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MG TD TF 1500 - tired of double clutching

I have an early 50 TD, if I try to shift above 3000 rpm I need to double clutch, to avoid clashing. Also the rearend is geared so low I am running 4300rpm at 60 mph. I can see two ways of solving this 1. rebild the transmission and put new gears in the rear end. 2. convert to a 5 speed transmission. What are the pos and cons of these?
Steve Bryan

Steve, a lot of us in the Minnesota Register have had the 4:55 rear end put in and it works great. John Twist can do them if you wish and I would suggest that. It is not as expensive as a new tranny and the car does not have to be cut up and is original as far as anyone knows. I have had mine in since rebuilding the car in 98 and have had no problems with speed since.
Tom

Steve, how do you shift? The synchro design is such (primative) that you always have to pause in neutral (I tell my passenger kids who shift left handed- "click-click"), or it will grind no matter what. A two step shift shouldn't grind much at all- if it does something is worn, etc. A draggy clutch will also cause problems. To downshift you almost have to double-clutch/rev match on the several T-series cars I have driven. My rear end gear change made a huge difference in crusing- definitely recommend that. My personal opinion only: if you are going to go with a modern tranny, do away with the bothersome leaky, fussy motor as well- go with something fuel injected- no more oil or SU gas leaks, etc. Parts for some of these obsolete 5 speeds are hard to get, so if you do go for a swap try not to alter anything so you could go back to the original.
George Butz

Your right... old MGs have that little "pause" between gears... Mine will grind shifting up if I don't do a "slow" shift.
I try not to do much down shifting... rather replace shoes ( I think) then transmission. Anyway, I only use 2nd/3rd and 4th... have only used 1st a few times... certainly don't need it with the stock gears.
gordon lawson

Shifting up doesn't require double clutching (or double declutching, as the Brits put it), just a pause in neutral as George suggests, shifting down is the same but can be done faster if one double clutches. All of my up shifts are at 4000rpm and the only gear that I have a real problem with is 1st to 2nd, and on that, I just pause a little longer. Of course, I am somewhat spoiled in that we had a 36 MG PB that didn't have any syncros in any gear. One of the things that I found out, was that I could shift as easily without using the clutch at all as when I did use it. I got to the point that the only time I bothered with the clutch was when stopping or starting out. In regards to down shifting, that shift should be done after having slowed to a speed that requires a lower gear and NOT to help slow the car down. Down shifting should not be used to slow any car down as it is hard on the engine, but on the T series, MGAs and early MGBs that have a split little end on the con rods, it can actually destroy an engine. When releasing the throttle, the cylinders develop a tremendous amount of vacuum as the engine slows down. If the car is shifted into a lower gear and uses the engine to slow it down by acting against this vacuum, the strain on the little end of the can rods can become high enough to literally pull the gudgeon pin pinch bolt apart. When that happens, one winds up with the loose top end of a rod doing all sorts of nasty things to the inside of the engine. I am with Gordon, brake shoes are cheap compared to new engine blocks.

My feeling about the transmission on our cars is that if I am going to drive a 50+ year old car, I need to learn to drive the way it was intended. I feel the same way about the rear axle ratio, I just grit my teeth and live with 4200 rpm for 60 mph. It doesn't hurt the engine, just the driver's nerves and then only for those of us who are used to the big, slow revving American cars. Going by the magic figure of 2500 feet per minute of piston travel being the point below which wear is kept to a normal level, 4350 is roughly the speed that the XPAG/XPEG engines can be revved and not suffer any excessive wear or damage. Change the transmission and/or the rear axle if you so desire, it is after all your car to do with as you desire, but to me a big part of the enjoyment of the car is learning how to drive it with all of it's idiocencries and listening to the engine wind up and down through the gears. By the way, MGs are all my wife and I drive. We have the TD and a MGB that are driven interchangably throughout the week - those are our only cars. Cheers - Dave
David DuBois

Another thing to do on downshifts is to heel/toe, something that was done pretty regularly in these cars at the time. After attending a racing school, I now heel/toe in my '68 midget all the time and it makes downshifts much smoother (and I don't use the engine for braking).

I fully agree regarding braking: Brakes are much cheaper than engine rebuilds; use the brakes to slow the car down, not the engine.

Scott
Scott Linn

There are a few long down hill runs around here, not many, but some. I've been using engine braking on those because I'm worried about the brakes fading to nothing at the bottom of the hill, where there's usually a tight curve. Just set in 3rd gear and back off the gas and chug down the hill at about 3500-4000 RPM.

Now I'm worried that I'm damaging the engine. What should I do in this case?

Mark B.

Carry an anchor? I'd use engine braking in that circumstance.
Tom

I agree with David about slowing down by downshifting. I don't think using a lower gear going down hill is the same. It would put a little strain on the motor, but nothing like zinging the revs up when downshifting. It would beat cooking the brakes and crashing any day! Maybe I have been lucky, but I always have driven the heck out of my TD with no problems.
George Butz

Syncro's seem to work better when oil level is at high mark, rather than normal mark.
Len Fanelli

To go along with Len's mention of oil I change my gear box over to straight synthetic three years ago. Immediately there was a marked improvement and as the years roll by the shifting has become better and better. Smoother transition from gear to gear, less gear noise, and it seems less heat radiating from the tunnel. Maybe just my immagination. I started out to change to Red Line but being in a hurry wanted to purchase on a Saturday morning. I could only find Amsoil which is serving well to date.

Jim Haskins

1953 MG TD
J. M. Haskins

I recently rebuilt my gearbox. Just changed the cluster and first gear plus fitted new bearings. When the Oil etc is cold I cannot change gear without a small crunch no matter how slow I do it. I have tried the pause in neutral.
When it has warmed up the problem disappears. Is the oil I am using too viscous. When warmed up does the viscosity drop and allow the gears to spin up to the same speed.

Alan Clapham
A J Clapham

Dave DeBois and I are cut from the same cloth.

Rebuild the tranny (mine does not need such treatment but then don't ask me about my popping out of first gear). A rear axle gear swap may do you a bit of good and really does not change the originality of the car as these gears were available at the time.

Keep in mind that the TD/TF were made for rallying and slower winding roads, not US 2005 Freeways.

Chris
Chris Couper

This thread was discussed between 14/06/2005 and 24/06/2005

MG TD TF 1500 index

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