Re: Ford 9 inch components in an MGB axle?
Darn it!!!
I was hoping to do good stuff last weekend. But I had a weepy head gasket which I changed at the track. During the course of stripping to replace the gasket I found I had a broken adjuster stud on one of the Kenne Bell roller tip rockers GGRRRR!!! So I made got some Loctite permanent stud lock and glued the sucker back in place after deep cleaning with carb cleaner. I didnt want to go mad so I set the shift light down at 4800rpm and decided to use that as my rev limit while testing the head gasket repair. When I reached the shift light in top gear I backed off the pedal a little to cut the nitrous just before the finish line. I hot lapped two 9.7 passes and called it a day. I have now removed the broken stud (which had not moved) and I am re tapping the rocker to take a Chevy Pro Comp adjuster which is slightly larger in diameter. So I can run next Sunday while I have some used rockers coming in the post. The axle seems fine as I did my usual burnouts and then let it drift out of the bleaches box while under power until it hooked just before the start line so it would give the axle a shock load. All seems fine so far :) |
Re: Ford 9 inch components in an MGB axle?
Hi Jim
I'm still using the factory V8 3.07:1 diff gears which now have over 110,000 miles on them ;) The car had 110,000 miles on it when I bought it back around 2000. I think i put around 2000 miles per year on it until 2007 when it came off the road for track use only. So it may be closer to 115,000 miles now. :) Perry |
mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Ford 9 inch components in an MGB axle?
Perry, Most over here use 4.10 or lower. Basil on the Mgexperience board has new 3.31 ratio also. You might have quicker times with the 3.91 gears but a lot harder launch. I was the pit crew on my brothers Pro Gas/Bracket Chevy Vega. SBC 400,Power Glide, 4.10 9" Ford rear. Just a gutted shell for the body with Art Morrison Suspension front and 4 bar rear. He was in the high 9s without Nitrous or blower.
Edited 1 time(s). Last edit at 05/08/2014 04:05PM by mgb260. |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Ford 9 inch components in an MGB axle?
Wow Perry, a 3.07 really? That's amazingly quick with that gear. A 3.54 or 3.73 might also be good choices.
Jim |
DiDueColpi Fred Key West coast - Canada (1365 posts) Registered: 05/14/2010 03:06AM Main British Car: I really thought that I'd be an action figure by now! |
Re: Ford 9 inch components in an MGB axle?
Ok, so it all makes sense now.
I think a lot of Perry's longevity is due to his gear choice. His car just runs hard all the time and doesn't tear things up very often. That gear ratio is very easy on everything. He doesn't have to RPM to make the car move. Which keeps his fragile engine together. Launching is softer so the chassis stays together. And the 3.07 ratio means that the pinion gear is larger so it has a much better chance at staying together. He might ET a little better with a higher ratio but the mph will drop and the breakage will increase. Such a light car with a blower and nitrous won't be as sensitive to a gear change as you would think. I would keep that ratio as long as you can Perry, and find the speed in the rest of the car. But most of all, enjoy the heck out of it. That's why we do this isn't it? Cheers Fred |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Ford 9 inch components in an MGB axle?
Good point Fred.
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MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Ford 9 inch components in an MGB axle?
I would think more gear, as well. Hard to argue with a 1.37 60' time, though.
Perry, what is your trap RPM & MPH? |
Re: Ford 9 inch components in an MGB axle?
""But most of all, enjoy the heck out of it. That's why we do this isn't it ""
Thats my intention Fred ;) Regards Perry |
Re: Ford 9 inch components in an MGB axle?
""I would think more gear, as well. Hard to argue with a 1.37 60' time, though.
Perry, what is your trap RPM & MPH?"" Hi Carl She has been running around 5200rpm across the line with 138mph. But recently since I started adding timing she has run 5500rpm with 141mph. But I think I am now driving through the torque converter or the gearbox is slipping as after a few runs with added timing giving me the better mph she is now slowing down to just under 140mph with the same rpm? I cant complain as the gearbox and coverter have been dragged now for 8 years solid. I have a new transbrake gearbox waiting to go in later this year. And I'm going to talk to Coan about a new converter. Some of my friends have pointed me to this company as they have had their converters done by them. Apparently I need to fill in a form to tell them about engine power and max rpm + gear ratios and tyres sizes etc. And they will come back to me with some details on the converter I should be using from now on. The converter I have fitted is a TCI nitrous holeshot unit that locks up around 2800-3000 rpm. But I make peak torque at 4000rpm now. |
Re: Ford 9 inch components in an MGB axle?
""Perry, Most over here use 4.10 or lower. Basil on the Mgexperience board has new 3.31 ratio also. You might have quicker times with the 3.91 gears but a lot harder launch. I was the pit crew on my brothers Pro Gas/Bracket Chevy Vega. SBC 400,Power Glide, 4.10 9" Ford rear. Just a gutted shell for the body with Art Morrison Suspension front and 4 bar rear. He was in the high 9s without Nitrous or blower""
I can see that a 6.5 litre (400 ci) engine which possibly revs to 7000 in a light body would hit the 9's. Mine is a small Rover 3.9 Litre maxxed out to 4.8 litres (293 ci) in a 2600 lb car. which isnt that heavy, but its no lightweight either compared to the tube framed MGB's with composite bodies that race the circuits. The reason for keeping the original factory MGB gear set is the same reason I still run a Rover V8. I need to be able to make the numbers with a Rover V8 engine as that is what my car came from the factory with. I have fitted better drive shafts but I have retained the original factory diff gear set and ratio. And changing the gear set = money I dont have.. ;) Perry |
Re: Ford 9 inch components in an MGB axle?
Thanks for the support Jim!
I am very happy with what the car has done so far with the Rover V8. Sadly, a lot of folk over here who run bigger cube American engines in their UK cars are not so happy for me when I beat them on the 1/4 mile? There does seem to be a trend over here where folk fit big ci engines in their UK cars, but then run them with a mild tune so they run reasonably quick without wanting to stress the motors. But they are not very quick on the 1/4 mile? I spoke to one guy who runs a small block chevy in his UK classic and he said it was tricked out to the max. But it only runs high 11's. When I asked him about using nitrous he said that he could not do that because SBC's are notoriously weak and would split in two if he used nitrous?? Who the hell told him that?? |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Ford 9 inch components in an MGB axle?
I forgot you were using an automatic. Is it the BW-35 or something else? That changes your choice of axle ratio of course and the 3.07 sounds a lot more reasonable with the small diameter tires you can fit under the MGB.
Jim |
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MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Ford 9 inch components in an MGB axle?
If you are now crossing the line at 5500, sounds like you have the gearing & tires figured out.
Hang on & have fun! |
Re: Ford 9 inch components in an MGB axle?
Hi Carl !
I'm crossing the line at 5500 but the mph is dropping off. I'm now talking to Craig a Coan about a new converter. My B&M converter is only rated for 350hp. And I think its slipping now. I need to make sure that the converter and gearbox are working ok to make sure I can have a stab at an 8 second run this year. Perry |
Re: Ford 9 inch components in an MGB axle?
Thanks Kelly!
That made me laugh :) It could be a name for the car?? I've been thinking about giving the old girl an identity. I'm very happy with the axle modification so far. I took it out last Sunday to run on an old airfield. I ran a 10.6 and then a 10.4 which is very good for a concrete surface. The 10.4 came from me launching at half pedal and then going flat out after a couple of seconds. So I had an idea to programme in a nitrous delay of 1 second and then launch flat out on boost only. I have to say that this was not one of my better ideas on track :) The tyres let go on the launch and then the nitrous dropped in and the tyres got to skipping and gripping and bouncing me all over inside the cabin. I leaned forward in the car as my helmet was banging on the roof and kept my foot in as long as I could. But I had to shut off a good way before the finish as the car was quite unstable. She still pulled a flat 11 with no power for the last 100 feet or so which was fantastic :) So I put her on the trailer and did something that I dont normally get to do at the track. I watched some racing for a couple of hours and also got dragged off to help some guys with BBC and SBC motors in their classic Fords who were having ignition timing troubles. Sadly one of the guys who had fitted the SBC into his old Ford Pop clearly had a bob weight spring broken. This news really upset him as he has to remove the engine and tranny to remove his distributor ??? Anyway! Here is a vid of how not to do it on concrete :) Regards Perry [www.youtube.com] |