:** October 12, 2015, 08:48:03 PM »

I just had a good look under the car. The floor seems to be parallel to the cross member, but it probably wouldn't hurt to place some rubber blocks to support it once the seats are back in with some bodies. There is about 15mm clearance above the gearbox so I should be able to lift that a decent amount. I'll fix the engine mounts first to get the front sitting down where it should be. I currently have spacers between the engine mount and block because things didn't line up properly. Now I have better access under there, I'll fix it properly.

Looking at the diff, shimming the front will drop the nose and make things worse. If I really get stuck I could reduce the thickness of the poly bush to lift the nose a little. I'll save that as a last resort.

bfit · « **Reply #98 on:** October 12, 2015, 11:04:37 PM »

Put you trans member under yout original box with rubber mount etc and measure up to the centre line of the box, then you will have a reference to whete the new box should be.
Bfit

Scott · « **Reply #99 on:** October 13, 2015, 08:30:00 AM »

I sold the old auto long ago, so that one won't work unfortunately.