Richard Cope Posted August 8, 2018 Report Share Posted August 8, 2018 Getting parts together to install new rear leaf springs on my 39 Plymouth business coupe. Purchased new springs from Eaton Detroit Spring, The current springs were modified somewhere along the line and the rear of the car is sitting low. The four "U" bolts that fasten the springs to the differential are unique in that the curved surface is flat. The ones on the car aren't that great, have been looking for NOS to replace, however have only been able to locate used ones, whiting to see what they are like. Does anyone know a source for purchasing these bolts or perhaps a later model that has a flat curved surface that could be used. Appreciate our your help. Regards Richard C. Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 8, 2018 Report Share Posted August 8, 2018 These special U bolts were also used on my 1940 Oz Dodge which is 40 Plymouth based , they may have been used for a while, the 41 plymouth I had used the normal style bolt tho and when I installed 2" blocks we just used longer U bolts..the 41 Plymouth had been "restored" so I can't be sure whether the special U bolts would have been there originally..............they are a neat style U bolt however I'd doubt whether you'd find NOS ones but they maybe out there............andyd Quote Link to comment Share on other sites More sharing options...
Richard Cope Posted August 9, 2018 Author Report Share Posted August 9, 2018 Thank you Andy. Are there any thoughts if the flat curve on the U bolt is critical. If not, can probably locate new bolts for a 1.75 in wide spring without the flat spot.. Another possibility, believe the Ford Ranger used U bolts with a flat curve, however don't know the width and length dimeniosns Regards, Rich Quote Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 9, 2018 Report Share Posted August 9, 2018 Richard I would have thought that the flat area was done to help place more tension on the U bolt but thats just a thoughty......lol.......I may have some somewhere around however as I'm in Oz sending them to you would be prohibitively expensive.............I'll let you know if I turn any up tho'...........any U bolts would work so long as they follow the axle curvature and fit thru the spring pad/shock mount ................andyd Quote Link to comment Share on other sites More sharing options...
Richard Cope Posted August 9, 2018 Author Report Share Posted August 9, 2018 Thanks Andy, I came across some used ones, was concerned for the information that I have found recommends always using new bolts when replacing springs. Before I start project will try to match the used ones with current ones of same size. Thanks for your help, Regards, Rich Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 9, 2018 Report Share Posted August 9, 2018 I suppose that in general it would be good to use new U bolts when replacing the springs but 1st you'd have to find new U bolts and that may not be doable.........I'd clean up the threads as much as possible and use what you have..........andyd Quote Link to comment Share on other sites More sharing options...
bobd1976 Posted August 9, 2018 Report Share Posted August 9, 2018 (edited) Round ones will be just fine. I always go to a local truck spring shop with my old u bolts and they make new ones as I wait. 30 minutes tops. They send me home with new nuts and washers. Edited August 9, 2018 by bobd1976 Quote Link to comment Share on other sites More sharing options...
Richard Cope Posted August 10, 2018 Author Report Share Posted August 10, 2018 Thank everyone for all of your help, I purchased a used U bolt and waiting to receive it. Eaton Springs indicated that they can make new bolts if I provide dimensions. I've gotten rough dimensions from those on the car, however will hold off on sending until receive the used one, will be easier to measure. The new bolts will be round and not have the flat surface on the curve, however they indicated that all replacement bolts are such and should not be a problem. Haven't received the parts yet, however at this time Eaton Detroit Springs seems to very knowledgeable and easy to work with. Regards, Rich Quote Link to comment Share on other sites More sharing options...
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