Gojira94

iTrader: (4)

1) What are the specs on the factory LT1 flywheel/ TOB / reach of TOB fork?
- Thickness of new/ uncut flywheel
- When (at what thickness) is a shim needed after machining?
2) if FW too thin, clutch won't engage fully (PP not snug against disc)
- Because the fork would be at the end of its reach
- PP/ TOB would be hung on fork, not fully engaged
- Does the factory TOB fork have so much travel this is a non-issue?
3) Aftermarket FWs: are they the same thickness as factory LT1 FW?
- If too thick, trouble disengaging PP/ TOB via TOB fork?
- If too thin, trouble engaging as speculated above?
4) Is there a guide for measurement/ when to shim for OE or AM FW?
5) Is the factory TOB self-aligning or not?***
6) Anyone use an aftermarket TOB like:
- McLeod 16010 (self-aligning / not?)
- Centerforce N1716 (self-aligning / not?)

I'm at a crossroads. I have one of the last Valeo clutch assemblies from 2009 and have run into questions after the slave cylinder went out. The clip on the fork may be toast as well, the fork is definitely off the TOB. I ran out of time at the shop were I was using a lift and didn't get to pull the trans yet. Forming plans for what to do the next trip to the shop, ahead of time.

One scenario:

I'd like to use my Valeo LT4 style PP and pick up a McLeod 261571 disc whether or not the Valeo disc is still any good. It slips when I get on it hard in 1st-2nd. Likely will need new TOB, saw the 2 AM TOBs above on Summit, not sure if a solf-aligning TOB is a must. Considering a new FW while I'm at it, or cutting the factory one (would be at least the 2nd time on this 77,000 mi car). I need to know whether or not to shim it if I do cut it again. If I go AM FW, should I have it mic'd and cut if needed to get a clean flat surface?

Thanks

Centerforce

The N1716 is a self-aligning throwout bearing. This neat little sheet should be included with the TOB.

Gojira94

iTrader: (4)

Thanks for the link. Upon further review, it doesn't appear that the N1716 is applicable to the 93-97 T56s behind an LT1. I browsed the Centerforce site and it shows that N1402 is the correct bearing. My mistake. But hey, if the N1716 would work, for half the price...

Centerforce

I didn't check part numbers the way I should have, shame on me. I don't see that same info on the N1402 so I'll assume it isn't self-aligning, but I'll get a definitive answer.

madhatter

Anyone here that bookmarked the really great thread made years ago regarding all the clutch/PP options out there for us? It may have been here or on CZ28.

Gojira94

iTrader: (4)

This one:

http://www.camaroz28.com/forums/driv...ptions-520404/

Good information for sure, but didn't answer my questions about machining specs on the stock flywheel or tell much about TOB options.

Gojira94

iTrader: (4)

No worries. What I'm really after is whether or not GM designed this engine/ transmission combo with a self-adjusting TOB. I've read a couple guys saying they are supposed to be. I'm only seeing 3 that seem to match and are self-adjusting:

Napa BRG N3068SA:
(missing the clip collar for the PP, maybe can be pressed off/ on to new bearing, but most likely for T5s behind an L32)

GM 10085246 ("discontinued" but still can be found here and there)

Image below Timken / National 614116:


Timken / National 614116

and the one at Autozone for $183.00

BALLSS

I don't know the stock thickness of the FW but did have mine resurfaced 3 times. Obviously how much is taken off would determine how many times it can be resurfaced. If 15 thousandths is taken off, 3 times max IMHO

If you do replace the disc with a McLeod DF disc, get the FW resurfaced or get a new one at auto part store. They are around $100 for a stock cast FW

The TO bearing....all the ones I see are all made in China. The original "square top" ones used on the Vettes LT4 cars used the square top ones. The pics below show the thicker top LT4 TO bearing. SPEC supposedly sells them for around $80 from what I hear...steep $ but IMHO a better TO bearing in terms of the top flange which on the round LT1 ones can peel back....although I have never had that happen.

I used the older square top TO bearing on my McLeod Twin clutch

If your clip broke off the fork you will be VERY hard pressed in finding a new fork. ebay or junkyard may have one. I bought one several years ago from thegearbox.com but I believe they are now out of stock. If just the bolt broke that holds the "T" pivot on then you can or should be able to get that bolt

The TO bearing is "self aligning". If your FW was cut so thin you would need a shim you can get a .050 shim that goes between the crank & FW at auto part stores. IMHO if you needed one I would get a new FW.

Aftermarket billet FW's are good if you want to go that route but not necessary on a basic bolt on car

ARP now makes the specific PP bolts if you do need them otherwise just re-use the stock ones. TQ is 22 ft lbs

Not a bad idea to replace FW bolts though. ARP also sells those

you can buy a complete sealed hydraulics (MC & slave) from auto part store or rockauto.com. I got a new slave when I put in my street twin from auto part store and it was exactly OEM brand sold under store brand name

Gojira94

iTrader: (4)

Looks like the best and most available/ reliable deals at this time are the Centerforce N1402 (LT1) and the N1401 (LT4)

N1402 (LT1):
$94.55 + shipping from Centerforce web site
$85.95 + shipping from Summit / Jegs

N1401 (LT4):
$89.05 + shipping from Centerforce web site
$80.95 + shipping from Summit / Jegs

The OE CT1090 LT4 bearing is about the same availability as the 10085246. Pretty spotty. Saw only one of each on Amazon and EBay, respectively. $119.00 + 17.99 shipping for the CT1090 and $132.24 + 8.00 shipping for the 10085246 and it's a China bearing. And nobody to go to for a warranty.

Eckler's Corvette has the OE CT1090 for $110.99.

I'll find out Sunday what exactly the damage is and see what I need and go from there. If I can fix what I've got and keep rolling I will, and make better decisions on future clutch options, buy what I want/ will need before I need it.

I'll stop by a couple of the big parts shops and look at a replacement flywheel and mic it while I'm there and post it up for reference comparisons/ average thickness of a new OE style replacement at Adv, Autozone, Oreilly.

guppymech

iTrader: (7)

Check out Powertorquesystems.com, click 'shop Corvette parts' lower left side of home page. They seem to have a lot of OEM LT1/LT4 clutch parts, kinda pricey.

Centerforce

Sorry for the delay. The N1402 is a self-aligning TOB. We're working on updating our site with that information right now.

Gojira94

iTrader: (4)

No worries, and thank you for supporting the LTx community!

My buddy wasn't able to meet me at the shop yesterday so I didn't get anywhere with it, still wondering what I'll see when I pull it and take a look.

Gojira94

iTrader: (4)

The walk of shame- I haven't touched the car in 4 months, finally got into it last night. Too busy with insane workload and the car's been inside my friend's shop (I don't have a key anymore). Ordered a Centerforce N1402 from Summit last night. Kind of disappointed I'm not biting the bullet on a lightweight flywheel and better performance clutch...

formula89383

If you make any real power you will kill a centerforce dual friction clutch. My stroker 383 built from a 96 SBC killed a race built th350 with reverse manual valve body in a month of mild (for me) driving. I got pissed and converted to a t56. New everything forward of the input shaft including a mcleod master. The clutch started slipping after about 600 miles. I went through break in period and the street tires never had enough traction to really stress the clutch but it was fried in no time. If you want a clutch that will hold you'll want to look at a spec stage 3. That is if your making at or over 450 hp at the flywheel. My 383 exceeds that by a decent amount. I'm going to replace everything again and go with the spec stage 3 with the sprung hub. Centerforce dual friction is junk and a major waste of time and money.

SS RRR

iTrader: (2)

If you don't want to spend the money on a twin disc clutch then Spec Stage 3+ is the next level below that. It's one of the best clutches I've ever had. Very streetable and is responsible for many 1.55 60' times with a 3750# race weight.

Gojira94

iTrader: (4)

The discussion here around Centerforce (N1402) is with throwout bearings and LT1 clutch geometry, not clutch discs so much. I put a NAPA kit in it (LUK) and it actually came with a TOB (Timken/ National 614116 just like the one above, so now I have a spare lol). I run a quality street style clutch these days and enjoy 'spirited' driving from a roll. No clutch shattering 5k clutch dumps. I'm too old for that. If I took this car to the track a few times a year, then yes, I would put a real clutch in it. And though Centerforce has had a decent name over the years, I'd go with a McLeod (first choice) or Spec (2nd choice) disc and a lightweight aluminum flywheel.

ACE1252

You can take it to the track all day long with the clutch you have on street tires and be just fine. When you put drag radials on it is when I suspect weak spots will start to show with high RPM launches.