Speedometer recalibration?

[jatonka]

I had to do some checking before I could post on this topic. The M35 deuce comes with a .187 speedo drive adaptor. To use 11.00 x 20 tires they install a .200 drive adaptor. I have had .212 drive adaptors, I installed one on my 1st JATonka 4x4 truck. It (.212) gives a 50mph reading while I am doing 55mph actually. This is with 14.00R 20 Michelins on the truck. The .200 adaptor should be about right for 11.00x 20s. I actually cleaned off these adaptors today to read what's marked on them. I have an adaptor on a transfer case PTO that looks the same as a speedo adaptor but it has no numbers stamped on it. It drove a governor on a gull wing shop set #2. I don't know where the supply of any of these adaptors is, maybe someone else can offer some ideas. JT

 

[vtach]

I have seen some deuces with 11.00x20 tire from the Gov't, surely they have an adaptor intalled to keep correct speed. I know they are particular about speeding and I have never seen any kind of sticker for speed correction.

 

[cranetruck]

I got my .200 ratio adapter from Clark Truck Parts in WV about ten years ago, they may still have some... A list member also sent me one from Norway from an M621 deuce. Sold the extra unit to our late Bruce Kalin....
According to the TM parts listing, the NSN does reflect the ratio (see above post (right click and open in new window for hi res image). The part should be marked with the ratio...probably not with the NSN.

 

[kurtkds]

I just pulled that adapter off my deuce for the 11.00's since I'm running 9.00's.

If anybody is interested....

I did like that having that adapter on the truck since it gave the impression that I could do well over 65mph!!!

For clarification the adapter I took off is the NSN2520-00-404-3098

 

[vtach]

PM sent.

 

[crazydad25]

slightly off but same subject

I have a slightly different issue regarding a part I took off one of the old blazer style cut-v's I got a NP 208 transfer case off one to replace my broken NP 241 on my '89 blazer the 208 had one of the stewart warner adapter things with a number of 777FI.3000BH can anyone tell me what ratio it is and why it is needed, I am thinking it might be due to a slight lift on the cut-v which I am going to swap over the suspension from the same vehicle. the tires on my vehicle are the same size as the cut-v a stock tire size of 31x10.50 15 any help would be awesomely appreciated, by the way I don't own any military vehicles but drive them every day I am still active duty MOS 92F but work with 63B everyday