| Author | Message | ||
| Roy Strickland
Rating: N/A |
Hey everyone, I stumbled on to what I think might be a small gold mine for me. I got the turdy mosquito control oil slick GMC RTS w/ 8v71 and the HIGHLY SOUGHT AFTER 5.36 rear end or whatever the slowest one is... LOL HOWEVER, I run across a fellow the other day who has a 1982 Grumman Flexible (Flxible) or whatever it is. It has a 6v92T. He sold his transmission, but he still has his rear end. He said it would only run about 57 too. He told me he'd sell me the rear end from it for about $500. If memory serves correctly, I seem to remember some talk about the transmissions (In those Flxibles) final drive ratio being like .825/1 or .850/1 or something vs. mine 1.0/1 or whatever it is. LOL I just would like to ask the experts how sure they are that the rear end in that thing is the 4.10. I need a 4.10. :-) What are the chances of that? Ole' guy doesn't know what in the world it is. (Neither do I) Obviously I'm not gonna get it if its close to mine, but the 4.56 or whatever falls between mine and the 4.10 would be an improvement. Any advise on the matter? What are the odds that it is the 4.10? I thought for sure I remember reading about them supposedly being 4.10s in the Flxible. Is that correct? Any insight on this matter would be GREATLY appreciated. I might keep the ole' clunker yet. RS '78 GMC RTS (8v71) 5.39 (or whatever.. I can't ever remember) w/ built in mosquito deterrent and automatic oil slick dispenser. :-) Hey you guys will crack up... I was backing in the driveway the other night and ran one set of wheels in the ditch... It cost me $375 to get winched forward about a foot and a half or so. Life really is dandy. :-) I did some hard core farming... ole' tires were just a gettin' it.. but I wasn't going nowhere. | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Rating: N/A |
Roy most RTS V730 and V731 are .88 overdrives there were some underdrive units made to mate with 6v71 engines - but they are rare Gruman Flx's tended to have a lot of 4.55 4.555 = (9 tooth pinion / 41 tooth ring) stamped at the end of the pumpkin (chuck) york shaft will be 9/41 or 41/9 (I forgot??) much fewer Flx's had the 4.10 rears 4.10 = 10 tooth pinion / 41 tooth ring) with 10/41 or 41/10 stamped on the shaft I don't think You see the stamp with the u joint yoke on Flx chunk do not have the mounting hole drilled in the cast boss for mounting the RTS emergency brake - Flx's had wheel emergency brakes - RTS's have drive shaft emergency brakes But - I'm told that all you need to do it drill a nice big hole in the cast boss to mount the RTS e-brake - that will save you $700 rear end gear set up/lash adjustment charge (They used to call it inking the gears) - If you can jack up one side of the FLX and release the e-brake - you can turn the wheel and count the # times the drive shaft turns (divide by 2 because of the differential effect of doubling the ratio when one wheel is staionary) - that will be the rear end ration - one wheel turn = 9 drive shaft turns = 4.55 4.10 will get you approx 78 mph at 2150 rpms 4.55 will get you approx 70 mph at 2150 rpms Pete RTS/Daytona | ||
| David Hartley (Drdave)
Rating: N/A |
Roy, The standard FLX ratio was 4.56, The rare one might have been a 4.10 but the chances you found one is pretty slim. The tranny ratios are the same so no banana there either. Granted the 4.56 is much better than your 5.31, 5.36 ( 54 to 57 mph ) or 5.13 which on a good day might get you to 62 mph it's not worth the time, money and aggravation to change out. Just face it, Your engine is probably pretty well worn out or it wouldn't smoke that bad and belch toxic waste. So being able to push it to max rpm and get the power needed to push your heavy beast to a respectable speed are also pretty slim. What you have there is a farm implement. The guy with the Flx will either end up with a redneck yard ornament or end up having to pay someone to haul it to the dump. there might be some salvagable parts but few if any that would help you. If you had/have the time and money and the RTS is in good structural shape you could invest in reworking it to a newer or rebuilt engine and rear-end gear change. The gear set costs between $2,000 and $3,500 to replace and setup since they are considered rare at best. The rockwell chunk with the right gearing may be out there but it won't be cheap. You might try Nimco Bus? There is no easy answer. It would be a wild guess that when you got stuck the chassis bottomed out and you started spinning a tire? Been there done that. I found a dirty trick. Go into the back of the bus with 2 7/16 wrenches and a small bungee cord. Lift out the floor cover between the wheelwells. Take the bolt out of the rear leveler and pull up on the swing arm and bungee it up, This adds air to the rear suspension ( all the way up. ) and gets the chassis off the ground. Then a little shovel work, and a bottle jack can be used to get some plywood or boards under the stuck side. If you didn't dig in too deep you might be able to just clear the mounds from around the tires and drive out with a little rocking action. I sank my RTS 3 times in ball bearing sand in my back yard and found it was cheaper to be patient and do a little shovel and cheat work to get it out. It was so buried that we buried a tow truck trying to pull it out. The airbag trick worked the first time. Sorry to sound so tough on your situation but I have been there so many times that it ceased being fun. Dave.... | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Pete, There is only one bevel gear ratio in ALL V730s and V731s. The 0.875 ratio bevel gear set is the only one, the rumor of an other 'underdrive' ratio while widespread is false. It may be this 'urban legend' is based on the VS2 transmissions where there were two versions, one with underdrive and one with overdrive. But nonetheless there are no,and there never have been, underdrive v730s or v731s Regards Jerry 4107 1120 | ||
| Geoff (Geoff)
Rating: N/A |
There is somebody around the bus boards that bought a V730 that had one of the urban legend lower gear ratios-- he calculated his engine rpm and tire rotations and found he had something like a 1.04 ratio transmission. I can't remember who the gentleman is, but this issue has come up from time to time in the last 8 years and a few people seem to have actual experience that indicates the existence of the underdrive V730. But then one guy went to an Allison dealer and tried to find the part number for the underdrive final drive and they couldn't come up with it-- he wrote me a very nasty personal email telling me I was spreading false rumors by saying there was an underdrive V730, but when he posted the same thoughts on the bus boards a few people stepped up and told him they had or had had one of the underdrive units. Somebody was supposted to find the part number but I don't remember what became of it. So maybe it is an urban legend, maybe it isn't. Getting back to the original question that started this thread, the rear end in the Flx is no better than what Roy has now. Some Flx Grummans had the 4:56 and possibly the 4:10, but my experience with these buses is that they had the higher ratio rear ends because they were running the Cummins L10 engines and Voith transmissions that only had a 1:1 final drive ratio. --Geoff '82 RTS AZ | ||
| john w. roan (Chessie4905)
Rating: N/A |
As I don't know where you live, I don't know if this will help, but you can check with NIMCO in New Jersey. They part out Many, Many RTS's. They may be able to get you a takeout 4:10 rear. and ship it if necessary.They have quite an operation there, especially how they separate steel, rubber,wood,etc. and aluminum.They dismantle older RTS's every day.Great source of many take off parts | ||
| Gary Carter Rating: N/A |
There was an underdrive v730 and somewhere in one of my old computers I have the build numbers and also the part number for the bevel gear. | ||
| john w. roan (Chessie4905)
Rating: N/A |
The only way to see whether there was an underdrive would be to find one of the first allison V-730 parts book to verify any existence. My parts book is from mid to late 80's and the only two variations are with or without pto takeoff.Since the VS series had two ratios and the bevel gears are somewhat similar; maybe they had both ratios early on, but since 4:10 is the lowest axle ratio, I dont know what good it would do anyone. What we need is a bevel gear ratio the same as the standard trans, or maybe just a little bit better so we could blow FF's doors off in his sports car of coaches. Oh wait, I guess that would be door!  What we really would like is to have someone have China make some oem quality 3:70 gear sets. | ||
| FAST FRED Rating: N/A |
Any time you want to race , we will put 10 gal of fuel in your coach and 10 in mine. The race will be 100 miles exactally up the Fl Turnpike.. With no pit stop it will be easy to get there first , even at 1950RPM and 73mph top end. FAST FRED | ||
| john w. roan (Chessie4905)
Rating: N/A |
Be interesting to see that against a 4104 6-71 with a hydrashift. | ||
| David Evans (Dmd)
Rating: N/A |
challenge race at the next new years rally! 5 gal outboard tank, most laps around the horse track |