Projects Northwest Vintage Dragster Group Build.

Let me read up real quick. To add to this we did have a sea saw wheel hop on an sdra car tho.

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to low tire pressure will give you wheel hop and poor stability at the top end. it is my belief that the wheel width should match the tread width. you can run more tire pressure with the same or close to the same footprint and have more stability at speed

 

Lots of good info here, we will keep an eye on things when we get it back together. The new trans is supposed to be ready today, and the rearend parts should be here anytime now too. I'm looking forward to getting this thing back together.

 

Thinking back to the days(1955-1960) wheel hop as we called it was a major problem for the lighter cars (1200-2500 lbs) with a locked rear end . What is different today, tires and pressure, auto trans and a couple other things. I have saw both sprung and unsprung cars do it, with the unsprung being the worse On our unsprung car we eleminated this by narrowing the rearend 18 inches overall. (1960) On the unsprung cars you may not have problems due to running a glide and by the way I never saw a car run a auto trans. before 1960 and they were rare for till about 1964 and things were changing and in the end we were all running one by the early 1970s.

 

So do we think that it is the long axles winding up that caused the oscillation and that is why shorter axles solved the issue?

 

Cannot anwser that question but my thoughts were , but with a narrow wheel tread width you do not have the leverage to lift a wheel and start this situation. We were the 2nd car in our local to do a narrow rear and by 61 all of our group (dragsters and altered,s) had them.

 

It's in the Vintage Dragster Rules, no narrowed rear ends. Probably for this very reason.
Warren

 

My take is that the axle housing tubes are bending and acting like springs as the car bounces up and down side-to-side, rather than winding up the axles themselves. If the axles were twisting and releasing, I think you'd expect the car to want to "sashay" rather than bounce up and down.

If the problem actually is the axles twisting and releasing, an easy solution would be to go to beefier aftermarket axles. If it's the housing tubes bending, they could be braced. Or, as I stated earlier, one of our cars solved the problem with a tire and air pressure change.

Leonard - do you have 28 or 31 spline axles? Curious to see if you experience this issue as most of us have not.

 

They are the 28 spline axles, i fought off the urge to buy 31 spline axles too, after all we are still at the maybe 225 hp level, should be fine.

 

The 31s will slow you down.

 

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Roo

 

I was thinking the heavier axles will take more to get the car moving.

 

Most of the SDRA cars are using 8" Ford rear ends with 28 spline stock axles and a 52" min track. We are all auto trans. The biggest problem with the tire shake or bounce has been a result of chassis twist. A slow motion video of a car that had that showed a lot of the twist. Solved it with a couple of tubes to stiffen the cage.
You can also help this by mounting the motor at the front , not the sides. This makes the stiff section longer taking away some of that motion. Once it starts the chassis becomes a spring. Winding and unwinding.

 

The extra amount of rotational inertia is so small that I can't see it making any difference.

Roo

 

Thank you for a real-world explanation. Looking at the chassis of the car I mentioned earlier, I can see how it may be less torsionally stiff than the rest of our cars. That could explain why his was the only one to exhibit the side-to-side bouncing.

 

Yes

 

The 52 in track can be achieved using a stock width housing and different back spaced wheels. That number was chosen when we were ask "how narrow can I make my rear axle". The one they ask about measured 52 in.

 

The guys came in tuesday afternoon, and replaced the truck pan with a car pan after one of us ripped a hole in it coming off the trailer(I wont say who because it was me), and we started putting the car back together making small things better as we went. We were doing so well and someone forgot to bring dinner(I wont say who because it was me) so a trip to the local steak house was in order.

 

We loaded up friday night and headed to the 1/8 mile in Walla Walla




The tranny is shifting...sort of, if you leave it in drive and let up when you want to shift it will, but manually shifting it won't....? Think I will have to give up on the good buddy back yard rebuild. Thinking a TCI valve body is in the future.

Anyhow traction is a big issue, you have to pussy foot it off the line or it spins baddly, the cheater slicks arent very square on the tread, if you look at the marks it leaves there are two dark patches on the edges and a faint mark in the center. We have been talking about chaining it to the pickup and burn them flat, any thoughts?

Beyond that it seems to be running around a 9 second 1/8th, so we need to find about a second and a half somewhere over the winter.

 

been done b4 treated with belt dressing or traction compound the day b4 results were marginal

 

I'm certainly no expert, but your "footprint" will change with air pressure adjustments. I can't tell you which way to go, but I know it's not always the direction you think.

 

Lock out the governor and start in second then shift to drive manual.
RacerX has a recipe to soften those tires.

 

Today we noticed that we weren't getting the tires dried out completely, so we started driving around the water box and it seemed to hook up better, not great but better. The track seemed stickier today. The car lost some power all day and we didn't figure out the cause just wasn't pulling as hard, lost nearely a second and 10 mph. The trans is frustrating, at this point i think we will see if the builder will make good on his moneyback guarantee, I hear there is a guy up in Spokane Wa that specializes in TH350's, think we will try his instead. But even with the teething issues we had an absolute blast, met a ton of cool folks, enjoyed answering all of the curious questions about the whats and whys we built this thing. And had good weather at a super fun track. If you want a layed back atmosphere Walla Walla is perfect, we didn't meet a single a-hole all weekend and we made a bunch of stupid mistakes not knowing what we were doing and they were all super patient with us.

 

Sounds like drag racing to me.
Just thinking all the quality work you have done one this car that at TH/350 should be a cake walk.

 

Saltflats gave you some good advice which I recommend or a power glide. You are loosing a lot some where as a car such as you have should be running some low sevens at 100 mph or so. These are the numbers we were running 50 yrs. ago with a altered ( chassis like yours) 23 T body on it. Wish I had a better photo.

 

christmastree is right regarding the Powerglide. With those little tires you don't need the torque multiplication of the 3 speed's low gear--that 2.52 gear is just too much. As light as the car is the 1.76 in the 'glide should launch the car without any issues if the converter is in the ball park stall wise.

Roo

 

I would probably use a Glide, however one of the cars I built for (Jerry Stauffer) using a 300 Ford and a C-4, has run 11.04 with Hurst Slicks.

 

Thinking about this transmission, it would not shift manually at wide open throttle, I never did try shifting it manually not at wide open throttle. It would shift in Drive provided I let off the gas, that would raise the vacuum signal and make it shift. Is it possible that maybe I just need two make some changes to the governor for a lower RPM? This transmission may have been out of something with a V8 in which case you probably would not want it to shift lower than 5000 RPM at wide open throttle. If the valve body is not a full manual valve body will it still shift up when you are manually shifting at wide open throttle?

I hear what you are saying, and I know you have a ton of experience with this, are you considering the power level here? I'm thinking with the carbs ironed out and a good tune we may have 225-250 hp.

 

If throttle pressure is still higher than govern pressure it will not shift.

 

If that is right, thats probably our issue.