Re: Building a 7 bolt... What clutch?
 

Thanks Jason... I gave my you my parents fax number which also happens to be the home phone number, they werent expecting a fax at 10:30pm so thats why they were answering it. I'll give you a call tonight and let you know when to send it.


I dont know about that. 2g's have 3 tranny mounts so it is definatly supported well. The only thing I could manage to think of out of that info is if the place you read that from meant the engine has a lack of mounts. I could see the crank being forced up by the weight of the engine pushing down on it while attached to the tranny considering there is only 1 motor mount on the engine (drivers side). Then by the crank pushing up it crushes the upper thrust bearing and while pushing in the clutch it moves the crank over and crushes the sides also. There for the crank is just flopping around in there. This is the only thing I could think of but if that was the case I think a lot more cars would have it.

Re: Building a 7 bolt... What clutch?
 

http://www.magnusmotorsports.com/crankwalktheory.htm

One of the better crankwalk articles.

Re: Building a 7 bolt... What clutch?
 

I "think" barton had a 2600 but I know it was defenitly crankwalked. I thought I heard it was at like .030 whick is huge.

Re: Building a 7 bolt... What clutch?
 

I have stuck with the 7-bolt because I know I won't be putting many miles on the motor. Even a shitty 7-bolt can handle a few thousand miles without crankwalking enough to cause too many problems, and I am cheap.

Re: Building a 7 bolt... What clutch?
 

It's not just from a heavy clutch, 1/3 of the CW cases have been automatics. And the engine mount theory, no dice. I came up with that 4-5 years ago, no response from anyone in the know.

Just make sure you have someone build the engine that knows what they're doing, use the correct size main bearings(there are three different sizes if I remember right) and if you are using ARP's on the mains, make damn sure you had the mains line bored and are using the dowel pins.

Any engine can walk, the 7-bolts just seem to have the problem more often than most motors.

Re: Building a 7 bolt... What clutch?
 

Mike sure as hell knows how to build a motor, but Careys walked last year?

Re: Building a 7 bolt... What clutch?
 

Shindley has probably built the most 7 bolts around here.

Re: Building a 7 bolt... What clutch?
 

Most people are smart enough not to build 7 bolts. Jakes case is a rareity, more ppl dont basically get given a "built" 7 bolt.

Re: Building a 7 bolt... What clutch?
 

I have a built 2.4 seven bolt with Eagle rods and Ross pistons and I still wish I just would have gone with the 6. The damn thing makes me nervous everytime I hear any odd noise. It's just not worth the risk. Mine is still running but so far it's only seen a stock clutch (12.5 quater mile with it) and an HKS twin disk. My HKS gave me problems. Besides being a bitch to install, I was never able to get it adjusted between not disengaging enough and having pedal pump up. Eventually some how I managed to snap 3 of the 6 flywheel studs. :confused: I'm now in the process of intalling a Horse Power freaks feramic disk with an ACT 2100.

My HKS clutch may still be usable if you buy some replacement studs and/or a rebuild kit. The disks didn't seem to have any problems before the studs broke but I'm no expert just looking at it. If you want to take a risk I'll sell what I have for $100. I'm to fed up with it to give it another try.

Re: Building a 7 bolt... What clutch?
 

Oh and I still remember the advise someone gave me before I started my build. "When you're adding up all the money you're saving don't forget to add in the price of a new moter after yours walks." ;)

When it comes down to it, it's a gamble. And currently the odds are much better if you just do a 6 bolt.

Re: Building a 7 bolt... What clutch?
 

And it was determined to be caused by a soft crankshaft. The new crank he has now has been re-nitrided.

Re: Building a 7 bolt... What clutch?
 

I'll quote mike. " Un even wear on the bearings". He said nothing about a soft crank to me. I'm not saying that was the problem, but he didn't mention that to me.

Point is even if you only spend 400 dollars to build this, that is 400 dollars you could have put into a good engine.

Re: Building a 7 bolt... What clutch?
 

Mike didn't mention anything about a soft crank to me either. He showed me a 7 bolt block and told me to look at the webbing in it. It is much thinner than a 6 bolt. The thinks it is allowing the crank to move around some. It seemed pretty viable to me. It definately is thinner than a 6 bolt.

Re: Building a 7 bolt... What clutch?
 

I say go for it jake! its cheap to do it and you got the parts at a killer price. If it walks...oh well. If it doesnt you will have a faster car for cheap. Plus how many motors actually walk anyway? not more than 50% do, and I hear if its less than a 50% chance, go for it. DO IT JAKE, YOU KNOW YOU WANNA!

PS if you need any help in your decision, give me a call!


-Colin

Re: Building a 7 bolt... What clutch?
 

*shrug*
I know when I saw the crank and the thrust bearing side by side Mike pointed out that the crank's thrust surface was severly worn, but aside from the metal deposits from the crank on the bearing, the bearing itself was fine.

Re: Building a 7 bolt... What clutch?
 

I too specifically remember Mike talking about the softer crank issue on the 2G 7 bolt. He had said that he was going to get it nitrided in an effort to prevent that damage again.

Re: Building a 7 bolt... What clutch?
 

Yeah, but the crank isn't even supposed to touch the bearing! As far as the bearings are concerned, the crank could be aluminum and be fine.

So how is the crank touching the bearing? There could be a lack of oil (or too much pressure breaking through the oil layer) or either the crank or bearing are getting out of position.

Re: Building a 7 bolt... What clutch?
 

Cudvig, since when does a built motor mean a faster car?

You still dont want to tune much different and the compression ratio is the same, so the only thing you are changing is the ring's, so a little bit better compression numbers, but not neccesarily any more power for the price.

Re: Building a 7 bolt... What clutch?
 

I would bet the 2900lb pressure plate pressing against the crank doesn't help. The oil layer in there is very thin, and can be seperated very easily. The point of nitrating the crank was to help prevent further wear once contact is made, but then the bearings die...
I say nerts to 7 bolts entirely, its like trying to make a ford fiesta fast, sure it can be done, sure it can be done for cheap, but why bother when there are better options?

Chris C's motor had alot $$ into the machine work (I won't disclose the amount, thats his decision). Everything was done to the block except maybe machine the block to retrofit thrust washers like the 6g72 and most honda motors... There was nothing conceiveable left to try to make it 'crankwalk proof' except switch the clutch out and give the crank a fighting chance.
I am sure it will still walk, its a 7 bolt, just hopefully at a slower pace. But thats just my $.02.

Re: Building a 7 bolt... What clutch?
 

$200 block, $150 in machine work including balancing, keep old front cover and oil pan, 700whp...