• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Gear ratio and tracks to run on?

Share this page

VelodromeRacer

VelodromeRacer

Jedi Trainee
Offline
While we are discussing the fuel MPG, I wondered what gears are better for the different tracks? For that matter, what gears a 948 Bugeye should run most of the time.....

My Bugeye currently has the 4:22 installed and VSCDA runs at Blackhawk, Grattan, Gingerman, Road America and Mid Ohio..I have a 4:55 sitting in a box. I don't have the skills to change out gears all the time and wondered what would be the best scenario?
 
Blackhawk 4.55
Grattan & Gingerman 4.22
Mid O & Elkhart 4.22 if it's all you have, but a 3.90 would work better at Mid O, and a 3.7 for Elkhart. With a 4.22 at Elkhart, you're going to be wound tight over a good portion of the 4 miles.
If you can make it over to play with us at Waterford, the 4.55. I run a 4.88 here.
No major skills involved in a gear change on a Sprite. You just change the entire center section. About a 45 minute job.
Jeff
 
Bugeye58,

Is there a good link to how to do it? I thought it involved some pretty technical settings, shims and axel removals?
 
Ah..you just have the gears, not the entire assembly. That's a different story entirely.
The manuals show a pretty good procedure, but there are some special tools required to do it properly.
I just have the entire differentials, and swap them out as needed.
Axle removal is a piece of cake. You just remove the wheel and brake drum, pull the retaining screw from the flange and slide the axle out.
I think I'd check around and try to find entire pumpkins in the appropriate ratios, or consider outsourcing the setup, perhaps to Hap Waldrop.
If you're going to be running different tracks requiring different ratios, it's the only way to go, rather than trying to swap gears back and forth in the same carrier.
Jeff
 
VeloDrome,

We were running the 4.2 at RA in our 948 Sprite. We ran 4.5 at Blackhawk. We never tried a 3.9 at RA, but I think it would be a better choice than the 4.2.

If you need full pumpkins give me a shout. I may one or two.
 
The car also came with a Quaife ATB Differential...?
Should that be used...?
 
VelodromeRacer said:
The car also came with a Quaife ATB Differential...?
Should that be used...?
Click to expand...
I sure as heck would be using it!! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
I've got a Trannex in mine.
Have you priced a Quaife lately? Sit down when you do.
Jeff
 
I figured for the price that I saw...that it should do more than sit in a box! The car I bought came with the 4:22 unit installed and a 4:55 gearset and a box with the Quaife unit in it. Do I buy another pumpkin to put the Quaife unit in? When you are talking about ease of installation, are you talking about installing the pumpkin unit into the existing housing? Is there a good reference for the install instructions?
I just don't want to screw this up, and knowing that I will be running different tracks, I feel I need to work on this over the winter.
At Putnam Park, I down the long front straight, I was hitting 7,000rpm and running out of gear/speed...
 
As for swapping pumpkins, it's only a matter of sliding the axle shafts out of the way, disconnecting the driveshaft, undoing the mount bolts and brake union bolt, and pulling it out. Installation is reverse of removal.
At only 7000 rpm you should have at least another 1500 to go, if the engine has been built correctly.
You may want to contact Hap for further advice regarding setting up the Quaiffe.
Jeff
 
Bugeye58 said:
I've got a Trannex in mine.
Click to expand...
PITA having to add 'slip juice'...

How do you like it?
A bit smoother than the Quaife....
Especially noticeable from apex to track-out (power on)
(But you 'lincoln-locker' road race guys, probably wouldn't notice unless yer coming out of a hairpin)

Noisy though when cold & sometimes at turn-in, the back end doesn't settle right away.
 
Dave, I like the Trannex. Definitely smoother than the Quaife, and seems more forgiving if the power application is a bit abrupt.
I dread having to ever being forced to run a welded diff. again. Not that it's going to happen, but if something breaks and the only spare I've got is a welded one..........
Jeff
 
In the Elva I run a 4.5 at Pittsburgh and Shenandoah, a 3.9 at Sebring and a 4.2 everywhere else. Changing the diff takes me about one hour when I am motivated.
 
I may have to try and look for a 3.9 then I will have a whole collection!
Taylor-racing has a rebuilt ribcase with straight gears and a changable drop in 4th gear...anyone have something similar?
 
VelodromeRacer said:
Taylor-racing has a rebuilt ribcase with straight gears and a changable drop in 4th gear...anyone have something similar?
Click to expand...

You have a Taylor dog box???? That's like a $5500 gear box, I have one, it's the best money will buy, this gear box depending on your gear selection will let you use first gear on the race track, does this gearbox have a hydraulic throw out bearing????
 
No not a Rocket Box, that is the 4 speed version of the Quaife, often times used in MGBs, but other applications as well. Craig Taylor used to rebuild alot of the Richmond RIC Spridget gearboxes, then went on tho make his own version of it, it's basically a Spidget case, modified to accept Webster/Hewland gears, pretty much umlimited gear ratio selections, they are pretty popular with the Spridget racers, go to https://www.taylor-race.com then select catalog, then select transmission, then select Sprite, then then click on the blue part description, and a pop up windw will appear and tell you all about the gearbox.

My Taylor dog box has 1.60 1st, 1.36 2nd, 1.15 third, and 1 to 1 forth. I only drop about 300 rpm between shifts, You can set them up to run a zillion different ratios, and it has a 4th drop gear so you can change just that and that will end up changing the remaining ratios as well. They have all new main shafts, and layshafts made form the best metals, billet steel adjustable shift forks, custom front cover, and either SABB 900 or Tilton hydraulic throw out bearings, thay are top notch gearboxes.
 
Well in the sense of the Formula Fords using the same gears, yes, but they were never used production transmissions, in fact the gear box casing used in formula Fords came from the VW Beatles. Alot of different production gearboxes in race prep have ended up using Webster/Hewland gears because there are so many choices for ratios, I seen Spitfire, Alfa, etc. box upftted for use of these gears, Spridet boxes being one of the most popular. Now here's a newsflash, I'm pretty tight with the guys at Taylor Race Engineering, would you believe more of their Sprite racing gearboxes have been sold to vintage customers than SCCA customers.
 
Hap,

Do the vintage guys frown on the Taylor box...or do they allow it as the original smoothcase boxes are gone and the ribcase units fail in racing too easily?
 
I know the VSCCA guys would have a kitten...

They'd probably make the offender eat Velveeta & drink wine out of a box.
 
Back
Top