70 L46 4 speed Transmission Removal and Clutch Replacement

[Bill L.]

Okay I searched the threads and still have some questions.

1. When you either remove or install the transmission will there be enough room to turn the trans and remove without damage to the insulation blanket in the transmission tunnel? Any suggestions on how to protect the insulation?

2. I have also read that it makes sense to remove the bell housing with the transmission. Does this mean to remove 4 bolts attaching the trans to the bell housing and the bell housing bolts or leave the trans attached to the bell housing to remove as an assembly?

3. I read that you can use a transmission jack. How is that possible with a fixed crossmember?

4. Based on all OEM parts existing should I still check run out on bell housing and flywheel and just replace clutch and bearing then reassemble?

I will be performing all work laying under the car with it on jack stands. I am going to rebuild shifter, replace side cover gasket, and shift lever shaft bushings while transmission is out. I may clean and detail under body and frame while there too.

5. Any other things I should consider while transmission is out?

I have only ever pulled a 4 spd. trans on my 68 GTO and it was a can of corn without the cross member in the way. That was many years ago when GM parts were still available for clutch replacement.

Thanks,


Bill

[Bill C.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

I think you will regret doing the work on your back.

I did it this way and it was HORRIBLE. Very little room even with the jacks all the way up.

I found a 2 post lift to use the last time I did this and it cut the time in half.

[Terry M.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

I did it on a two post lift using the instructions in the Chevrolet Service Manual. It wasn't too hard, but I did have several students helping me.

No damage to the fiber insulation in the tunnel.

We were able, for the most part, to use a transmission jack -- except for the part where we turned the transmission to get it farther back so the input shaft would clear. Even at that the transmission jack will help support most of the weight.

Do NOT take the bell housing off with the transmission. Remove the transmission and then the bell. That is the way Chevrolet tells you to do it. I don't think you will get it out if the bell housing and transmission are bolted together.

I would never ever think of doing that job laying on my back. If you don't have access to a lift, find someone with one that you trust.

[Bill L.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

Thanks Bill and Terry.

I wish I did have a lift as described.

I have the entire rear suspension out, rebuilt, detailed and ready to go back in but figured while up on jack stands maybe I could take care of the transmission and related items too.

I work REALLY slow and even if I can get a lift it would only be for a day or so. I will check it out based on the advice.

Geeze I wish that crossmember was removable. Was there a GOOD reason they welded it in on 4 speed cars?

Thanks, Bill

[Terry M.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

I took two days but did a lot of cleaning and photos (real camera, before the days of digital). I could have easily done it in a couple of hours if I was focused only on the clutch/pressure plate R&R.

There are trans jacks that work at lower levels for little money -- try Harbor Frieght. It probably isn't a tool that will work repeatedly, but then you are not likely to do this more than once, one hopes.

http://www.harborfreight.com/catalog...nsmission+jack

[Edward J.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

Bill, I am sure there have been a lot of people have done it this way. If you already have the exhaust out it makes for easier access to shifter and linkage.

Start the job by removing the drivers front pipe- to access the shifter
remove the trans. mount and center hanger- jack up by the bell housing using a piece of 2x4
unhook speedo. and back up light switch driveshaft and yoke if not already removed.
while the bell housing is still has jack under it. remove the 4 bolts that secure the trans to bell. next step is to slide back trans. and rotate the trans. so the side cover is facing about 7 o'clock this will aid in removing. the transmisson will nose down after sliding back.

The rest should be a piece of cake with clutch replacement.

It would make a little easier if you have some help during the removel and install of the trans. I have done this without the use of a jack also, It will only be in the way when doing it on the floor as you are. JUST MAKE SURE YOU EAT YOUR CHEERIOS.
.

[Duke W.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

The shop manual says move the trans to the rear until the input shaft clears the bell housing opening then drop the front of the trans... didn't happen for me. There was still about an inch to go, so I unbolted the bell housing and dropped it together with the front of the trans. Reverse the procedure to install

You have to be careful not to damage the tunnel insulation. Consider wrapping up the levers with duct tape or removing them and wrapping up the shafts with tape.

It's possible to do this job alone - well maybe in my twenties, but nowadays you definitely want a helper and two might be better - one to help you wrestle the trans and another to work the bell housing. The four-speed weights about 66 pounds.

Duke

[Patrick H.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

I did it on my back in my garage in my pre-lift days. You may need to loosen the exhaust, but as always the worst part is getting enough room to move the transmission back. I'd remove the shifter, rods, bracket and anything else.

Yes, it's a pain but it can be done. If your car is clean underneath it's so much nicer.

Patrick

[Bill L.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

Thanks for all the responses! I am going to try and do this on my back. I can have someone give me a hand as I am not nearly as strong or unwise as I was back in my twenties

I will also have a platform under the transmission so that if it slip it will have a soft landing.

Bill

[Ralph S.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

When i work at Luby Chevrolet in the late sixties there was a mechanic who would disconnect everything mentioned above and use a Porta-Power between the bell housing and the front of the transmission and push the trans back enough to be able to remove the bell housing, i remember it would tear up the insulation and lift up the floor inside the car. There were some real butchers in those days.

[Edward J.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

Bill the key to getting the clearance that Duke is explaining is the rotation of the trans housing.(side cover should be about facing the ground) and slide back. If your arms get tired you can rest shaft on edge of bell housing. good luck.

[Larry M.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

Bill:

When I used to do frequent clutch replacements there were two things that I found to be needed (almost mandatory) to do the job quickly and correctly. One was a set of alignment pins that you can insert into two (or more) of the transmission to bellhousing bolt holes to make it easier to remove and reinstall the transmission. These can be easily made by cutting the heads off a few similar sized bolts about 3-4 inches long, and cutting a screwdriver slot in the end. They can also be purchased. MR GASKET is one brand.....but I found that these were just a bit too short for my needs. I usually just make what I need.

The second item is an actual old/new transmission input shaft to correctly align the clutch plate when installing it. Without this you are guessing. The plastic alignmnet shafts that are sold today are okay if you have nothing else, but they are often a bit off, which causes install problems. With an actual input shaft, things go smoothy and without any issue. If you cannot get one in time, you can have a helper work the clutch pedal to free up the clutch plate alignment during the reinstallation process.

If you replace the pilot bushing, get an Oillite one and trial fit it to the transmission shaft before you install it into the crank. Making a wooden or aluminum installation tool and putting the bushing in the freezer overnight before installing will also greatly help. I recommend using only the Oillite non-magnetic bushing.

I also recommend buying and using a floor sissors transmission jack for doing this work if you do not have lift access. They are not to expensive. I never had the luxury of having a lift for this work, and always did it on my back. Sometimes in the rain. But that was years ago. I probably have ONE more clutch replacement left in my old body......and I'm saving it for when I have to do it for the LAST time.

Larry

[Joseph K.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

I pulled my 69 4 speed out last month and put it in the same day to replace the throw out bearing. The worst was getting the linkage/shifter out. Wrestled the trany out by hand by rotating it clockwise as I pulled it back rested the nose on the bell hosing temporarily. re-positioned myself then pulled it back, dropped the nose and it comes out forward If you don't want to hurt the insulation use two people. I left the exhaust on but un-bolted them at the manifolds.

Also if you need to replace the battery cable this is the time to do it. Suggest a insulation change it is not that costly.

[Bill L.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

Well I think I am working up the strength to do this. Great suggestion on putting the bearing in the freezer.

I have been trying to get my hands on an input shaft as suggested.

I may pick the harbor freight jack. It will help with the reinstallation of the rear too.

Thanks,


Bill

[Paul Y.]

Re: 70 L46 4 speed Transmission Removal and Clutch Replacement

The shop manual says move the trans to the rear until the input shaft clears the bell housing opening then drop the front of the trans... didn't happen for me. There was still about an inch to go, so I unbolted the bell housing and dropped it together with the front of the trans. Reverse the procedure to install

You have to be careful not to damage the tunnel insulation. Consider wrapping up the levers with duct tape or removing them and wrapping up the shafts with tape.

It's possible to do this job alone - well maybe in my twenties, but nowadays you definitely want a helper and two might be better - one to help you wrestle the trans and another to work the bell housing. The four-speed weights about 66 pounds.

Duke

I agree with Duke. That is the only way I have ever been able to remove the transmission on either a C2 or a C3.