Need help with TC /flexplate install

-
threewood

threewood

Well-Known Member
Joined
Nov 11, 2014
Messages
441
Reaction score
270
Location
Artesia, NM
Engine / transmission is a 1962 318 Poly with TF-8 19 spline. Bought a new PTC torque converter and ARP fasteners, 19 spline, 7/16" bolts. Old torque converter has an 11 1/8" bolt pattern but the new one is 10".

1) Besides needing a new flex plate, is this an issue? I have heard the 10" is for a 904?

2) My biggest concern is the mounting pads. The old converter has .475" tall mounting pads. New converter has .270" tall mounting pads. Flexplate is .105" thick. Bolts have .500" reach. New bolts WILL NOT work as they bottom on the converter before coming close to tightening up the flex plate.

With both converters side by side, snout down, the distance from the snout to the pad mounting surface is the same. The difference is that the new converter has a raised ring around the perimeter of the TC body whereas the old one does not.

Can I use washers? Cut the bolts down? Send converter back? I am awaiting a reply from CRT and am getting antsy as I was planning to drop the motor back in my car this weekend.
View attachment TC1.jpg

View attachment TC2.jpg

View attachment TC3.jpg
 
just grind the bolts.....? I hope it fits the older tranny, Im sure you told them the application and they sold you the correct spline count.
 
If the spline count is right and the snout is right, and it falls into the pump ok , then you are in good shape. You then have three choices with the bolts; cut, replace, or space. I don't like to mess with those 4 little bolts cuz all the power the engine makes has to pass through those babies, so for me the choices are replace or space. If I were to space them, I would use hardened washers, which might be a trip to the hardware shop, so I would try to get the shorter bolts first, since I'm going there anyway.

EDIT I say try cuz I don't think they're out there.So hardened washers it might have to be. I suppose Hardened or grade 8 loc-washers would be ok, but they tend to chew up the relatively softer flexplate. I might install those between the plate and the TC, and then the loc-tite as mentioned, below.
 
Thanks for the answers. John suggested the upgrade to 7/16" bolts so that is what I went with (those ARP bolts are pricey!) New converter is correct for my transmission, everything else is correct. I suppose washers would be the easiest way to go. Would lock washers be ok? Either way, I am loosing thread engagement with this converter.

Also, I have not been able to find any large head TC bolt in 7/16 thread shorter than .50"
 
The '62 FSM calls for 10-3/4" diameter TC for the TF-6 and 11-3/4" for the TF-8. But we don't know what you are doing with this application. Is this stock or ??

I would grind the bolts down. If washers are used, then hardened flat ones really are needed. The side torque on these bolts in single shear loading will make them want to 'tilt' and flex the plate and TC, so the closer the heads are to the plate, the better. And the thread engagement is the same regardless with the new blocks, and the 7/16" will help. Make sure they are grade 8. I like to use blue LockTite on them.

BTW, the TC bolts take about 4-5 times less torque than the crank bolts due to the much longer distance from the crank centerline to the bolt center. The weak point always looked to me to be the welds of the nut blocks to the TC.
 
I talked to John Cope and he recommended that I surface grind the bolts, chase threads. He said washers could work but they would have to go between the flex plate and converter otherwise the heads could contact the motor.

He seemed surprised that they bottomed out but understood the problem. I pick up my flex plate tomorrow and will get to work on it. Now I wish I had trial fit everything when I got it in. Hope it all comes together, I at least need the motor in this weekend.

Edit: This is for a mild street build. 9.2-1, bigger cam, head / valve work, headers, lower gears, 4 bbl. TC is around a 2400 2500 stall.
 
Aaaw snap, someone agrees with me! ;-) good luck whatever you do.
 
threewood said:
I talked to John Cope and he recommended that I surface grind the bolts, chase threads. He said washers could work but they would have to go between the flex plate and converter otherwise the heads could contact the motor.

He seemed surprised that they bottomed out but understood the problem. I pick up my flex plate tomorrow and will get to work on it. Now I wish I had trial fit everything when I got it in. Hope it all comes together, I at least need the motor in this weekend.

Edit: This is for a mild street build. 9.2-1, bigger cam, head / valve work, headers, lower gears, 4 bbl. TC is around a 2400 2500 stall.
Click to expand...

I was getting ready to warn about them hitting the block or the dust cover if spaced, and that washers vary in thickness and can cause a converter or flexplate failure. (cracks)
I'd be ok with machined spacers or washers that were measured and matched thickness.

I also could have sworn there were 3/8 length bolts around.
 
If it makes you feel any better, we had to 'tweak' the length of the TC bolts in an install last week for a Hughes TC. We bought some 3/4" grade 8 bolts, and cut/ground them to 1/2" and they were still a bit longish. Of course, we found the originals right after we were done LOL
 
threewood said:
Are you talking about the nose of the converter that fits in the back of the crank? I'll measure when I get home but it looked the same as the old TC.
Click to expand...

Yes......No need to measure, just look. The early / late difference is obvious
 
I'm feeling better about it now. Got the 10" flexplate, enlarged the holes to 7/16" and mounted it up. Used blue loctite. Mounts perfectly to the TC and crank. I was getting worried about the TC fitting the trans as it didn't want to drop in. Finally got it to clunk in. Got my engine dropped in and have about 1/8" between the TC and flex plate. I haven't mounted the 4 TC bolts yet as I was too busy getting the motor mounts bolted and the headers in place.

Here is a comparison of the old bolts from my converter and the new arp bolts (the old ones are shorter than 1/2", figures). Night and day difference.
 

Attachments

  • 20151107_104714.jpg
    23.4 KB · Views: 160
  • 20151107_104723.jpg
    35.4 KB · Views: 164
  • 20151107_161241.jpg
    41.9 KB · Views: 150
I just cut the bolts down if I need to...If you worry about getting them hot, the just use a hacksaw and dress them with a file. You have to get a bolt very hot before it will change it's strength characteristics..
 
Bakerlite said:
I just cut the bolts down if I need to...If you worry about getting them hot, the just use a hacksaw and dress them with a file. You have to get a bolt very hot before it will change it's strength characteristics..
Click to expand...

I used a sanding disc on my angle grinder and had a spray bottle of water to quench every couple of passes. All 4 bolts are on and torqued down, blue locktite used. Glad I have that behind me, now I get to weld up the exhaust.

Thanks for the help:)
 
You must log in or register to reply here.
-

Back
Top