Cornering technique with a welded rear

D

dcharnet

Member
I noted a fast Morgan Plus Four while racing at the VSCDA Fall Vintage Festival at Road America. Coincidentally, there was an article about the car and its driver in the January edition of Classic Motorsports.

In it the driver, a retired college professor from Minneapolis, says, "The rear end is welded, so one must be on the throttle at turn-in. Steer the front with the wheel and the rear with the throttle."

This would preclude trail braking.

I found the comment from this fast vintage driver (2.45 at Road America) puzzling and contrary to how I am trying to race my welded-rear vintage MGB as I gain more experience with it.

Do you ignore modern cornering theory with "antiquated technology" like a welded rear? Is throttle-on at the point of turn-in the Big Secret about racing with one? Are there any types of corners where you would not be on the throttle at turn-in with a welded rear?

Any comments from you production racers would be appreciated.

(I use the words "antiquated technology" with irony. It may be old technology, but I think it is the best choice at least for the vintage race MG).

Don Charnetski
 
I have been racing with a welded rear for the forty years that I have been doing this. I started with a limited slip rear that ratcheted especially while it was getting up to temperature and I didn't like that sensation so I sold it and have run welded ever since. Because of that I don't have much to compare to other than racing against other cars with Quaifs and Tranex's. If someone with a limited slip rear schooled me on a corner I would put one in, but I have never felt a need to do it. I suspect that the handling characteristics that your Morgan driver is relaying to you has much more to do with the Morgan and how it is set up than it does to the welded rear.

There is supposedly a slight tendency to push caused by the rear, but I can tell you that I don't see that and I can make the car as tight or as loose as I want by spring and bar settings. Of course you want to get on the gas as soon as you can after braking if you are leading on to a straight. That is the fast way around a track. That is why if there is a high speed sweeper that can make a big difference in lap times I set the car up to be neutral to a slight push so that you can get back on the gas as soon as possible. I find that a loose setup forces a late apex and delays putting the power down. If a welded rear causes a little push, that would be a good thing for high speed corners. Giving up a little bit of rotation on a slow corner is an easy choice, and there is no reason why you can't trail brake into a tight corner after a long straight.

In short - don't worry about it. Continue doing what you are doing.
 
+1 on Ron's comments. I suspect that a vintage race Morgan would still have wood in the body-thus little help in stiffening the chassis. Also doubtfull the rollcage is integrated into the frame and suspension mounting points enough to help much. In other words, the car flexes as part of the spring rate like most antique pre-unibody cars. I don't know how people drove those cars in the day, especially on actual road courses. I am not suprised they would gather in the bar afterwards.

I will say that the slight push on turn in that Ron references and the tendancy to go in a little hot and scrub off a little speed through the push/slip angle is far easier to deal with using bias ply slicks than radials.
 
I can not speak to Morgans and such, but many years ago I ran a DSR with a solid spool rear end. What the car liked best was to do your braking in a straight line, no trail braking. Pick up the power as you start to turn in, have your foot all the way down by the time you get to the apex.

Worked for me, your mileage may vary.
 
Dave Headley of Fab-Tek engineered and installed the suspension on my MGB. Here is his response to my question:

"Car design and set up dictate how that car needs to be driven. I've always set my cars up with roll understeer, especially in the rear. This allows a very aggressive use of throttle from the apex out of the corner without the rear end stepping out. Increasing corner exit speed give the biggest improvements in lap times. Kind of point and squirt. This roll understeer almost always required one to trail brake into the corner for good turn-in response. Under braking the rear suspension lifts a bit reducing the roll understeer helping the car turn with a locked rear. If I knew that I was going to be racing on a wet track I'd use a limited slip.

I've done comparisons of locked Vs. Detroit locker Vs. true limited slip diffs. Same car, same track, same day, same tires. The conclusion was locked was fastest, LSD was easiest to drive. Leave the Detroit lockers to NASCAR."
 
Dave Hadley summed it up well.

My experience is it depends on what you started with. That introduction usually ends up being what you are most comfortable with. The first experience l had with a locked/spool rear was testing a GT1 car at Daytona. I had problems adjusting to it on the first lap thru the infield.

Still on the first lap and at speed thru NASCAR 3 & 4, had to suddenly lift the throttle.
Have had great difficulty ever since trying to close my eyes.
 
You must log in or register to reply here.
Back
Top