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View Full Version : rear ratio w/ richmond 6 speed



Colin Frolick
02-08-2006, 08:32 PM
howdy all. i'm about to fill a new 9" rear with gears and would appreciate some input on a ratio. the car is a 65 tempest with a 455 and the aforementioned richmond 6 speed. i looked through the forum and alot of people were asking about rear ratios with a t56 but this trans has a little different gearset, specifically the ratios are 3.27/2.13/1.57/1.23/1.00/0.76 the car had a 3.23 stock rear and 27" tires; 3000 rpm in 6th was 100 mph.

I'm thinking of dropping to a 3.00 rear, since 6th could be a little taller and 1st was too low. this trans is a little hurt though, which brings up the opportunity to freshen it up and change some gear ratios if needed. i know they sell it with 3.01 and 2.77 1st, and up to .62 6th, and there's a ton of other possibilities. i'm not into drag racing so i don't need a real low 1st gear. the next 455 should have 600hp, so i'd also prefer a numerically lower 1st for strength. i know this trans is probably not as strong as a t56, but it's what i have, and i do like the close ratios and 1:1 5th. and it sounds good and fits easily behind a pontiac v-8.

so, ideally, what combinations of rear and transmission ratios could perform well?

thanks

USAZR1
02-14-2006, 11:27 AM
Just me but I think I would leave the 3.23's in the car and try them out,first.

Colin Frolick
02-15-2006, 11:40 AM
the old rear end can't go back in... the car has truckarms now.

thanks for the input

USAZR1
02-15-2006, 03:00 PM
A .76 sixth gear,3.00 rear cog,and a 27" rear tire would have the engine turning around 2,000rpm at 70mph,,or in that neighborhood.
I'm running a Viper T56 (.50 sixth) and with a 4.11 rear cog & 26" rear tires,that's what I'm seeing.

David Pozzi
02-15-2006, 10:13 PM
What will your max redline be?
We put 3.08's behind our Richmond 5 speed, it yields the same ratio in the first 4 gears as a close ratio muncie with 4:10's. We drove it at an open track event and it's nice, don't have to shift to 5th until around 120mph. Sixth gear would drop cruse rpm's more and improve mileage over the 5 speed.
Her is my 6 speed ratio chart using 3.08 gears. I have a Richmond six speed I'm planning on installing in my 67 Camaro. Note the rpm's on the left line up with the little X's on the chart, the horizontal grid lines on the chart are 500 rpm's in-between.

https://static1.pt-content.com/images/pt/2006/02/Richmond206202520tire-1.jpg

jeffandre
02-16-2006, 06:19 AM
What will your max redline be?
We put 3.08's behind our Richmond 5 speed, it yields the same ratio in the first 4 gears as a close ratio muncie with 4:10's. We drove it at an open track event and it's nice, don't have to shift to 5th until around 120mph. Sixth gear would drop cruse rpm's more and improve mileage over the 5 speed.
Her is my 6 speed ratio chart using 3.08 gears. I have a Richmond six speed I'm planning on installing in my 67 Camaro. Note the rpm's on the left line up with the little X's on the chart, the horizontal grid lines on the chart are 500 rpm's in-between.

https://static1.pt-content.com/images/noimg.gif

David,
What tire diameter do you have? What do you think the chart would look like with 27.4" tires? I have 3.73's right now with a Richmond 5 with the same gear ratios your 6 has (but no 6th). Thanks,

David Pozzi
02-16-2006, 10:20 PM
I used a 25" tall tire.
I have a spreadsheet you can play with here: http://www.pozziracing.com/richmond_transmission_swap.htm
scroll to the bottom, then look for the spreadsheet link and right click and save.
I think that version has a couple of muncie trannys and a richmond 5 speed in it. I don't remember if it does charts like above. I do mine on a Mac but saved a PC compatable version for my web page that should work in MS works or Excel.

I have a six speed version now which I may post there in a fiew days.

The Richmond trannys are nice in that the rpm drop in each gear is less, and the driveshaft speed is lower.

David Pozzi
02-17-2006, 10:28 PM
I updated my chart, I had the legend for RPM and MPH reversed.

andrewb70
02-18-2006, 08:16 AM
David,

I would love to play with that spreadsheet, but when I download it it seems to be corrupt.

Help!

Andrew

David Pozzi
02-18-2006, 02:24 PM
Andrew,
often the name extension get's lost.
Try putting an Excel suffex on it, ".xls"

I updated and corrected the file, it downloads to my Windows Laptop now. Just click on the link, and a dialog box should recognize it as an Excel file and ask you if you want to download it. If not, right click on it and save it.

There are no charts, they didn't get translated, If I get time, I'll add them to the windows version and upload that.

andrewb70
02-19-2006, 06:52 AM
I was trying to do the graphs but didn't have much luck. What kind of graphs were they?

Andrew

David Pozzi
02-19-2006, 11:56 AM
https://static1.pt-content.com/images/pt/2006/02/Richmond206202520tire-1.jpg
I originally did the spreadsheet on my Mac, I set up charts like I posted above only I made one for each transmission, so I had a numerical spreadsheet with calculated speeds at rpm's, then made a chart for each that was auto updating to show the results. I like graphs for gearing choices.

I print out the graph, then draw a vertical line down from first gear redline to second gear, this shows me the rpm's I'll be at after I shift. I do this for each gear, this gives me the rpm drop for each shift. On the Lola Hewland gearbox, I can change each ratio to whatever I want, so there is a lot of flexability. I usually use more rpm drop in the lower gears, then space them closer at high speeds. Low speeds don't have the aero resistance, so there is more power available to accelerate the car.

I'll have to add the charts on the my laptop, then post it on my web page. But I dont know Excel as well as my Mac spreadsheet, - Clarisworks.

You could do a graph like this manually pretty easy, just calc a high rpm and low rpm speed for each gear, you don't need any of the numbers at other rpm's, just mark the high and low, then connect the dots with a straight line, do this for each gear.