Replacing the flexplate without removing engine or transmission
 

I thought some of you may enjoy these pictures. I replaced the flexplate without removing engine or transmission. My truck is a 1969 CST/10 with 350 engine and TH400 automatic transmission. I am a newbie for such an in-depth repair, so if I can do it anybody can. Some of you may recall a recent post of mine where I talked about chewing up my flexplate and needing to replace it.

First of all, the research. I found this interesting forum article:
https://ls1tech.com/forums/automatic...l#post18644698

The only special tool I ordered for the job was a Lisle Flywheel Turner. I highly recommend this tool, it is just great.
https://www.amazon.com/dp/B000FN7JE2/

I did some things slightly different than the article. I did not remove the driveshaft. Instead I just took loose the rear u-joint and the carrier bearing mount bolts, and rested the driveshaft on a strap so it could move front to rear with the transmission.
Attachment 1645001

I disconnected the negative lead of the battery. Instead of removing the starter, I just loosened the inner bolt and remove the outer bolt, and rotated the starter out of the way.
Attachment 1645002

I removed the parking brake cable guide that is right behind the transmission and pushed it up the cable and out of the way, and put a small bolt and nut in place, and hooked the cable under it. It is out of the way for when the transmission moves back. This picture shows the transmission already moved back.
Attachment 1645003

I took out the flexplate-to-torque-converter bolts with help of the flywheel turner tool. I removed the various transmission connections and mount bolts. I put in the 4 long bolts one at a time, and took out the top 2 transmission bolts. I put a jack under the transmission to lift just a little bit of weight. It probably wasn't mandatory, but I thought it was a good idea. The truck was on ramps for the operation. My Home Depot was out of 4 inch 3/8 grade 8 bolts, so I got some 5 inch bolts. It worked great. The transmission slid back on those bolts with little effort, and what I saw was a big work area to get at the flexplate-to-engine bolts.
Attachment 1645004

Here is what the flywheel turner tool looks like.
Attachment 1645005

Re: Replacing the flexplate without removing engine or transmission
 

Look's like you have it under control. Good talking with you today. Good luck with the truck it looks like a keeper.

Re: Replacing the flexplate without removing engine or transmission
 

Nice Job! Bravo!
I have done that many times and I learned something today, glad I clicked on the post, never thought to use long bolts to slide it back on, I always pushed it back and propped it up with wood and such across the frame rails. I also like that you left the driveshaft in, much less mess and no fluid lost!

Re: Replacing the flexplate without removing engine or transmission
 

Oh and where did you get the flywheel turning tool? My snap-on one is just like that except a different handle, wouldn't mind getting another one if it were reasonably priced.

Re: Replacing the flexplate without removing engine or transmission
 

Amazon: https://www.amazon.com/dp/B000FN7JE2/
Just click and a couple days later here comes the tool.

Re: Replacing the flexplate without removing engine or transmission
 

Sweet tool and price. I put one in my cart so I can find it later.

Do you know you can ratchet with it on the flywheel to get the proper span of teeth? I jam the tooth attached to the handle in the flywheel the move the handle to engage another tooth with the springed portion, then turn the flywheel, makes it quick to engage when rotating the flywheel to line up the bolts.
Another tip you may not know...each of the holes in the flywheel are elongated, 2 are the same elongated around the circumference. One is 90 degree opposite elongated. (from the center of the crank outwards) If you install that bolt first you can fully tighten it then when you turn the flywheel the others will line up because they are elongated around the circumference for the bolt to line up.
Saves time as you don't have to start all the bolts before tightening them up.

Re: Replacing the flexplate without removing engine or transmission
 

I didn't know that. Good info, thanks.

Re: Replacing the flexplate without removing engine or transmission
 

Works on old chevy,not newer dodge.I had rear seal go on 2005 dodge ram 4x4.Tried this.Did not work out as well. Congrads on working around extra work.

Re: Replacing the flexplate without removing engine or transmission
 

I'm in the process of doing the same thing. I've done it before. I'm replacing the starter and flexplate ate the same time.

Re: Replacing the flexplate without removing engine or transmission
 

Great post !!
I haven't had the pleasure..... yet .
Looks like the deal.
Time saver and like Randy said , much less fluid loss.
Thanks for the info.

Re: Replacing the flexplate without removing engine or transmission
 

That's a great tip with using the five inch bolts to keep things lined up.
I didn't do that when I replaced mine. It sure will make things easier. :metal:

Re: Replacing the flexplate without removing engine or transmission
 

All I would add is use a piece of wood, like a 3/4" piece of ply wood about 12" x 12" between that transmission pan and the floor jack.

Good job!

Gary

Re: Replacing the flexplate without removing engine or transmission
 

My dad and I did it on my 73 BB 2WD suburban. Not too hard, just needed enough room for hands and a torque wrench.

Re: Replacing the flexplate without removing engine or transmission
 

I did the same last year...drop drive shaft at diff, unbolt tranny at crossmember, 4 long bolts, slide tranny back & wala. Used the same tool also.

Re: Replacing the flexplate without removing engine or transmission
 

The longer bolt thing is a good idea. We used to run into a lot of 2000ish s10s with cracked flexplates at my old job. I just took all the bolts out and backed the top 2 halfway out and just let the gap happen. Had just enough room to get in there with box end wrenches.

Re: Replacing the flexplate without removing engine or transmission
 

I have a 72 coming tomorrow. PO said the ring gear needs to be replaced and I started researching how to do it and found this post. First off, thanks! So I've seen ring gear can be purchased separately but feel you may as well replace flexplate with ring gear at the same time. Do you recall where you bought your flexplate?

Re: Replacing the flexplate without removing engine or transmission
 

A manual trans flywheel has replaceable ring gear. The automatic flex plate is welded so the whole flex plat must be changed.

Re: Replacing the flexplate without removing engine or transmission
 

I got mine through Amazon:
https://www.amazon.com/gp/product/B000C8RDCS/

I compared them when I took the old one off, and the new one was exactly the same.

Re: Replacing the flexplate without removing engine or transmission
 

Was this on a 2 wheel drive truck? I'm attempting this on a four wheel drive Blazer which with the transfer case may make it more difficult.

Re: Replacing the flexplate without removing engine or transmission
 

The fact you could just remove one starter support bolt and turn the starter tells me the support bracket at the end of the starter is not in place...

I would make sure the starter support bracket is in place at the end of the starter when you put it back together....

These missing support plates are the number one reason the starters break out the outer mounting bolt hole in the ear on the block.

Nice work on the flex plate R&R ...

:gmc2::chevy::gmc2::chevy:

Re: Replacing the flexplate without removing engine or transmission
 

It is 2 wheel drive truck, no transfer case. I do suppose it would be different for a 4 wheel drive truck. In 1969 there was no additional support bracket for the starter on trucks. I would like to get one anyway before I do anything to the timing that could cause kickback.

Re: Replacing the flexplate without removing engine or transmission
 

Make sure the block is tapped for the bracket then...I just checked my 69...it has the bracket, as does my 67....maybe previous owners had em fitted...

:chevy::chevy::chevy:

Re: Replacing the flexplate without removing engine or transmission
 

Is this what the one I need looks like? I have the original style starter with diagonal mount holes, and 168 tooth flex plate.

Re: Replacing the flexplate without removing engine or transmission
 

Thats the bracket....it bolts to one of the starter thru bolts, the one with the extended threaded section

There should be a threaded hole just above the oil pan rail approx at end of starter.

The block also appears to be drilled for both offset and straight bolt pattern...

:chevy::gmc2::chevy::gmc2::chevy::gmc2::chevy:

Re: Replacing the flexplate without removing engine or transmission
 

OK, thanks. I ordered one just now. When it comes in I'll crawl up under there with a hand full of different bolts and wrench, and have a look around and try to bolt it in place. I've been meaning to do this because I know they are a super good idea.

Re: Replacing the flexplate without removing engine or transmission
 

Do you have a link for that bracket, I'm assuming you got from Amazon.

Re: Replacing the flexplate without removing engine or transmission
 

I ordered it from eBay by searching for "Bracket 3965589". It should be for a 350 with 168 tooth flex plate and starter with diagonal mounting holes, if I believe the Internet.
http://www.ebay.com/itm/272011458486
I'll let you guys know how it goes when I try to install it.

Re: Replacing the flexplate without removing engine or transmission
 

Thanks

My son and I started on it yesterday, got all the bolts out in the bell housing with the middle one on the driver side the 4-inch bolt is too long it hits the body. All the other bolts we're no problem. So I'm going to try and put it in three and a half inch bolt in that spot and proceed according to your plan. With mine having the transfer case being a four-wheel drive I have to also figure that out. I'm thinking I might have to remove those brackets that hold it and at the same time support it along with the transmission to slide it back. If that doesn't work I'll probably end up having to drop the transmission do the job and then have the pain in the ass task of lining up the dowels when I reinstall it. Wish me luck.

Re: Replacing the flexplate without removing engine or transmission
 

If you figure out a good way to get it done, post some pictures. abig84 had an interesting comment earlier about just needing a small amount of space opened up, just enough to get wrenches in there. The way I did it I had a luxurious amount of room, but that was probably overkill. You may be able to get by using abig84's method.

Re: Replacing the flexplate without removing engine or transmission
 

yeah I'm thinking I don't need all the space you had. I'm a pretty skinny guy with skinny forearms and skinny hands and skinny fingers, LOL and my son, 16 years old he's even skinnier still. I'll take a bunch of pictures and post them in this thread.

Re: Replacing the flexplate without removing engine or transmission
 

How many bolts are supposed to be holding the flexplate to the torque converter? I'm thinking somebody did a s***** job. I have them all out and there are only three. 1972 Chevy Blazer automatic transmission. Th350 with a 350 SBC.

Re: Replacing the flexplate without removing engine or transmission
 

There are just 3 flexplate-to-torque-converter bolts on my 350 engine with TH400 transmission.

Re: Replacing the flexplate without removing engine or transmission
 

The long bolts deal to slide the trans back for clearance is a neat deal but me, I would take this opportunity to replace the front pump seal while it is apart. If it has been in there for a long time and is now disturbed it could go to leaking once you button it back up. This means the trans will most likely have to be lowered to remove the torque converter and replace the seal. It's cheap insurance. ;)

Re: Replacing the flexplate without removing engine or transmission
 

I think if you look at your torque converter you will only see 3 places to run bolts into.

Re: Replacing the flexplate without removing engine or transmission
 

Five bolts holding the flexplate to the crank and three bolts hold the torque converter to the flexplate.

Re: Replacing the flexplate without removing engine or transmission
 

Thanks oh, I thought three was half as many as necessary. Glad to hear it was not a problem. I'll look into that front pump seal while I have it open, thanks.

Re: Replacing the flexplate without removing engine or transmission
 

so I have to drop the transmission and remove the torque converter to get at that am I right? I'm thinking that might have to happy anyway, the transmission being dropped as transfer case is proving to be a bit of a problem. Anybody else can chime in and tell me what else I should do while I'm there? I'd love to get as much accomplished as possible, $13 part here and $20 Part there while it's all opened up

Re: Replacing the flexplate without removing engine or transmission
 

Yes. The pump seal is behind the converter.

Re: Replacing the flexplate without removing engine or transmission
 

I dunno, maybe a rear main seal?

Re: Replacing the flexplate without removing engine or transmission
 

And by the way I did not buy the flywheel spinner. I simply put a wrench to each side of the flexplate to torque converter bolts and took them off. before I took off the second one I moved the flexplate to the position of the first one by doing it with only one wrench which then exposed the third one removed the second one, and moved to the other side of the transmission to get the third one, and it wasn't a problem. Hope that makes sense.