1967 Dana 18 Gear Ratio

Hello,

Can anyone tell me what a 1967 Dana 18 transfercase came with for a low ratio? I'm not sure if it's 1.97 or 2.43 ? If anyone has a chart or info detailing the ratio's dependent on year it would be appreciated.

I'm trying to calculate the various ratio's per gear in low range. I'm running Dana 60's with 36" tires and a 4.10 ratio. If anyone has a recommendation for an axle gear ratio which will improve street performance and not overgear the low range, I'd love to hear from you. Currently the low range performance is great but taking off from a stop in High range sucks and 4th gear is unusable(overgeared).

Also, I do know this is a 67 case, when looking at used cases is there a way to tell the year by the casting numbers ?

Thanks for any help....

Extreem

 

With 36" tires, I would think you should have 4.56-4.88 gears maybe even 5.13. the reason you go to lower gears with larger tires is to regain performance, otherwise you have the motor running out of it's power band.

 

A 67 CJ5 dana 18 should have 2.46:1 low range..

Heres a link to a page of info about the dana 18's history:

http://www.jeeptech.com/xfer/d18.html

The easiest way to ID older d18's vs newer d18's is by the rear input hole size. Newer ones have 4" diameter, older ones have 3" diameter.. Also another way is by looking at the intermediate shaft size.. it can be seen by looking at the outside of the housing, since it is installed flush from the outside of the case.

For regearing the axles.. I'd go with 4.88's. Since our cj5's came from the factory that way.. low range isn't "overgeared". High range in 4th gear is suitable for the speeds we travel on the hwy's anyway. With your bigger tires.. you will have lower rpms going down the hwy comparing to stock cj5's.

 

Thanks for all the replies.....I'm happy with the performance in low range but in high range on the street it's tough getting rolling in 1st gear and the 4th gear of the tranny is pretty much unusable since it's an overdrive gear. I'm thinking 5.13's but I can't make up my mind just yet....

 

You're 4th gear should not be an overdrive if you have a granny geared 1st, 4th should be 1:1. Your 36" tires are whats killing your gears. What axle ratio do you actually have. With that size tires you would need at least 4.88's. If you actually have a granny geared 1st you shouldn't have problem getting rolling even with 36" tires, I'd say you have the t18 with the 4.0? 1st gear not the 6.32 1st gear.

 

I've got 4.10's in my Jimmy with a .030 327, an SM465 with an NP205 and 4.10 gears. I personally find the 4.10's to be ideal. I have the same tires and turn 2500 rpm at 65 mph in a 4500# vehicle.

If you take the 6.32 first gear and multilply by the 2.46 low range in the t-case and then times the 4.10 ratio, you wind up with a 63:1 crawl ratio. My NP 205 has only a 1.95 low range in comparison.

If you need more power, I'd think about more motor. A 350 would give you a ton more power in the same package. and isn't any more expensive than a re-gear of both ends.

My M.38A1 with its 2.97 first gear and 2.46 t-case and 5.38's only has a 39:1 overall crawl ratio.

 

Mcruff,

You're right. Verified today the toploader 4 sp does not have a granny low first. From what I'm able to gather, it was a car tranny. Looks like an SM-465 is in the works. I'll convert from that and keep the 4:10's for now...

Extreem

 

The motor is strong as hell, verified today the tranny doesn't have a granny low. Looks like it's time for the SM 465....thanks for the reply.

Extreem