• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Engine Race under hard braking

Share this page

S

SaxMan

Darth Vader
Country flag
Offline
I have an interesting issue on the '69 Sprite, when I go for the brakes hard, the engine RPMs increase significantly, by about 500 rpm by my ear, but I haven't looked at the tach to see what is going on. Usually. I have the clutch let out while slowing down, but one time I did it in gear, and it was definitely scary. I quickly popped the clutch and got the situation back under control.

My guess is that when I am on the brakes hard, it sucks down all the vacuum, causing the engine to go faster to make up for the lost vacuum pressure. I don't know if that means I have to replace the master cylinder, or if I just need to tune the engine better, or if this is just one of those idiosyncratic things.

Thanks for putting up with my million questions. This is a very new experience for me, but I know from my other mechanical experiences that you can get yourself in a lot of trouble very quickly if you "head down the wrong path".
 
Odds are that you wear a shoe of size 11 or bigger and that when you push on the brake peddle you are also hitting the gas peddle. If you remove the gas peddle from the floor and just use the swinging pendant as the gas peddle you will probably fix your problem.
BillM
 
How about this for an off-the-wall diagnosis. Tired motor mounts, on hard braking the motor shifts slightly briefly affecting the carb linkage ! Bob
 
Bob Claffie said:
How about this for an off-the-wall diagnosis. Tired motor mounts, on hard braking the motor shifts slightly briefly affecting the carb linkage ! Bob
Click to expand...

I was thinking the same thing if it isn't what Bill said.
 
Size 8 shoe, and I'm definitely not hitting the gas pedal. I'm thinking that Bob may have the winner, as it doesn't do it consistently. So, the next question is, does the motor need to be pulled to replace the mounts, or can you do one at a time? As far as I can tell, the motor has never been taken out, so I could be dealing with 44 year old motor mounts.
 
You can do it one at a time with a floor jack. 6 bolts hold the entire drivetrain in place. IIRC I just loosened front bolts and jacked up. With more knowledge now might loosen tranny bolts(4) before jacking.
 
Billm said:
Odds are that you wear a shoe of size 11 or bigger and that when you push on the brake peddle you are also hitting the gas peddle. If you remove the gas peddle from the floor and just use the swinging pendant as the gas peddle you will probably fix your problem.
BillM
Click to expand...

So, I fired up the Sprite this morning, this time paying attention to every detail of my braking, and I'll be darned if my size 8 shoe wasn't ending up on the gas pedal. I usually "pivot" my foot on the ball of my ankle to go from gas to brake, which is from years of playing piano and operating the sustain pedal. The clearances between the two pedals isn't sufficient enough for that technique.

Thanks BillM! This brings back yet another lesson: The obvious answer is more often than not the correct one.
 
SaxMan said:
So, I fired up the Sprite this morning, this time paying attention to every detail of my braking, and I'll be darned if my size 8 shoe wasn't ending up on the gas pedal. I usually "pivot" my foot on the ball of my ankle to go from gas to brake, which is from years of playing piano and operating the sustain pedal. The clearances between the two pedals isn't sufficient enough for that technique.

Thanks BillM! This brings back yet another lesson: The obvious answer is more often than not the correct one.
Click to expand...

Playing piano - "NOTE to self" hee hee hee
 
SaxMan said:
So, I fired up the Sprite this morning, this time paying attention to every detail of my braking, and I'll be darned if my size 8 shoe wasn't ending up on the gas pedal
Click to expand...

See, your problem is that your feet are normal size, so you're not used to that. With the snowshoes I've got for feet, it's always an issue. :grin:

A least it's a simple fix. Cut your feet in half and all will be well.
 
drooartz said:
See, your problem is that your feet are normal size, so you're not used to that. With the snowshoes I've got for feet, it's always an issue. :grin:

A least it's a simple fix. Cut your feet in half and all will be well.
Click to expand...

As often as my feet end up in my mouth, I'd probably be able to chew them in half in short order.
 
Glad that it was that simple-
You and LOTS of other folks have the same problem (including me)
Bill
 
Great for heel and toe driving...don't need the heel, just the toe!


Kurt.
 
This morning I took the car out with my wife and paid attention to my feet positions. Part of the issue is that I keep my left foot too far to the right on the clutch pedal, which then caused my right foot not to have enough room to depress the brake pedal without interfering with the gas. Once I slid my left foot over and made room for the right foot on the brake, everything went well, including one panic stop when some @#$@#$# jumped out in front of me.

I propose to call this new dance the Spridget Shuffle.
 
I just bought my Sprite yesterday, and driving it home for the first time I too had clumsy feet making the engine race while braking. Since I now have a Sprite I clicked over to the Spridget forum and saw this post--I knew right away what the problem was!

Here is something you guys already know and I am just learning--these cars are a hoot and a half to drive!

Glad to now be around the Spridget forum as well as the Austin Healey forum.
 
Welcome to the Sprite club!!

Don't take it as offence but you will now find out why we folk's with the little Healey's refer to the bigger Healey's as the " heavy Healey's".:glee:

Kurt
 
Welcome and thank you for making me realize I'm not the only person to do this!
 
I've been using only the pendant for years on my '72. It works great and IMHO is much safer. At Midget 50, David Lieb told me about auto crossers that had accelerators stick in the middle of runs.
Phil
 
nomad said:
Welcome to the Sprite club!!

Don't take it as offence but you will now find out why we folk's with the little Healey's refer to the bigger Healey's as the " heavy Healey's".:glee:

Kurt
Click to expand...

Now I know!
 
Has anyone fabricated a pedal for just the pendant? The pedal I have now has a nasty habit of popping off the pendant and wedging the throttle full open. Seems the repro pedals do not hold up too well.
 
Back
Top