12a vibration

striegels6 · 02-16-2010, 06:59 PM

I have recently picked up a 12a powewred B2200. It has a serious vibration issue when the engine is being reved.
1. Could someone have used the wrong flywheel. How long would a 12a last with the wrong flywheel used?
2. Could compression differences cause vibration?
3. How about engine + transmission angle?
It also has a Holley 600 rigged up on it.
Could fuel discrepencies on #1 and #2 cause this?
Any help would be greatly appreciated.

rx4ur7 · 02-17-2010, 01:38 AM

Could be a wrong flywheel. Do not know how long it would last never ran one like that. The only one I came across was pretty subtle.
Flywheel loose, yes
Compression yes.
Ignition/related yes.
Fuel delivery possible

12arotary · 02-17-2010, 02:25 PM

I had a huge vibration issue with my 82 when my pressure plate decided to loose two of it's teeth and threw it off balance, does it drive fine?

striegels6 · 02-17-2010, 07:19 PM

It's a mess. I am trying to weigh my options at this point. If i could find a good used intake and carb I might try to keep the 12a in it. A 13bT sounds like a better option.

t_g_farrell · 02-18-2010, 10:02 AM

I run the lightest flywheel for a 12a in my 80 SA stockport. Its an 82 I think only weighs 23# versus 30# for the stock. I get some very minor vibrations from it but nothing too bothersome. Its been on there the last 4 or 5 years no problems.

I also talked to some folks that race 12as and this is a pretty common mod to do and still stay legal for the flywheel in some classes.

Madaz · 02-19-2010, 12:56 AM

If the vibration IS present when the vehicle is static and clutch is engaged then remove the gearbox and check your flywheel,counterweight and pressure plate. If nothing obvious doublecheck the counterweight is indeed a 12A counterweight.

Kentetsu · 02-19-2010, 12:20 PM

When I installed my current motor (82), we mistakenly used the flywheel from the 85. Right away at startup we had vibration and knew something was wrong. It wasn't very severe, but more than enough to know that something was funky. Replaced the flywheel with the one that came with the 82 and all was fine.

.

striegels6 · 02-21-2010, 03:15 PM

I fixed the problem. I have had a new streetported 12a sitting in my garage for 2 years. It also has a Racing beat aluminum flywheel and new Mikuni on it. So the 12a (with Holley 600)that came out is for sale, $250. I also have a 6 port 12a for sale with intake. Previous owner said it made excellent Hp. I may post all of my rx7 extras in the classified section at a later date. Items are in Iowa and I will ship.

Jeff20B · 02-26-2010, 05:02 PM

6 port 12As are pretty cool. I'm building one for a friend. Good luck with your sales.

02-17-2010, 02:25 PM	#3
12arotary tumor-syphilis-itis-osis Join Date: Sep 2008 Posts: 191 Rep Power: 17	I had a huge vibration issue with my 82 when my pressure plate decided to loose two of it's teeth and threw it off balance, does it drive fine? __________________ 82 300d 82 Gsl 84 b2200 Diesel 88 gxl

02-18-2010, 10:02 AM	#5
t_g_farrell Waffles - hmmm good Join Date: Aug 2008 Location: Huntersville, NC Posts: 757 Rep Power: 0	I run the lightest flywheel for a 12a in my 80 SA stockport. Its an 82 I think only weighs 23# versus 30# for the stock. I get some very minor vibrations from it but nothing too bothersome. Its been on there the last 4 or 5 years no problems. I also talked to some folks that race 12as and this is a pretty common mod to do and still stay legal for the flywheel in some classes. __________________ 1980 GS stockport, Fat Nikki, RB Dual Facetfuel pumps, Holley regulator, RB Street port exhaust, 2GDFIS, MR2 MK I electric fans, 2G strut bar, relayed fans, lights and fuel pump, LEDs Project Fat Nikki Budget 12A rebuild Video setup < $30.00

02-19-2010, 12:20 PM	#7
Kentetsu RCC Contributor Join Date: Feb 2008 Location: Grand Rapids, Michigan Posts: 530 Rep Power: 18	When I installed my current motor (82), we mistakenly used the flywheel from the 85. Right away at startup we had vibration and knew something was wrong. It wasn't very severe, but more than enough to know that something was funky. Replaced the flywheel with the one that came with the 82 and all was fine. . __________________ "Learn from the past, or it will become your future...." '85 GS 12a + LSD/Sterling carb/Respeed coilovers/Respeed front swaybar/Respeed adj. rear spring perches/Illuminas/Bilsteins on rear AutoX vids @ http://www.youtube.com/user/Kentetsu1

02-16-2010, 06:59 PM	#1
striegels6 The Newbie Join Date: Feb 2010 Location: Iowa Posts: 6 Rep Power: 0	12a vibration I have recently picked up a 12a powewred B2200. It has a serious vibration issue when the engine is being reved. 1. Could someone have used the wrong flywheel. How long would a 12a last with the wrong flywheel used? 2. Could compression differences cause vibration? 3. How about engine + transmission angle? It also has a Holley 600 rigged up on it. Could fuel discrepencies on #1 and #2 cause this? Any help would be greatly appreciated.

02-17-2010, 01:38 AM	#2
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	Could be a wrong flywheel. Do not know how long it would last never ran one like that. The only one I came across was pretty subtle. Flywheel loose, yes Compression yes. Ignition/related yes. Fuel delivery possible

02-17-2010, 07:19 PM	#4
striegels6 The Newbie Join Date: Feb 2010 Location: Iowa Posts: 6 Rep Power: 0	It's a mess. I am trying to weigh my options at this point. If i could find a good used intake and carb I might try to keep the 12a in it. A 13bT sounds like a better option.

02-19-2010, 12:56 AM	#6
Madaz Rotary Fan in Training Join Date: Jan 2009 Location: Burleigh Heads QLD Australia Posts: 56 Rep Power: 17	If the vibration IS present when the vehicle is static and clutch is engaged then remove the gearbox and check your flywheel,counterweight and pressure plate. If nothing obvious doublecheck the counterweight is indeed a 12A counterweight.

02-21-2010, 03:15 PM	#8
striegels6 The Newbie Join Date: Feb 2010 Location: Iowa Posts: 6 Rep Power: 0	I fixed the problem. I have had a new streetported 12a sitting in my garage for 2 years. It also has a Racing beat aluminum flywheel and new Mikuni on it. So the 12a (with Holley 600)that came out is for sale, $250. I also have a 6 port 12a for sale with intake. Previous owner said it made excellent Hp. I may post all of my rx7 extras in the classified section at a later date. Items are in Iowa and I will ship.

02-26-2010, 05:02 PM	#9
Jeff20B Rotary Fanatic Join Date: Mar 2008 Posts: 215 Rep Power: 18	6 port 12As are pretty cool. I'm building one for a friend. Good luck with your sales.