Differences between a 6 and 7 bolt

[trbn8tr_cal64]

Can someone explain in detail what the differences between a 6 and 7 bolt DSM are? I'm new to this DSM stuff and looking to buy one, and I am trying to learn as much as i can about them. And I wouldn't mind also knowing what the differences are between a 1st gen and a 2nd gen are (mechanically). Thanks!

 

[97gsx_zeclipse]

as much as you can? vfaq.com has it in there. Also this site has a bunch of useful how to's at the top left where it says tech/diy.

 

[Locke]

Hint: using the Way-back machine on VFAQ.com will yield long lost content.

 

[TSG59_Steve]

The difference b/w a 6 bolt and 7 bolt are the motor. The reason they call them the 6/7 bolt is because the number of bolts holding the flywheel on. The 6 bolts came from the 1st generation (90-94) but not all of them did, I'm just not sure where the cut off was and too lazy to look it up. All the second gen (95-99) TURBO models came with the 7 bolt. The reason people make a point to mention whether they have a 6/7 bolt is because the 7 bolts have a tendency to fail, for whatever reason. People have tried saying that the 97-99 7 bolt was a revised version but I think that's just a rumor that's been passed around because I've had a 95 gst spin a bearing and a 97 gsx spin a bearing. The 7 bolt motors seem to be flawed. People try saying that they are notorious for "crankwalk" but I've never actually seen it. This forum has a lot of information on the differences though as well as the link already posted. Just be careful of what you read because there is a lot of misinformation out there.

 

[Talesin]

90-92 had the six-bolt, 92.5(after a certain month)-94 had the seven-bolt. 1G seven-bolts do not suffer from the chronic crankwalk problems that seem to follow 2Gs around, and are considered to be almost as good as the six-bolt.
Other differences are that the six-bolt had thicker headbolts, and the '90 had much bigger con-rods, allowing them to theoretically hold more power on the stock part.

All 1G (six and seven bolt) had much larger intake ports on the head, and larger runners on the intake manifold, and a larger throttle body. The exhaust manifolds are more prone to developing cracks, but a 2G manifold can be swapped on with only a little grinding on one corner for the power steering support bracket.

Mechanical differences mostly run to the sensors... 1G used either an optical sensor (90-91) or a hall effect sensor (92-94) for the CAS, which is adjustable to set the timing. 2G use a hall effect CAS which is non-adjustable, as well as a crank angle sensor (which the 1G does not use). The MAS on the 2G will flow more, the turbo (14b) on the 1G is better than the bitty t25 that comes on the 2G.
90-91 AWD DSMs had a three-bolt rear end, 92-94 had a stronger four-bolt. The 'desired' 1G is the 92 6/4, unless you like popups... go for a 91 at that point, as it reduces a LOT of the 90's electrical kludginess.

All that comes to mind at the moment. Oh, if you're going for a DD, you may want to grab a GS-T instead of a GSX.. the FWD gearing is MUCH longer, allowing far greater fuel economy while cruising the freeway. Was a real shock going from 30mpg+ on my old GS-T to ~20mpg on the GSX. :b

 

[trbn8tr_cal64]

90-92 had the six-bolt, 92.5(after a certain month)-94 had the seven-bolt. 1G seven-bolts do not suffer from the chronic crankwalk problems that seem to follow 2Gs around, and are considered to be almost as good as the six-bolt.
Other differences are that the six-bolt had thicker headbolts, and the '90 had much bigger con-rods, allowing them to theoretically hold more power on the stock part.

All 1G (six and seven bolt) had much larger intake ports on the head, and larger runners on the intake manifold, and a larger throttle body. The exhaust manifolds are more prone to developing cracks, but a 2G manifold can be swapped on with only a little grinding on one corner for the power steering support bracket.

Mechanical differences mostly run to the sensors... 1G used either an optical sensor (90-91) or a hall effect sensor (92-94) for the CAS, which is adjustable to set the timing. 2G use a hall effect CAS which is non-adjustable, as well as a crank angle sensor (which the 1G does not use). The MAS on the 2G will flow more, the turbo (14b) on the 1G is better than the bitty t25 that comes on the 2G.
90-91 AWD DSMs had a three-bolt rear end, 92-94 had a stronger four-bolt. The 'desired' 1G is the 92 6/4, unless you like popups... go for a 91 at that point, as it reduces a LOT of the 90's electrical kludginess.

All that comes to mind at the moment. Oh, if you're going for a DD, you may want to grab a GS-T instead of a GSX.. the FWD gearing is MUCH longer, allowing far greater fuel economy while cruising the freeway. Was a real shock going from 30mpg+ on my old GS-T to ~20mpg on the GSX. :b

Thanks a ton for the reply! The car I am looking at is a 96 talon tsi FWD, the car has 140K miles on it and the motor has 40K. I have not actually seen the car yet,im just going off of what someone has told me about the car. Ill know more about the car when i go see it saturday. Here is the deal though, the guy is selling the car for about 1k, that seemed extremely low to me. My assumption as of now is that the engine has crankwalk, (remember it is not the origonal engine either). But then again for all i know he could already have a 1G motor in it or something? If i can get that for that cheap, ill have about 2500 to 3000 $$ extra to use on it. What do you guys suggest i do? Do you think thats enough $$ to fix the engine if it is plagued by crankwalk, or swap in a 1g engine? Thanks!

 

[Talesin]

That's incredibly cheap for a 2G turbo DSM. Even just as a rolling chassis (with a clean title) that would be worth it, assuming no rust and a decent wiring harness.

I'd say to check for oil leaks/water leaks if it starts and runs, and check the strut towers for rust... but with a price THAT low, I'd say to keep an open mind as the car may have been T-boned or nailed in a head-on.

Yes, you could afford to do a six-bolt swap into that. DO THE RESEARCH NOW. Learn everything that needs to be done before you start, and get a good idea of the costs involved. It's not a simple drop-in-and-go procedure. For one, as noted above the 2G uses a CAS and a crank angle sensor... RRE sells a harness so you can just plug in the 1G CAS and run both signals off that. There's sensor differences, mounting alterations, and a WHOLE LOT to do to successfully swap in a six-bolt.
Hell, you could probably drop in a fresh 2G seven-bolt for that leftover cost, assuming the tranny and everything else is good, and the only problem is crankwalk or a toasted motor.

 

[trbn8tr_cal64]

That's incredibly cheap for a 2G turbo DSM. Even just as a rolling chassis (with a clean title) that would be worth it, assuming no rust and a decent wiring harness.

I'd say to check for oil leaks/water leaks if it starts and runs, and check the strut towers for rust... but with a price THAT low, I'd say to keep an open mind as the car may have been T-boned or nailed in a head-on.

Yes, you could afford to do a six-bolt swap into that. DO THE RESEARCH NOW. Learn everything that needs to be done before you start, and get a good idea of the costs involved. It's not a simple drop-in-and-go procedure. For one, as noted above the 2G uses a CAS and a crank angle sensor... RRE sells a harness so you can just plug in the 1G CAS and run both signals off that. There's sensor differences, mounting alterations, and a WHOLE LOT to do to successfully swap in a six-bolt.
Hell, you could probably drop in a fresh 2G seven-bolt for that leftover cost, assuming the tranny and everything else is good, and the only problem is crankwalk or a toasted motor.

I don't want to say im 100% sure, but (my dad knows the guy selling it) and he said he saw the car the other day in a parking lot at work, so (just maybe) it's running. Ill keep this post updated though after I see it saturday.

 

[Ho0ked]

90-92 had the six-bolt, 92.5(after a certain month)-94 had the seven-bolt. 1G seven-bolts do not suffer from the chronic crankwalk problems that seem to follow 2Gs around, and are considered to be almost as good as the six-bolt.
Other differences are that the six-bolt had thicker headbolts, and the '90 had much bigger con-rods, allowing them to theoretically hold more power on the stock part.

All 1G (six and seven bolt) had much larger intake ports on the head, and larger runners on the intake manifold, and a larger throttle body. The exhaust manifolds are more prone to developing cracks, but a 2G manifold can be swapped on with only a little grinding on one corner for the power steering support bracket.

Mechanical differences mostly run to the sensors... 1G used either an optical sensor (90-91) or a hall effect sensor (92-94) for the CAS, which is adjustable to set the timing. 2G use a hall effect CAS which is non-adjustable, as well as a crank angle sensor (which the 1G does not use). The MAS on the 2G will flow more, the turbo (14b) on the 1G is better than the bitty t25 that comes on the 2G.
90-91 AWD DSMs had a three-bolt rear end, 92-94 had a stronger four-bolt. The 'desired' 1G is the 92 6/4, unless you like popups... go for a 91 at that point, as it reduces a LOT of the 90's electrical kludginess.

All that comes to mind at the moment. Oh, if you're going for a DD, you may want to grab a GS-T instead of a GSX.. the FWD gearing is MUCH longer, allowing far greater fuel economy while cruising the freeway. Was a real shock going from 30mpg+ on my old GS-T to ~20mpg on the GSX. :b

This post is good info, nicely done

Think you covered it all pretty well.
I'd like to add that I'd be ecstatic if my 2G got 20mpg , with a 50trim and 650's she sucks serious gas if im on it alot, like I can burn 1/4 tank running around in a 5 mile radious, fairly fast , but sometimes I drive hard

As far as cost, yea unless that car has major body damage/repair, it's a steal, and Don't bother doing a 6bolt swap, it's way more work then its worth, if you need to rebuild or replace the motor stick with the same one and just put bigger rods in it if able, or a full build, eaither way crankwalk is more myth then fact, ive yet to even meet anyone that has seen it 1st hand. and a rebuild ussualy makes it a non issue.

Good luck

 

[TSG59_Steve]

...and Don't bother doing a 6bolt swap, it's way more work then its worth...

Have you done the swap? Can you explain to me what makes it so hard? I don't remember having any problems... Like I've already said, I've had two 7 bolts crap out on me. So tell me it's not worth it. But lets not get too off topic here.

Post up some pictures if you can.

 

[99gst_racer]

TSG59_Steve - Read his reputation, then read his line again. Speaks for itself....

trbn8tr_cal64 - Please spend some time reading through THIS first. Then, when you're done, read through V-FAQ. Bookmark both.