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Fri Jun 15, 2012 6:13 pm

I have a Meyers Manx with a bus swing arm trans with gear reduction boxes, link pin front end , and 1776 motor. I am looking for some input on tire size, type and rim size for street driving, fire roading, beach and off rode parks. Can you give me some suggestions on what size, type where to buy.
thanks Mrjanitor

Fri Jun 15, 2012 6:26 pm

The Reduction Gear Box (RGB) gives a real low speed ability for your buggy. Usually, a person puts a tall, big tire on the rear and it bogs down the engine, but with the RGB's, it will not hardly phase it.

My suggestion is a 31 10.50 15 rear tire and a 215 75 15 for the front. 7 inch wide rear rims and 4.5 to 5.5 inch wide front rims.

Depending on how much traction you need for mud would dictate what type of tread for the rear tires. A BF Goodrich AT makes a good all around tire for the rear, sand, mud and mild rocks.

Front tire I would go with a medium mud/snow type of street tread design.

Fri Jun 15, 2012 6:43 pm

Welcome to the Samba and having a dune buggy.
With the Bus reduction transaxle there are several different gear ratios that were available in the reduction boxes.
Not knowing what you have for a final gear ratio at the wheels would be hard to recommend what size tire to use.
A 31in tall tire is common with using the Bus trans, but depending on what inside the trans for gearing, a 31in may not be tall enough to travel at highway speeds without turning too many RPMs.
If traveling on the highways you really don't want to be limited to less than 60mph with the engine turning 4,000rpms.
I am using 33in BFG KM2 on my buggy using a later model IRS Bus trans and at 70mph the engine is at 3,000rpms.
You can find close to what your gear ratio is by turning the engine over with trans in 4th gear and watching the wheel turn one revolution then counting how many times the engine turn over.

Fri Jun 15, 2012 6:45 pm

Thanks for the info I will start shopping around

Fri Jun 15, 2012 6:50 pm

Joseph
I am in landpark. neighbors. i am sure it is a stock trans and stock gear reduction boxes. But i don't know what year the trans is at this point.
thanks
Mrjanitor

Fri Jun 15, 2012 7:14 pm

Yes we are close, I live in the county with both Citrus Heights and Folsom trying to steal more land for their cityhoods.
Last night I was at the car show inside the Sacramento Zoo with the NorCal Baja's group. Did you make it to the show?

Fri Jun 15, 2012 7:38 pm

One way to get an idea what ratio is in the RGB tranny is to look at two features of the trans.

1. Does the tranny split down the middle? The split case trans was used up to 1960 and had a complete left and right side that splits apart just like the VW engine. Bolts can be seen on the bottom and top indicating if it is a split case.

2. Is it a large nut or a small nut RGB? This refers to the castle nut that holds the brake drum on the axle stub on the outside. It is a small nut RGB if the castle nut is 36 mm. It is a large nut if the castle nut is 46 mm. The small nut was used on all RGB's through mid year '63. The large nut was used from Mid '63 through '67.

Ratios.
The small nut, split case had a 4.37:1 ring and pinion with 1.36 reduction gears. This gives a final drive of 5.94:1 The small nut, non-split case tranny had a 4.37 ring gear and the 1.36 reduction gears also.

The large nut RGB had either a 4.37 or a 4.12 ring and pinion with a 1.26 reduction ratio. The 4.12 and 1.26 gives a final drive ratio of 5.19:1. The 4.37 and 1.26 gives a final drive ratio of 5.51:1.

To find out the exact ratio of the RGB, take out the top 17 mm allen plug on the RGB box, mark a tooth on the top gear, spin the brake drum and count the teeth. 18 Teeth you have a 1.36 reduction. 19 teeth you have a 1.26 reduction.

The reason I suggested a 31 inch tall tire is it will clear the body and spring plate caps/torsion bar ends with stock suspension. A 32 inch tall tire may not clear stock components.

Fri Jun 15, 2012 8:30 pm

I have a issue with 31 inch tires. It leaves no space between the tire and the bar that adjust the higth of the buggy. Im running 30x15x10.5. Im going to replace that with 30x9.5x15. That will also help with mud etc.... I also have gear boxes and bus trans axle. If you can go with a taller tire than i would do it. You can effect the top end. Right now if im doing 60 in my buggy i run to many RPM and will suck all the oil up from the bottom. Also it asks less of you motor to turn those big tires(I have a 2010 stroker).

Fri Jun 15, 2012 11:13 pm

The are 4 different ratios that I know of for the early small nut reduction boxes. 1.26, 1.38, 1.40,and 1.68. The 1.68 are rare and are referred to as the "Alpine" because of the low ratio. Only one ratio that I have seen for the later large nut reduction box is the 1.26.
Every full syncro trans I been into has from the factory the 4.125 R&P with the reduction boxes. Only ones I seen using something else has been done after it left the factory.
As for clearance between torsion bar and tire, use the 61-68 torsion bars and caps since they are the shortest and clear 33in tires without any problems. I used 33in tires on my 1962 Baja way back in the 1970s without any clearance issue between body or torsions. And this was with a trans I built using the 4.125 R&P with 1.38 reduction boxes. It cruised very easily at 70mph using a 1911cc Type IV engine. Same gear ratios with my Dad's 61 Baja. We both use our own home made NoHop setup that we built our self in the garage.
And as for tire tread patterns, I used both the BFG All Terrains and the KM2 and prefer the more open pattern the KM2 has for directional stability in soft terrain. There is nothing wrong with All Terrain I have use them in sand, dirt and for street use as they are a little more quiet when traveling on pavement.
You can use any brand of tire you want, I prefer the BFG as they have a strong sidewall.
Wheel size I am using with the 33-10.50R15 is 6.5in between beads. It works fine for me. Have tried using a 6in wide wheel with the 10.50in tire cross section and had more squrim on the highway then I felt comfortable with.
The reason you want to use as narrow of rim as possible is to protect lip of the rim from getting bent from hitting rocks or other things.

Sat Jun 16, 2012 8:29 am

Thanks to everyone for all the info I will do some research to see what I have and will start looking for tires. I have 5.5 aluminum wheels for the front and will be looking for some 6.5 to 7 inchers for the rear. Thanks again for everyones help.
Joseph
I have been working a lot of crazy hours and missed the show at the zoo. I just sold my Baja to put the money into my manx. See ya around
Mrjanitor