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MG MGB Technical - Installing A New Rivergate 5 Speed

I am about to re-install my MGB's engine. I have just purchased a new RiverGate 5 Speed conversion. I chose to purchase the Deluxe Kit and their Rebuilt Nissan 5 Speed Gearbox. It all looks straight forward enough. Anyone out there ever done this conversion? Any ideas? Anything I need to watchout for? It can't be as simple as it looks.

Any help?

Thanks in advance,
Danny
Danny T.

Good choice. The Datsun is a good tranny. Used one in a 240 I had. Good luck.
Mike MaGee

Make certain the input shaft hole is cetntered in the pilot bush (it wasn't on mine). Do a trial fitup without clitch installed to assure it assembles easily- if notm find out why- mis-located dowel pins, holes out of location- this stuff will cause the car to jump out of gear and prematurely wear the input shaft bearing and layshaft bearings. Assemble sans clutch to see if there are any tight fit conditions

Once you add a clutch it will be a little more difficult to install the transmission, so you may not see any misalignments
Greg Fast

Danny:

I installed a Rivergate 5 speed in my midget. No problems. Just read the instructions and follow closely. Been using my Midget for about two years as a daily driver and no problems - just great driving!

John
John Hewell

I'd be interested in hearing what the difference in rpms in each gear is compared to an overdrive gearbox.
Greg Bowman

John

I'm with Greg "be interested in hearing what the difference in rpms in each gear is compared to an overdrive gearbox."

Ray
Ray Gordon

Danny, I have been doing the 5sp. datsun conv. for 4-5 years & in the early days we were useing the novis kit & the backing plate was off, were the input shaft bearing & pilot bush would wear out in a short time. WE SAW THE LIGHT when we got the rivergate backing plate!!!!! (I through away the old junk backing plate)What I like about this conv. is you can pull the 5sp. & have a clutch job in 3 hrs! It goes in & out so easy! 35 lbs LIGHTER than the B 4 spd! The R.P.M. change in the gears is JUST RIGHT!!! in th Z trans, in the B trans. there is a BIG jump from 2nd. to 3rd.& in the Z trans. you don't get the big r.p.m. drop. & in 5th you will get 500 to 750 r.p.m. drop. I have 3 B.G.T.s, that I am keeping with the 4 cyl. & thay will ALL have the Z 5sp with the rivergate backing plate.
Glenn Towery

Hey Glenn,
Aside from teh backing plate is there any other major custom work needed to fit the tranny, ie drive shaft, cross member, tranny tunnel cutout?
Bill Mertz

There is other things that are needed & to do. In my kit I have a backing plate gasket,backing plate, pilot bush, lighten flywheel, clutch pressure plate & 8.5" disc, through bearing, rebuilt 5sp., mod. gear shift lever, rebuilt slave cyl, mod. crossmemder, datsun drive shaft made to fit, 90 degree speedo drive to cal. speedo, new speedo cable, clutch line up shaft.
Glenn Towery

There are no modifications needed to the tunnel, crossmember, or frame. Only change that is not simply bolt on is the need to drill 2 holes in the transmission crossmember for the transmission mount. You do have to remove the old "stands" for the old transmission mounts too. This kit is fully reverseable if wanted.
Danny Thomason

Is there a performance clutch upgrade available for this kit? How about a roller-type throwout bearing? I'm loking for a more positive engagement than with the stock Borg&Beck setup.
Jeff Schlemmer

The Rivergate kit DOES come with the Datsun / Nissan 280Z Clutch disc and modern Roller Throwout bearing as stnadard equipment. Uses the original MGB Clutch cover / Preasure plate though. Also comes with a new pre-assembled drive shaft too.

I will keep everyone updated on how this all goes.

Thanks for all the input,
Danny
Danny T.

MG Enthusiast magazine this month had an article on the Rivergate diff unit they sell to offer a LSD type performance. Are you going to try this as well, Danny? Has anyone else already done it?

TIA
Martin
Martin ZT

Hi Martin,

No, I will not be doing the LSD. I am actually not trying to make a high performance "B", but rather a "Driver Friendly" MG. From what I've been told, this conversion makes the "B" as road compatable as any modern car. It gives you the ability to cruise at 65, 70, 75, or even 80mph with no major strain on the engine. I drove around 300 miles to a car show a couple of months ago, and most of that was on the interstate. I ran around 70mph just trying to keep from getting run over. By the time I arrived, I was afraid I might have damaged the engine by such a long sustained high RPM run. That was when I started seriously looking into the conversion.

Basically, you should have the same benefits of the overdrive, with slightly high gearing, along with a rock solid, almost in-destructable, transmission.

I'll keep everyone posted
Danny T

Danny: Where did you find the transmission, and what did you pay for it?
Andrew Blackley

Overdrive is nice, whether its a 5th gear or electric, but I always wonder why people think the 'B engine can't handle running at highway speeds. Redline is at 6,000 rpm, 70mph is about 3,800 rpm. I've run my car at 4,000-4,500 for several hours at a time and the engine sounds very happy to be there. As have my other MGs in the past 15-20 years. I don't want to sound like a jackass, but if there is no reason to make the change except for the sake of the engine I wonder if you're working on the wrong thing. If the driver likes cruising at lower rpms, that's a different story, but the engine itself can handle it.
Wade K

Hi Andrew,

I purchased my transmission directly from Rivergate. It is a fully rebuilt unit, with a 12 month complete warramty. It cost an additional $695.00.

Hi Wade,

My "B" will NOT run at 70mph @ 3800 rpm. It is closer to 4200 to 4500 rpm's. I realize that the car was designed to red line at 6000rpms, but that was a long time ago on a new engine. Anytime I can cut my rpm's almost in half, I feel it HAS to be good for the car. Also, 70 mph doesn't cut it on most of the interstates today. You will have occasions when you will need to pull it up a little faster. (Our state highway speedlimit is 70, and NOBODY runs at that. Most people cruise around 75 to 79. I want to at least run with the traffic. I have been driving MGB's since I was 16 years old and bought ny first 1967 b. I fell in love, and have had at least one in the garage ever since. (currently have 3). Since a full rebuild on my "B" transmission will run around $800.00, or to buy a rebuilt one from Moss, Victoria British etc, runs $1200.00, I felt that an upgrade to a nice, quite, strong 5 speed for $1500.00 was a deal. Same labor involved.

I'll know more soon. I need to stop typing and strat turning bolts!! haHa :)

DT
Danny T

Danny: Assuming standard diameter tires you should be turning around 3800-3900 rpm at a true 70 mph. Overdrive will drop the engine speed to around 3100-3200 rpm. Sounds like you have an error in your speedometer or tach, maybe both. FWIW, Clifton
Clifton Gordon

Clifton,

I think you may be right on.

I read some where, in the owners manual I think, that in overdrive, the speed should equate to 22mph per 1000 rpm.

Therefore 3200 rpm x 22 = 70.40 mph.

Regards


Graham
GRAHAM HOYLE

Danny,
I hope you just have an out of wack tach and/or speedo and nothing more serious.

Good luck, Wade
Wade K

This thread was discussed between 26/11/2003 and 06/12/2003

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